A simple ground plane to turn your favorite HT SMA antenna (a Signal Stick, of course!) into an external ground plane antenna.

The panel mount coax adapter and nuts/bolts/washers came from Amazon and the radials  are  THHN 12 gauge solid copper.

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.