A simple ground plane to turn your favorite HT SMA antenna (a Signal Stick, of course!) into an external ground plane antenna.
Editors Note, 11/30/22: As I’ve made several more of these, I now use these UHF Female “antenna seeds” (as I call them!) It is easy to add a whip and radials for any band you’d like to receive – such as 1090mHz for ADS-B. Also it is much more effective to solder the radials and whip. The nuts and bolts method will still work fine, just be sure to keep it tight.
I cut each radial to about 21.5 inches before assembly, then trimmed to a final length that achieves the best SWR on my preferred frequency range.
On this antenna radials ended up being 18.75″, as measured from the corner of the flange to the tip.
Also, as you trim be sure to keep the angle of all radials consistent at a 45º angle.