I just finished putting up a 6m long aluminum tube for a vertical for
10/15/20m. Its length is just over 1/4 wavelength on 20m and just
under 5/8 wavelengths on 10m. The vertical is located at the apex (8m
above ground) of a sheet metal roof top, that slopes approx. 30
degrees down to all sides from the vertical. I use use the roof metal
as a counterpoise and feed the vertical with an autotuner at the base.
A coax runs 6m (18ft) from the autotuner, down through an attic
window and to my TX.

Now, simulations (EZNEC 3.0) and common wisdom predict a fairly good
performance for this antenna. Not so. When the tuner is set for 1:1
VSWR the RX signals from the vertical on 15m are consistently 4
S-units below a 20m (60ft) long sloper at the corner of the house. I
use this sloper for 160m and 80m. When going to the 20m band the
vertical is about 8 S-units below the sloper. Even more irritating,
the vertical is constantly outperformed by a leftover horizontal wire,
approx. 6m long, lifted only 1m (3ft) above the roof.

Switching to the vertical from either wire antenna the background
noise and signals drop noticably. This led me to check out the tuner,
the feedline, connections, but all seems to be fine. The bottom line
appears to be that the vertical is simply a much poorer antenna than
either of the wires I have up already - contrary to the theory and
conventional wisdom.

Any comments, anyone, before I remove the vertical and turn to another
design?

73 de TF3KX, Kristinn