[TowerTalk] 1/8 wave spaced 80m verticals

[Michael Tope]

----- Original Message -----
From: "Jim Lux" <jimlux at earthlink.net>
To: <n4gi at tampabay.rr.com>; <towertalk at contesting.com>

> If you feed them out of phase, you're basically building a W8JK type two
> element beam, where the gain increases as you bring the elements closer
> together, but so does the relative losses.   The actual current gets quite
> high too (think of that series element in the pi net... closer together
> means lower impedance, so more current into the feedpoint)
>
>

There is a good illustration of this in Kraus's antenna
book (2nd ed page  455). He plots the gain for the W8JK
array as a function of spacing for the ideal lossless case,
and for the real case with various values of finite loss
resistance. You can see from his plots that for the ideal
case, you get maximum gain of 3.9dB at zero spacing
(that's right ZERO spacing). Don't throw away those
long pieces of irrigation tubing yet. In real life you can't
get the elements much closer than about 0.1 lambda
before the ohmic losses start to add up and the gain
begins to fall off (in the lossless case at zero spacing
the element currents go to infinity). Sorry no free
lunch :):)

73 de Mike, W4EF..............................