An MMIC-Based Microwave Sensor for Accurate Clearance Measurements in Aircraft Engines

A novel microwave sensor for accurate noncontacting clearance measurements in turbine engines has been designed, fabricated, and successfully tested. The sensor consists of a microwave resonant cavity probe, a MMIC based microwave module for signal generation and detection, and a signal conditioning and processing unit. To enable high temperature operation the probe is fabricated by using metal and ceramics, the operating frequency range is 22-24 GHz. The clearance measurement range is some millimeters, the achieved sensitivity and accuracy are very high.