Microwave Tunable Bandpass Filter with MEMS Thermal Actuators

This paper presents an approach to linearly tune the center frequency of a microwave bandpass filter using MEMS thermal actuators. A three-pole microwave tunable bandpass filter operating at Ka-band is designed, fabricated and tested. The fabricated filter has a center frequency at 33 GHz and a 14% relative bandwidth. The mid-band insertion loss is 2.7 dB and the return loss is better than 10 dB. A 15% continuous linear tuning range from 28 GHz to 33 GHz is achieved with a midband insertion loss better than 3.3 dB over the tuning range.