[TowerTalk] Radial question

[Richard (Rick) Karlquist]

On 2/29/2016 10:06 AM, Jim Thomson wrote:

> This is from the ARRL antenna book:
>
> ------------------------------------------------
> Practical Suggestions For Vertical Ground Systems
>
> At least 16 radials should be used if at all possible.
>
> Experimental measurements and calculations show that with

These rules of thumb are useful on the higher bands.  On
160 meters, most stations are working with less than
1/4 wave verticals.  Because of the lower radiation
resistance, the effect on efficiency by the number and
length of radials is much greater.  Radial systems that
would be considered "overkill" based on general guidelines
may be nothing of the kind with shortened verticals.
Experience with broadcast stations is of limited value
because they normally use full 1/4 wave verticals.

What I do is model my actual system over my actual ground
using NEC-4 (via EZNEC pro).  Sometimes the results are
surprising.  I consider the software a good investment for
any serious 160 meter experimenter.

It might be very interesting to model the A35T antenna to
figure out where they went wrong.  I was barely able to
work them due their tiny signal.

Rick N6RK