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Letter to the Editor: Elevated Concerns

Ben Dawson replies to a reader comment

The nice letter from Mr. Vanhooser in the April 22 edition of RW Engineering Extra [“Elevated Counterpoise,” page 8] responding to my earlier article in the Feb. 12 edition was slightly off-point. So I thought I’d reply to his comment.

cover of RWEE Feb 12 2020
Ben Dawson’s original article appeared in the Feb. 12 issue of RWEE

The elevated radial system works very well, since, of course, the primary purpose of the “ground” system for a vertical monopole is to provide a return path for the displacement currents. And this was shown clearly in Al Christman’s work that led to the acceptance and use of this system.

But it is not a technique for minimizing the necessity of an extensive “ground” system, merely a different technique, but one which may require as much or nearly as much real estate as a conventional buried radial system.

The same thing is true of two low-profile antennas in common use, the heavily top-loaded “Kinstar” antenna and the inductance loaded electrically short Valcom antenna. Both also excellent solutions to some situations.

And the point of the paper was to describe situations with minimum “ground” systems.

An interesting point about the use of elevated radials in directional arrays is that the return currents aren’t uniformly radial as they are in a single monopole. But numerical analysis techniques can also be used to modify the geometry and perhaps area of above ground systems as well. The currents in a conventional ground system for a directional array were described and discussed in an excellent paper by the late Oggie Prestholdt 30 or 40 years ago.

Regards, and stay safe!

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