Ground Plane

[lwford]

I'm curious, has anyone added a ground plane to their Bellanca? My crate has a noticeable difference between comm 1and 2. There are a number of ways to make a ground plane. I have an antenna mounted on the top fuselage behind the baggage compartment. It is mounted where the rotating beacon used to be and I used a series of .040 safty wire splines for the grd plane. If you recall, they built these crates with a beacon on top and on bottom. I still retain the bottom beacon. The top is now the antenna for comm 2 and I would like to install a better ground plane as that is the weaker radio. I did a little test on this by swapping antenna leads and listening to Atis 20 miles from the airport. I have Collins comm and nav and they were installed back in the early 70s still work and once in awhile I have to replace a burnt out digit from my spare parts. If they fail I would put in an Icom a great comm at a good price. Getting old mid 70s and the insurance keeps going up: over 70, tailwheel complex airplane> I press on Lynn the crate :idea:

 

[Rob58]

Hi Lynn, a quick disclaimer: I’m not an RF expert but have done a lot of research to understand how to achieve the best performance out of an aircraft radio. Having made several long cross county trips in my new ride (Dave Lynn’s old bird) I can tell you firsthand how frustrating it is to have a weak radio signal while on flight following and somewhat demeaning to ask a Delta jet to relay messages to ATC. So I want these problems solved too! A few years ago at OSH the folks at RAMI antennas had a demonstration setup specifically to show the signal strength difference with and without a suitable ground plane. Really dramatic. My strategy is to use copper foil to fashion the ground plane and bond this to the underside of the fabric, with a yet to be determined adhesive. This way I can form the foil to fit around anything that might be in the way. The legs of the gp needs to be a minimum of a quarter wavelength, but larger is good. There is also the issue of tuning the antenna connection to achieve the lowest SWR – another process that I am experimenting and learning more about. I plan to do some testing similar to what you have done. Please keep us posted on your progress.

 

[Ralph925]

I used thin aluminum strips about 5/8” wide running under the fabric and following the bottom of the fuselage around the corner and up the sides for some distance, also running fore and aft as far as practical. I fiddled with the length of the strips using an SWR meter.
Every once in a while, I need to clean connections as the radio gets scratchy over time. This winter the problem was the connection from the radio to the tray. Removing it and reinserting fixed the problem.