Empirical Tests of Wireless Sensor Network in Jet Engine Including Characterization of Radio Wave Propagation and Fading

This letter describes how to replace a wired telemetry system for structural health monitoring (SHM) in jet engines with a wireless sensor network (WSN). With a WSN, the time required for engine preparation can be reduced from several months to only a few weeks. The WSN is tested in a military jet engine used in the Swedish jet fighter JAS 39 Gripen. Also, the wave propagation is characterized in the real engine and a half-scale engine with both linear- and circular-polarized antennas. The measurements are analyzed by using K-factor and path loss. Finally, the complete system is tested in a full-scale test with a running engine. The intended WSN will operate in the 2.45-GHz ISM band. The K-factor for the real engine ranges from about 2 to 8 and for the half-scale engine from about 1 to 15. The use of circularly polarized antennas does not always reduce the fading. The complete system measured the bit error rate (BER) and temperature. The performed tests were successful, and the BER were 2.8%-10.5% during the test. The practical test also showed the possibility of using a WSN as a monitoring system in jet engines.