Topband: Modeling a shunt fed tower with EZNEC

[Earl W Cunningham]

Gregg, W6IZT wrote:

"It appears that by altering the spacing of the shunt wire slightly and
changing the value of the gamma cap I will be able to use the same shunt
wire on 160, 80 and 75 with gamma cap values of 200pf, 46pf, and 30pf
respectively."
==========
Unless there is some unusual coincidence, I seriously doubt that, in the
real world, this will work at all three frequencies.

For example, the 80-meter shunt wires on my towers are tapped to the
tower at about the 40-foot level to get 50 ohms resistive at the
feedpoint.  My 160-meter shunt feeds on both towers are at about 54 feet
to match 50 ohms on that band.  If I wanted to go to the 75-meter phone
band, I would have to lower the 80-meter tap points about two feet.

As I said before, you can't rely on using an equivalent diameter
conductor for a top-loaded tower when modeling.

73, de Earl, K6SE