A Novel Differential Frequency Dielectric Resonator Based Microwave Sensor for Angular Displacement Detection

Abstract: A differential frequency microwave sensor for angular displacement detection is reported. A metal strip-loaded cylindrical dielectric resonator (SLCDR) is excited with a 50 ohm microstrip transmission line through a rectangular slot made on its ground plane. Analysis of the transmission coefficient (|S21|) of the circuit shows that for the parallel alignment of SLCDR, dual-transmission zeros are excited at frequencies fL and fH, while for the perpendicular alignment, a single transmission zero is excited at f0 such that fL < f0 < fH. In the range, frequency fL increases towards f0 while fH decreases towards f0. Based on this trend, a differential frequency parameter f = fH-fL is framed as the indicator of the angular displacement following a simulation study with ANSYS HFSS. Subsequent prototype fabrication and VNA measurement confirm the simulations with 15.5 MHz/0 sensitivity over the sensitivity over 900 dynamic range with excellent linearity. Subsequently, using linear inverse regression, the measured differential frequencies are mapped to the angular displacement, and the calculated regression metrics prove very good mapping.