Feasibility of multi-probe over-the-air antenna test methods for frequencies above 6 GHz

This paper discusses the feasibility of two multi-probe over-the-air antenna test methods at frequencies higher than 6 GHz. The two methods considered in this paper are prefaded signals synthesis (PFS) and plane wave synthesis (PWS) methods. Both methods suffer from huge challenges of the large number of dual-polarized probes required in emulating realistic standing waves in the antenna test zone, because physically small antennas become electrically large at the higher frequencies. However, the PFS method can take advantage of the nature of radio propagation channels at the higher frequencies, i.e., the sparsity of multipath channels and their angular selectivity, in order to reduce the number of active probes and hence signal feeds from a fading emulator. In contrast, the PWS method always needs signal feeds to all the probes and hence the implementation complexity is not reduced even under sparse multipath channels. The required number of probes is derived for the two methods using heuristic theoretical analyses and through practical antenna examples on a mobile-phone-sized ground plane at 5, 15, 30 and 60 GHz.