In evaluating diversity gain of a Z1501D active antenna against various transmitting antennas, I use two spectrum analyzers, one connected to the two antennas to be evaluated. The spectrum analyzers are set for 0 Hz span and a 100 second sweep, providing a signal strength data point every 100 ms.
Under software control over the IEEE-488 bus, both spectrum analyzers start sweeps at a synchronized time. The signal strength data from each is saved to the controlling computer hard drive. The sweeps are repeated and data collected for a reasonable time, usually 24 hours per frequency. The data is then post processed to derive useful statistics, such as the probability that antenna A provides a stronger signal than antenna B as a percentage of time, in the form of signals from "Antenna A are X dB stronger (or weaker) than Antenna B Z percent of the time." Of course, other interesting things can be observed from the data, such as fading statistics - is it Rician or Rayleigh fading, for example. Writing this up is on my list of things to get to, but there are many things ahead of it in the list. A short answer is that in fact even modest separation (100 feet or less) between the broadband active antenna and a wire antenna can provide useful diversity gain even at 7 MHz and some gain at 3.6 MHz. Jack K8ZOA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
