432 Feed - Antenna Range Measurements Sept. 29, 2001 |
(Evaluation of the K4QI feed as constructed by KL6M)
(Actual K4QI Design is available here: http://www.alaska.net/~ptt/Feeds/k4qifeed.pdf )
Range setup:
80 feet separation between RX and TX
TX - 5 element yagi 0.6 dB cable loss (RG-214), 0 dBM input
RX - UUT and 1.3 dB cable loss (RG-58)
Absolute measurements:
-39 dBm Horizontal = 0 Reference
-42 dBm Vertical = 0 Reference
-28 dBm X-pol (H to V)
HORIZONTAL RANGE MEASUREMENTS
VERTICAL RANGE MEASUREMENTS
Conclusions:
A 0.45 f/D dish requires a feed radiation pattern which has a beam width of about 118 degrees at the 10 dB points. The K4QI dual dipole feed produces a beamwidth of very close to this target. It is slightly skewed, probably due to mechanical anomolies, but in general the design does a good job of illuminating the dish.