Topband: Shunt fed tower plus Marconi vertical phasing on 160 and80?

[Tom W8JI]

> ...and reasonable instrumentation and a good understanding of what is
> actually going on.  "Difficult" or "hard" is a judgment call from one's 
> own
> particular expertise and experience perspective.  Antennas are a wonderful
> interest area of amateur and professional radio.  Experiment and enjoy.
> Read good engineering books if you are interested in antennas.

It doesn't take much instrumentation. When I set mine up, I used a "pinger" 
on 1843 kHz.  I placed in out a few wavelengths in the direction of the 
null, and adjusted the T networks for minimum signal.  Because I had 
dissimilar antennas, the  "T" adjustment was different in each direction.

One element's impedance, the front, generally remains somewhere around what 
it was as a single element. Use that element as the common point and do the 
equivalent of leading phase to the rear. That would be a conventional T 
network, provided the values have enough range. The rear element, if fed 
through 1/4 wave of line or the TOTAL of 1/4 wave counting effects of the 
feed system,  generally is a pretty high impedance (because it is very low 
at the element current maximum).

Delay lines would, of course, result in almost no gain or F/B with shunt fed 
systems, unless someone deviated from normal procedures and compensated for 
the transmission line effects of the shunt system.

73 Tom