I have just put up an Inverted "L" ant for topband (+ higher) and am trying
to decide how long the top loading wire should be for best dx performance.
At present the "vertical" section is 50 feet (sloping at 70 degrees with
respect to ground level) from my smart tuner feed point on ground with
radials. The top section is 132 feet gently sloping from 50 feet to 35
feet at house. There is also a 2 x 20 foot Z bend in the horizontal plane
at the far end to accomodate total ant length at my qth. This arrangement
should put the current max near to the bend in the L as the top wire is a
quarter wavelength on topband. But this also means that quite a lot of
current will flow in the top wire giving the less desirable high angle
radiation as well as some desirable vertical.
If, on the other hand, I cut the top wire such that the total length of
wire is a quarter wavelength, then the current max is at ground level and
more shielded by the neighbouring houses nearby at my qth.
As a compromise I could envisage cutting the ant wire to locate the current
max, say, 2/3 of the way up the vertical. Not sure where the optimum is.
Any comments/experience of this issue? I would place a higher priority on
DX as opposed to local contacts on 160 m, and would like to operate this
config also on 80 m and 40 m as well.
Geoff Cottrell
G3XGC
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