---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 10/24/20: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:34 PM - Re: ADS-B and Transponder antenna... (Charlie England) ________________________________ Message 1 _____________________________________ Time: 01:34:24 PM PST US From: Charlie England Subject: Re: AeroElectric-List: ADS-B and Transponder antenna... On Thu, Oct 1, 2020 at 8:59 AM andymeyer wrote: > > > > So, all this chatter about the ELT antennas got me thinking about the > ADS-B antenna I made. I dove into the math, made some estimates, and > designed two on Upverter and had parts made. I got luck in that my SlimJim > ADS-B antenna has picked up airborne traffic over 100 miles away connected > to a Stratux (I have both SDR radios tied into a single antenna - criminal > - I know, but it works and it's small and light.) > > Attached are the layouts of the two antennas and links to the actual > designs on Upverter. > I had 5 of each made. Anyone interested in testing and sharing data - > maybe make this a shared design as well. Cost is just a few bucks. > > Slim Jim: https://upverter.com/eda/#tool=pcb,designId=1d1c59be761e9901 > DiPole: https://upverter.com/eda/#tool=pcb,designId=9eb3fbd043861e96 > > > (Upverter is a pretty awesome cloud based schematic and layout tool that > allows collaboration on designs, etc... Think Google Docs for circuit > design.) > > > Hello group, Andrew sent me a couple of the antennas he mentioned, above, to play with (Thanks, Andy), which got me motivated to take my 1st dive into using a nanoVNA. I promised Andrew I'd share results of testing the two antennas. Let me remind everyone that while I consider myself reasonably adept at electronics troubleshooting (3 or 4 'lives' in electronics maintenance), I'm not formally educated in the field nor am I a HAM operator. I hope the attached images will be viewed more as an invitation to teach me more about how to use the nanoVNA than an actual analysis of the antennas. Starting from a knowledge level of near zero, here we go: Since Andrew is splitting the signal using one antenna to feed two SDRs that are tuned to 978MHz & 1090MHz, I set the center frequency on the VNA at the midpoint between the two freqs (1034MHz), & span to 200MHz. On the *very* slim chance that I set up the VNA correctly, It looks like the dipole has a worst case SWR of around 4.6 & the Slim Jim was basically off the chart at 1090MHz.Measurements were taken with the antennas hanging on the 6" long cable that came with the nanoVNA. Even if I did the tests correctly, I'm not sure if the above has any real meaning for a receive-only antenna. If there's a better test that can be accomplished with the nanoVNA and someone is willing to walk me through the setup, I'll be happy to run the test(s), or I can forward the antennas to someone with more RF-foo. Shoot me a direct email if you're interested. Charlie ------------------------------------------------------------------------------------- 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.