Ted had a vacant feed line at the top of one of his towers and
decided to try a 40 meter delta loop fed at the top with horizontal
polarization.
The antenna seems to be stronger than a similar vertically
polarized loop in most cases, but it also hears more noise.
Top fed at 95', each leg is approximately 48 feet 5 inches. The
vertical height of the antenna itself is 34 feet 3 inches resulting in this case
with the bottom 60 feet 9 inches above ground.
Pictured below is an AIM-4170 scan of the antenna using calibration that negates
the coax feed line. These results were used to calculate the dimensions of
the required 72 ohm matching section.
EZ-Nec predicts over 7.5dBi gain at 27 degrees elevation broadside to the loop.
|