Integrated Microwave Sensor for Simultaneous Angular and Linear Displacement Sensing Based on Hybrid Series–Parallel Wing Structure

In this article, a novel hybrid angular–linear displacement sensor (HALDS) for simultaneous angular and linear displacement sensing is proposed. A hybrid series–parallel wing (HSW) structure, consisting of a pair of transmission lines and a pair of open-ended stub sections, is employed as the fundamental structure. By leveraging multilayer circuit technology, the transmission lines and open-ended stubs were innovatively implemented as slider and rotor structures, respectively, while the stator of the angular part was monolithically integrated into the slider structure. The sensor ingeniously achieves synergistic operation of angular and linear displacement sensing and inherent decoupling of sensing parameters, enabling 2-D displacement sensing. The linear displacement is detected based on insertion phase shift ( ∠S₂₁ ) at the center frequency, while the angular displacement is determined by the frequency difference ( Δf_TZ ) between two transmission zeros (TZs). Comprehensive theoretical analysis and design procedures are presented. To validate the proposed method, a 2-D microwave displacement sensor prototype was designed, fabricated, and experimentally characterized. The results demonstrate a satisfactory performance, achieving an average sensitivity of 4.5 MHz/° for angular displacement and 10.4°/mm for linear displacement.