This paper aims to study the problems exposed during the Russia-Ukraine conflict， such as the close-range blind area of radar monitoring， difficulty in detecting small multi-rotor unmanned aerial vehicles （UAVs） within 5 km around the position， and vulnerability of the self-defense capability of surface-to-air missile positions when coping with penetration reconnaissance and fire attack guidance by small multi-rotor UAVs. Methods Three types of signals emitted by small multi-rotor UAVs are collected. FEKO software is adopted to simulate radar cross-section （RCS） patterns of UAVs under radar operation in different frequency bands. The time-frequency domain characteristics of the signals are analyzed， and the feasibility of employing these characteristics for effective detection is demonstrated. Results The adopted software defined radio （SDR） equipment can successfully intercept and identify the video transmission signals at distances of 100.33 m and 70.129 m from UAVs. By employing the azimuth information provided by SDR， the guidance radar can rapidly detect and track UAVs， which saves 9 min compared with the full-airspace independent search mode of the guidance radar alone， thus verifying the feasibility and practicability of the proposed method. Conclusion By carrying out analysis and verification， a detection method combining radio frequency （RF） signal monitoring and precise radar positioning is proposed. Real-flight UAV tests are conducted， and SDR equipment is employed for RF signal detection， identification， and bistatic direction finding. The guidance radar utilizes the directional information provided by SDR to achieve precise positioning and tracking of UAVs.
