On 9th November, Yu wrote...
"...To reduce the length of coaxial feed line, I am
thinking about the 'Upside down vertical antenna'. Do[es] anyone have
experience for this kind of configuration?"
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Good Morning Yu,
For several summers not too many years ago, we used to rent a summer cottage
on Ocracoke Island, North Carolina, at the tip of what's commonly referred
to as "...The Outer Banks" in the Atlantic Ocean...naturally, the rig came
with me, and it gave me the opportunity to help some guys pursuing their
IOTA awards...
Anyway, the cottage (as were all of the cottages there) was elevated a
considerable distance above the ground atop tall wooden posts --- as well,
it was a two storey affair.
The opportunity presented itself for me to put up an "upside-down"
groundplane for 40-meters, which employed two 1/4-wave long (each)
"counterpoise" wires, and a 1/4-wave vertical, the tip of which safely
cleared the ground.
I can't say for certain whether it was the antenna itself --- or the salt
marshes that faced the cottage within a stone's throw on two fronts(!) ---
but I could work anything & everything that I heard on 7-MHz with very
little effort, AND with only 100-watts of output...
~73~ Eddy VE3CUI - VE3XZ
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