Compact Tunable Bandstop Filter Integrated with Large Deflected Actuators

This paper presents a novel approach to construct a low cost, compact tunable bandstop filter. The tunability is achieved with the use of thermal actuators and square plates as tuning elements to change the loading effect of slot resonators etched in the ground plane. A unique fabrication process is developed to allow monolithic integration of tuning elements and the bandstop filter on the same substrate. A 3-pole tunable bandstop filter is designed, fabricated and tested. The experimental filter has a center frequency of 6 GHz and a 20 dB rejection bandwidth close to 0.8 GHz. The measured result for the 3-pole tunable bandstop filter reveals that the proposed filter can be continuously tuned over a range of 500 MHz.