Re: SP5EWY's posting on this reflector about half-slopers.
I'm no expert on them, having only used one on 80m for a year. It was a
very effective antenna, but it totally messed up my 160m shunt feed for
the tower it was hung from. For that reason, I took the half-sloper down
and shunt-fed the tower on 80m. The slight effect this had on 160m was
easy to correct.
I also shunt-fed my other tower on 80m, and the array is definitely
superior in performance compared to the 80m half-sloper.
Many think the half-sloper is the radiator, when indeed it is not. The
main radiating element is the tower from which the sloper is hung, as any
modeling software will show. Apparently the half-sloper acts something
like an elevated radial, causing the tower to radiate. The pattern is
nearly omnidirectional (with low-angle radiation), but favors the
direction of the sloper by 4 or 5 dB. Perhaps three or four
half-slopers, equally spaced around the tower and fed in phase (one
feedline), would circularize the pattern (I'll have to try that one in
my modeling software).
It might be interesting for anyone using a half-sloper to try reversing
the coax connections, i.e., center conductor to tower, shield to the
sloper. I'm not sure what might happen, but my guess is nothing would.
Could the sloper/tower combination be classified as an upside-down
vertical (with max current at the top)?
It is indeed a mysterious antenna, but an effective one on the low bands.
73, de Earl, K6SE
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