Pattern and Polarization Diversity Antenna for Indoor Wireless Communications

Abstract

A pattern and polarization diversity antenna is presented. The antenna consists of two vertically oriented antennas. The lower antenna is a vertically polarized monocone antenna. And the upper antenna is a horizontally ±45° polarized microstrip antenna. The lower antenna is loaded with a cup-shaped patch to broaden the impedance bandwidth further and to improve the isolation between the two antennas. The microstrip antenna consists of a parasitic patch and a bottom patch with a coupling structure. The microstrip antenna is fed by two broadband out-of-phase power divider using dual-feed technique. The two antennas reuse part of their structure while remaining very small impact between the two antennas. The reusing technique makes the antenna more compact and reduces the effect of the coaxial cables. An antenna prototype is fabricated and measured. The lower antenna has a bandwidth of 117%. The upper antenna has a bandwidth of 46.5%, which is broader than most of the dual-polarize microstrip antenna. The isolation between any two of the three ports of the proposed antenna is better than 20dB. The lower antenna has a conical radiation pattern. The microstrip antenna has a broadside radiation pattern. Pattern and polarization diversity characteristics are obtained in the overlapping working band (1710MHz-2690MHz) simultaneously. The results show that the proposed design is suitable for indoor wireless communications.