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Re. the ongoing discussion about loops. I agree
that loops are very inefficient,not surprising since the radiation resistance is
so low for a neccessarily very small loop on 136.(even a single turn loop
several hundred feet long is far short of a wavelength)And of course the DC
resistance cannot be made anywhere near low enough.HOWEVER for recieve
purposes where the ant signal far exceeds reciever noise the loops directional
properties can be used to good effect.Both single and multi-turn loops exhibit a
"fig of 8" pattern with very deep nulls on the side, or if
configured as an EWE the pattern can be cardoid giving some gain in the favoured
direction and some b/front. Grounded bi-poles as described earlier are single
turn loops using ground as one leg of the loop.No doubt the grounding helps with
local noise/static etc. but by putting a resistor in one leg the
"fig8" pattern can be made into a cardoid. I am using a grounded loop
here to reject the Loran station in France (only 150 Km from this QTH) with very
great success.
In conclusion I would not use a loop for
transmitting ! but dont forget its valuable properties as a recieving antenna.
73s Laurie.
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