RF RAT-RACE COUPLERS WITH U-TYPE DGS MICROSTRIP ELECTROMAGNETIC BAND GAP ELEMENT

Abstract

In this letter, an investigation of a novel compact rat-race hybrid coupler incorporating a U-type defected ground structure (UDGS) is presented. Served by this microstrip electromagnetic band gap element (MEBE) technology, the size of the coupler is reduced due to its slow-wave effect and its band-stop effect enables strong high-order harmonics rejection. In the meantime, the measured performance of the proposed coupler is comparable to that of a conventional microstrip hybrid coupler. This miniaturization and harmonic suppression technology has great potential application in MICs and MMICs to reduce circuit size, lower material cost and improve the overall performance of wireless communication systems.