HS wrote:
One easy thing that you might try, is to slope a 1/4-wave wire from the
top of your tower, connecting your coax to the wire, and coax shield to
the tower at the feedpoint, this way your tower will be the "other leg"
of the dipiole, or a "counterpoise". Then just trim the 1/4-wave wire
for swr.

The ARRL Antenna Book says that works if the tower is 1/4WL
tall or taller. A 1/4WL tower on 160m would be about 130 feet
tall. If the tower is less than 1/4WL tall, it seems to become
the major radiating portion of the antenna. I just modeled a
33 foot tower and a 100 foot wire on 1.9 MHz. That total length
is just about 1/4WL and winds up looking something like a gamma
fed inverted-L. The feedpoint impedance at the top of the tower
is low at ~8 ohms.

Such an antenna has a 50 ohm feedpoint impedance somewhere
along that horizontal wire. In my 33'-101' version above, the
50 ohm feedpoint is about 40' from the open end of the 100' wire.
And, of course, the feedpoint currents are unbalanced.

100' total
+-----------------------FP---------------
| 60' 50 ohm 40'
|
|33' tower
|
|
+-----GND
--
73, Cecil, http://www.qsl.net/w5dxp