---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 03/28/20: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:10 AM - Re: ADS-B Ground Plane Question (Charles Brame) 2. 07:32 AM - Re: ADS-B Ground Plane Question (user9253) 3. 11:13 AM - Re: Re: ADS-B Ground Plane Question (n1dw) 4. 01:48 PM - Re: ADS-B Ground Plane Question (markfw) ________________________________ Message 1 _____________________________________ Time: 07:10:57 AM PST US From: Charles Brame Subject: AeroElectric-List: Re: ADS-B Ground Plane Question Time: 03:15:12 PM PST US Subject: AeroElectric-List: ADS-B Ground Plane Question From: "markfw" > Mark, Mark, I mounted my uAvionix echoUAT ADS-B antenna on the belly of my RV-6A and just aft of the firewall. It is located less than 30 inches horizontally from the transponder antenna. Works like a charm. Charlie Brame RV-6A, N11CB San Antonio =94=94=94=94=94=94=94=94 =94=94=94=94=94=94=94=94 =94=94=94=94=94 I will be mounting a uAvionix echoUAT ADS-B antenna on the belly pan of my cub. The vendor says to keep it 1 meter from my transponder antenna, which is mounted 14" forward of the leading edge of my belly pan. The pan itself is an isosceles triangle with a 15" base and a length of 32". The pointy part of the pan is oriented facing aft. Thus I have to place my Rami blade antenna toward the narrow (aft) part of the belly pan to stay 1 meter away from the transponder antenna. My problem is that at the location that is sufficiently far from the transponder antenna the belly pan has narrowed so that it does not provide the 5" diameter circular ground plane that is apparently required. SO (after all that), my question is whether the ground plane is only the part of of the belly pan that is immediately adjacent to the antenna, or is it the whole belly pan? A related question is whether I can "cheat" the antenna forward a few inches? Since antenna radiated power varies inversely with the square of the distance does that imply that I could move the antenna 6' - 8" closer to the transponder antenna without a significant problem? I am just trying to establish what my boundary conditions are with respect to the antenna location. Thanks. Mark Read this topic online here: http://forums.matronics.com/viewtopic.php?p=495455#495455 ________________________________ Message 2 _____________________________________ Time: 07:32:28 AM PST US Subject: AeroElectric-List: Re: ADS-B Ground Plane Question From: "user9253" I would cheat, but only 3 or 4 inches. Move the antenna forward so that the two antennas are about 36 inches apart. The ground plane does not have to be a perfect circle. If the ground plane extends the correct distance in 3 equally spaced directions (120 degrees), that is good enough. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=495457#495457 ________________________________ Message 3 _____________________________________ Time: 11:13:57 AM PST US From: "n1dw" Subject: RE: AeroElectric-List: Re: ADS-B Ground Plane Question Charlie, I recently installed a vertical monopole antenna on the belly of my Glastar (haven=99t had a chance to test it yet). The instructions for the antenna specifically said NOT to use a circular ground plane (apparently it can set up some interference with the antenna function) and suggested using a rectangular shape to reduce the interference possibility. The 5=9D dimension is a minimum, twice as large is more effective, but the benefits beyond that diminishes quickly. In your situation, with the antenna very near the apex, the ground plane would probably act more like a foil ground with two foil ribbons both facing forward (essentially along the edges of your triangle. Doesn=99t sound like a good arrangement to me. I used a 10=9D square of .020 aluminum for my ground plane. Could you possibly do the same? Either mounting the ground plane aft of your triangle, or near the apex if that option is not practical? Doug Windhorn From: owner-aeroelectric-list-server@matronics.com On Behalf Of Charles Brame Sent: Saturday, March 28, 2020 7:10 AM Subject: AeroElectric-List: Re: ADS-B Ground Plane Question Time: 03:15:12 PM PST US Subject: AeroElectric-List: ADS-B Ground Plane Question From: "markfw" < markwheelermd@icloud.com> Mark, Mark, I mounted my uAvionix echoUAT ADS-B antenna on the belly of my RV-6A and just aft of the firewall. It is located less than 30 inches horizontally from the transponder antenna. Works like a charm. Charlie Brame RV-6A, N11CB San Antonio =94=94=94=94=94=94=94=94 =94=94=94=94=94=94=94=94 =94=94=94=94=94 I will be mounting a uAvionix echoUAT ADS-B antenna on the belly pan of my cub. The vendor says to keep it 1 meter from my transponder antenna, which is mounted 14" forward of the leading edge of my belly pan. The pan itself is an isosceles triangle with a 15" base and a length of 32". The pointy part of the pan is oriented facing aft. Thus I have to place my Rami blade antenna toward the narrow (aft) part of the belly pan to stay 1 meter away from the transponder antenna. My problem is that at the location that is sufficiently far from the transponder antenna the belly pan has narrowed so that it does not provide the 5" diameter circular ground plane that is apparently required. SO (after all that), my question is whether the ground plane is only the part of of the belly pan that is immediately adjacent to the antenna, or is it the whole belly pan? A related question is whether I can "cheat" the antenna forward a few inches? Since antenna radiated power varies inversely with the square of the distance does that imply that I could move the antenna 6' - 8" closer to the transponder antenna without a significant problem? I am just trying to establish what my boundary conditions are with respect to the antenna location. Thanks. Mark Read this topic online here: http://forums.matronics.com/viewtopic.php?p=495455#495455 ________________________________ Message 4 _____________________________________ Time: 01:48:00 PM PST US Subject: AeroElectric-List: Re: ADS-B Ground Plane Question From: "markfw" Thanks everyone for your replies. It seems that the consensus is that I need to be far enough forward to have 5" of belly pan on each side of the antenna, which for me would be about 32". And, for at least one person, that distance worked. This helps me establish the boundary conditions that I was looking for. Mark Read this topic online here: http://forums.matronics.com/viewtopic.php?p=495459#495459 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.