[Towertalk] Snake Antennas

[Tom Rauch]

Here is a copy of something I just posted on the 160m reflector, and 
on the topband reflector. The snake antenna is really just a random 
wire laid on the ground. It may have specific construction details, 
but in reality it is a random hunk of wire laid out on the ground.

Before or after trying a "snake", I'd compare it to other wires I 
already had up.

copy follows:

This question comes up frequently, and a brief summary might be 
useful.

Magnetic loops can offer improvement in S/N if you have local noise 
from one primary direction. For skywave noises or QRM, they are 
somewhat useless. The "shield" is meaningless, except a properly 
implemented "shield" can sometimes improve balance of the loop. They 
are really NOT magnetic antennas, except immediately next to the 
antenna. At a distance of about 1/10th wavelength or so a small 
"magnetic" loop's response is primarily electric, and at about a half-
wave or further they are no different than any other antenna type you 
might use. In a location free of noise or interference coming from 
one well-defined direction in the loop's null, they generally will 
*not* improve S/N ratio. 

K9AY Loops, Flags, Pennants and EWE's all work on the same 
principles, since they are all small terminated loops. They behave 
like small two-element vertical arrays, with an internal phasing 
system. The termination insures each "vertical" element has equal 
current, phase is inherent in the design and comes from the 
horizontal component of the wires.  They are primarily useful when 
noise or QRM is directly off or near the rearward direction.

These loop antennas (even the single unterminated loop) are all 
moderately low-impedance antennas, and despite rumors you CAN use a 
metallic mast with any of them as long as the mast is isolated from 
the element, not much taller than the antenna, and non-
resonant.

Snake Antennas are really just a "random luck" antenna. There isn't 
any science, reliability, or planning to successful installations. 
Sometimes you'll find a wire or antenna that helps under some 
conditions. It might be an antenna for another band (like an 80-meter 
dipole) that just happens by random chance to work, or it might be a 
wire strung out on the ground like a snake.

One thing all these antennas (like most smaller 160 receiving antenna 
system) have in common is results will vary greatly with each 
individual application.

73, Tom W8JI
W8JI@contesting.com