The two ultra-high frequency outer antenna sensors are made with wide band and narrow band respectively. The gain of two sensors is both greater than 1 and VSWR of the sensors is less than 2 in effective bandwidth range. So they can be used for PD detecting in GIS. The high-powered amplifier and half-distributing parameter UHF filter are designed with work band 300～1 000 MHz covering the band width of the sensors. Testing results show that performance of the sensors filter amplifier combination is great and can meet the demand of signal pre-processing. The sensors are used to detect PD which is produced by the defect of metallic particles on insulator surface. Results show that the system of UHF antenna sensor can be used to detect the feeble PD signals and suppress the low frequency interference

which has tremendous engineering application values.