folding an antenna leg
On Thu, 09 Jun 2005 05:06:52 GMT, Justín Käse
wrote:
Which is a better method of folding the legs;
having them form spiral or zigzag patterns?
Hi OM,
Without becoming too exaggerated, almost anything will offer the same
results. Even by being too exaggerated, there is barely any problem
to anticipate. At some level, you achieve what is called linear
loading which at the extreme would be all the wire formed up in a
loose coil 1/10th the size of a normal antenna. This too would work,
but you are bordering efficiency issues. However, if you could force
it to tune, it would probably do just as well (±6dB, or the mythical
S-Unit).
So the question becomes one of what is the continuum of performance?
As long as the wire is remote from structures and earth, excess up to
a 25% of the total length of the element could wave in the breeze, or
be folded back upon itself (without shorting) or follow any path you
choose. Likewise you could zigzag the entire length to absorb that
same 25% that would not fit otherwise. Take care that the arbitrary
line at 25% is arrived at by no better choice at limiting it at 10% or
50%.
This problem has enough complexity, but not too much, that you could
examine the variations by using the free form of EZNEC.
73's
Richard Clark, KB7QHC
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