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In this paper, experimental results of micro-Doppler effect on a multi-rotor drone with digital television based passive radar are discussed. First, the bistatic passive radar micro-motion model of the drone is established. Second, key techniques of micro-motion signal extraction are briefly described. Finally, the experimental process is introduced, including experimental scene configuration and analysis of typical experimental results of micro-Doppler effect. The experimental results agree with the theoretical analysis of the motion parameters of the drone, thereby confirming the technical feasibility of detecting the micro-Doppler effect of the multi-rotor drone using the digital television based passive radar.

While Wireless Fidelity (WiFi)-based passive radar can achieve high detection resolution in both the range and Doppler domain, it is difficult to extract the reference signal because of the complexities of its signal format and application scenarios. In this study, we analyze a typical application of WiFi-based passive radar and discuss different methods for reference signal extraction. Based on the format and features of WiFi signals, we propose a method for reference signal reconstruction, and analyze the influence of the reconstructed reference signal’s performance on detection. The results show that higher reference SNRs generate lower decoding bit rate errors and better clutter suppression with the reconstructed reference signal. Moreover, we propose a method for removing irrelevant signals to avoid the impact on target detection of a non-direct path signal in the receiving signal. The experimental results validate the efficacy of the proposed signal processing method.

To broaden bandwidth of the receiving antenna for VHF/UHF band passive radar, a broadband improved biconical antenna loaded with resistor‐inductor‐capacitor (RLC) circuits is designed. Firstly, by introducing six metal rods into the biconical antenna to replace part of the cone, the feature size of the antenna is effectively reduced. Secondly, by introducing six parallel RLC‐loading circuits into the antenna, the bandwidth of the antenna at the low frequency end is effectively broadened, and at the meantime mutual coupling of the array composed of the proposed antenna becomes weak. The measured results show that the impedance bandwidth of the antenna corresponding to reflection coefficient less than −10 dB is 174–843 MHz. Moreover, the antenna also has good omnidirectional pattern in the horizontal plane, and the pattern characteristics have good consistency in the whole impedance bandwidth. [ABSTRACT FROM AUTHOR]