In the over-60-day period since I put up my first ADS-B receiver, I’ve learned a bit more about the general performance and about 1090 MHz propagation.

I set up a second identical receiver to see if my approach was reproducible, and so far it appears to track the first one, but since the antenna on the second one is just a ground plane, the coverage is somewhat worse. Also, In comparing my receiver(s) to those around me, especially the high-performing stations, it looks like the day-to-day fluctuations I see (and which had me worried more than once) are endemic to all those stations within a 50 mile range, which to me means that it’s not just something peculiar with my station.

I’ve dared to go on Alibaba and found a cavity filter manufacturer in Shenzen who can provide a low-insertion-loss 1090 MHz 10 MHz wide filter, with exceptional out of band rejection from DC to light otherwise. I hope to receive the first sample soon and give it a try. Assuming it works well, the next step will be to move one of my two receivers to a site atop a significant mountain around here, where my radio range should be far superior to my location down here on the valley floor.