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MJKTuck(at)cs.com
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 Posted: Sat Dec 23, 2017 3:23 pm Post subject: Transponder Ground Plane |
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Merry Christmas everyone.
I have a Garmin 327 transponder and a short antenna with a small ball on
the end. When I installed it, Bob Nuckolls advised that the ground plane
should to be an aluminum disc the radius of which is the same as the
length of the antenna. So my disc is probably 5-6 in diameter. It seems
to work OK, around this area at least which is about 10 nm from ATC.
Looking at upgrading to the Dynon Transponder in order to meet the 2020
NextGen requirement here in the States. Reading the install instructions
it says:
<<The ground plane should be as large as you can sensibly make it.
Because it is a function of the wavelength of the transmission, the
smallest practical ground plane for a transponder is a square around 120
mm per side; as the size increases the performance improves until the
ground plane is around 700 mm on each side. Anything much larger than
that size is unlikely to show significant further improvement.>>
So my disc is slightly larger than the 120 mm square referenced but
according to Dynon the bigger you make it the better the performance.
As I have plenty of room, is there any merit in increasing the size of
the ground plane? What have others done - particularly for a Dynon set up?
Regards,
Martin Tuck
Europa N152MT
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erichdtrombley(at)juno.co
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| Posted: Sat Dec 23, 2017 9:12 pm Post subject: Transponder Ground Plane |
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Hello Martin,
| Quote: | From your description it sounds like I have the same ball transponder antenna and ground plane setup. I too converted from the Garmin 327 to Dynon’s transponder. I did not modify the antenna and performance has not been an issue. I operate out of class B airspace.
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Merry Christmas,
Erich
N28ET Classic 914
____________________________________________________________
Duchess Says Goodbye To Royal Family
risingstarnewspaper.com
http://thirdpartyoffers.juno.com/TGL3131/5a3f36fcd2b4336fc1be0st03vuc
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Ivor
Joined: 23 Jul 2015
Posts: 51
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| Posted: Sun Dec 24, 2017 12:17 am Post subject: Re: Transponder Ground Plane |
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like wise i fitted a trig 21 mode S replacing my Garmin 327 and kept the
same size ground plane as Bob Nuckolls suggested,
it works fine so why put in more weight for no quantifiable return
merry christmas
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h&jeuropa
Joined: 07 Nov 2006
Posts: 645
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| Posted: Sun Dec 24, 2017 9:33 am Post subject: Re: Transponder Ground Plane |
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Martin,
From my experience as a ham radio operator, the ground plane antenna you describe is made correctly. The radiating element (the vertical rod) is 1/4 wavelength and the ground plane should be the same dimension. That is exactly what I have in my Europa and it has worked flawlessly for over 15 years and two transponders (Garmin GTX 327 and now Appareo ESG).
Why Dynon suggests a larger ground plane I don't understand. Antenna theory says that the ground plane should be the same 1/4 wavelength as the radiating element.
Jim
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Fred Klein
Joined: 26 Mar 2012
Posts: 503
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| Posted: Mon Dec 25, 2017 10:38 am Post subject: Transponder Ground Plane |
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| Quote: | On Dec 24, 2017, at 9:33 AM, h&jeuropa <butcher43(at)att.net (butcher43(at)att.net)> wrote:
Why Dynon suggests a larger ground plane I don't understand. Antenna theory says that the ground plane should be the same 1/4 wavelength as the radiating element.
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In their instructions regarding antennas, does Dynon make any distinction between metal & FG composite airframes…?…or is that irrelevant…?...
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r.vogel(at)ggs.ch
Guest
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| Posted: Fri Dec 29, 2017 8:46 am Post subject: Transponder Ground Plane |
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An other solution is a dipole antenna inside the fuselage.
There is no Ground Plane with this kind of antenna and nothing outside
the fuselage.
Available from Spruce. Part #: 11-04212.
See:http://www.aircraftspruce.com/catalog/avpages/antennasystems1.php
See the attached pictures about the installation inside my Classic with
the TRIG TT21 main unit
close to the antenna. The same installation has been made with the radio.
These installations has been passed all the checks and work fine.
Best regards, Ruedi
Am 24.12.2017 um 09:17 schrieb Ivor:
| Quote: |
like wise i fitted a trig 21 mode S replacing my Garmin 327 and kept the
same size ground plane as Bob Nuckolls suggested,
it works fine so why put in more weight for no quantifiable return
merry christmas
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476732#476732
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--
Ruedi Vogel
Wiesenweg 6
CH-3380 Wangen a.A.
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tennant
Joined: 19 Apr 2011
Posts: 121
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| Posted: Fri Dec 29, 2017 11:33 am Post subject: Re: Transponder Ground Plane |
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Hi Ruedi,
I thought that you had secretly photographed inside my fuselage!!
My Setup is absolutely identical and has been working perfectly for 20 years. I can only recommend it.
Best regards and HAPPY NEW YEAR
Barry Tennant
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_________________
Barry Tennant
D-EHBT
At EDLM - Germany |
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Duncan McFadyean
Joined: 18 Jan 2011
Posts: 220
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| Posted: Fri Dec 29, 2017 12:02 pm Post subject: Transponder Ground Plane |
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Ruedi,
Can you confirm the precise dimensions of the small alloy plate covering the tufnol of the comms antenna please, and the thickness of the tufnol.
Rgds.,
Duncan McF.
| Quote: | ----Original Message----
From: r.vogel(at)ggs.ch
Date: 29/12/2017 16:37
To: <europa-list(at)matronics.com>
Subj: Re: Re: Transponder Ground Plane
An other solution is a dipole antenna inside the fuselage.
There is no Ground Plane with this kind of antenna and nothing outside
the fuselage.
Available from Spruce. Part #: 11-04212.
See:http://www.aircraftspruce.com/catalog/avpages/antennasystems1.php
See the attached pictures about the installation inside my Classic with
the TRIG TT21 main unit
close to the antenna. The same installation has been made with the radio.
These installations has been passed all the checks and work fine.
Best regards, Ruedi
Am 24.12.2017 um 09:17 schrieb Ivor:
| Quote: | --> Europa-List message posted by: "Ivor" <g-iver(at)live.co.uk>
like wise i fitted a trig 21 mode S replacing my Garmin 327 and kept the
same size ground plane as Bob Nuckolls suggested,
it works fine so why put in more weight for no quantifiable return
merry christmas
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=476732#476732
|
--
Ruedi Vogel
Wiesenweg 6
CH-3380 Wangen a.A.
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