<snip>
>
> Radials help any ground mounted or near-ground vertical, the more the
> better.
>
> Radials do two jobs:
>
> 1.) They give some antenna designs something to "push"
> against, so current can be forced up in the element. The sum of
> currents flowing up in the radiator MUST equal the sum of currents
> flowing out (or in) at the ground connection point.
>
> 2.) Radials divorce or "shield" the fields near the antenna (both
> induction fields and the radiation field) from lossy ground around
> the antenna.
>
> Some neat things to remember:
>
> A vertical dipole will eliminate problem one, but not problem two
> above. The only way to substantially eliminate problem two is with
> height (more than 1/2 wl at the antenna base typically), or a darned
> good counterpoise (typically one with wire spacing less than .025 to
> .05 wl maximum at the wire ends, and wires 1/4 to 1/2 wl long).
>
(snip)
I asked Roger Cox of Hygain whether putting radials under a DX-77
vertical (also a vertical dipole) would be of any benefit. He said NO.
73 Barry
--
Barry Kutner, W2UP Internet: w2up@itw.com
Newtown, PA Frankford Radio Club
It, like the GAP, are 1/2-wavelength antennas. Radials are primarily
designed for 1/4-wavelength antennas and supply the missing quarter
wavelength. As pointed out, the higher you get off the ground, the fewer
radials are needed.
Remmember Gooch's Law! "The RF gotta go somewhere." (I wonder if
Kurt N Sterba is familiar with that one.)
73, Bob AA0CY
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