In article , Richard G Amirault
writes:

There are commercial versions out there. Radio Shack has (had?) one.
Diamond also makes a nice one. They can be home made however.

The RS *looks* like a Diamond, but in typical RS fashion, it's a cheap knockoff
of inferior construction. (Remember the old CB days when RS antennas looked
like Hy-Gains, but fell apart in the first ice storm?)

Spend the extra $20 and get the Diamond. You'll be glad you did.