On 10/25/2021 9:17 AM, Grant Saviers wrote:
Don't connect elevated radials to on/in ground radials.
There is a huge ground loss for 4ft high radials on 160m. 7ft is far
better and 10 ft is pretty good.
When I first installed radials this low, there was, indeed, high ground
loss. N6BT, an excellent antenna designer who has done extensive work on
verticals, advised me that 16-20 feet was a minimum height, and when I
raised them to about 20 ft, efficiency improved significantly.
There are "W" shaped radial feeds with the base near to the ground but
IMO it is better to elevate the feedpoint to radial height and add a bit
of wire to the top load to get back to resonance.
Radials can be a bit shorter than 1/4wl ~ 85% for 4, even shorter for
more. see antennasbyn6lf.com Or a single high Q inductor to shorten
them more, but modeling is needed.
I've followed Rudy's advice and made them slightly shorter than a
quarter wave.
73, Jim K9YC
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