Wilson Firestik ground plane antenna

They are excellent for throwing at attacking dog's, knocking squirrels and cat's off the fence's, or as a self defense weapon to chunk at your attacker...As for anything remotely "CB" related...They're pretty much useless...

 

Wilson marketed a no ground required j pole antenna at one time. I didn't have much luck with it, never saw one mounted on another truck so they must not have been very popular.

 

That "ground plane" is built to intensify one's belief that his/her/its system must be somehow better by having installed one, simply because it's now installed.
Unfortunately, a lot of CB & related accessories are like fishing lures: designed to attract fishermen, not fish.

*If* that device were installed immediately below the feedpoint of a vertical antenna that's tuned for somewhere around 360 mHz, then it would have a chance of benefiting the same antenna sans "ground plane".
It somewhat resembles a capacitance hat, which is a device usually installed at the top of the vertical radiating element on an antenna to add capacitive reactance, which is there to cancel the inductive reactance of a coil in order to lower the resonant frequency of an antenna.

Otherwise, it's just sorta "window dressing", intended to improve one's "wow factor" when they're seen by others. Sorta like the fashionable blue radio face lighting, which is just about the worst color to shine into one's eyes during darkness; the blue takes your eyes longer to recover from than nearly any other color in the visible spectrum.

Hope that helps somewhat.

73

 

I've got a 2 Meter J-pole antenna at the house, and it offers some manner of performance at the third harmonic, but without a great pattern up there at 440 mHz. That J-pole is about 9 feet tall, and provides a fair amount of wind loading even though it's constructed out of 1/2-inch copper tubing.

A J-pole for 27 mHz would be.....lessee..... 19 feet of length for the half-wave radiator, than another quarter wave parallel from just below the feedpoint, and a fraction (can't remember the formula right now) to make the trombone-like matching stub at the bottom of the antenna. All of this *without* the mounting height and strong brackets.

You didn't actually mention what band the J-Pole is for, but if it's for CB, it would be at its very best around 24 feet (or so) high. As you pointed out, one of its advantages is that it requires no ground plane, being an endfed halfwave radiating above its matching secdtion. Mine here at the house works great on 2M, adequately on 440, but nowhere else that's useful to me.

But if you're hilltopping and intend to erect it just whilst parked someplace for a DX contest, I think you'd be pleased. I actually sweated on a threaded coupling in order to shorten the longest (half-wave) element, and it'll fit in my XYL's car trunk.

73

 

The mobile J pole Wilson was probably 4 ft or less. I had it mounted on a freightliner cabover. It was designed for 27mhz. There was a movable metal band between the 2 sides. Instructions were to move the metal band up or down the antenna to achieve optimum swr. I never got the swr down below 1.5 and shelved the antenna after less then a month. Later threw it in a trade deal for a courier base station.