The problem of electromagnetic monitoring, detection and tracking of low-power radio emission from unmanned aerial vehicles (UAVs) using the amplitude-difference method is being solved. An overview of the most commonly used signals of telemetry and control of UAVs has been conducted, their spectral electromagnetic portraits have been evaluated, an amplitude-difference method for tracking low-power radiation sources of UAVs has been described, and an automatic air space monitoring system has been developed. Special attention is paid to the multi-lobed nature of the antenna-feeder system's directional patterns, methods for reducing side lobes, and the resulting nonlinear effects. The effectiveness of the proposed method of increasing the sensitivity of the radio locator is analytically shown, the possibility of linearization and increasing the average steepness of the direction-finding characteristics of the antenna system by introducing a decoupling device is demonstrated. The described decoupling device is a flat multilayer dielectric structure with losses capable of effectively absorbing electromagnetic radiation over a wide range of wavelengths and incident angles. A distinctive feature of the proposed monitoring system is its operation in a completely passive mode, i.e. without emitting electromagnetic energy into the surrounding space, which significantly increases electromagnetic compatibility and simplifies the process of implementing the system into existing information and communication networks. The described system is designed to solve the problem of airspace zoning, increase the safety of the civil engineering sector and critical infrastructure facilities. The described problems and methods of their solution can be useful in the construction of similar amplitude-difference angle-measuring locators, as well as low-power radio direction finders and electromagnetic field sensors.
Vytovtov et al. (Tue,) studied this question.