Re: NEC-LIST: Fw: Lambda/4 monopoles lamdba/4 apart

At 11:00 AM -0700 9/22/03, Jim Lux wrote:
>Since the monopole above a perfect ground is really like a dipole in
>free space, have you tried a pair of dipoles spaced 90deg apart fed
>90deg apart (in free space) to see what you get?

That won't help; in fact, the results will be essentially the same as
for monopoles.

His problem was the use of voltage sources, in combination with the
great inequality of the feedpoint impedances (due to the strong
coupling between the monopoles).

My (corrected) suggestion to put the two voltage sources each behind
one-quarter wavelength of TL solves the problem by transforming the
voltage sources to current sources.

In case anyone is thinking of driving the monopoles from a single
voltage or current source via TL's whose lengths differ by 90
degrees: it won't work. Try it; you'll see. I leave the explanation
as an exercise for the student. :-) Hint: The explanation is
implicit in what I've already written.

-Chuck, W1HIS

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