Document Type

Honors Thesis

Publication Date

Spring 2019

Abstract

High temperature sensors that can operate up to 1000 °C or beyond are in high demand for defense, aerospace, energy exploration and power industries. Wired sensors for high temperature operation has low reliability and high installation costs. Wireless communication provides functionality for operation in harsh environments. Wireless communication in harsh environments must be battery-free because semiconductor electronics is unable to operate beyond a few hundred degrees Celsius and there is a very limited number of alternatives for energy storage at extreme temperatures. The University of Maine’s Microwave Acoustics Laboratory (MAL) group has developed Surface Acoustic Wave (SAW) devices which can communicate wirelessly in high temperature environments without power supplies (i.e., passive). Field coupling wireless interrogation technology is attractive for harsh environment applications because of reduced antenna size. The present state-of-the-art allows for operation up to tens of millimeters, where attenuation of the two-way communication can reach 50 to 70 dB. The research presented investigates the possibility for improvement of power transfer to the sensor and from the sensor back to the interrogation unit. The improvement in performance was sought through the refinement in impedance matching for both the interrogating antenna and the sensing antenna and SAW sensor. SAW sensors operate between 180 MHz to 340 MHz. The work entailed radio frequency (RF) circuitry simulation using Advanced Design Systems (ADS) and High Frequency Structure Simulator (HFSS) commercial software packages, fabrication, test, and adjustment. The obtained results for interrogating and sensor antennas and matching circuits presents positive impacts high-temperature harsh-environment wireless SAW sensor communication links.

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