An Improved UHF Antenna for Partial Discharge Detection Based on Coplanar Waveguide Feeding

The ultra-high frequency (UHF) method has found widely application in the field of partial discharge (PD) detection in gas insulated switchgear (GIS). UHF sensor is an essential component and whose performance highly correlates with the effectiveness of PD detection. In this paper, a microstrip antenna is designed as a new UHF sensor for PD detection by adopting coplanar waveguide feeding. The geometric model is firstly established based on electromagnetic theory. The key dimension parameters are optimized considering the demands of PD detection. A trident-shaped feeding strip is loaded to further enhance the sensor performance. Obtained results demonstrate that the working band of the proposed UHF sensor is 500-1120 MHz with an acceptable size, while the radiation characteristics are good with a peak gain of 4.6 dB. PD experiments are carried out for two typical artificial defects of corona and internal air-gap discharge to verify the effectiveness of the designed sensor. It is indicated that the sensor can effectively detect PD signals, and is expected to be used for PD detection in GIS.