Results: 16 cases intracavity type show with round or half-round filling defect on X-ray image, 8 cases extra cavity type with light press partly in barium meal examine.

The equivalent circuit of the three-gap coupled cavity type output section is given, with which resonant frequency of resonant modes and gap impedance matrix are calculated.

With the help of simulation, the optimally designed resonant cavity type wetness sensor has acquired good high-frequency electromagnetic as well aerodynamic characteristics.