I would like to request the assistance of experts on this
reflector with respect to determining the optimum antenna
configuration for my "city lot" 160 meter antenna.
Current Configuration
A 50 foot #10 wire is vertically offset from my tower,
feeding twin 80 foot "horizontal" wires - one to the front
yard and one to the rear. In this sense the antenna is a
double inverted L or "T". The horizontal wires are actually
sloped downward significantly, running to the lot lines,
making a 90 degree turn, running across at the lot lines,
making another 90 degree turn and returning to the house.
This 50 foot vertical radiator with "heavy" top loading is
fed through an antenna tuner against five 135 foot radials
that snake here and there throughout the yard. A three
element beam with 40 meter extension kit and beams for 6 m,
2 m and 70 cm also adorn the top of the tuner, adding to the
capacitive loading.
Alternative Configuration
Some experts suggest that I should extend the 80 foot
horizontal wires to quarter wave (135 feet) length, fed in
the center with either coax (single band 160 meter inverted
vee) or ladder line, using a true "balanced" tuner to
provide multi-band operation.
I am not convinced that a low inverted V or dipole
configuration, whether fed balanced for multi-band or as a
single band 160 meter antenna will be any better in
performance than my top loaded "T". Conventional thinking
might suggest a dipole / inverted vee approach would be
better inside of 500 miles, while the "T" (vertical)
polarization) would be better out beyond 500 miles.
Opinions on this key question from those monitoring this
reflector would be very much appreciated.
Bill Evans, VE4UD
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|