Topband: Dual band shunt-feeding tower on 160/80

[N1BUG]

> I've done exactly what Herb suggested: hung a sloper for 80M off the
> side of my 160M shunt-fed tower.  Neither antenna knows the other is there
> and both work pretty well - meaning I'm satisfied with what I get out of
> them.

Interesting. I have tried verticals, slopers, inverted V's and other 
80 meter antennas on or near my 160 meter tower with little success. 
The impedance of any such antenna seems to be severely altered by 
the nearby tower. I suspect it depends on the electrical length of 
the tower. Mine is close to an electrical half wave on 80 - 100 feet 
of Rohn 25 with a 7 element 6 meter yagi, approximately  30 foot 
boom sitting at 103 feet.

At one point in time the 160 meter shunt feed could be made to 
provide an excellent match on 80 simply by changing the series 
capacitance. However, after I cut down several nearby trees that no 
longer works.

73,
Paul N1BUG