View Full Version : Mobile Antenna Radial Kits

07-29-2021, 12:08 AM

I was curious if anyone has ever tried a radial kit for a mobile antenna? I have seen a few of these... but

have never heard of anyone ever commenting on them. I guess, if a base station antenna can have

radials... why couldn't a mobile antenna? Has anyone ever heard of such a thing?

Here is a link to a radial kit that I ran across.


What are radials for anyway? Do they improve reception?

The DB
07-31-2021, 03:49 PM
I actually answered this a few days ago with a fairly long and detailed answer about what this device actually was, and why you don't see "radials" on mobile installations. Apparently for some reason that post never made it on here...

I will give you the short version.

This device does not add radials to your antenna. It attaches on the wrong side of the feed point. This is what is called a capacity hat, and based on where it actually is it is a very poor one at best, in fact it is at the worst possible location to put a capacity hat. "Snake oil", a common phrase in this industry, is a perfect description of what this device is.

Now, when it comes to radials, that in and of itself is a very complex topic. There are antennas that require radials, or something in their place. When it comes to mobile antennas, this is the chassis of the vehicle, so you car already has what you seem to be looking for.

There are also other antennas that work beautifully without radials and not only don't require them, but the antenna actually works better without them. I know, hard to believe, and you don't tend to see them used for CB, but hey do exist.

Then there are antennas where radials are optional, such as the typical 5/8 wavelength base antenna design. In this case, the radials actually have nothing to do with performance, but they do have other effect, for example making it much easier to match the antenna to a feed line. They are also one way to to "trap" RF rather than letting it travel back up the outside of the feed line in the form of "common mode currents", which can cause problems of their own.

When it comes to radials, I can go on here and literally type up pages of information, and still not get everything. Also, a rule of thumb, CB operators chase performance, and if these devices really gave any performance benefit, even a small one, everyone and their brother would not only use them, but would be talking about them. When you see CB antennas on cars, look to see how many have such a device.

One thing about radials that you really do need to know is that they need to be about electrically 1/4 wavelength long, or on CB frequencies between 8.5 and 9 feet long to be effective. There are tricks and exceptions that can be used to physically shorten said radials to some extent, and this comes at a cost, but none of them will get you anywhere close what that device is trying to call radials, and if it actually did, the price in performance you would be paying would be so high that it likely wouldn't even function.

And just think, as long as this is, this is the short version...

The DB

08-05-2021, 08:55 PM
thanks DB .
i'll add that on a mobile your vehicle is you ground radial ...... unless you're using one of those NGP's that use the coax as a ground element .