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