A Novel Over-The-Air Measurement Method for Linear Frequency Modulation Signals Using Continuous Wave Receiver

This paper presents a novel over-the-air (OTA) measurement method for linear frequency modulation (LFM) and frequency modulated continuous wave (FMCW) radar signals. Conventional measurement techniques, often relying on expensive spectrum analyzers, face challenges such as high cost, logistical difficulties, and limited adaptability in dynamic or real-world environments. To address these problems, the proposed method leverages interference phenomena to measure critical signal parameters, including chirp interval, bandwidth, and frequency slope, without requiring complex time-frequency analysis or additional hardware. The method was validated using automotive mmWave radar evaluation boards operating in the 76–81 GHz range. Experimental results demonstrated high accuracy, achieving average measurement errors of 3.43%, 2.23% and 1.35% for three different radars under test (RUT). Measurements were completed within a single frame of 115.2 ms, showcasing the method’s efficiency. The study also explored the impact of varying sampling rates, revealing that higher rates generally reduce errors, with optimal results achieved when the sampling interval aligns harmonically with radar chirp intervals. This method significantly reduces computational overhead compared to traditional approaches, while providing robust performance in diverse scenarios, including environments with multiple signals. By eliminating the need for specialized hardware, it offers a practical and cost-effective solution for radar signal characterization. The findings suggest the method’s potential for real-time applications, including cooperative and networked radar systems, where OTA measurements are essential for efficient operation.