Reading a story in a german amateur radio magazine about a "big" 80m magnetic
loop from Karl DL1VU gave me an idea of a small topband antenna with the
possibility of working DX. Well, Karl reported to have worked VK6HD with this
antenna and 100W on 80 Meters.. so it can't be too bad.
The antenna with dimensions for 160m would be:
l = 15.3m ( 50.2ft)
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l * * l
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Coax Shield Coax Center
C1: about 130pF C2: about 3000pF Cs are variable
Polarisation: vertical
Well, it is sure that this is not a optimum as using a circleinstead of the
triangular configuration.
Also you have to use a good conducting and thick wire. I think of coax shield
from RG 213 or so. Karl reportet a bandwidth of 60kHz on 80 (SWR less 1:1.5)
that would mean about 30kHz on 160. Maybe the losses in the circuit pay its
price, but on the other hand it should be less than a small loop. Bigger
dimensions for the loop are not usefull, cause C1 runs to 0.
Well, I'm thinking of an antenna for DXPedition and making DX from a place,
where you are not able to put up a higher one. 15m high trees are everywhere
and the wight of this construction is much less than a vertical.Sure a tall
vertical or Inv. L over a really good radial-net workes better.
DL1VU gives a good mathematic fundamental ground for this antenna. I decide
not to repeat it here cause it is in many antennabooks.
Did anyone try such a configuration?... any command ?
73s Dieter
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