Application of Orthogonal Frequency-Division Multiplexing Waveforms in Highly Precise and Efficient Radar Cross Section Measurements.

This article presents a fast and accurate radar cross section (RCS) measurement technique. The current best practice collects measurements over the desired bandwidth by sequentially transmitting and receiving a single frequency before stepping to the next frequency. This process is slow, particularly as the receiver bandwidth is reduced to lower noise power. The proposed method implements an orthogonal frequency-division multiplexing (OFDM) waveform to simultaneously send and receive multiple frequencies. The OFDM structure is commonly used in communications, but the waveform has begun to be implemented for radar applications due to the increasing accessibility of software defined radios (SDRs). Measurements are conducted with the OFDM method and the current state-of-the-art under similar conditions to compare the performance. Four different measurement scenarios are studied to compare the speed and performance of the two techniques in extracting the RCS of a 12-inch sphere. Across all the tests, OFDM measurements achieved an average error of 4.68%, while the classic step frequency continuous wave (SFCW) measurements yielded a 5.67% average error. In general, the proposed RCS measurement technique offers an alternative to traditional techniques with potential time and cost savings. The OFDM measurement conducted with an entry-level SDR was 2.75× faster than the traditional SFCW method in one measurement scenario, and even more time-savings are possible with a more efficient SDR implementation. Utilizing the OFDM waveform may enable measurements in environments that change too quickly, such as the outdoors with variable clutter properties, to collect accurate results with traditional methods.