A Tunable MIMO Antenna With Dual-Port Structure for Mobile Phones

In this paper, we develop a new frequency reconfigurable dual-port antenna that has two independent signal feed ports in a single antenna element for multiple-input multiple-output capable mobile handsets. The proposed antenna is composed of a cross-coupled semi-loop (CCSL) structure with a single pole 4-throw controlled by a logic circuit for frequency tuning capability and a Planar Inverted-F Antenna (PIFA) with a coupled pattern for wideband characteristics. The operating frequency ranges are 2.5-3.6 GHz, which corresponds to Band 7 (2500-2690 MHz), Band 22 (3410-3590 MHz), Band 38 (2570-2620 MHz), Band 41 (2496-2690 MHz), and Band 42 (3400-3600 MHz). The good isolation between the two signal input ports is achieved due to the CCSL radiator which creates orthogonal current flow direction with respect to the current induced by the PIFA radiator. The parametric study results of the dual-port antenna are presented to explain the optimization process based on the simulation works and experiments. We show that the proposed dual-port antenna has frequency tuning ranges up to 800 MHz while maintaining the port-to-port isolation greater than 10 dB.