Design of a Flexible UHF Hilbert Antenna for Partial Discharge Detection in Gas-Insulated Switchgear

This letter presents the design of a new flexible Hilbert antenna for built-in detection of partial discharges (PD) in gas-insulated switchgear (GIS). The fractal antenna is designed on flexible polydimethylsiloxane (PDMS) material of 124 mm × 122 mm × 0.5 mm, fed by CPW, and loaded with one circular slot and two rectangular slots in the ground plane of each subblock, and with a rectangular slot at the narrow opening to broaden the matching band and improve the gain of the antenna. The actual bandwidth of the antenna without bending is 422–800 MHz, 1.23–1.58 GHz, 1.65–1.7 GHz, and 1.79–3 GHz, covering 73.6% of the detection band, and the bending deformation has little effect on the antenna bandwidth. The measured peak gain of the antenna at a bending radius of 350 mm reaches 1.34 dB, exceeding the reported Hilbert antenna. The test and analysis of the antenna sensitivity are performed by 220 kV GIS PD experimental platform. Experimental results show that the flexible antenna designed in this article can effectively detect the high-frequency electromagnetic wave signal radiated by PD with a discharge amount of about 46 pC. The phase-resolved partial discharge analysis yields that the designed antenna has a high PD detection sensitivity.