20m Delta loop - the antenna that keeps on giving!

Being a private pilot, I've recently started using my RSP1a SDR to receive AM aviation radio, especially London Information (125.475MHz), which provides simple en-route information to aircraft.  It's a busy frequency!

Weekend at Caernarfon Airport.

London Information is quite a long way from me for a ground-based VHF station, so the receiving antenna needs to be pretty good.

I tried a broadcast FM vertical dipole, which gave rather weak reception due to low height.  I then tried a simple quarter wave vertical for the aviation band, but that wasn't very much better, even with good height.

I then started to consider buying (yes, buying!) a log periodic from Innovantennas, which is £200 and so not justifiable for this use.  Building a three-ele quad came to mind, but I'm not in the mood for that at the moment.

As a last effort that involved no money, I tried my vertical delta loop for 20m.  This is almost exactly 9 wavelengths long for the aviation band and, remarkably, it yields a strong signal from London Information, with aircraft, benefiting from altitudes of typically 2500 feet, being strong all the way out to northern France.


Good old delta loop!