Date: Sat, 11 Jan 1997 15:43:36 -0500 From: ponciroli@postoffice.worldnet.att.net Subject: COZY: Antenna Instalation in the Canard I need some information regarding antenna installation in the canard of a Cozy MKIV I want to install Nav antennas in both sides of the canard, one as the active Nav and the other as a spare. I am installing both antennas on the under side leading edge of the canard My question to the gentry is, is this the best location for the Cozy MKIV? If it is, how should I route the antenna wire? I would appreciate any input from my learned brethren, Thankyou. Don Ponciroli ponciroli@postoffice.worldnet.att.net Date: Sat, 11 Jan 1997 14:25:54 -0700 (MST) From: Ron Lee Subject: Re: COZY: Antenna Instalation in the Canard I am redoing my LE canard and intend to leave out the VOR antenna this time. I will use GPS for navigation. You may want to check the status of VORs since I think they will be phased out because of GPS. Do not know the timetable. Ron Lee At 15:43 97/1/11 -0500, you wrote: >I need some information regarding antenna installation in the canard of a >Cozy MKIV > Don Ponciroli ponciroli@postoffice.worldnet.att.net > From: Marc J. Zeitlin Subject: COZY: Antenna Instalation in the Canard (fwd) Date: Mon, 13 Jan 97 10:20:10 EST Don Ponciroli wrote; >I want to install Nav antennas in both sides of the canard, one as the >active Nav and the other as a spare. I am installing both antennas on the >under side leading edge of the canard > >My question to the gentry is, is this the best location for the Cozy MKIV? >If it is, how should I route the antenna wire? According to Jim Weir, this is a perfectly fine location. Get the RST info pack for more info on wire routing, etc. - check the archives for RST info, or check their web page: http://www.rst-engr.com/ I've got my Marker Beacon antennae (yeah, like I'll ever use _that_ :-) ) in my canard, one NAV in the fuselage, one NAV in one wing, the GS in the other wing, and a COM in each winglet. The GPS will go in the nose. For $5/antennae for the NAV/COM/MB/GS, what the heck, put them in. NAV antennae should be horizontally polarized (hence the wing, canard, or fuselage bottom location) and COM should be vertically polarized (hence the winglet location). Check the archives for more infor on antennae - there's a lot. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Mon, 13 Jan 1997 11:50:21 -0500 From: Jeff Subject: Re: COZY: Antenna Instalation in the Canard At 10:20 AM 1/13/97 EST, you wrote: >Don Ponciroli wrote; > >>I want to install Nav antennas in both sides of the canard, one as the >>active Nav and the other as a spare. There might be a problem with this. If two antennas (even a passive, spare antenna) are in close proximity with each other and have resonant frequencies that are close, then they may interact with each and alter the radiation pattern and system impedance. I am not enough of an antenna man to say for certain - Jim Weir ought to be able to confirm or debunk this. Jeff Rosson From: Lee Devlin Subject: COZY: Canard antenna Date: Sun, 19 Jan 1997 9:49:40 MST I was about to install a nav antenna in my canard and am a little undecided about which antenna would be best to put there. I have the choice of the Nav, Marker Beacon, or Glide Slope. I've already got a nav antenna in the belly and will probably put one in the wings. I'm also a little unsure about the future of Nav, MB, and GS signals. The FAA is making a lot of noise aobut decommissing the VOR stations, but one would think that the marker beacons may stay indefinitely. Also, will glide slope play a role in in precision GPS instrument approaches? I am also a bit concerned with the canard-mounted Nav antenna's ability to receive signals while flying away from stations since the occupants and the engine are in the way. It's looking more reasonable to install either the GS or MB antenna up front in the canard. Any other opinions? Incidentally, I have one of those MFJ SWR meters and checked out the canard-mounted nav antenna on my LongEZ and found it wasn't very good (~3:1). I thought this might have to do with the fact that there's a long metal structure (torque tube) so close to it. Lee Devlin Date: Sun, 19 Jan 1997 17:22:56 -0500 From: Jim Hocut Subject: Re: COZY: Canard antenna At 09:49 AM 1/19/97 MST,Lee Devlin wrote: >I was about to install a nav antenna in my canard and am a little >undecided about which antenna would be best to put there. I have the >choice of the Nav, Marker Beacon, or Glide Slope. >...... I believe you'll be better off with the nav antennas in the wings, so that you can orientate the 2 legs at 90 degrees to each other. In the canard you won't be able to get near that angle, and performance will suffer from the sides. Plus, as you suggest, performance will be further degraded by the metal torque tubes in close proximity. The marker beacon antenna you'll want to run lengthwise in the fuselage. As it was explained to me, the signal orientation from the transmitter is from side to side, and by orienting the recieving antenna lengthwise it will be at 90 degress to the transmitted signal, and therefore less prone to tell you you're there until you'e really there. I did some computer simulations in regards to the glide slope antenna in proximity to the torque tubes, and by being in front of the torque tubes receive sensitivity is actually slightly enhanced in the forward direction (~ 1 dB). I've decided to put the glide slope antenna centered on the leading edge of the canard. In this location it will be inside the nose, so it doesn't matter if the antenna or coax are a little bit ugly. Jim Hocut jhocut@mindspring.com From: Epplin_John_A@hpmail1.90.deere.com Date: Wed, 5 Feb 97 13:00:32 -0600 Subject: COZY: FM & Marker antenna Anyone have the details for wing mounted marker and F.M. antenna? Lengths and toroid specs etc. Or the phone no. for the company that supplies kits. RST? John Epplin Mk4 #467 Date: Wed, 05 Feb 1997 14:55:58 -0500 From: "Jeff S. Russell" Organization: AEROCAD INC. Subject: Re: COZY: FM & Marker antenna Epplin_John_A@hpmail1.90.deere.com wrote: > > Anyone have the details for wing mounted marker and F.M. antenna? Lengths and > toroid specs etc. Or the phone no. for the company that supplies kits. RST? I installed a F.M. antenna in the top turtle back over the mainspar. I used no toroids for the antenna. The length of the antenna was from longeron to the center of the turtle back(1 leg on each side) conected in the center ti coax. I can pick up 100-1000 channels when at 3000' Works for me. The marker antenna will work better under the longeron on the co-pilot side. Run the coax up the back of the front seat bulkhead and join the antenna right below the longeron. You will to notch the seat back for the antenna to go through. The coax will be much shorter installing the antenna in that location. All the Velocity's install them there. -- AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 phone/ call first for fax 910-961-2238 NEW E-mail: JRAEROCAD@yadtel.net NEW homepage address: http://www.binary.net/aerocad Date: Thu, 06 Feb 1997 08:46:09 -0500 From: Jim Hocut Subject: Re: COZY: FM & Marker antenna I concur w/ Jeff as to the location for the marker antenna. RST has a page at rst-eng.com. They send a fact sheet showing all the antenna lengths you'd ever need w/ their antenna materials kit. Jim Weir makes no bones about the fact that there are other places you can get the copper tape for less, but for what little bit it costs I'll give the business to RST. Jim Hocut jhocut@mindspring.com Date: Tue, 25 Feb 1997 13:41:16 -0800 From: jerry kennel Subject: Cozy:ELT Antenna Location What is the best location on a Cozy Mark IV for the ELT antenna? From: "Rob Cherney" Organization: Ellicott City, Maryland Date: Fri, 18 Jul 1997 20:10:37 -0400 Subject: Re: COZY: Ferrite torroids for the coax > toroids are available at most ham radio shops. if they dont have them they > can get them or tell you where to get them in the city All torroids are not created equal. You need to have the proper ferrite formulation for VHF. Check the archives. Some time ago I identified a type from Amidon Associates that has acceptable properties. Either order from them or wait for Jim Weir to return from Oshkosh. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ Date: Tue, 29 Jul 1997 09:45:18 -0400 From: Bill Theeringer Subject: COZY: Ferrite Beads Hello to all who havn't yet left for Oshkosh; A few days ago someone was looking for some of those ferrite beads for th= e coax cable termination. I have them in stock for anyone needing them. = They are made by Amidon Associates of Torrance and their part number is FB43-2401. Amidon sells them for $16.00 per 100. Unfortunately they als= o have a minimum $100 order. I carry them as a convienence item and will give them free of charge to any composite builder/owner who needs them. = I was leaving for Oshkosh 2 days ago but have a bad mag harness which is now being repaired. Look for my YELLOW (cool:) Long EZ with Infinitys retract installation. = Bill Theeringer N29EZ Santa Barbara, CA. Date: Wed, 30 Jul 1997 00:49:16 -0400 From: Bill Theeringer Subject: COZY: More Ferrite Stuff I forgot to mention that for those who want to retrofit their coax with these ferrite coils but don't want to remove the coax fitting to get them= on, Amidon also manufactures a split ferrite block that clamps over the e= nd of the coax. Their part number is 2X43-251. The -43 core material has a= band width of 50 - 200 Mhz. The block is about 9/16" square and about 1+= 1/8" long. You can hold it in place with a couple of small tie wraps. I= t is made out of the same material as the beads and one block is overkill f= or our purposes. These are far more expensive than the beads but I will shi= p then for $5 a set. I only have 4 sets left so they are here if anyone needs them. = Bill Theeringer N29EZ Santa Barbara, CA = Date: Thu, 07 Aug 1997 09:38:25 +0200 From: Jean-Jacques CLAUS Subject: COZY: Transponder antenna in a winglet ? hi fellow builders, Has anyone put a transponder antenna in a winglet ? I don't want to have it under the passengers area and i am searching another good solution. All replies aprecied. Jean-Jacques CLAUS Aix-en-Provence - FRANCE Cozy Classic #CC1056 Finishing the second wing Starting winglets e-mail:fpjjc@hol.fr Subject: COZY: Re: [canard-aviators] Date: Thu, 7 Aug 97 11:07:41 -0700 From: Dick Kreidel I do not suggest that you put the transponder antenna in the winglet. Due to the high frequencies involved, there is a lot of signal loss in the coax cable - most avionics techs keep the run as short as possible (ie, 1 meter or less) with as few curves as possible. Also, I was not successful in having the transponder or DME antennas buried under the skin. Most people who I was asociated with 15 years ago eventually moved the transponder antenna to a nose (external) location. A lot has changed since I built mine, so I'm sure someone has figured out how to make it work. My tests indicated that the gray primer/and or white Imron was the culprit, not the glass or foam. By the way, the cheap ball type work just as good as the nice blade type. You only need to have about 12mm of the rod and ball hanging below the fuselage skin, if you have a suitable ground plane inside - copper screen works great. dick kreidel Date: Thu, 07 Aug 97 13:52:40 EST From: MISTER@neesnet.com Subject: Re: COZY: Transponder antenna in a winglet ? Jean-Jacques Claus Asked: "Has anyone put a transponder antenna in a winglet ? I don't want to have it under the passengers area and i am searching another good solution." First off, you want to keep the antenna lead on the transponder as short as possible because the signal is at 1000 Mhz frequency and the line loss for small coaxial cable at those frequencies is substantial. Mounting the antenna and the groundplane in the nose near the passenger or pilot's feet doesn't really present any hazard due to the short pulse duration of the transponder. This is probably the best location. I've seen sketches for mounting the antenna and ground plane in the wing leading edge near where it meets the strake. My suggestion would be to put it in the nose. Bob Misterka N342RM Date: Thu, 7 Aug 1997 18:14:25 -0400 (EDT) From: TEAMEZ@aol.com Subject: COZY: Transponder Antennae Wisdom In addition to flying my Long-EZ, am also the Transponder Program Manager for a large (OK, REALLY large) avionics company that makes 80% of the world's transponders, so here are some "hints": * Do NOT bury your transponder antenna in a winglet or wing; it won't work * Use a "real" ground plane/antenna, not a dipole * Make the ground plane as broad and flat as possible (at least 12" diameter) * Locate the antenna on a flat, LOWER aircraft surface * Keep the coax as short as possible (max. 6' is best, but can be longer) * Avoid sharp bends in the coax * Secure the coax so that it can't move/vibrate * Avoid using the Radio Shack 90-degree connectors -they're junk * Have your avionics shop adjust your frequency so that, in the plane after 30-minute's warm-up, you're at exactly 1090. 1088 or 1092 isn't "good enough". * If the ground plane is internal to the skin, and the antenna protrudes through the skin, seal the hole COMPLETELY so that no water can enter (VERY common mistake on EZ's) * Remember to get your biennial transponder check - it's required by FAR's and you could be violated on a ramp check for not having it. I hope this helps, Tom Staggs Long-EZ N13YV Olathe, KS From: "Krasa-1, Paul" Subject: RE: COZY: Transponder antenna in a winglet ? Date: Fri, 8 Aug 1997 07:18:41 -0400 I thought about it, and consulted my local radio shop. They said the lead for the transponder should be less than 6 ft. (2m) long. I installed the transponder antenna under the pilots seat. This position has worked well for many others. Paul Krasa Long EZ 214LP >---------- >From: Jean-Jacques CLAUS[SMTP:fpjjc@hol.fr] >Sent: Thursday, August 07, 1997 3:38 AM >To: cozy_builders%hpwarhw.an.hp.com@hplb.hpl.hp.com >Cc: canard-aviators@canard.com >Subject: COZY: Transponder antenna in a winglet ? > >hi fellow builders, > > >Has anyone put a transponder antenna in a winglet ? > >I don't want to have it under the passengers area and i am searching >another good solution. > >All replies aprecied. > > >Jean-Jacques CLAUS >Aix-en-Provence - FRANCE > >Cozy Classic #CC1056 >Finishing the second wing >Starting winglets > > >e-mail:fpjjc@hol.fr > > Date: Fri, 8 Aug 1997 10:38:41 -0400 From: wilhelmson@scra.org Subject: Re: COZY: Transponder Antennae Wisdom I am sure your rules for transponder installation are good advice, however; I installed mine in my strake with a 12 in square flat grd plane. It has worked fine for the last ten years. Murphies law works both ways sometimes. Jack Wilhelmson N711CZ Date: Fri, 08 Aug 1997 13:05:27 -0400 From: bil kleb Organization: NASA Langley Research Center Subject: Re: COZY: Jim Weir's Forum at Oshkosh Pmsunset@aol.com wrote: > > Haven't heard anyone say anything about attending Jim Weir's > forum on wire-marking, intercoms, etc. awesome homebuilding attitude present in the front of that tent that morning. > Eric and I caught the last portion: The wire marking was colored marks on > clear heat shrink coded similiar to resistors...ie red= 1, blk=2, etc. there was a guy between jim and peshak that talked about how to build a gps antenna for a couple bucks as opposed to the two to four hundred commercial jobs. > other gentleman talked about GPS. this is keith peshak. burt quoted him in one of his lectures. > does anyone know more about this......PS they > gave out schematics, etc. on the intercom, wire-marking, etc. jim was going to try and put the stuff on his web site (http://www.rst-engr.com/) when he got home. the peshak talks are already there, the "Navigation >From WWII Through GPS Cat III" is a must-read. -- bil Date: Sat, 9 Aug 1997 08:49:37 -0700 (PDT) From: "Mr. Radon" Subject: COZY: NAV ant. const. Well I was hopping to talk with RST but still no contact. Received the torriods from a fellow builder but am glassing the bottom today. How long are the copper tape leads and what angle separates them? Also does the width of the copper tape matter? RSVP ROY Date: Sat, 09 Aug 1997 09:44:45 -0700 From: Michael Antares Subject: Re: COZY: NAV ant. const. > Well I was hopping to talk with RST but still no contact. Received the torriods from a fellow builder but am glassing the bottom today. How long are the copper tape leads and what angle separates them? Also does the width of the copper tape matter?> You will want to get the pamphlet from RST Engineering (The RST-802 Antenna Reference Text). They're at 916-477-7388 in Grass Valley CA (at least according to the info I have and you probably know this already). All the info you need and more is in this document. To sort of answer your questions, the lead length depends on what kind of antenna you are doing; assuming it's a nav antenna, each lead is 22.8 inches. The separation angle should be as broad as possible and for the antenna on the bottom of the fuselage, be careful to install it so that it will clear the landing gear cutout! The width should be at least 1/2 inch (the width affects the bandwidth of the signal reception, wider is better). Regards, Michael 6077 Old Redwood Highway Penngrove, CA 94951 707.792.7971 Systems engineering hardware/software From: gperry@usit.com Date: Sat, 9 Aug 1997 19:38:47 -0400 (EDT) Subject: COZY: Antennas To sort of answer your >questions, the lead length depends on what kind of antenna you are doing; >assuming it's a nav antenna, each lead is 22.8 inches. The separation angle >should be as broad as possible and for the antenna on the bottom of the >fuselage, be careful to install it so that it will clear the landing gear >cutout! The width should be at least 1/2 inch (the width affects the >bandwidth of the signal reception, wider is better). > >Regards, >Michael You might want to clear the nose gear cutout area by at least an inch so that you can make a nice flox corner for the nose wheel cover one day. I didn't and had to do some repair of the antenna lead after I accidently routed through it trying to do the above. Sometimes, the learning curve sucks! :-) Gregg Perry Date: Sun, 10 Aug 1997 09:28:48 -0400 (EDT) From: TEAMEZ@aol.com Subject: COZY: Transponder Coax Cables and antenna locations According to the installation manual for the AlliedSignal Bendix/King KT76A and KY76C transponders (as well as the guy who designed the things), ensure that: 1) "To prevent rf (radio frequency) interference, the antenna must be physically mounted a minimum distance of three feet from the transponder and its wiring harness" (pg. 2-4) 2) "Where practical, plan the antenna location to keep cable lengths as short as possible and avoid sharp bends in the cable to avoid VSWR" (def'n: reflected standing waves in the coax, which destroys output power) 3) The maximum allowable coax length is 11' if you use RG-400 coax, although some installations are permissible with coaxes up to 38' in length with the right cable and connector combinations (pg. 2-24/5) 4) " All antenna mounts should be sealed around from the outside for moisture protection using RTV or equivalent." What does this imply? On EZ's, keep the antenna under the thigh support or passenger's back seat. It's simple, safe, and it works. Tom Date: Wed, 13 Aug 1997 15:05:38 -0700 From: Michael Antares Subject: Re: COZY: COZY III: Installing a Nav antenna before glassing At 05:37 PM 8/13/97 -0400, you wrote: >Hi everyone, > > I'm planning on installing some RST copper tape for a NAV antenna before glassing the outside skin on my Cozy III fuselage (gulp). I'd appreciate advice on a couple of points : > > What is the best way to secure this tape to the foam? The tape is self adhesive, but should it be microed into the foam or applied onto a cured micro surface, -rather than stuck on bare foam? > I simply applied it directly to the foam surface (which I had vacuumed to remove any dust/debris). I then did the micro fill prior to glassing which, when squeegeing, pressed and retained the tape tight against the foam. I didn't notice any bump after glassing. > Also, can anyone out there tell me the best way to place the antenna and route the coax through the skin? It looks as though I should be able to put the apex of the antenna V under the instrument panel and then route the cable straight up behind the panel. Is that path available, any better solutions? > That is how I did it, the V on mine starts about 18" back from the F22 bulkhead and angles forward--I actually let it go slightly around the sides, being a compromise between not having too sharp a V and still trying to keep the antenna horizontal. As others have mentioned, take care not to put it where it will be in the way of the front landing gear cutouts later. Michael 6077 Old Redwood Highway Penngrove CA 94951 707.792.7971 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 20. One wing/winglet finished, working on second. From: Marc J. Zeitlin Subject: COZY: COZY III: Installing a Nav antenna Date: Thu, 14 Aug 97 10:02:48 EDT John Ellor wrote: > I'm planning on installing some RST copper tape for a NAV antenna >before glassing the outside skin on my Cozy III fuselage (gulp). I'd >appreciate advice on a couple of points : ............ Deja Vu, all over again :-). Michael Antares gave a good explanation - I did about the same thing. You can read the full discussions regarding antennae installation and recommendations (ad nauseum :-) ) by getting the archives for antennae from 1995, 1996, and 1997. Use the instructions in your charter to do so. Or (for those of you who _DON'T_ have your charter pinned up on the wall next to your computer :-) ) just send an email to: majordomo@hpwarhw.an.hp.com with the lines: get cozy_builders topics95/antennae.txt get cozy_builders topics96/antennae.txt get cozy_builders topics/antennae.txt end in it. Happy reading. -- Marc J. Zeitlin Email: marcz@an.hp.com From: RGCardinal@aol.com Date: Tue, 2 Sep 1997 17:21:17 -0400 (EDT) Subject: COZY: Xponder locations Looking for some input on locating the transponder antenna. Various options include the nose area or the aft lower fuselage or even the very bottom of the cowl at the firewall. I'm interested in avoiding microwave exposure, hence am reluctant to locate in the nose. Any input from those who've done it would be appreciated Regards Robert Kittler SN 589 From: Marc J. Zeitlin Subject: COZY: Xponder locations (fwd) Date: Tue, 2 Sep 97 17:36:50 EDT Robert Kittler wrote; >I'm interested in avoiding microwave exposure, hence am reluctant to locate >in the nose. Any input from those who've done it would be appreciated Oooh, that old bugaboo about protecting the "family jewels" from the nasty microwaves :-). Jim Weir (RST) and others have debunked this fear a number of times, and we've had discussions about this in the past. The power levels are too low to worry about, according to people who should know about these things. Just don't put the antenna directly under the pilot's seat, or if you do, line the bottom of the seat with aluminum foil. I've seen a number of installations in the nose, all of which I've been told work just fine. Some of them have the antenna completely internal (as mine will be) and some of them have it sticking out through the skin. I've seen other installations with the antenna in the strake (I'd be more worried about microwave radiation into my head, from that vantage point :-) ), and some under the passenger seat (with foil protection). -- Marc J. Zeitlin Email: marcz@an.hp.com From: cdenk@ix.netcom.com Date: Tue, 2 Sep 1997 17:57:41 -0500 (CDT) Subject: Re: COZY: Xponder locations (fwd) On 09/02/97 17:36:50 you wrote: > >Robert Kittler wrote; > >>I'm interested in avoiding microwave exposure, hence am reluctant to locate >>in the nose. Any input from those who've done it would be appreciated > >Oooh, that old bugaboo about protecting the "family jewels" from the >nasty microwaves :-). Jim Weir (RST) and others have debunked this fear >a number of times, and we've had discussions about this in the past. The >power levels are too low to worry about, according to people who should >know about these things. > >Just don't put the antenna directly under the pilot's seat, or if you do, >line the bottom of the seat with aluminum foil. > >I've seen a number of installations in the nose, all of which I've been >told work just fine. Some of them have the antenna completely >internal (as mine will be) and some of them have it sticking out through >the skin. I've seen other installations with the antenna in the strake >(I'd be more worried about microwave radiation into my head, from that >vantage point :-) ), and some under the passenger seat (with foil >protection). > >-- >Marc J. Zeitlin Email: marcz@an.hp.com > > I have transponder antenna under passenger seat, with 16" dia. .012 alum. ground plane. Probably will move to strake/wing surface with now available mylar PCB antenna. Date: Wed, 24 Dec 1997 16:09:16 -0600 From: Curt Smith Subject: COZY: Transponder Antenna I'm in the process of installing a transponder antenna in the Long Ez that I recently bought to keep me in the air while finishing the Cozy. It's a "streamlined" Narco antenna. How much of the antenna has to hang out in the breeze? It's 3.5" tall and there is 1.5" of foam/fiberglass where I'm installing it. Is 2" exposure enough? When I did this on my VariEze, I used a short whip version and, as I recall, only the tip had to be exposed for it to work properly. With just an 1" or so exposed, it worked great. Also, what's the rule of thumb on the size of a ground plane? Curt Smith From: cdenk@ix.netcom.com Date: Thu, 25 Dec 1997 09:09:27 -0600 (CST) Subject: Re: COZY: Transponder Antenna C. Smith writes My installation is a similar blade antenna mounted under the right seat (COSY) on the fuselage bottom surface. There is a 0.012" aluminum 16" diameter ground plain above the fiberglass outer skin. To improve bond there are .5" holes at about 2" centers all over the aluminum. The foam fuselage bottom was routered out to provide a recess for the aluminum. There is a doubler plate atop the .012 aluminum with nutplates to anchor the antenna. There is a separate ground wire to the airframe ground. The installation works very well and its extremely rare that our transponder signal is not received. We fly radar contact frequently. I am concerned with the microwave energy being so close to wife and self backside. Considering one of the new foil antennas mounted on the strake end aft of the wing leading edge. Could use some comments, has anyone had experience? I think the blade antenna is intended to be mounted directly to the ground plane, since for an aluminum skin the manufacturer would try to minimize the projection. If the ground plane would be mounted to the inside fuselage bottom foam, then the question is how much of the signal is going to be blocked, reflected, absorbed by the foam, outer glass, and paint. I can't answer that, but if I go with a new antenna, I will preserve the mount and wiring for the old. From: Marc J. Zeitlin Subject: COZY: Transponder Antenna (fwd) Date: Thu, 25 Dec 97 11:40:28 EST Curt Smith wrote: >...... How much of the antenna has to hang out in the >breeze? It's 3.5" tall and there is 1.5" of foam/fiberglass where I'm >installing it. Is 2" exposure enough? With a fiberglass plane, as long as you've got an antenna with a ground plane, NONE of it _has_ to be "exposed" - the glass/epoxy doesn't attenuate the signal, so the whole antennae could be inside the plane. >Also, what's the rule of thumb on the size of a ground plane? According to Jim Weir (RST) the ground plane for a transponder antennae should be odd multiples of 5.3" in diameter (that's why Carl Denk's 16" works well - it's almost exactly 15.9"). I made a 5.3" diameter 1/16" thick ground plane from aluminum, mounted a stub antenna from Aircraft Spruce in the center, and mounted that to a tab in the nose of the COZY. Nothing protrudes from the plane. I don't know if this info on ground planes applies to anything other than the stub antenna, but the 3.5" height makes them sound pretty similar. With respect to Carl's concern about microwave energy, there is no evidence that the tiny amounts of energy radiated by transponder antennae have any deleterious effects whatsoever. This has been discussed in the archives before. -- Marc J. Zeitlin Email: marcz@an.hp.com From: melshire@imt.net Date: Thu, 25 Dec 1997 12:58:37 -0700 Subject: Re: COZY: Transponder Antenna (fwd) Marc J. Zeitlin wrote: > > Curt Smith wrote: > > >...... How much of the antenna has to hang out in the > >breeze? It's 3.5" tall and there is 1.5" of foam/fiberglass where I'm > >installing it. Is 2" exposure enough? > > With a fiberglass plane, as long as you've got an antenna with a ground > plane, NONE of it _has_ to be "exposed" - the glass/epoxy doesn't > attenuate the signal, so the whole antennae could be inside the plane. > > >Also, what's the rule of thumb on the size of a ground plane? > > According to Jim Weir (RST) the ground plane for a transponder antennae > should be odd multiples of 5.3" in diameter (that's why Carl Denk's 16" > works well - it's almost exactly 15.9"). > > I made a 5.3" diameter 1/16" thick ground plane from aluminum, mounted > a stub antenna from Aircraft Spruce in the center, and mounted that to > a tab in the nose of the COZY. Nothing protrudes from the plane. > > I don't know if this info on ground planes applies to anything other > than the stub antenna, but the 3.5" height makes them sound pretty > similar. > > With respect to Carl's concern about microwave energy, there is no > evidence that the tiny amounts of energy radiated by transponder > antennae have any deleterious effects whatsoever. This has been > discussed in the archives before. > > -- > Marc J. Zeitlin Email: marcz@an.hp.com One thing to remember when you mount any ant inside the fusalage. Any metal, moisture[your body], inst panel,engine, just think of anything that might block the sig from getting to the station. Very directional. I,ve had instalations with the antenna mounted in the tail section and when inbound wouldn,t work.Turn the a/c a few degrees either way and every thing is fine. Also remember that the radar isn,t always on the airport.When you go to the work to hide the antenna and it doesn,t work then most of the time you end up mounting it on the outside of the a/c someplace you wouldn,t want it. Martin Elshire cozy N615PM Email:melshire@imt.net Date: Sun, 28 Dec 1997 15:14:04 -0500 From: Eddie VANN <100740.3723@compuserve.com> Subject: COZY: Transponder Antennas & Fuel Guages 1) I used Antennas from R.S.T. for both Transponder and D.M.E. on my Long-Ez. I mounted them in the space between the tank end and the end of the strake so they were both completely inside the structure. They worked= very well. Stupidly, I did not protect the connections from moisture and = so I started to loose performance after about 4 years due to corrosion. I ha= ve re-done the connections on the D. M. E. antenna, and added silicon goo protection, and this is working as before. In removing the antennas for service, I damaged the one for the transponder one and to save time I fitted the blade antenna supplied with the (Narco) transponder mounted entirely outside the fuselage underside with the "ground plane" supplied = by Narco on the inside of the skin. This works fine but not noticeably bette= r than the previous, fully concealed, installation. 2) I fitted fuel sight gauges from Paul Prout plus a micro mointor from Rocky Mountain Instruments. Thus I have "What-you-see-is-what-you-have" plus analyses of where it's going and how long you can keep up the enjoyment (complete with audible warning). This still seems a better sche= me than fitting an electronic equivalent of the sight guages. The micromonit= or covers fuel use and lots more in a very small panel space. I heartily recommend it. For the guy who habitually obscures his sight gauges!!!, I recommend careful verification of the time flown on each tank coupled wit= h the deliberate emptying of a tank when at altitude. From this one has a pretty good idea of when the noise will stop definitively. 3) I have just fitted an Aiflow Performance injection system, primarily t= o eliminate the risk of carb icing. It is working very well, with more powe= r and smoother running. There is no reasonable comparison with the 1920's e= ra Marvel-Schriber device. I am building a controllable ram-air inlet using the redundant hot air control cable. I need a coarser prop to handle the power. I hope your Noels were Joyeuses and that your Nouvelles Ann=E9es will be = full of Bons Vols Eddie Vann, Long-Ez F-PGEV