A displacement sensor based on principle of resonant cavity is designed

which can carry out displacement test through change of resonant frequency. It can bear harsh working environment such as high temperature and pollution

and is suitable for application in tip clearance test of aeroengine. On the basis of theoretical analysis

model of microwave sensor working at 24 GHz is established

test sensitivity is more than240 MHz / μm at range of 0

6 mm obtained by simulation calculation and verifies that this design is correct.