On 12 Jun 98, Tom Rauch <w8ji.tom@MCIONE.com> wrote:
> > I don't think radials will help the Gap because it's a vertical dipole.
> > 73, Dick, WC1M
> Radials help any ground mounted or near-ground vertical, the more the
> 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).
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.
Barry Kutner, W2UP Internet: firstname.lastname@example.org
Newtown, PA Frankford Radio Club
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