[TowerTalk] 4-Square Question

[Carsten Esch]

Hi there,

over the last weeks I did some investigation on 4-Squares build with a
hybrid coupler. 

In a NCJ article (http://www.yccc.org/Articles/4sq_ncj.htm) it is said, that

the "desired frequency" is not what you think it is! Say you want the system
optimized for 3510 kHz. Due to mutual coupling, the resonant frequency of
the verticals in the array shifts upward. Comtek recommends tuning the
individual verticals 5% lower than the desired frequency. Following their
recommendation, that means 3335 kHz!"

In a test made with 4 verticals for 40m spaced @ 10.6m (34.8ft) I see the
opposite. Something wrong here? In fact here the array with the hybrid is 9%
LOWER in frequency (than a single vertical with the other 3 elements in
place but 'floating') ... 

I am using a home-made hybrid designed for 50 Ohm antenna feedpoint
impedance. For what kind of impedance are the Comtek hybrids designed?

Thanks!

Carsten, DL6LAU