Hello Bill,
I following the discussion on loop antennas with great interest. I'm far
from a specialist, but trying to learn ...
What really looks interesting for a loop installation, according to the
math, is the effective power gain that can be achieved by stretching the
horizontal dimension. On my property I can make this 350ft (if it were
legal) because of this strange narrow "L" shape out back in the woods. The
effective power, then, increases 50x! Tried this for an hour at very low
power (don't tell the FCC), and it works!
What math do you use ?
I dug up a formula for small loops (I suppose any ham-sized loop is 'small'
at 2.2km / 1.33mi wavelength) :
R = 320*Pi^4*A^2/L^4 , where R = radiation resistance in Ohm, A = loop area
and L = wavelength.
So based on that a 10m high and 100m long loop should perform as well 32m
high square loop. Doubling the length of a long&low loop should increase
the radiation resistance by 4 and the loss resistance by 2, resulting in an
overal gain of 2 (= 3dB).
Does the above fit with your math ?
I like the idea of an L-shaped loop ( I suppose you mean lazy-L, so the
loop is not straight in the vertical plane) as I presume that this will
reduce the sharp nulls in the radiation pattern.
My first TX loop article just appeared in the US Longwave Club's 'Lowdown'
publication. The second is to follow next month.
Sounds interesting, is it available on the web ?
73, Rik ON7YD
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