Design of a miniature broadband internal antenna for PD detection in GIS

According to the analysis of the relationship between the impedance and bandwidth of the dipole antenna, a novel elliptical plane internal antenna feeding by a coaxial line is presented. It consists of an elliptical monopole and a rectangular grounding piece and has the virtues of broad band, high gain and small size. The antenna can be used for ultrahigh frequency (UHF) partial discharge (PD) detection in the gas-insulated switchgear (GIS). The size is achieved by using the simulation software Ansoft HFSS and the optimum size of total antenna is 90mm×45mm. A prototype is constructed and studied, and then measured. The antenna covers a large band from 781MHz to 2.00GHz, with the VSWR less than 2.5 and a max gain of 3.55dB. Simulated and tested results are in good agreement and the radiation pattern and gain characteristics are given.