Date: Tue, 23 Jan 1996 07:59:57 -0600 From: tims@enet.net (Tim Sullivan) Subject: Anttenna Installation Info Just thought I would pass on some useful information from a good friend on mine who now works for a company that builds TV Stations. He's a real radio guru. Tim Asks: >> Speak of the devil I'm just about to install my VOR anttenna this week. Two >> copper strips 20.8 inches each with a rg 58 coax connected and three ferroids >> around the coax just before the strips. Ther are to be in a "V" >> configuration under the front seat. Any particular angle of the "V"? It >> look like 90 degrees in the plans but does not specify (weak). I'm finding The Guru replies: >The angle is not critical - use anything from 0 (horizontal) to 90 degrees, >as the space available dictates. Electrically, the angle merely changes the >impedence of the antenna from about 30 ohms up to 90 ohms. Since this is >a receive-only antenna, actual impedence achieved is not critical. > >For least distortion of the antenna pattern, which will be sortof circular, >lead the feedline straight away from the center of the antenna for at least >1/4 wavelength (the length of one of the leads of the antenna) past the >end of the antenna. > > > \ / > \ / > \ / > \ / > \ / > \ / > \ / > + > ^ | > | * <- bead > 21 inches | straight before any turns (if possible) > | | > v | > | > > > > or > > > + > /|\ > / * \ > / | \ > / | \ > / | \ > / | \ > / | \ > | > ^ | > | | > 21 inches | straight before any turns (if possible) > | | > v | > | > >Winglet comm antennas - this will work without a ground plan (it provides >it's own): > >Take a piece of RG-8 Coax (Decent stuff, *not* Radio Shack!) > >Strip about 22 inches of the outer insulation, exposing the copper braid >underneath: > > >Outer insualtion -> ---------------------___________________ <---outer braid > > ___________________ > --------------------- > > >Then, push the outer braid back over the outer insulation (to the left) >exposing the insulated center conductor. > > --------------------+ >Outer insualtion -> ---------------------_| > ------------------- <-Inner Conductor > _------------------- > --------------------- | > --------------------+ > >Leave the insulation on the inner conductor - it won't hurt. At the >end of the exposed braid, place two or three of those ferrites. The >ferrites keep the RF radiated from the antenna from flowing back up the >outer shell of the coax (and into your radios). Put a connector on the coax >extending from the left end to mate to RG-58 (or whatever you're running). > >Presto - a coaxially fed dipole! The exposed center conductor should be the >same length as the exposed braid, about 22". It shouldn't need much tuning, >a VSWR bridge will verify that the antenna is tuned at the right frequency, >but that's a long way off. > >Hang it vertically from in the leading edge of the winglets, one on each >side. Bury it in the foam. Test a small piece of coax with some resin to >see if the resin is going to attack the plastic. If so, slide a long piece >of heatshrink tubing over the whole thing first. > >Before closing out the section, you should check the tuning and range of the >antenna. You can probably borrow someone's handheld and vswr bridge to >verify. Once it's closed, I doubt you want to hack the skin to fix it. > >Bury the GPS antenna in the nose. It'll work, as the glass is transparent >to the RF. Try one out and see! (Buy Marie one of the cheap hiking ones >to test with...) > >Same with the transponder spike. I've seen a number of gliders with the >spike down near the pilot's feet. They use the regular a/c transponder >antenna, mounted on a circular disk about the same radius as the length of >the antenna for a ground plane. Mount it vertical. Done. Tim Sullivan (tims@enet.net) Phoenix, AZ | * | Cozy MK IV Builder #470 |-----(/)-----| The journey begins 8/10/95 / \ Current Status: Ch 7 o o Date: Tue, 23 Jan 1996 13:48:52 -0500 From: Nigel.Field@HQPSB.SSC.ssc-asc.x400.gc.ca (Field, Nigel (1416)) Subject: Antennas While on the subject of antennas here is what I did for VHF comm. A thin antenna will exhibit high Q (efficiency) on its resonant frequency and start to reflect power back to the transmitter (SWR) as the frequency varies from resonance, in other words it will exhibit a very narrow bandwidth. A half wave (resonant) center fed dipole in free space can be calculated as follows: L (in feet)= 492/Frequency (in megahertz). Bandwidth is primarily a function of aspect ratio much like a wing, so the wider the elements the less reflected power when off resonance, with a slight loss of efficiency at resonance. Thats a bit of an oversimplification but basically true. Since we go from 118 to 136 Mhz we need bandwidth. The .25 inch copper foil strip gives narrow bandwidth (high Q), its hard to install without damage and bond to the skin, and not readily available in my shop. For a cheap effective alternative use four parallel pieces of copper hook up wire about 20 gauge or so spaced .5 inch apart. Cut slits in the foam with a knife and straight edge and push the wire into the slits until just below the surface. At the center feed point bring the 4 strands of each side(element) together and solder to the co-ax center conductor for one side and the braid to the other sides 4 strands. Add the ferrite chokes and skin your winglet. The RF will see this as a 2 inch wide element, with lots of bandwidth thus lower SWR over the comm band. For VOR you could use the same approach but I have GPS and my handheld available for VOR back up although never needed it. Happy communicating, Nigel Field Date: Tue, 23 Jan 1996 17:10:04 -0500 From: PBurkha238@aol.com Subject: Re: Anttenna Installation Info Just a note on the transponder antenna. I like the transponder antenna that Bob Archer sells. It fits in the end of the strake and has no exposed "pole" as there is in the standard transponder antenna (which of course adds in asthetic hanger speed). It costs 50.00 from Bob direct, or 78.00 froms spruce(plus shipping). The only downside I can see is that the length of the cable is extended considerably. If any of you subscribe to Central States there was an article dealing with antennas from Bob Archer . There are cable upgrades you can install which can offset increased length in cable. I believe the antenna will work just fine the way in it though. Paul Burkhardt From: Marc J. Zeitlin Subject: Re: Anttenna Installation Info (fwd) Date: Tue, 23 Jan 96 20:23:47 EST Paul Burkhardt writes: >Just a note on the transponder antenna. I like the transponder antenna that >Bob Archer sells. It fits in the end of the strake and has no exposed "pole" >as there is in the standard transponder antenna (which of course adds in >asthetic hanger speed). It costs 50.00 from Bob direct,....... While I'm sure that this antenna will work fine, RST published some data on making your own transponder antenna from parts that couldn't cost more than $5, and that's if you bought everything new. The transponder antenna is no more affected by the glass and epoxy than any of the other antenna's is, so it can go inside the nose (pointing down) with the GPS antenna (pointing up). Very short cable run. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Wed, 24 Jan 1996 07:28:34 -0600 From: timothy j busch Subject: Re: Antenna Installation >Just a note on the transponder antenna. I like the transponder antenna that >Bob Archer sells. It fits in the end of the strake and has no exposed "pole" >as there is in the standard transponder antenna (which of course adds in >asthetic hanger speed). It costs 50.00 from Bob direct,....... >While I'm sure that this antenna will work fine, RST published some data >on making your own transponder antenna from parts that couldn't cost >more than $5, and that's if you bought everything new. The transponder >antenna is no more affected by the glass and epoxy than any of the other >antenna's is, so it can go inside the nose (pointing down) with the GPS >antenna (pointing up). Very short cable run. I vote for the $5 special. Antennas are one thing that anyone can do easily as well as a manufacturer. Plus the further away you can get it from human flesh, the better. The transponder is a microwave transmitter with high power level that can cook our little pink bodies as we sit, so take great care in its placement and make sure you have a good ground screen built in. That is one place where the spam canners have a big advantage: built in RF shielding. Tim busch@cacd.rockwell.com "My opinions are just that...mine" From: Marc J. Zeitlin Subject: Re: Antenna Installation (fwd) Date: Wed, 24 Jan 96 9:05:46 EST Tim Busch writes: >Plus the further away you can get it from human flesh, the better. >The transponder is a microwave transmitter with high power level >that can cook our little pink bodies as we sit, so take great care >in its placement and make sure you have a good ground screen built in. Ground screen yes, high power levels, no. While the transponder IS a microwave transmitter, the frequencies are NOT the same as those in an oven, and the power levels (on the average) are so low as to be totally safe. Even at the maximum power levels (I believe when being interrogated), the energy output is minuscule due to the very short pulse time. Jim Weir (of RST) and others have written about this recently in rec.aviation.homebuilt, and shown that there is no danger no matter where you put the antennae (although mounting it right in between your legs might be tempting fate just a bit too much) :-). -- Marc J. Zeitlin Email: marcz@an.hp.com Date: 24 Jan 96 12:53:11 EST From: Chuck Wolcott <75501.356@compuserve.com> Subject: Re: Transponder Antenna's I got my transponder antenna (the same as in all the catalogs) from Bob Nuckolls of AeroElectric Connection fame! He bought a bunch surplus and was selling them for $10 (??? I think) Not bad for a ready to install, just hook up the coax antenna. He has an internet address of 72770.552@compuserve.com If you need any additional help on wiring your bird, I highly recommend his notes...soon to be book, on aircraft wiring and electrical systems. He covers everything from engine instrumentation to solid state panel dimmers. Excellent stuff! Well worth the $$. Chuck Wolcott - N154CW Date: Thu, 1 Feb 96 8:19:20 EST From: "Nick J Ugolini" Subject: fwd: Re: Transponder Ant. For your information: ------------- Original Text >From "Robert L. Nuckolls, III" <72770.552@compuserve.com>, on 1/26/96 12:59 PM: To: Nick, They are new, surplus, King antennas in original packaging. I don't recall the part number but these are single hole mounted monopole devices with BNC connectors. They're $10 each postpaid. Since they tend to get broken off when you scub the gunk from the belly of your airplane, I'll suggest that you buy two. Can take visa/mc or you can mail check to AeroElectric Connection, 6936 Bainbridge Road, Wichita, KS 67226-1008. Regards, Bob . . . Date: Mon, 5 Feb 1996 16:21:01 -0500 From: KSPREUER@aol.com Subject: Re: Antenna Installation (fwd) I may have missed some info on this subject but there is one very important lesson I learned about the Transponder antenna. It is very sensitive to Coax length. The shorter the better. Running it out to the wing or strake plain does not work. I mounted mine in the floor under my seat with a large ground plane. (I don't plan any more children, but don't beleive that is a real problem) It worked flawlessly there. That installation only had about 4 feet of coax. I figure you get less radiation with it directly below you and a ground plane than if it were in the nose per plans From: Marc J. Zeitlin Subject: ADF and FM Antennas (fwd) Date: Sat, 17 Feb 96 11:46:31 EST Daryl Lueck writes: > I'm prep'ing the top of the wings for glassing, (I'm building the >AeroCad quick build wings), and can't find the length or positioning for >the ADF and FM antennas. The plans say to install in the top of the >wings, but I couldn't find any lengths, orientation or locations on the >top of wings...... Jim Weir (RST) says he won't discuss ADF antennae (probably because they're AM). I'd guess that if you took a cheap portable radio and used the antenna from that, you'd be OK - what do the E.E. types out there say? With respect to the FM radio, Jim says to just use the same antenna as you would for a NAV radio - i.e. 22.8" leg lengths for the copper foil. He says the mismatch won't matter as far as picking up stations goes. The conduit for the lighting wires runs just in front of the spar near the bottom of the wing. I'd vote for putting the antenna near the leading edge, running the cable straight back until it's just in front of the spar, and then dropping it down into the lighting wire conduit. I assume that the electrical system won't interfere with the antenna signals because the antenna wire is coax. Once again, E.E.'s? -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Mon, 19 Feb 96 09:26:09 EST From: "Wilhelmson, Jack" Subject: Re: ADF and FM Antennas Daryl: ADF antennas are about the same thing as LORAN antennas. They must be as long as possible and even then they are a untuned antenna. This type of antenna is what you probably have seen in pictures of WWII airplanes with the antenna strung from the tip of the vertical stab. to the front of the canopy. Some newer ADF receivers use a preamp system that looks like a rounded rectangle about 4"x6"x1". It is usually mounted on the under side of the airplane. You need to know what ADF you are going to use. With Loran and GPS it is hard to imagine ADF being installed in a new airplane. Broadcast FM antennas can be the same as NAV antennas and a splitter is much more desirable than a separate antenna. In any case the use if FM radios at the same time you are using VOR for navigation is not recommended by the FAA. This is because the local OSC. in the FM receiver operates at or very near the same frequency and can cause interference. If you are thinking about FM radio for entertainment, you will find that in a fast moving aircraft it is hard to maintain good reception. Most folks use a tape player for this purpose. If you are thinking about cellular phones (FM). This is also not legal except on the ground. In any case you don't need a built in antenna for a Cellular phone in a composite airplane. The built in antenna will work the same as if you were in free fall. with SMTP (MailShare 1.0b8); Tue, 20 Feb 1996 18:41:02 +0000 From: "Daryl H. Lueck" Subject: Wing Antennas Date: Tue, 20 Feb 1996 18:31:24 -0000 I'm about to cover the top of the right wing and the plans call for the = installation of the Marker Beacon and/or FM radio antennas. There is no = positioning or length for the copper strips. Any of you got the RST book or installed yours already? thanks,=09 Daryl Lueck Cozy IV #243 From: "Rob Cherney" Organization: Ellicott City, Maryland Date: Tue, 20 Feb 1996 22:30:48 -0400 Subject: Re: ADF and FM Antennas (fwd) > > I'm prep'ing the top of the wings for glassing, (I'm building the > >AeroCad quick build wings), and can't find the length or positioning for > >the ADF and FM antennas. The plans say to install in the top of the > >wings, but I couldn't find any lengths, orientation or locations on the > >top of wings...... > > Jim Weir (RST) says he won't discuss ADF antennae (probably because > they're AM). I'd guess that if you took a cheap portable radio and used > the antenna from that, you'd be OK - what do the E.E. types out there > say? As far as I know, ADF antennas require two antennas: one for determining direction with a plus or minus 180 degree ambiguity and another for resolving this ambiguity. The directional antenna is usually two loop antennas in one enclosure oriented 90 degrees to one another in the horizontal plane. These antennas often have embedded active preamplifiers and they appear as a puck-shaped bumps on the bottom of an aircraft. The other antenna is called the sense antenna and is a wire running from the top of the cabin to the vertical stabilizer. The directional antenna is typically matched to the receiver with which it is used. I don't think that this type of antenna should be buried in a wing since it may require servicing in the future. As for the sense antenna, it might require being oriented along the long axis of the fuselage. So, from a practical standpoint, I feel that embedding the ADF antennas in the wing is not possible. That said, I would ask the question: Why are you considering installing an ADF system? GPS is the way to go (although I have to admit that IFR certified units are kind of expensive). > The conduit for the lighting wires runs just in front of the spar near > the bottom of the wing. I'd vote for putting the antenna near the > leading edge, running the cable straight back until it's just in front > of the spar, and then dropping it down into the lighting wire conduit. > I assume that the electrical system won't interfere with the antenna > signals because the antenna wire is coax. Once again, E.E.'s? I don't like the active leg of the antenna being close to any other conductor. Although it might work acceptably, I would recommend placing the nav antenna on the underside of the canard rather than in the wing. This would keep it away from other conductors that are parallel to and in the same plane as the antenna radiating elements. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ From: Marc J. Zeitlin Subject: Wing Antennas (fwd) Date: Wed, 21 Feb 96 0:09:29 EST Daryl Lueck writes: >I'm about to cover the top of the right wing and the plans call for the >installation of the Marker Beacon and/or FM radio antennas. There is no >positioning or length for the copper strips. MKR BCN: 34.3" legs. FM: same as NAV - 22.8" legs >Any of you got the RST book or installed yours already? As we all know, we've had a lot of discussions lately regarding antennae, as we have in the past as well. I just (hot off the presses) received this message from RST: ------------------------- Dear Mr. Zeitlin, Doug Ashby gave me your e-mail address today. He referred Nat Puffer's mention of RST Antennas. RST Engineering now has a Web site at http://www.rst-engr.com/ Our latest catalog and data sheets on all RST products are available at the Web site. Our company e-mail address is rst-engr@oro.net. We will be happy to answer all inquiries and questions. Gail P.S. If you are interested, Jim Weir (RST vice-president) will write brief (you tell us how brief) articles to answer questions that your e-mail group members might have. Gail Allinson RST Engineering, Grass Valley CA 916-272-2203 gailla@oro.net http://www.rst-engr.com/ ------------------------- I wrote back thanking her for the offer, and assured her that they will rue the day they made it :-). So, the canonical source for cheap composite aircraft antenna info is on-line, and accessible to all of us. The COZY mailing list archive for antennae info is at: http://www.ultranet.com/~marcz/cozy_mkIV/mail_list/topics/antennae.txt and last year's discussions are at: http://www.ultranet.com/~marcz/cozy_mkIV/mail_list/topics_95/antennae.txt Between all these sources of info, we should never have to ask another antennae question again :-). If anyone CAN'T find the info in the archives, or at the RST web page, and Jim Weir gives you a good answer (via voice, email, or that other paper based system the name of which I can't remember) by all means post it to the mailing list. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Mon, 22 Apr 1996 15:56:21 -0700 From: harvey3@ix.netcom.com (Neil K. Clayton) Subject: The black art of Antenna Design Could any Electrical Engineers pls give a humble Mech Eng ("it's only real if it hurts when you drop it on your foot") some guidance into the black world of antennas; Re the V-shaped Nav Ant under the front fuse skin; Antenna legs; Leg length of each "V"? Angle between the legs? Fore-aft position of the V-apex to avoid the nose gear retract Ferrite Toroids; (BTW - what do they DO????) Position of them relative to the end of the RG58 co-ax? Number of them? Diameters (inside & outside) of them? Axial length of each toroid? Position relative to each other?/insulate between them? /touching OK? Fit over the co-ax cable - loose/tight? RG-58 cable; Connection method to the antenna tape? Solder? Anything special about threading it through the floor? Finally...if I'm not doing Loran, do I still need a ground plane in the fuse floor? Thx...sorry for all the questions but I know NOTHING about antennas. If one of you comes back and says sacrifice a chicken at dawn and chant as you install this antenna, I'd probably do it. Neil. Date: 22 Apr 96 22:53:16 EDT From: "Edmond A. Richards" <103235.1336@compuserve.com> Subject: Re: The black art of Antenna Design Neil, RST Engineering sell a package of magazine articles written on the subject of installing antennas in plastic airplanes for $5. The articles do a pretty good job of explaining how to go about installing each of the various antennas. The address is: RST Engineering 16214 Jacks Road Nevada City, CA 95959 (916)-478-0641 They also sell the toroids, copper tape, etc. They also might be able to tell you just how to prepare that chicken for sacrifice:>) Ed Richards From: "Rob Cherney" Organization: Ellicott City, Maryland Date: Mon, 22 Apr 1996 23:07:04 -0400 Subject: Re: The black art of Antenna Design From: cherney@clark.net To: harvey3@ix.netcom.com Subject: Re: The black art of Antenna Design Date: Mon, 22 Apr 1996 23:03:45 Hi Niel: > Could any Electrical Engineers pls give a humble Mech Eng ("it's only > real if it hurts when you drop it on your foot") some guidance into the > black world of antennas; I'll give it my best shot. > Re the V-shaped Nav Ant under the front fuse skin; > > Antenna legs; > Leg length of each "V"? For a Nav antenna, each leg should be 22.8 inches long. > Angle between the legs? Anywhere from 90 to 180 (stretched out straight) degrees should work just fine. Closer to 180 is better. > Fore-aft position of the V-apex to avoid the nose gear retract Whatever fits. Try to avoid any metal that might be close to the TIPS (high impedance ends) of the "V". > Ferrite Toroids; > (BTW - what do they DO????) They form what is technically called a "common-mode choke". In this case they perform a balanced to unbalanced conversion -- that is, the conversion from the unbalanced RG-58 coax cable to the balanced dipole antenna. This is sometimes referred to as a "balun". The net effect is to prevent unwanted radiation of the coax cable by preventing current from flowing on the outside of the cable. They are desireable but not essential. > Position of them relative to the end of the RG58 co-ax? As close to the antenna elements as is practical. > Number of them? Three or four will do. > Diameters (inside & outside) of them? Inside diameter should clear the outside of the coax cable (something over 0.25 inches). > Axial length of each toroid? About 0.2 inches or more. Actually depends upon the torroid. You cannot use just any torroid. The ferrite formulation is important. Check Marc Z's archives on antennas. I have specified a type made by Amidon Associates. > Position relative to each other?/insulate between them? > /touching OK? Not too important. Leave a small gap in between to prevent any thermally-induced stresses that might result from them being encapsulated in micro. > Fit over the co-ax cable - loose/tight? Again, not important. Too tight, though, and they might crack over time. > RG-58 cable; I usually suggest the plenum-rated LAN (local area network) cable. This is slightly smaller in diameter than run-of-the-mill RG-58U. It is the proper impedance (50 ohms), has the same loss characteristics, and is easier to solder than regular coax since it is a PFTE material; it doesn't readily melt. It also has a 100% shield coverage since the outer shield is formed by a braid over metal foil. You should be able to get spool ends (scrap pieces) from a local LAN installer. > Connection method to the antenna tape? Solder? Expose a one inch length of center conductor and the braid. Strip the insulation of the center conductor back the same amount as the foil tape is wide. If the antenna is mounted off center, connect the braid to the inboard element, and the center conductor to the outboard element. Use ROSIN-core solder, not plumbing type acid-core solder (60/40 lead-tin solder is standard). > Anything special about threading it through the floor? Keep the coax as perpendicular to the antenna elements and as far away as practical. > Finally...if I'm not doing Loran, do I still need a ground plane in the > fuse floor? I don't think so, but check with some others. > Thx...sorry for all the questions but I know NOTHING about antennas. If > one of you comes back and says sacrifice a chicken at dawn and chant as > you install this antenna, I'd probably do it. Read the latest Central States Association newsletter; there is a good article on antennas. I would strongly suggest that you check the SWR before glassing over the antenna. Make sure it is below 2:1 over the Nav frequency range. E-mail if you have any other questions. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ Date: Tue, 23 Apr 1996 08:21:59 From: JRaerocad@gnn.com (Jeff Russell) Subject: Re: The black art of Antenna Design Rob Cherney writes: >Ferrite Toroids; >>(BTW - what do they DO????) >You cannot use just any torroid. The ferrite formulation is important. >Check Marc Z's archives on antennas. I have specified a type made by Amidon >Associates. Seems like this can not be true that the ferrite formulation is important. When I built the Velocity RG the plans called out ferrites and said that they could be replaced with metal nuts as long as they not touch each other. I have use this on all three airplanes, Cozy,Velocity and AeroCanard and have had NO problem. The Com picks up about 120-150 NM away. The Nav, Marker B. and Glide Slope also work great. So tell me what I did wrong? AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com From: "Steve Campbell" Subject: Ground Plane Date: Tue, 23 Apr 1996 09:00:54 > Finally...if I'm not doing Loran, do I still need a ground plane in the > fuse floor? I had this question as well. If you are not going to use Loran, is it still worthwhile to install the ground plane? Are there any other avionics out there on the horizon that would benefit from one? I noticed that Marc's photos showed that he didn't use one. Any comments? **************************************** Stephen A. Campbell Associate Professor, EE University of Minnesota **************************************** May you die peacefully in your sleep like my uncle the airline pilot, and not screaming in terror like his passengers. **************************************** From: Rob Cherney Date: Tue, 23 Apr 1996 10:29:23 -0400 (EDT) Apparently-To: >From Jeff Russell: >>Ferrite Toroids; >>>(BTW - what do they DO????) >>You cannot use just any torroid. The ferrite formulation is important. >>Check Marc Z's archives on antennas. I have specified a type made by Amidon >>Associates. > >Seems like this can not be true that the ferrite formulation is important. >When I built the Velocity RG the plans called out ferrites and said that >they could be replaced with metal nuts as long as they not touch each other. > >I have use this on all three airplanes, Cozy,Velocity and AeroCanard and have >had NO problem. The Com picks up about 120-150 NM away. The Nav, Marker B. and >Glide Slope also work great. > >So tell me what I did wrong? You did nothing wrong. To quote myself: "They are desireable but not essential." The torroids will prevent the coax shield from radiating. This radiation can have two effects: 1) it will disturbe the uniformity of the transmitted and received signal, and 2) it can potentially affect other avionic equipment. I have observed RF interference with my active noise-cancelling headsets due to RF in the cockpit. Also, certain frequencies within the Com band can affect a GPS receiver. Minimizing the amount of RF leakage in the cockpit is a good thing. So...the use of the torroids is generally a good thing. The proper selection of the ferrite material is important to get the maximum amount of benefit from their use. Using metal nuts probably has no beneficial effect. Your antenna will still work as will an antenna that has no torroids. I hope this is sufficiently confusing :). Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ From: Marc J. Zeitlin Subject: Ground Plane Date: Tue, 23 Apr 96 12:12:56 EDT Stephen A. Campbell writes: >> Finally...if I'm not doing Loran, do I still need a ground plane in the >> fuse floor? > > I had this question as well. If you are not going to use Loran, >is it still worthwhile to install the ground plane? Are there any other >avionics out there on the horizon that would benefit from one? I noticed >that Marc's photos showed that he didn't use one. Any comments? According to RST's (Jim Weir) published info, the only use for the ground plane was for Loran. RST's articles clearly describe ALL the different antennae (except GPS) for composite aircraft - they're really worth getting. -- Marc J. Zeitlin Email: marcz@an.hp.com From: Lee Devlin Subject: Antenna copper foil Date: Tue, 23 Apr 96 12:24:10 MDT I also recommend Jim Weir's articles. One of the best pieces of advice I got from him at Oshkosh was not to buy the copper tape from him but instead to get at a stained glass shop. It only cost $9.80 for 100'. Lee Devlin Date: Wed, 24 Apr 1996 10:15:54 -0400 From: RSiebert1@aol.com Subject: A Good Man at RST I recently called RST Engineering and was surprised to have Jim Weir answer the phone. We had a very pleasant 20 minute conversation in which I discussed my antenna layout dilema (I have no com antennas in my wing-tips, sigh...). He happpily answered all my questions and gave me some valuable advise, and tips. Some of the tips have yet to appear on this mail list. I went ahead and ordered everything I needed from him, rather than scout around town for components. For $70.00 I got a box that had all the torroids I needed, and then some; 100 feet of copper wire; 100 feet of coax cable, and the priceless reference text of magazine articles he has published. I thought this was money well spent for the expert help I received from him. He even went so far as to say I should buy my coax from Radio Shack, because it was cheaper. I commented that I'd rather give him the business, he probably would appreciate it more. In the end I received my box of stuff via UPS, and it cost me no time, frustration, or gas money, and in return for the extra $20.00 I spent I got peace-of-mind knowing that what I'm doing with my antennas will be the right way to do it. I pay shareware fees for good software I download and use, and I think that paying a good man a few dollars for his knowledge might just keep him around aviation a little longer. I feel the same way about Bob Nuckolls at AeroElectric Connection, that's why I am one of his suscribers. And I would happily pay $20.00 to keep this Cozy mail list service alive. Support those who support and advance our industry! Reid Siebert P.S. : Angle your nav antenna legs a few degrees from the straight 180-degrees, you'll be glad you did....(a Jim Weir tip) Date: Mon, 19 Aug 1996 15:12:38 -0400 From: DevoCoach@aol.com Subject: COZY: Loran Antenna Hello all! I'm new to the group and this is my first post. I am completing a Cozy III and am installing radios. I have purchased a King KLN-88 Loran with the whip antenna. Anyone have any suggestions regarding the successful installation of same? Where should the antenna be placed, turtleback or belly? Ground plane? Where, what materials should be used? Thanks, Jeff Mallia Devocoach@aol.com Date: Fri, 23 Aug 1996 09:24:55 -0400 From: wilhelmson@scra.org Subject: Re: COZY: Loran Antenna JEFF: I ASSUME THAT YOUR LORAN USES A ANT. AMPLIFIER NEAR THE ANT. MOST OF THEM DO. LORAN ANTENNAS ARE VERY INEFFICIENT BECAUSE THEY CANNOT BE MADE THE CORRECT LENGTH(TOO LONG). THEREFORE, LORAN ANT INSTALLATION IS NOT TO CRITICAL (EXCEPT FOR THE VERY LOW SIG. LEVEL FROM THE ANT. TO THE ANT. AMP.). GROUND PLANES ARE NOT REQUIRED EXCEPT TO GROUND THE ANT. MOUNT TO THE OTHER METAL PARTS OF THE AIRLANE (WHICH SHOULD ALL BE BONDED TOGETHER WITH FLEX BONDING WIRE. THIS IS IMPORTANT IN A COMPOSITE AIRPLANE TO REDUCE VIBRATION STATIC RF NOISE.) I MOUNTED MY LORAN ANT. UNDER THE AIRPLANE BETWEEN THE LANDING GEAR AND THE FIREWALL. I CUT A FOOTBALL SHAPE AND SIZE INSPECTION DOOR IN THIS AREA. I LAID UP A LIP SO IT IS FLUSH AND MADE A AL. COVER HELD IN PLACE WITH CTSK 4-40s AND PLATE NUTS. THE ANT. IS MOUNTED ON THIS METAL COVER. IT WORKS VERY WELL AND GIVES ME A INSPECTION DOOR TO EXAMINE THE LANDING GEAR BOLTS AND HAVE ACCESS TO THE FRONT SIDE OF THE FIREWALL. From: "Dewey Davis" Date: Fri, 23 Aug 1996 15:36:57 -0400 Subject: Re: COZY: COM Antenna On Aug 23, 12:31, Lee Devlin wrote: > Subject: COZY: COM Antenna > As some of you may know, I recently purchased a LongEZ. During my trip > to Oshkosh and back this year, I was disappointed to find that although > the COM radio would receive for great distances, I couldn't raise a > Unicom unless I was within 5 or 10 miles of it. At close distances, I > get good signal reports, but I'm afraid that my signal doesn't get out > very far. I'm beginning to suspect the SWR (standing wave ratio) of the > antenna may be responsible for it. > > I read an excellent article by Dave Black in the April issue of the > Central States newsletter regarding the SWR of a COM antenna he had > installed in his winglet. His SWR varied all over the map going from > 1:1 (desirable) to off the scale (>6:1) within the COM band. The main > problem seems to stem from the fact that the standard method for > building these antennae is to use 50 ohm coax connected to a 150 ohm > half-wave dipole without a balun. Dave believes that the ferrite > torriods do not work as a balun and thus do not provide a match > between the coax and the dipole. I'm considering using an SWR Analyzer > before proceeding any further with the installation of antennae in my > Cozy. I don't think it is as big a concern with the NAV antenna since > that's a receive only antenna and by the time I'm flying my Cozy there > probably won't be any signals to receive with it:). The SWR is much > more of a concern when you're trying to radiate energy _from_ the > antenna. > > I also found that I could not raise a single Flight Watch station in my > EZ although I knew other planes (fortunately) in my vicinity had no > trouble getting weather reports. This was the same statement that the > editor of the Central States Newsletter made at the end of the Dave's > article. Dave also praised the Sportcraft 008 antennae made by Bob > Archer and found it had a very flat response < 2:1 SWR across the entire > COM band. His opinion, and I am beginning to feel the same way, is that > we spend $1000-$2500 or more on a NAV/COM so what sense does it make to > connect it to an antenna that costs pennies if it doesn't work when > something that does work costs only $50. > > My main concern is that once these antennae are buried in the airframe, > there's virtually no way to fix them if you find that they don't work. > Some of statements that I hear praising the cheapie antennae are made by > pilots who slink around the ATC system and rarely make a radio call > from more than 10 miles away. I'm a slinker too, but on occassion I > need to raise ATC and right now I'm concerned that I'll have to buzz the > Tower to make that happen in the EZ :-). > > I'd appreciate it if anyone else who is flying a plane with the copper > tape COM antenna to share your experiences. > > Lee Devlin >-- End of excerpt from Lee Devlin I think there is a lot more to the story. I know of plenty of examples of airplanes built with the traditional copper tape and toroid antennas that work just great. Mine is one of them. I have communicated many times for over a hundred miles with GREAT quality using this kind of comm antenna. I have a King KX-165, which is a nice radio, standard RG-58 coax, and the standard copper foil antenna with toroids designed by Jim Weir years ago. I have communicated from Melbourne Florida to an aircraft that just departed Great Harbor Cay in the Bahamas. I routinely communicate between my homebase in Manassas Virgina to other EZs near Hampton Va, over a hundred miles away, even at altitudes as low as 4500 feet. I have never had a problem with any tower, even when I call from 30+ miles out. My airplane is notorious for great comms sound and distance. On the other hand, I know of plenty of EZs that have poor comm performance just as you describe. So why does one airplane work well and another one doesn't? Plenty of possibilities. Sometimes it is the radio, but quite often it is the antenna installation. One of the most common problems is the copper foil is run too close to another metal object, like the antenna cable itself. It does no good to carefully build a nice copper tape antenna and then route the coax cable right next to one of the copper elements. I have seen this in more than one case. Sometimes the coax connectors are dirty, the solder connections are poor, etc. etc. Dave Black is right that the toroids do not perform the same function as a balun and they don't perfectly match a 50 ohm coax to the antenna. But that doesn't explain the poor VSWR that he measures in some of the installations, it doesn't even come close. Yes you can spend a lot more money on an antenna, but you can also install it improperly and get the same poor results. You can get fantastic performance with the simple copper tape antennas that most people are using if you are careful about where you put it and solder it carefully and use a good cable, etc. Many others have done it successfully. I think the discussion about toroids is simply a red herring, IMHO. Dewey Davis Date: Fri, 23 Aug 96 15:52:30 est From: "Larry Schuler" Subject: COZY: COM Antenna Lee, Here's a few thoughts: The SWR is the likely culprit. A couple of other possibilities are: poor power out from the transmitter or a lose connection (it happens). One of the two antenna connections may be bad or broken. Don't go out and buy an SWR bridge; find a local ham radio operator (may be one in local EAA chapter) and borrow his/hers. A ham radio operator's stuff is more likely( but not always) better than a CB shop's. I tend to agree with the idea that slipping a few ferrite doughnuts over the coax may not provide the appropriate impedance match between the radio (50 Ohms), the coax (should be 50 ohm, but may be a 75 ohm type), and a blanced 150 ohm antenna. The doughnuts would need to be placed and sized properly. If they are wrong they may tend to act more like a choke. The gap between each leg of the antenna also affects the impedance (a lot). You bought someone else's work, so you are kind of stuck with anything that is epoxied in. If the antenna lengths and foil size is wrong, you might be stuck with installing a new one. If you can get hold of the coax at the antenna end while watching the SWR meter (with the mike keyed on), try moving the cable around (don't overdo it); if it's a bad connection at that end, the SWR will go up and down like a yoyo. As a side note: if all connections are good and it is a high VSWR problem (mis-match) and you can't get to the antenna end of the coax to adjust/fix the balun, then you might be able to get away with installing a balun at the radio end of the coax. Not the best solution, but should be a fair fix if the coax length is very short. Call me if I can help further 715-359-9429. Be glad to help find and fix the problem. I do communications electronics for a living. Larry Schuler MKIV-#500 Date: Sat, 24 Aug 1996 00:06:57 -0400 From: RonKidd@aol.com Subject: Re: COZY: COM Antenna I have used the copper foil antenna's (antenni?) for 6 years. I have never had any problems with communication to ATC, flight watch etc. What I hear, I can talk to. I am using a VAL 760 com radio that has worked great! I wouldn't worry about them if I were building again. Ron Kidd Cozy, N 417CZ id <01I8NTPLQVXS8ZMOFY@InfoAve.Net> for cozy_builders@hpwarhw.an.hp.com; Sat, 24 Aug 1996 17:05:40 -0400 (EDT) Date: Sat, 24 Aug 1996 17:05:40 -0400 (EDT) Date-Warning: Date header was inserted by InfoAve.Net From: Nick Ugolini Subject: COZY: Antennas I have a varieze, with an original RST Engineering design antenna in the landing gear strut. Discription: down the port leg is the emitter, then straight across the baggage compartment and part way down the stbd leg is the ground plane. There are 4 ferite beads with shrink wrap at the connecting point. The antenna is on the leading edge of the the strut. I belive it is the copper tape design. Although this is good comprimise, it was found later the original design was prone to breaking due to the flexing of the strut and the thin copper imbeded in the glass. Question I am not sure how to test the existing antenna to see if it is working ok, other than to put the radio in, take it up and see who I can pick up. How do I test the original design? The updated RST recommendation is to put some tubing in the rear of the strut, feed your antenna wire down the tubing (one side the emitter and one side the ground). Exactly the e same as what I already EXCEPT the antenna is in tub housing and is allowed to move a bit. Question: If I install the tubing and the new antenna, would the radiating pattern from the antenna in the back of the strut (range, transmitting ability) be affected by the presence of the old copper tape in the front of the strut? Thanks, Nick Ugolini unick@mail.charleston.net Varieze N89RS Date: Thu, 29 Aug 1996 15:32:57 -0400 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: coaxial cable (antennas) This is a multi-part message in MIME format. --------------2F1C7DE14487 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit two questions/answers i couldn't locate in the archives: 1) how many feet of RG-58 50 ohm coax cable should i order? 100 feet? 50 feet? 2) can i hold off on getting the bnc connectors/antenna splitters until instrument installation time? (actually maybe a couple bnc connectors would be good to check the standing wave ratio before glassing?) --------------2F1C7DE14487 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename=".sigeaa" --- bill kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc 9! cz4 -> aerocanard --------------2F1C7DE14487-- Date: Fri, 30 Aug 1996 14:51:12 -0400 From: Jim Hocut Subject: Re: COZY: coaxial cable (antennas) >1) how many feet of RG-58 50 ohm coax cable should i order? > 100 feet? 50 feet? No good answer to this question, you'll have to attack your fuselage with a tape measure to make an estimate. Lots of variables, so be sure add about 50% to whatever you come up with. I happened to have some extra RG-58 laying around (I'm also into ham radio - I've got TONS of stuff laying around) that was leftover from some cell phone installations. That is someVERY good quality cable, I'd choose it in a heartbeat over Radio Shack if at all possible. >2) can i hold off on getting the bnc connectors/antenna > splitters until instrument installation time? (actually > maybe a couple bnc connectors would be good to check the > standing wave ratio before glassing?) Checking the SWR before you glass is a very good idea. I'd suggest leaving your coax from each antenna extra long, and using a cheap screw on type BNC connector from Radio Shack for the purpose of testing SWR. You can then easily remove the connector and use it on your other antennas, and when your ready for installing your radios cut the cables to length and install high quality connectors. (I'd still leave the cables a little long and find someplace to neatly coil the excess). Jim Hocut jhocut@mindspring.com Date: Fri, 30 Aug 1996 19:30:36 -0400 From: Jim Hocut Subject: COZY: Antennas I've been out of town for some time, and in looking over old messages noticed some discussion on the subject of the copper foil antennas we put in our wings, winglets, fuselage, etc. Since I'm not flying my Cozy yet, I don't have any experience per se. However, in over 15 years of ham radio I've played with all kinds of antennas, the uglier and cheaper the better. There's no reason why one of these antennas, IF PROPERLY INSTALLED, won't do a wonderful job. If anyone has questions about antenna problem or installations, I would suggest contacting Jim Weir of RST directly. I've bugged him a couple of times with antenna related questions, he's always been extremely quick to help. His e-mail address is jim@rst-engr.com and RST's home page is at www.rst-engr.com/ Jim Hocut jhocut@mindspring.com Date: Sun, 6 Oct 1996 10:07:05 -0400 From: DevoCoach@aol.com Subject: COZY: elt antenna I am about to install an ACK-450 ELT in my cozy III. It comes with its own exterior antenna that requires a 36" ground plane. Not something I would like to install! I have two com antennas built into each winglet as per plans. I am only using one of these for my com radio. Could I connect the ELT to the other built-in com antenna? Is there any reason this would not work? Date: Sun, 6 Oct 1996 13:20:32 -0400 From: RonKidd@aol.com Subject: Re: COZY: elt antenna I also used the ACK ELT. I made a ground plane out of copper foil tape in a grid pattern in front of the rear seat. I then covered it with one layer of glass. It works well (even eliminated loran problens I used to have. Ron, Cozy 3, N417CZ Date: Tue, 08 Oct 1996 11:58:42 -0400 From: Jim Hocut Subject: Re: COZY: elt antenna >I am about to install an ACK-450 ELT in my cozy III. ..... Could I connect the >ELT to the other built-in com antenna? Is there any reason this would not >work? > This option will work just fine. It's transmitting qualities are little different than the ground plane. Jim Hocut jhocut@mindspring.com Date: Sun, 13 Oct 1996 15:49:23 -0400 From: SBLANKDDS@aol.com Subject: COZY: COZY - Coaxial Cable I am installing cable in the winglets and ran out. The old cable is RG 58 A / U. ( I don't remember the supplier??) Radio Shack has RG 58 U What is the difference? Will the RG 58 U work? What do the letters A & U represent? Thanks for the info Steve Blank Cozy Mark IV #36 sblankdds@aol.com Date: Sun, 13 Oct 1996 16:58:23 -0400 From: Paul Burkhardt Subject: Re: COZY: COZY - Coaxial Cable SBLANKDDS@aol.com wrote: > > I am installing cable in the winglets and ran out. The old cable is RG 58 A > / U. ( I don't remember the supplier??) > > Radio Shack has RG 58 U > > What is the difference? Will the RG 58 U work? > > What do the letters A & U represent? > > Thanks for the info > > Steve Blank Cozy Mark IV #36 sblankdds@aol.com I believe that the Radio Shack " stuff " has a solid core copper conductor which you don't want on an aircraft. I don't know what the A & u stand for .... Aircraft and you ? I don't know. Paul Burkhardt Date: Sun, 13 Oct 1996 16:18:09 -0700 From: Michael Antares Subject: Re: COZY: COZY - Coaxial Cable At 03:49 PM 10/13/96 -0400, you wrote: >I am installing cable in the winglets and ran out. The old cable is RG 58 A >/ U. ( I don't remember the supplier??) > >Radio Shack has RG 58 U > >What is the difference? Will the RG 58 U work? > >What do the letters A & U represent? > >Thanks for the info > >Steve Blank Cozy Mark IV #36 sblankdds@aol.com > Here's the info--as you can tell, it's a little esoteric. RG58/U has a dielectric (that's the material between the outer shield and the inner conductor) of solid polyethylene and has a solid inner conductor. RG58A/U has the same dielectric and has a stranded (flexible) inner conductor. RG58C/U has an outer jacket of non-contaminating polyvinylchloride, the other two are just plain PVC. >From this info it is obvious that you do not want to use RG58/U because of the solid inner conductor. Hope this helps clear up the confusion. Michael 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 19, one wing finished. by SERV05.SLAC.STANFORD.EDU (PMDF V5.0-6 #10979) id <01IAMN3XGW0M0003Q3@SERV05.SLAC.STANFORD.EDU>; Mon, 14 Oct 1996 09:42:41 -0800 (PST) Date: Mon, 14 Oct 1996 09:44:23 -0700 From: hrogers@SLAC.Stanford.EDU (Howard Rogers) Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna >1. I used a router to plow a 3/8" deep trough for the foil. I peeled of the >waxed paper and stuck the foil to the bottom of the trough. I then microed >the trough and filled in a .5" square piece of blue foam. I'll sand it down >tonight and then just glass over. the foam. >2. I also used the router to cot a 3/8" deep by 1/4" wide trough for the RG58 >cable. I poured some micro in the trough, pushed the cable (with toroids) as >far down as I could.I held it in place with finishing nails till things set >up. > >Not the only way or even quaranteed to be the best way. It was just my way. > >Dick Finn Dick, The 3/8" deep trough is fine for the coax, but *not* for the foil. The ideal antenna would be lying right on the surface, so the object is to bury the antenna as *shallow* as possible. Some guys have even used some very light weight glass cloth from the RC hobby store to cover the foil, to keep the covering to a minimum. Your deeply buried antenna will still work, but it will not "get out" as well as one very close to the surface. --Howard Rogers, N6BYL; A&P 2005148 --Howard Rogers hrogers@slac.stanford.edu Date: Mon, 14 Oct 96 14:23:55 est From: "Larry Schuler" Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna Howard Rogers wrote: >The 3/8" deep trough is fine for the coax, but *not* for the foil. >The ideal antenna would be lying right on the surface, so the object is to >bury the antenna as *shallow* as possible. Some guys have even used some very >light weight glass cloth from the RC hobby store to cover the foil, to keep the >covering to a minimum. Your deeply buried antenna will still work, but it will >not "get out" as well as one very close to the surface. rs@slac.stanford.edu Howard, Prove me wrong, but I'm not sure I agree with the idea that copper foil antennas need to be as close to the surface as possible, unless either or both have some mtalic properties. If they do, then we should be using external antennas. Glass and epoxy that we use are both essentially transparent to RF causing only an extreemly small difference in propagation time vs air. Adding 3/8" of foam isn't going to change that it any "PRACTICAL" manner. Many radar domes are made of fiberglass (not carbon) for same reason. I havn't gotten to that point yet, but seems to me that the copper foil adhesive and strength qualities are not as good as micro/foam and could result in a "weak" strip just under the skin. The method described seems like a neat attempt to recover some of that lost strength. And, it allows the surface to be faired back into the surrounding area nicely. Am I all wet? Maybe you have heard or read something I havn't.... Larry Schuler MKIV-#500 Ch-6 Date: Mon, 14 Oct 1996 19:22:58 -0400 From: CCady@aol.com Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna In a message dated 96-10-14 12:47:34 EDT, you write: >1. I used a router to plow a 3/8" deep trough for the foil. I peeled of the >waxed paper and stuck the foil to the bottom of the trough. I then microed >the trough and filled in a .5" square piece of blue foam. I'll sand it down >tonight and then just glass over. the foam. >2. I also used the router to cot a 3/8" deep by 1/4" wide trough for the RG58 >cable. I poured some micro in the trough, pushed the cable (with toroids) as >far down as I could.I held it in place with finishing nails till things set >up. I have used copper braid in place of the copper foil because I used to read of people having the foil break on them. I don't know if this is really a problem but it is pretty thin. I use the RST plans and have gotten their antenna kits and basically replaced the copper foil with copper braid. They have allways worked great for me. Also unless I am mistaken the RST kits came with solid copper core coax cable and I've had no problems with it so far. Cliff Date: Mon, 14 Oct 1996 17:46:45 -0700 From: Michael Antares Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna Let me add my two cents (speaking somewhat officially as an EE) that I agree with Larry. Certainly, quoting from Jim Weir, he doesn't think it matters where the antenna is placed..."The copper foil and ferrites may be placed anwhere in or on the foam or fiberglass. You can put it on the surface, inside the glass on the foam surface, or embedded in the foam, absolutely no difference." This is quoting from his "The RST-802 Antenna Reference Text". I put the tape on the styrofoam directly with no channel. There is no visible bump in the glass going over the copper foil. I route a 3/16" channel for the RG-58 something like a half inch deep and then press the cable into the channel. No hold-downs are required. I also just push the ferrites down the same channel and the styrofoam displaces easily to accomodate the extra size. Then I fill the channel with micro and voila, I'm done. Michael 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 19, one wing finished. From: "James E. Marker" Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna Date: Tue, 15 Oct 1996 10:46:03 -0400 ---------- > Michael Antares & Larry Schuler & Howard Rogers Were Discussing: > Subject: COZY: Chpt. 20 - Winglet / Com antenna <> Talking about solid conductor or multistrand conductor coax going to your antenna's..... Here is the logic we use putting in supervised systems (systems that know they have wiring problems - Fire & security systems): 1. How important is loss of the item? 2. How important/consequences of loss of the item not being detected? 3. Would a false alarm (and any associated automatic actions) place the system is a less safe state. 4. Is this a hostile environment that requires multiple cables/sensors? If you must know when you are having problems with the equipment then we use solid conductor. It tends to fail catostrophically (big time open or big time short), which makes it easy to call bad. With multiconductor we tend to get intermittent failures (or just bad signals) that are more difficult to locate. What I am getting at is would you like to have complete failure of an antenna so that you know what is bad, or would you rather live with signal degradation or transient failure? Aircraft with 2 com's would probably be better off putting in solid coax IMO. Aircraft without 2 com's would probably be better off putting in multistrand coax. Jim Marker | JEMSTONE@csra.net http://www.csra.net/jemstone | Dad of Jacob (singleton), Kassidy, Zachary, Skyler (Triplets - Nov 95). University of Illinois - Nuclear Engineering 1990 Desert Shield/Storm Vet - XVIII Airborne Corps - Dragon Brigade Date: Tue, 15 Oct 96 12:10:59 est From: "Larry Schuler" Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna Cliff Cady wrote: >I have used copper braid in place of the copper foil because I used to read >of people having the foil break on them. I don't know if this is really a >problem but it is pretty thin. I use the RST plans and have gotten their >antenna kits and basically replaced the copper foil with copper braid. >They have allways worked great for me. Also unless I am mistaken the RST >kits came with solid copper core coax cable and I've had no problems with >it so far. Braid sounds like a neat idea; I had been wondering how long it would take thin and soft copper tape to break under normal flexing inside the epoxy/glass matrix... Couple things to think about: 1. If I remember correctly from my ham radio days (I won't say how long that's been), the "Size" of wire, or in this case, antenna ellement, is important as well as length. I think the formulas used to deal with area as well as wavelength to achieve a good match at operating frequency. If reflected power is sufficiently low (SWR), then it should be no problem at all. Even if you use formulas it's best to check SWR "before" epoxying an antenna in place. 2. Copper braid is like BID. It changes shape easily (trades length for width etc). Varying the cross section along it's length would change the antenna's radiation/reception pattern somewhat {probably as major as the variation looks to the eye; just remember that the variation is, essentially, amplified by the distance from the antenna}. Just make an effort to maintain an even cross section along it's length and it will probably be fine for our use. Thanks for the idea; hadn't thought of braid yet. They make flat braid (normally used for ground straps) of various widths all the way down to what we use as a solder wick (about 1/16"). Neat! Radio Shack, here I come.... Wonder if it would be even better to lay the antenna in a thin trough, without epoxying the wires/tape? In other words, let the copper expand, contract, and move independantly of the layup..... just a thought. Might even allow replacement if there is some way to get to the end of it later..... Something to ponder. BTW, the main reason to NOT use solid center conductor coax is that it will eventually weaken or break from flexing. For those of you that have cable TV, check the coax comming out of the wall; you will find that it's a solid center conductor (I garantee it). If your application moves or flexes more than the cable feeding your TV set, then use stranded center conductor. If it will be a permanent installation [never move], solid will work OK. The electrical performance of the two is, for all "practical" purposes, the same. The two types can also be mixed in the same coax run with no bad side effects. Just make sure the "Impedance" rating (normally 50 Ohms for RF/antenna applications) is the same and matched to the radio AND antenna. DO NOT use the cable TV coax comming out of your wall for antennas; it's rated at 75 Ohms [or "Should Be"] and will result in a mis-match in your airplane. Larry Schuler MKIV-#500 Ch-6 (sanding after step 1) Date: Tue, 15 Oct 1996 10:20:05 -0700 From: Michael Antares Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna I suspect that if someone were to actually take a wing or other part of the Cozy that has an embedded antenna and do a vibration test like we were Boeing(!) we would discover that neither the solid conductor or the stranded conductor coax would fail in any reasonable time and that the stranded conductor would be the last to go but that both of them would last well beyond the lifetime of the plane. Where a difference might occur in a way that would be short enough to hurt our pride would be outside the structure where the cable is free-hanging. If it was capable of becoming mechanically resonant at some frequency within the engine vibration spectrum, it could conceivably fail in short order and here is where I think the stranded conductor would have a better chance of survival. In any case I think we should try and secure all harnesses and cables in a way that doesn't allow them to go into resonance. In this regard I am speaking from the experience of having worked on the Appollo project, the Atlas missile system and various communications satellites all which underwent strenuous vibration testing. For any of you who haven't witnessed it, you would be amazed at what happens at mechanical resonance! Michael 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 19, one wing finished. Date: Tue, 15 Oct 1996 14:28:27 -0400 From: DFinn7971@aol.com Subject: Re: COZY: Chpt. 20 - Winglet / Com antenna In a message dated 96-10-14 15:31:02 EDT, lschuler@cellular.uscc.com (Larry Schuler) writes: << The method described seems like a neat attempt to recover some of that lost strength. And, it allows the surface to be faired back into the surrounding area nicely. >> Larry hit on the reason that I tried digging a trough for the antenna. I put my antenna in the boittom of hte fuselage using a slightly different technique. First, I tried putting the copper tape directly against the foam -- It peeled off rather handily. I then masked off the outline of the tape on the foam and microed the area and covered it with peel ply. This base allowed the tape to stick. Given the discussion on hard shelling I might not have been so careful about masking off the area. Still, this was about four years ago when I was young and dumb (now I'm old and dumb). I layed up the skin directly over the tape. It seemed that there were bubbles over the tape despite my best efforts to squeegee them out. After several years of thinking about it, I decided that there may or may not be a weakening of the structure due to poor adhesion between the glass, tape and foam. Regardless, I decided to try something different -- hence I dug a trench for the antenna. One earlier comment related to possible breakage of the antenna if it were embedded in micro. While I confess I didn't think of beakage when doing the work, I did stick the tape directly over the foam. I then poured in some micro followed by a strip of foam. The sequence was foam-antenna-micro-foam-micro-glass. Hopefull the antenna will be able to flex against the foam. Dick Finn Cozy Mark IV #46 DFINN7971@AOL.COM id <01IAOAV86AN48XD2G3@asu.edu> for cozy_builders@hpwarhw.an.hp.com; Tue, 15 Oct 1996 14:13:35 -0700 (MST) by smtp1.asu.edu (8.6.12/8.6.12) with ESMTP id OAA02735 for ; Tue, 15 Oct 1996 14:13:10 -0700 id OAA04942 for cozy_builders@hpwarhw.an.hp.com; Tue, 15 Oct 1996 14:13:33 -0700 Date: Tue, 15 Oct 1996 14:13:33 -0700 From: jdbohn@general1.asu.edu Apparently-To: cozy_builders@hpwarhw.an.hp.com I thought that digging a trench, laying down an antenna, and finally covering it with micro seemed to be an unnecessarly heavy way of holding the antenna in place. Has anyone considered filling the trough with expandable foam. After all sanding foam is easi er then micro, and then you would still have your foam/fiberglass contact. I am just now begining to get my workshop setup so I am not to knowlegable on this subject. John Bohn Date: Tue, 15 Oct 1996 17:42:40 -0400 From: CCady@aol.com Subject: COZY: Re: Antenna In a message dated 96-10-15 17:18:00 EDT, you write: << Has anyone considered filling the trough with expandable foam. After all sanding foam is easi er then micro, and then you would still have your foam/fiberglass contact. >> I've done that but be warned to solidly micro or 5-min your coax and antenna elements down or else the expanding foam can lift them out and your have a real mess. Sound like I've done that? Yep!! Cliff Date: Tue, 15 Oct 1996 22:03:09 -0400 From: SBLANKDDS@aol.com Subject: COZY: Re: Expansion foam over antenna > This is a response to John Bohn's question about using expansion foam over the copper foil antenna in a trench. If any expansion foam gets under the foil, you are trashed. The foil rises to the surface. Just put it there yourself, skip the trench. Avoid ideas that create work without any positive benefit. I tried this on one winglet, what a waste of my time!!! Micro over the cable, I tried expansion foam there too! Time waster. Just put the foil on the foam and glass the thing. You will be finished while these other guys are still sending E-mail. I burried the solder joints and torrids in silicone, to prevent fracture from any vibration, without creating the hard edges that micro would leave near the foil. Let the silicone set completely before doing the layup. This spot may be slightly weaker and more susceptibla to a lateral bird strike in flight. No flight test data on that one yet...ha ha Steve Blank Cozy Mark IV #36 Chapter jumping, winglets almost finished, back to installing the canard. Date: Wed, 16 Oct 1996 02:10:37 -0400 From: StetsonE@aol.com Subject: Re: COZY: elt antenna In a message dated 96-10-08 12:05:01 EDT, Jim writes: > I am about to install an ACK-450 ELT in my cozy III. ..... Could I connect >the ELT to the other built-in com antenna? Is there any reason this would not >work? Just so happens I'm at the same spot - thinking about what to do about an ELT antenna. Assuming your other built-in antenna is in the other winglet, I'm not sure this is such a good idea. In a major crash there's a chance that one or both of the wings/winglets are history. This would put your ELT out of commission, wouldn't it? I don't know a good place for an ELT antenna for my Long-EZ. The most protected area of the plane seems to be in the back seat area - not much vertical space for a foil antenna. When the decision gets critical I'm going to see what Jim Weir suggests. Stet Elliott stetsone@aol.com Perpetual Long-EZ builder Date: Wed, 16 Oct 1996 15:20:37 +0200 From: Rego Burger Subject: COZY: ELT ANTENNA SERIES Hi All, Bob wrote: "On my 3 place Cozy, I built a copper foil vee (same lengths as a dipole) diagonally across the back of the front seat. The corner of the vee is near the left armrest where the ELT is mounted. It seems to work okay. Bob Misterka N342RM" He inadvertently has a good point here.( intentionally or not ) To my knowledge an ELT only works when everything else has gone horribly wrong. If you are going down over heavy woods/forest etc. your crafts wing will more than likely be ripped off,... bye-bye antenna on the wing tip. The fuselage is often intact and you can be found. Whizz, I hope you all talking about an Emergency Locating TX and not some new nav/com we haven't heard of yet? Hope this will help some guys make up their minds on it's placement. >From my knowledge this antenna is not very long and often is on the back of c150's etc.( about 18" ) Rego Burger P.E. S.A. Cozy MK IV #139 Date: Wed, 16 Oct 96 08:46:53 EST From: MISTER@neesnet.com Subject: Re[2]: COZY: elt antenna Stet Elliott wrote: "I don't know a good place for an ELT antenna for my Long-EZ. The most protected area of the plane seems to be in the back seat area - not much vertical space for a foil antenna." On my 3 place Cozy, I built a copper foil vee (same lengths as a dipole) diagonally across the back of the front seat. The corner of the vee is near the left armrest where the ELT is mounted. It seems to work okay. Bob Misterka N342RM Date: Wed, 16 Oct 96 14:41 EET From: edegov@aztec.co.za (ernie de goveia) Subject: COZY: Re: Coax cores Hi all ref coax solid cores versus stranded cores. Years ago I heard/learnt? that Radio Frequencies(RF) travel on the outer surface of a conductor, this is one of the reasons a wave guide is hollow. And a stranded cable will have a greater surface area than a solid core of the same diameter, also a smaller impedance(z). All of this suggests that stranded core coax is the way to go. Have I got it wrong ?. Could someone add to this ? Ernie de Goveia cozy3 ch11 by SERV05.SLAC.STANFORD.EDU (PMDF V5.0-6 #10979) id <01IAPEQ9ZFDK0007BS@SERV05.SLAC.STANFORD.EDU> for cozy_builders@hpwarhw.an.hp.com; Wed, 16 Oct 1996 09:14:59 -0800 (PST) Date: Wed, 16 Oct 1996 09:16:48 -0700 From: hrogers@SLAC.Stanford.EDU (Howard Rogers) Subject: COZY: Re: antennas on glass aircraft To Larry and the group, As per Jim Weir's comments, I apologize and stand corrected. Perhaps it was in the Canard Pusher that I read about the desirability of keeping antennas near the surface, but I totally trust Jim's advice as a true expert in this area. On the subject, and in reference to several other related areas, such as foil breakage, I may be able to shed some light on this. I definitely remember reading the articles about breakage, and to the best of my knowledge, these strictly related to the "inverted vee" antennas that some guys had run down the gear legs, usually on the inboard edges. I have never heard of a winglet or canard antenna breaking the foil. The gear legs can see a *lot* of flexing in normal use, unlike the canard or winglet, especially on the inboard sides, as a landing tends to put the foil in tension. The suggestion for a fix was to run the foil (or braid) down the leading or trailing edge, and tape over it. This way, it would be exposed only to bending, not the intense stretching that it would see on the inside surfaces. I bonded an extra tube down the trailing edges of my gear legs that can be used as a backup brake line, if needed, or as a place to run antenna wire down into, where it can hang limply inside and not get stretched. I had in mind experimenting with various airborne ham antennas, and this would allow for easy replacement or trimming. You guys who have already installed copper tape on winglets and canards can breathe easy, I think. There's not much chance the tape is going to break, there! I also agree that the tape, laid directly on foam, could cause an area of weak bond under the skin, and Larry's idea would totally solve this problem. The method I used (because I believed they should be close to the surface) was to lay the copper tape on the surface of the completely finished, peel-plied outer skin, and glass over it with one layer of lightweight glass cloth, and peel-ply that. The coax was laid in a trough, as described earlier, and terminated in a slight indentation in the foam, so that the torrids and solder-connections will be flush, or lower. This indentation can be microed and faired afterward. This works, but is more work, in the end, than Larry's method. The only possible advantage I can see, now, to doing it this way, would be in the event of a damage-repair situation. If the antenna-area had been damaged, severing the foil tape, in one small spot, it would be fairly easy to sand down to the antenna through a thin layer of outer skin, and strip the whole thing (or just one half) completely away, repair the damage, and lay down a replacement foil and thin cover over the top of everything again. -Regards --Howard Rogers, 415-926-4052 hrogers@slac.stanford.edu Date: Thu, 17 Oct 96 10:07:58 est From: "Larry Schuler" Subject: COZY: Re: Coax cores Ernie de Goveia wrote: >Years ago I heard/learnt? that Radio Frequencies(RF) travel on the outer >surface of a conductor, this is one of the reasons a wave guide is hollow. >And a stranded cable will have a greater surface area than a solid core of >the same diameter, also a smaller impedance(z). Partially true. The higher the frequency, the greater the tendancy is for RF current to travel near the surface of the center conductor. It is NOT a significant issue at our operating frequencies. Waveguide is irrelevant to our frequencies. Impedance in a transmission line such as coax is, very basically, a function of center conductor size (inductance) and it's spacing from the shield (capacitance). We could get into a lot more detail here, such as copper-clad aluminum conductors etc, but it won't mean much to the application we have before us. Impedance is impedance. ALL coax (and waveguide too) is constructed [there are more variations than you can imagine] with a certain impedance. For us, the key number is 50 Ohms. Shielding is also important. Look for a rating of 95% or better (not many of us can afford the solid copper shield which is rated at 99.9%). 97% to 99% is pretty good stuff and may have more than one shield. >All of this suggests that stranded core coax is the way to go. For the radio application, stranded is ok; but so is solid. Stranded provides some advantages in mechanical quality (ie vibration, flexibility and so on). You decide; If you want perfection, use stranded (I will). If you have a bunch of solid in the shop and it meets all other requirements, use it; you won't be wrong. >Have I got it wrong ?. Could someone add to this ? The outer jacket of the coax may also be important. PVC is ok; teflon is better. Pay for what you get normally. If there are three spools to pick from (no fire sale etc.) that all have a) Stranded center b) 98% Shield c) 50 Ohm impedance; I pick the expensive one. I have never been disapointed [except in the price]. Hope this helps someone. I have worked in communications electronics for 25+ years (everything from turbine generators to tropospheric scatter to HF air-to-ground to satellite comm and more) if that means anything to anyone except my employer. Never got an EE degree, but should have..... don't like quantum mechanics. Larry Schuler MKIV-#500 Date: Fri, 18 Oct 1996 19:46:51 -0700 From: Michael Antares Subject: COZY: Coax, et al Just in any case there is anyone who is not aware of it, EVERYONE installing antennas should have a copy of Jim Weir's booklet "The RST-802 Antenna Reference Text" available from RST Engineering (see the archives). Michael 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 19, one wing finished. Date: Mon, 21 Oct 96 11:36:37 est From: "Larry Schuler" Subject: Re[2]: COZY: Chpt. 20 - Winglet / Com antenna Richard Riley wrote: >> Just make sure the "Impedance" rating (normally 50 Ohms for >> RF/antenna applications) is the same and matched to the radio AND >> antenna. DO NOT use the cable TV coax comming out of your wall for >> antennas; it's rated at 75 Ohms [or "Should Be"] and will result in >> a mis-match in your airplane. >How about LAN cable? You can get spool ends for free if you beg. Richard, Absolutly a good thing. Might have a winner there. May be best shielding (might even have a double-braid shield); normally done to shield data from very "noisy" flourescent lights in offices. If it's the stuff rated for air plenum use (above false ceilings and not requiring conduit), it will have a fire-retardent jacket, or at least one that will not give off toxic fumes when it burns {another good thing}, probably Teflon. EtherNet LAN coax is 50 Ohm. Good. Someone else might find this a neat idea; I'll send it to the group; hope you don't mind. Larry Schuler MKIV-#500 Date: Tue, 22 Oct 1996 08:55:34 -0500 From: Mahan Subject: Re: COZY: elt antenna Bob Misterka wrote: On my 3 place Cozy, I built a copper foil vee (same lengths as a dipole) diagonally across the back of the front seat. The corner of the vee is near the left armrest where the ELT is mounted. It seems to work okay. Bob, were you to have a (shudder) accident, the foil might fail if the glass in the seatback cracked. I've used a wire antenna, which would probably not break in an accident. Just a thought. Fred Long-EZ N86LE > > Bob Misterka N342RM Date: Tue, 22 Oct 1996 13:03:45 -0400 From: DevoCoach@aol.com Subject: Re: COZY: elt antenna >Bob, were you to have a (shudder) accident, the foil might fail if the >glass in the seatback cracked. I've used a wire antenna, which would >probably not break in an accident. Just a thought. Fred, did you use the wire antenna supplied by the manufacturer? Where did you install it? Jeff Mallia Cozy III N46WM Date: Tue, 22 Oct 1996 17:33:18 -0500 From: Mahan Subject: Re: COZY: elt antenna DevoCoach@aol.com wrote: > > >Bob, were you to have a (shudder) accident, the foil might fail if the > >glass in the seatback cracked. I've used a wire antenna, which would > >probably not break in an accident. Just a thought. > > Fred, did you use the wire antenna supplied by the manufacturer? Where did > you install it? > > Jeff Mallia > Cozy III N46WM I used the wire antenna supplied by the manufacturer of the ELT. Put the ELT to the right of the passenger's (rear seat) feet, and curved the wire back and under the top longeron. It's not elegant, but it should work in an accident. Fred Date: Wed, 23 Oct 1996 11:44:38 -0400 From: DevoCoach@aol.com Subject: Re: COZY: elt antenna Fred, my ELT antenna recommends at least a 36" ground plane for their antenna. Did your build any sort of ground plane for yours? Date: Mon, 4 Nov 1996 01:24:43 -0500 From: StetsonE@aol.com Subject: COZY: Antenna for ELT I posted to rec.aviation.homebuilt a request for ELT antenna suggestions. Jim Weir from Radio Systems Technology (RST) answered. Here is his suggestion in case some of you didn't see it. Subject: Re: Antenna for ELT From: jim@rst-engr.com (Jim Weir) Date: Wed, 30 Oct 1996 18:55:09 GMT stetsone@aol.com (Stetson E) shared these priceless pearls of wisdom: ->Anyone know of an antenna suitable for a composite aircraft that doesn't ->require alot of space vertically? The odds of the airplane coming to rest in a "normal" (wings horizontal) position in a real whappity-frammis crash are slim to none. I'd be less worried about keeping the antenna vertical than having the elt-coax-antenna combination stay intact. The second point is that the elt satellite has a rotational moment so that your chances of being heard horizontally and vertically are about the same. Yes, when the bluesuits come to find the biggest pieces of your wreckage, they are coming out with vertical sniffers, but like I said, the antenna will probably have a horizontal AND vertical component if you alight smartly with the earth. Finally, the elt antenna needs to be resonant at 121.5 as well as 243.0 MHz., so we need to figure out how to do that little maneuver also. I'd love to tell you to use copper tape, but since you are at a spot frequency instead of trying to cover a bandwidth, I'd probably recommend making it out of plain old solid copper wire, say a #16 or #18 or so. Get it at the handyman store. Here's how I'd do it. Find the place in the airplane that has the greatest probability of survival. Mount the elt in the center of this place. (Note that it doesn't matter if it is around the "human" area; if you aren't conscious enough to get out of the airplane after the incident, it doesn't matter how long it takes to find your body. You are as comfortable as you are ever likely to be.) Cut four pieces of wire, two 22" and two 11" pieces. Run the two 22" pieces out from a central tie point with as much verticality as you can get without compromising the rest of the airframe or systems. Run the two 11" pieces out at right angles to the 22" pieces from the same central tie point, again with as much verticality as reasonably possible. You will get, in essence, an X with one crossmember shorter than the other. Solder one 22" and one 11" wire together and to the braid of the coax. Solder the other 22" and the other 11" wire together and to the center conductor of the coax. Slip three ferrite donuts over the coax close to these connections like the "RST antenna book" shows you how to do it to make a balun. Hook the other end of the coax to the elt. Jim Jim Weir VP Engineering | You bet your sweet patootie I speak for the RST Engineering | company. If I don't, ain't nobody gonna. Grass Valley CA 95945 | http://www.rst-engr.com | AR Adv WB6BHI--FCC 1st phone---Cessna 182A N73CQ jim@rst-engr.com | Commercial/CFI-Airplane/Glider-A&P-FAA Counselor From: "Krasa, Paul" Subject: RE: COZY: Antenna for ELT Date: Mon, 4 Nov 1996 05:46:14 -0500 In addition to what Stet said, I emailed Jim with a suggestion to make one of those neat RST drawings, and he said he would be using the idea in an up coming Kitplanes Article. Jim is a really great guy, and just as he supports us in our quest, I try to support him and RST when ever possible. Paul Krasa Long EZ 214LP !---*---! Project Status: Fuselage primed and filling millions of pin holes. Date: Mon, 04 Nov 1996 13:34:01 -0500 From: Mahan Subject: COZY: [Fwd: Re: ELT Antenna] Received: from li.oro.net (root@NewsLink.oro.net [198.68.62.43]) by digital.net (8.8.0/8.7.3) with ESMTP id NAA16900 for ; Mon, 4 Nov 1996 13:33:11 -0500 (EST) Received: from oro.net (root@Au.oro.net [198.68.62.42]) by li.oro.net (8.7.4/8.8.96-smj) with ESMTP id KAA22320 for ; Mon, 4 Nov 1996 10:33:08 -0800 Received: from rst-engr.oro.net (rst-engr.oro.net [204.119.228.208]) by oro.net (8.7.4/8.6.12) with SMTP id KAA26259 for ; Mon, 4 Nov 1996 10:33:05 -0800 Date: Mon, 4 Nov 1996 10:33:05 -0800 Message-Id: <1.5.4.16.19961104103206.19976c4c@oro.net> X-Sender: rst-engr@oro.net X-Mailer: Windows Eudora Light Version 1.5.4 (16) Mime-Version: 1.0 To: mahan@digital.net From: Jim Weir Subject: Re: ELT Antenna Content-Type: text/plain; charset="us-ascii" At 11:54 AM 11/4/96 -0500, you wrote: >Jim: > >Regarding the info you posted on ELT antennas: Instead of soldering two >11" pieces of wire to two 22" pieces of wire, why not cut two 33" pieces >of wire, and bend each into an L of 11" and 22"? Sounds easier to me, >and you don't risk unsoldering the connection when you solder on the >leads. Why didn't I do it this way? Because you thought of it first!!! I hope you posted this comment to the newsgroup; it's an excellent idea. Jim Jim Weir VP Engineering | You bet your sweet patootie I speak for the RST Engineering | company. If I don't, ain't nobody gonna. Grass Valley CA 95945 | http://www.rst-engr.com | AR Adv WB6BHI--FCC 1st phone---Cessna 182A N73CQ jim@rst-engr.com | Commercial/CFI-Airplane/Glider-A&P-FAA Counselor Date: Mon, 4 Nov 1996 16:50:32 -0500 From: "David R. Kuechenmeister" Subject: Re: COZY: Copper Foil At 4:13 PM -0500 11/4/96, COZYMK4@aol.com wrote: >Does anyone have about 4 foot of the RST 3M type copper foil tape that they >would be willing to sell and send to me? > One thing you could consider is to strip the braid out of some coax and just use that as you would use the foil. I put an antenna in the landing gear with that method and it finished just fine. Regards, Dave Kuechenmeister -- David R. Kuechenmeister Georgia Tech Research Institute Atlanta,GA 30332 e-mail: David.Kuechenmeister@gtri.gatech.edu Voice: (770)528-7738 From: Lee Devlin Subject: Re: COZY: Copper Foil Date: Mon, 04 Nov 1996 16:33:41 MST > 3M has an on-line catalog and shows the tape for $8.95 for the 100 foot roll. > The RST on-line catalog shows it for $20.00. RST on-line is at > http:\www\rst-engr.com not rst.engr.com like I had copied down earlier. It > seems a waste for the little bit that I need. I also can't find any copper > braid around here that would be appropriate for the job. Jim Weir's advice at Oshkosh was to buy your copper tape at a stained glass shop. As I remember it only cost me around $8 for 100'. You might even convince them give you a 4' piece if that's all you think you'll ever need. Lee Devlin Date: Wed, 06 Nov 1996 16:57:27 -0500 From: Nigel Field Subject: Re: COZY: Thanks regarding copper foil At 04:12 PM 11/6/96 -0500, Kevin wrote: ........... I thought about hammering the smallest copper tube or just >running wire, but these options are unacceptable due to weight and narrow >bandwidth respectively. Hi Kevin, May is suggest using 4 or 5 lengths of copper wire in parallel strips as so: Cut 4 or 5 slits in your winglet core same length as the tape would be about 1/16 inch deep and 1/2 inch apart parallel using a knife and straight edge. Push #22 or so solid hook up wire of the correct length same as the tape dimensions into these slits until just below the surface. At the coax feed point bring the strands together and solder to the center conductor on one end and the braid at the other, just like it was wide tape which it becomes to the RF. Add your RF toroids (dont use iron nuts they're real lossy at these freq's) and bury your coax. What you get is a broad band element 2 to 2.5 inches wide thats virtually free and easy to glass over. Mine are done that way and the SWR is very flat accross the band. ------------------------\ /------------------------------ --------------------------\ /-------------------------------- ----------------------------\/---------------------------------- --------------------------/ \-------------------------------- ------------------------/ \------------------------------ |-------------------------- W/2 ------------------------------- | Tape length as called out Nigel (VE1NC) Date: Thu, 7 Nov 1996 18:29:52 -0500 From: CCady@aol.com Subject: Re: COZY: Thanks regarding copper foil In a message dated 96-11-06 20:57:53 EST, you write: << ........... I thought about hammering the smallest copper tube or just >running wire, but these options are unacceptable due to weight and narrow >bandwidth respectively. >> How about using Tinned copper flat braid? I have had good luck with it replacing the copper foil using the RST antenna plans. You can order some from Mouser Electronics, (800) 346-6873, item # 172-5001FT $199 per ft, $1.81 per ft > 5', $1.65 per ft > 10'. You can get it at widths from 1/8" to 1" Date: Thu, 07 Nov 1996 16:24:12 -0800 From: berkut@loop.com Subject: Exp. w/Spruce "High Gain" antennas? Has anyone used the "high gain" (no manufacturer listed) antennas from Spruce? The drawing makes them look like a copper foil dipole. 2 VHF models for Nav. Com and ELT, with slightly different BNC connectionsn, one Transponder model. PN's VHF-51, VHF-51 T and L-2. The catalog claims they out-perform everything available. Any comments on them? -- Czech Sikhs! Richard Riley "The important things are always simple. The simple things are always hard." See the Berkut at http://www.berkut.com Date: Thu, 7 Nov 1996 21:52:26 -0500 From: COZYMK4@aol.com Subject: Re: COZY: Copper Foil Thanks again for the offer! Last night, I did the other winglet using the copper foil from my friends stained glass hobby and it worked great. I was concerned since I knew that the 3M stuff had "electrically conductive adhesive" and this stuff might not. So like a good homebuilder, I checked to see if the product would suit my purpose. I found the with a simple testing setup of two pieces of wood pulling on the tapes, the adhesive on the stained glass one was a little weaker, but the metal was tougher. I then stuck 4 pieces on to each other with a tiny overlap, forming a zig-zag line of foil with various degrees of overlap and adhesive compression. When I used the resistance meter, the whole distance across all of the joints, in series, was zero. I was surprised to find that this adhesive was conductive also. Maybe all of them are, but I won't ever make assumptions about building my plane if I can help it. Kevin Antennas, wings, ailerons, canard, nose, gear, spar all done. Controls and fasten winglets to wings comes next. From: Lee Devlin Subject: COZY: Copper tape and conductive adhesive Date: Fri, 08 Nov 1996 9:10:38 MST > Last night, I did the other winglet using the copper foil from my friends > stained glass hobby and it worked great. I was concerned since I knew that > the 3M stuff had "electrically conductive adhesive" and this stuff might not. > So like a good homebuilder, I checked to see if the product would suit my > purpose. I found the with a simple testing setup of two pieces of wood > pulling on the tapes, the adhesive on the stained glass one was a little > weaker, but the metal was tougher. I then stuck 4 pieces on to each other > with a tiny overlap, forming a zig-zag line of foil with various degrees of > overlap and adhesive compression. When I used the resistance meter, the > whole distance across all of the joints, in series, was zero. I was > surprised to find that this adhesive was conductive also. Maybe all of them > are, but I won't ever make assumptions about building my plane if I can help > it. I wouldn't be too concerned with whether or not the copper tape has conductive adhesive when using it as an antenna. It's being stuck to something that is an insulator anyway. The electrical connections to the antenna are made with solder joints. The conductive adhesive is only important when you're using the tape to seal off gaps in enclosures (which otherwise may act like slot antennae). This type of tape is generally used to locate the leaks of unwanted radiated signals during the development of electronic devices. Lee Devlin | HP Greeley Division | Long EZ N36MX Piper Colt N4986Z | 700 71st Ave. | Cozy MK IV under const. 'Spirit of rec.aviation'| Greeley, CO 80634 | (Chapter 10) Date: Sat, 07 Dec 1996 16:54:23 -0500 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: measuring nav antenna swr [long] i posted a note in the r.a.h. newsgroup concerning the need and technique of measuring the standing wave ratio of my fuselage nav antenna before glassing---as recommended in a recent central states newsletter. i received a few hits from the magnanimous jim weir. he is offering to set-up a switch-box to use to measure the poor performance he expects from the fuselage-mounted antenna as compared to the weir-recommended location in the wing or canard. i am certainly nowhere near the point that i could help, but maybe someone else could... following is a bit of the exchange (starting mid-way) and the offer: i wrote: so are you saying that the antenna is so simple that i should not worry about testing the vswr since it'll require testing techniques/equipment beyond my capabilities, and if i mount it in the right location i shouldn't have to worry? in other words, if i cut the tapes to the right length and put the toroids in place, i should only have to measure the resistance from antenna tip to bnc connector to make sure i knew how to solder? ps: i am putting another nav antenna in the wing, so fear not the possible dismal performance of the belly mounted one---and i will share the blame for its non-optimal location and cramped orientation with the one who directed me to put it there. Jim responded: No, I was merely reacting to about ten years of flames from builders who measured my stuff with a CB meter and one of their "good buddies" pronounced the antenna "lousy" because it didn't "peg the meter". Or the builders who mounted my antennas inside of carbon fiber skins, on top of metal capstrips, on the engine cowling, or inside a tube and rag fuselage and then called raising holy hell about this "rotten antenna design". Sorry, after a few dozen like this it sort of gets to you. No, satisfy yourself that the thing is good before you glass it over. I'd be very interested in an x-y test between the one in the wing and the one in the tub -- distance, needle waver, and all that stuff. If you are willing, I'll rig up an x-y switch box if you will do the test after you get it flying. Jim Weir VP Engineering | You bet your sweet patootie I speak for the RST Engineering | company -- and I'm damned proud to do so. Grass Valley CA 95945 | Airport: O17 (Grass Valley Intentional Airpatch) http://www.rst-engr.com | AR Adv WB6BHI--FCC 1st phone---C-182A N73CQ jim@rst-engr.com | Comm'l/CFI-Airplane/Glider-A&P-FAA Counselor --- bil kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc 9? cz4 -> aerocanard Date: Mon, 09 Dec 1996 23:04:43 -0800 From: Chris van Hoof Organization: C van Hoof - Architect Subject: [Fwd: Re: [Fwd: COZY: measuring nav antenna swr [long]]] This is a multi-part message in MIME format. --------------3097753913DE Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hi there Folks, I Forwarded the question regarding the measuring of the Nav antennae to the local Guru, and he came up with the attached reply. All references are ... Rudi= Kis builder, any other ask and i'll answer Chris # 219 --------------3097753913DE Content-Type: message/rfc822 Content-Transfer-Encoding: 7bit Content-Disposition: inline Return-path: Envelope-to: cvh@iafrica.com Delivery-date: Mon, 9 Dec 1996 22:59:07 +0200 Received: from MailMunch.cis.co.za [196.2.16.18] by relay01.iafrica.com with smtp (Exim 1.59 #1) id 0vXCn1-0003S3-00; Mon, 9 Dec 1996 22:59:05 +0200 Received: from net-48-177.cis.co.za (net-48-177.cis.co.za [196.2.48.177]) by MailMunch.cis.co.za (8.7.1/8.7.1) with SMTP id XAA32599 for ; Mon, 9 Dec 1996 23:00:40 +0200 Message-Id: <199612092100.XAA32599@MailMunch.cis.co.za> Disclaimer: The views expressed in this message are those of the author, and not necessarily those of WNA and/or it's employees. Comments: Authenticated sender is From: afriair@falcon.cis.co.za To: Chris van Hoof Date: Mon, 9 Dec 1996 22:56:02 +0000 Subject: Re: [Fwd: COZY: measuring nav antenna swr [long]] X-Confirm-Reading-To: afriair@pop3.cis.co.za X-pmrqc: 1 Return-receipt-to: afriair@falcon.cis.co.za Priority: normal X-mailer: Pegasus Mail for Windows (v2.23) X-UIDL: 79938251f43014d53095e6629d496bd2 X-Mozilla-Status: 0011 Chris, Jim is right about fuselage bottom mounting, when the structure is anything other than glass or wood. Your canard might be a good place, if there is not a long piece of steel tubing forming a torque tube, very close to it. Many composite aircraft are becoming difficult regarding antenna placement. It's OK with putting the COM antenna in a glass fiber fin, when the rest of the aircraft is carbon, but what do you do about antenna spacing for COM-2's antenna? On Rudi's KIS Cruiser, no one thought about the NAV antenna position until after the stabaliser was completed, mostly because Rudi initially was not going to use NAV at all. Because his whole leading edge of the wing is fuel, he was going to mount the NAV antenna in the fuselage floor, along with the glide slope antenna. On the Glasair III that we are building, the stabaliser is carbon. The owner wants to fit wet wing tips, so the only place left for the NAV antenna is on the bottom of the glass fiber fuselage. If it were carbon, the only place would have been on the outside. As far as the length of the foil strips are concerned for your NAV antenna, I think that it is good enough to just add to the length that we tested for the COM antenna in inverse proportion to the frequency. Use the center of each band as the frequency to calculate from. Perhaps we will be lucky and the CAA will publish GPS non precision approaches and we can dump all these old fashioned schemes like VOR and NDBs for navigation. None of it works where you need it in Africa anyway. I would have thought that by now, with all the glass fiber aircraft out there, someone would have tested a NAV antenna inside the bottom of a fuselage shell. I don't know offhand where Grob mounts the VOR antenna in their G115. It certainly is inside somewhere. On the G109B motor glider, the antenna was not in the stabaliser. I can check with GROB and Becker, if anyone is interested to know. Regards, Peter How Composite Technologies email: afriair@tiga.cis.co.za Tel/Fax: +27 11 805 1491 "A million parts just an email away" --------------3097753913DE--