Serpentine Antenna with Hilbert Unit for Corona Discharge Detection

Corona discharge is an abnormal discharge phenomenon on overhead lines, which causes insulation damage and energy loss. For overhead lines to operate safely and profitably, corona discharge signals detection is essential. Based on techniques for detecting high-frequency electromagnetic waves, this paper proposes a broadband radio frequency antenna to detect corona discharge signals. The antenna combines serpentine curve and Hilbert fractal structures. The structure is composed of a 2nd-order Hilbert fractal unit and 7-layer serpentine curve, which is determined according to the space occupancy rate of the fractal curve for optimization. The optimization process of the antenna also considered the uniformity of the electric field distribution on the antenna wires. The antenna is 130 mm×130 mm×1.6 mm and works in the frequency range of 100 MHz to 500 MHz. Subsequently, a prototype antenna, weighing only 58 g and suitable for unmanned aerial vehicle (UAV) carrying, is created by standard printed circuit broad techniques. The experiment shows that the amplitude of the time domain waveform detected by the designed antenna increased by 82% compared with a spiral Hilbert antenna.