Tunable Duplexing Antenna System for Wireless Transceivers

A tunable antenna pair for wireless transceivers using RF MEMS tunable capacitors is presented. This design utilizes antenna frequency agility to cover a frequency tuning range from 1850 MHz to 2170 MHz (16%) corresponding to the PCS and IMT bands of the cellular systems, although the same concept can be extended to additional bands. Each antenna in the pair is designed to operate at the transmit and receive channels of the band, respectively, while the narrow impedance bandwidth of the single element provides built-in filtering between antennas. The level of isolation between elements is studied for several antenna arrangements depending on their relative orientation within the handset. High isolation levels can help in relaxing the duplexer specifications. A fabricated prototype is presented and measured to prove the concept and validate the design performance.