Multiband Diversity Antenna Performance Study for Mobile Phones

Spatial diversity is a popular multiple antenna system technique, due to its simplicity in implementation. However, its application has thus far been limited to systems where the electrical separation between adjacent antennas typically exceeds half a wavelength. This is because a more compact design induces higher antenna correlation and impedance mismatch, which results in lower diversity gains. In this paper, the performance of a compact multiband diversity antenna is investigated in both simulations and measurements. The dual-antenna structure is designed for the future WCDMA bands of WCDMA850, WCDMA1800 and 3G EU (UMTS), where the antenna separation at the WCDMA850 band is 0.24*wavelength. The measured results indicate that an average effective diversity gain of 7.3 dB at the 1% probability level can be achieved for the three bands.