---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 04/13/22: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:38 AM - Re: Transponder antenna ground plane (Eric Page) 2. 09:22 AM - Re: Re: Transponder antenna ground plane (Robert L. Nuckolls, III) 3. 10:35 AM - Re: Re: Transponder antenna ground plane (Charlie England) 4. 11:37 AM - A fascinating watch . . . (Robert L. Nuckolls, III) 5. 11:52 AM - Re: A fascinating watch . . . (Daniel Clark) 6. 01:13 PM - Re: A fascinating watch . . . (Bill Settle) ________________________________ Message 1 _____________________________________ Time: 07:38:49 AM PST US Subject: AeroElectric-List: Re: Transponder antenna ground plane From: "Eric Page" Yes, I seem to remember reading something about that. I have no plans to fly into Canada, but I wonder what will be required, hardware-wise, to satisfy their requirement. I presume you would need a transponder designed for multiple antennas. It looks like uAvionix's tailBeaconX satisfies the Canadians, but beyond that, I have no idea! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=506545#506545 ________________________________ Message 2 _____________________________________ Time: 09:22:21 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Transponder antenna ground plane At 09:41 PM 4/12/2022, you wrote: > >Next year Canada is going to require aircraft flying in Class A & B >airspace to be able to send transponder signals to satellites. This >requirement can be met either through antenna diversity (the use of >a top and bottom antenna) or with a single antenna that is capable >of transmitting both towards the ground and up towards satellites. > I have never seen transponder antennas on top of airplanes > either. But chances are that an antenna on top would work just as > well as one on the bottom. The quater-wave, ground-plane antenna has a radiation patter like shown in this illustration. Very attenuated response 'below' the ground plane. Probably even more attenuation on a 'large' ground plane like an aircraft skin. Looking at the elevation pattern we see the major lobe is displaced about 30 degrees off the ground plane . . . i.e. favoring ground based stations when mounted upside down. Response out to the horizon is only down 3db . . . Talking to satellites? Got any links to expand on that? I'm wondering what service is expected to use xponder data . . . and for what purpose. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 3 _____________________________________ Time: 10:35:42 AM PST US Subject: Re: AeroElectric-List: Re: Transponder antenna ground plane From: Charlie England On 4/13/2022 11:17 AM, Robert L. Nuckolls, III wrote: > At 09:41 PM 4/12/2022, you wrote: >> >> Next year Canada is going to require aircraft flying in Class A & B >> airspace to be able to send transponder signals to satellites. This >> requirement can be met either through antenna diversity (the use of a >> top and bottom antenna) or with a single antenna that is capable of >> transmitting both towards the ground and up towards satellites. >> I have never seen transponder antennas on top of airplanes either. >> But chances are that an antenna on top would work just as well as one >> on the bottom. > > The quater-wave, ground-plane antenna has a > radiation patter like shown in this illustration. > Very attenuated response 'below' the ground plane. > Probably even more attenuation on a 'large' ground > plane like an aircraft skin. > > Looking at the elevation pattern we see the major > lobe is displaced about 30 degrees off the ground > plane . . . i.e. favoring ground based stations > when mounted upside down. Response out to the > horizon is only down 3db . . . > > Talking to satellites? Got any links to > expand on that? I'm wondering what service is > expected to use xponder data . . . and for > what purpose. It's just ADS-B, with a/c transmissions received by satellites. To the FAA: Can I get a 'duh...'? https://aireon.com/resources/overview-materials/its-just-ads-b/ Charlie -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 4 _____________________________________ Time: 11:37:52 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: A fascinating watch . . . Get a bowl of popcorn and a large enough jug to last 80 minutes. Found this documentary to be rather spell binding . . . https://youtu.be/2ayA2UE-p8M Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 5 _____________________________________ Time: 11:52:46 AM PST US Subject: Re: AeroElectric-List: A fascinating watch . . . From: "Daniel Clark" Great documentary on Bob Hoover ! > > Get a bowl of popcorn and a large enough jug to last > 80 minutes. Found this documentary to be rather > spell binding . . . > > https://youtu.be/2ayA2UE-p8M > > > Bob . . . > > Un impeachable logic: George Carlin asked, "If black boxes > survive crashes, why don't they make the whole airplane > out of that stuff?" > ________________________________ Message 6 _____________________________________ Time: 01:13:07 PM PST US From: "Bill Settle" Subject: RE: AeroElectric-List: A fascinating watch . . . Bob, Thanks for sharing! Bill Settle From: owner-aeroelectric-list-server@matronics.com On Behalf Of Robert L. Nuckolls, III Sent: Wednesday, April 13, 2022 2:37 PM Subject: AeroElectric-List: A fascinating watch . . . Get a bowl of popcorn and a large enough jug to last 80 minutes. Found this documentary to be rather spell binding . . . https://youtu.be/2ayA2UE-p8M Bob . . . 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