I look forward to every issue and read them front to back and back to front. This month they show a couple war birds. The YL-15 and the awesome single seat A-20G Havoc. Love both these airplanes. But looking at the pics of the YL-15 I noticed a round ring type of thing on the top of the tail boom. I then noticed this same thing on the Havoc. This must be an antenna of some sort. Could someone explain what these round rings are on both these airplanes

Love the Magazine.

Tony