WA4SZE wrote:
"We are going to drop using the shunt feed tower no matter how hard we
work on it we don`t think it`s going to work any better than it does
right now."

Shunt feed is a valid means to excite a grounded radiator. Its
disadvantage is difficulty in predicting the best place to tap into the
radiator to feed it if you want a particular impedance.

Bill Orr wrote: "The
performance of a shunt-fed antenna is substantially the same as one with
conventional series feed, provided the resistance of the ground return
path is low.

Unloaded vertical antennas as short as 0.15 wavelength may be shunt-fed.
Below this length, the tap point of the feed wire may be higher than the
physical height of the antenna."
See "Vertical Antennas" Radio Publications, Inc., ISBN 0-933616-09-0,
1986.

E.A. Laport has extensive information on low-frequency and medium
frequency antennas in "Radio Antenna Engineering".

Any unbalanced antenna must work against some sort of ground system. The
shorter the antenna is with respect to respnant length, the more
critical its grounding is because its radiation resistance is similarly
lowered, thus even a very small ground resistance can make it
inefficient.

The T antenna needs a good ground too, but the capacitive top loading
provided by the horizontal section brings the antenna closer to
resonance and raises its radiation resistance which improves its
efficiency. Balanced currents in opposite directions of the horizontal
section eliminate its radiation. The vertical section of the T is its
radiator.

Advantage of the shunt-fed tower is its near lossless capacitor needed
to tune the loop which feeds it. A series-fed short tower needs a large
inductance to bring it to resonance and it is usually lossy.

WA4SZE`s problem can be fixed by simply adding ground radials to to the
tower until he hits the point of diminishing returns.

Best regards, Richard Harrison, KB5WZI