Smaller (== lower gain) antennas are harder to measure FB due to the fact you have to measure a weaker signal on the range.
For example, if you measure FB on an antenna that has a peak gain of 45 dB, then at the peak the signal is pretty strong and well into a nice area of your detector. As you swing the antenna around and start measuring sidelobes referenced to the peak, going 60 dB down from that strong peak signal still leaves you in a nice functional area of the detector. But on a small antenna that may have 25 dB of gain, all signals are 20 db down (compared to the bigger antenna) for all the sidelobes too as far as the detector is concerned. Trying to measure 60 dB down on a low gain antenna leaves you in the fuzzy bottom of detector sensitivity. I would amp my tx antenna on the range and preamp my detectors and was always a bit unsure at 60 dB down on any antenna under 30dBi. The guys with their fancy indoor nearfield ranges can probably do it without problem. From: Tim Hardy Sent: Friday, April 20, 2018 9:18 AM To: [email protected] Subject: Re: [AFMUG] 18GHz Licensed Link best power and Rx Sensitivity Yeah, I know that Commscope’s antennas are rigorously measured and tested on a range in Scotland - think the other guys just simulate the patterns using software.
