A single square patch antenna for pattern diversity is investigated. The proposed antenna consists of a double-feed square patch antenna with a rat-race network. By switching the feeding ports, the different radiation patterns for two modes (TM10 mode and the capacitive-loaded monopole radiating mode) operating over an overlapped frequency band from 1.88 to 2.34 GHz are achieved. TM10 mode reveals good broadside radiation patterns and the capacitive-loaded monopole radiating mode shows conical radiation patterns.
The antenna is fabricated and tested. The measured gains across the common frequency band are 8.9-9.9 dBi and 2.8-3.8 dBi for TM10 mode and the capacitive-loaded monopole radiating mode, respectively. Besides, the measured bandwidths of -10 dB reflection coefficient are 750 MHz (1.59-2.34 GHz, 38.2%) for TM10 mode and 880 MHz (1.88-2.76 GHz, 37.9%) for the capacitive-loaded monopole radiating mode. High isolation (<-20dB) between the two feeding ports for the common impedance matching band is achieved. These results make the single dual-port patch antenna an attractive solution for 3G/4G pattern diversity applications such as in gym scenarios.