In order to more effectively monitor the ultra-high frequency（UHF） partial discharge of gas insulated switchgear（GIS）

the design technology of GIS internal disc-type UHF sensors is optimized in this paper. Firstly

the internal UHF sensor simulation models of the GHz transverse electromagnetic（GTEM） equivalent height and the return loss parameter(S

11

) are built respectively. The influences of hand hole and internal sensor structure parameters on detection performance parameters are studied. The experimental results of sensor performance are compared with simulation results.The results show that

with the increment of the diameter of the hand hole

the resonant frequency decreases gradually.The sensor equivalent height is inversely p

roportional to the hand hole depth. As the increment of electrode diameter

the lowest resonant frequency gradually decreases. And the thinner the electrode is

the more favorable the signal reception of the sensor is. Finally

the optimization internal sensor is designed

and its average equivalent height is 14.0 mm

which is basically consistent with the simulation equivalent height curve. The experimental results show that the detection sensitivity of the optimized sensor is better than that of the commercial sensor.