High Power Capacity Mechanical RF Switch Using Liquid Metals as Wetted Contacts

Radio frequency (RF) switches used in reconfigurable antennas often face reliability issues such as low isolation, high insertion loss, and limited power handling capability. To address these issues, this study presents a mechanical RF switch with high power capability that uses liquid metals as wetted contacts. It utilizes the rotation of a DC motor, together with a gear-rack meshing drive, to push the movable contact electrode to achieve contact or disconnection with the fixed electrode contacts wetted by eutectic gallium–indium alloy, thus realizing the on/off action of this RF switch. The electrode contacts are made of tin-plated copper, experimentally verified to have good wetting characteristics and low contact resistance with gallium-based liquid metals. For RF performance, small-signal measurements show that the RF switch has a return loss of less than −10 dB, an insertion loss of less than 3.5 dB, and an isolation of more than 13 dB from 0 to 5 GHz, while large-signal measurements suggest that it can handle a maximum power of 45.1 dBm in the 0–3 GHz band. This study also confirms the good performance of the designed RF switch for frequency reconfiguration of microstrip antennas.