Ultra-Wideband Vivaldi Antenna with Resistive Loading

Based on the requirements of antenna size and operating bandwidth for time-domain through-wall radar system, an ultra-wideband Vivaldi antenna with resistive loading is proposed. The traditional Vivaldi antenna is slotted to form a loop radiating structure, and resistive loading is applied to the loop to expand the lower limit of the operating frequency band. Multi-stage feedline matching is used to optimize the impedance matching of the antenna. Simulation results show that the antenna has a bandwidth of 0.4-6 GHz (S11 < -10 dB) and a maximum gain of 7 dB. The proposed antenna has lateral dimensions approximately 0.3 times the wavelength at the lowest operating frequency. This antenna features lightweight, low profile, and ultra-wideband, making it suitable for time-domain through-wall radar system.