On 3/25/2022 11:43 AM, Charlie wrote:
Sorry folks, I don't totally agree. Granted, this may be a bit of semantics.
But, for the last 3 or 4 years we've used what's known as a Double L on 160
at PJ4K. The top's about 130 feet with the vertical section running down to 30
feet. The feed points at about 85 feet which is a bit of a PITA for making
measurements. Is half of this bent 1/2-wave dipole the great ground system?
You guys can argue the point.
Hi Charlie,
No, half of your antenna is not a ground system -- they're only needed
for end-fed antennas. You're describing a very different antenna from
the end-fed vertical that 99% of topbanders use -- it's center-fed, with
top and bottom loading. The best commercial all-band verticals are
loaded center-fed; W6GJB and I have built center-fed 80M verticals that
are top and bottom loaded for Field Day and portable CQP and 7QP county
expeditions.
Another point. The importance of radial systems is obvious for TX
efficiency, but where it matters much more is for producing pattern
nulls. Nulls are produced by deep cancellation between arrivals at the
various elements, which in turn depends strongly on symmetry between the
elements, as well as their phase and geometric relationships.
73, Jim K9YC
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