A tunable antenna-filter module for simultaneous UHF RFID-based power facility monitoring and partial discharge measurement

In this paper, a tunable microstrip antenna-filter is proposed based on a double U-shaped defected ground structure (DGS) and compact tunable square-loop dual-mode bandpass filter using capacitively loaded resonator. The antenna structure consists of a simple trapezoid monopole with a DGS microstrip feedline for excitation and this also yields a broaden impedance bandwidth covering 0.8 GHz to 2 GHz for UHF RFID operation and electromagnetic emission of partial discharge of traditional power facilities. In addition, the capacitively stepped impedance resonator of the filter allows frequency tuning between 1.2 and 1.6 GHz so as to steer the principal emission detection of partial discharge.