Packaged Microwave Displacement Sensors With Wideband Filtering Function

In this letter, a novel packaged linear displacement sensor with inherent bandpass filter (BPF) is presented. The proposed filtering sensor is composed of a multi-mode resonator (MMR) and a pair of transmission line. Based on the insertion phase shifts of the topology, a displacement sensing function can be obtained along with a wideband filtering response. For verification, a microstrip prototype is simulated, measured, and implemented. Measured results of the proposed sensors are in good agreement with the simulated ones, exhibiting an average phase sensitivity about 14°/mm with a wideband Chebyshev bandpass filtering response centered at 3.2 GHz of 56.7% 3-dB fractional bandwidth (FBW).