The Inverted-L and the T are pretty close in performance, if one considers
less than a decibel to be close. In the case of the 50' x 83' Inverted-L, the T
is better by about 0.7 dB at a TOA of 10 degrees. The T in this simulalation
is 50' with a top wire of 120'. The radiation resistance of the T is lower by
about 1 ohm. If the effective ground loss resistance is 10 ohms the Inverted-L
and the T are equal in performance. That is, the lower radiation efficiency of
the T nullifies the advantage it has in low angle radiation.
The ground current distribution is a bit different too and this will affect
things unless the ground is quite good. With the Inverted-L there is more
ground current in the direction of the horizontal wire. With the T the ground
current is symmetrical. For the antennas in this example the T will require
more
ground wire.
Given an equal length horizontal wire the ground losses will (I think) affect
each antenna equally. If the T is shorted so that the top wire is 83' it
should require the same amount of ground wire as the Inverted-L. Placing the
loading coil at the top or at the base looks almost like a toss-up as far as
signal
strength goes.
Dave WX7G
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