Angle and polarization diversity in compact dual-antenna terminals with chassis excitation

For multiple antennas on a compact terminal chassis, chassis current excitation can severely increase mutual coupling between the antennas. This is because the same characteristic mode of the chassis may be strongly excited by more than one antenna. Here, we propose to use one antenna that exploits chassis excitation and introduce a second antenna that minimizes chassis excitation. In this way, angle and polarization diversity can be realized. The concept is illustrated and verified through the design of a practical dual-antenna prototype at 920 MHz, which achieves an isolation of over 30 dB and total efficiencies of above 80%.