Diversity Properties of Multiantenna Small Handheld Terminals

Experimental data are presented on the viability of multiple antennas on small mobile handsets, based on extensive measurement campaigns at 2.14GHz with multiple base stations, indoors, from outdoor to indoor, and outdoors. The results show medium to low correlation values between antenna branch signals despite small antenna separations down to 0.16λ. Amplitude distributions are mainly Rayleigh-like, but for early and late components steeper than Rayleigh. Test users handling the measurement handset caused larger delay spread, increased the variability of the channel, and induced rather large mean branch power differences of up to 10 dB. Positioning of multiple antennas on small terminals should therefore be done with care. The indoor channels were essentially flat fading within 7MHz bandwidth (−6dB); the outdoor-to-indoor and outdoor channels, measured with 10MHz bandwidth, were not. For outdoor-to-indoor and outdoor channels, we found that different taps in the same impulse response are uncorrelated.