Hi Herb,
You will see snake antennas in various conflicting dimensions.
That's because they all behave pretty much like any old hunk of
wire laying on the ground from the point where the shield and
center are reversed out to the far end would behave.
The outside of the shield from the reversal point (of the shield and
center) to the distant end does all of the receiving, if the ground
connection is good. Otherwise the whole shield of the cable, all the
way to the receiver, picks up signal.
The better the ground, the less the cable on the house end of the
point where the shield and center are reversed contributes to the
signal.
Most designs make the center conductor 1/4 wl long electrically on
the inside from a short to the reversal point. In that case, the center
simply appears as a very high impedance "open circuit". If they
don't make the center electrically 1/4 wl long from the reversal point
to the short, the antenna appears to have an inductance or
capacitance shunting the reversal point.
If you think of the "Snake" as half of a double bazooka laying on
the ground, worked against a ground rod, it might help you get the
idea. Since it is used only for receiving, it doesn't hurt much if the
design is goofed up a bit.
73, Tom W8JI
w8ji@contesting.com
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