Jerry, K3BZ wrote:
----- Original Message -----
From: "Jerry Keller (K3BZ)" <k3bz@arrl.net>
To: "(Reflector) TopBand" <topband@contesting.com>
Sent: Friday, August 31, 2007 9:07 AM
Subject: Topband: INV L Directionality
> Is an inverted L directional at all? If so, is it directional off the
> sides
> of the horizontal element?
> 73, Jerry K3BZ
Many on the Topband Reflector have modelled inverted-L antennas. There is
generally a 1 or 2 db vertically polarized gain away from the top loading
wire. If the toploading wire is long, i.e., more than 1/8 wl, then there is
also a horizontal polarized sky wave.
This can be also seen in the models for the EWE antennas, where the "far
end" is returned to the ground with a loading resistor. The inverted-U then
becomes highly directional away from the horizontal wire direction.
Relative to 165 and 185 foot long inverted-L's they approach 1/4 wl
horizontally on top of the vertical wire, which sends a lot of energy nearly
straight up, reducing the low angle energy. One can build a 1/4 wl
inverted-L and feed it with an UnUn or L-network or maybe go 7 feet (2
meters) long and put a shunt capacitor to ground to raise the impedance to
about 50 ohms. (The extra wire is about 2 uHy of inductance as half of an
L-network)
73 George K8GG
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