If the tower were self resonant, the current distribution would be
linear and a voltage shunt feed will be just a folded unipole.
When the radiator is not resonant, but loaded, the current distribution
is not linear and it is a good advice to keep the shunt tap as much as
it is possible in the antenna portion where the current distribution
approaches the linear one. (With very short radiators it's not
raccomandable to shunt feed, but rather to series feed only)
To cancel reactance and match 50 Ohm we have to consider the tap
position, the ratio between tower and gamma rod and the gamma capacitor
capacitance.
The pratical solution for any tap position is single but useful tap
positions are many.
Last but not least, althought true that an omega match is theorically
lossyer than a gamma, the wrong capacitor type in a low Z shunt feed
gamma can be much lossyer than an omega with proper capacitors (i.e
vaacum types) at higher Z.
73,
Mauri I4JMY
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