Reconfigurable coupler with two operating modes for transceivers and diversity systems

A novel reconfigurable coupler with two operating modes is presented. The proposed structure can be electronically configured to operate as either a forward coupler or backward coupler, which is very useful in transceivers and diversity systems. Flat coupling in backward mode and high isolation in forward mode can be obtained, respectively, while the bandwidth is enhanced at the same time. For demonstration purposes, a 3 dB reconfigurable coupler at the centre frequency of 2.4 GHz is fabricated and examined. Both simulated and measured results are presented, and good agreement between them is observed.