ADS-B antenna and stats – Antenna B

My initial (decent) stab at an ADS-B antenna

This is a work-in-progress and relates to this article on further developments beyond the details below.

See also Antenna A’s stats and design here.

The design is a basic 6.5-element coaxial collinear antenna with a whip, feedline, chokes and a decoupling sleeve. Further developments will assess improvements (or not) available by modifying the whip design, adding a ground plane, adding a decoupling sleeve and adjusting the length of, and connections to, the feedline. I may also extend beyond 6.5 elements to see whether any gains are worthwhile. I’d also like to test the impact of various covering pipes/tubes so as to waterproof it and mount it outdoors – its currently in my loft!

Performance with this antenna, in summary, is as follows:

• Max range: 267 nautical miles (regularly obtained 250-265nm)
• Max angle: around 180° of reasonable range – an opinion, I know, but I see considerably further in one half of the 360° than in the other due to a very large chunk of the Pennines nearby
• Max aircraft at any one time: approx. 50
• Max aircraft in any one hour: 155
• Max msg/s: approx. 600

The above was written in late 2020. It is now late 2021 (22nd November, to be precise) and, while nothing has changed with the antenna – it is still the same construction, connected to the same feedline, receiver and Pi, in exactly the same location – the dump1090 software has been updated and there are fewer restrictions on flights due to the global pandemic. So, I have been watching the numbers again and they look like this:

• Max range: 257 nautical miles (although that’s only over a 24-hour period so may be higher with a comparable test)
• Max angle: much as it was
• Max aircraft at any one time: approx. 70
• Max aircraft in any one hour: 214
• Max msg/s: approx. 1400

So, next steps are to build another identical antenna, ensure it is performing similarly to this one then start making tweaks to see what improvements can be made. Watch this space…

See here for a stats comparison.