Time gating based on sparse time domain signal reconstruction from limited frequency domain information

摘要

Time gating is one of the most widespread techniques to suppress the effect of unwanted echoes on antenna measurements. It just requires the measurement of the antenna under test (AUT) for a carefully chosen bandwidth and frequency step size and the isolation of the direct AUT signal contribution from the echo contribution in time domain is quite intuitive. Although a frequency sweep is usually fast compared to the axes movement, it might become the speed limiting factor for large measurement bandwidths. Thus, time gating techniques that need a minimum bandwidth are beneficial. Therefore, a gating method is presented that reconstructs a time domain signal with high resolution from a minimum measurement bandwidth based on the assumption that the time domain signal is sparse, i.e. it mainly consists of samples with low amplitude and only few samples with high amplitude which are related to the peaks of the direct and the echo signal. The effectiveness of the proposed method is compared with the well known fast Fourier transform (FFT) and matrix pencil method (MPM) based techniques using echoic near-field antenna measurement data.