Suppressing Undesired Echoes by Sparsity Based Time Gating of Reconstructed Sources

The free-space radiation characteristic of an antenna under test (AUT) is determined from measurements in proximity of a scatterer by time gating reconstructed equivalent currents for the AUT and the scatterer. The presented approach effectively combines spatial filtering methods with time domain methods while mitigating their individual drawbacks. In contrast to conventional time-gating methods which usually work on the measured probe signals this approach allows to get rid of undesired echo perturbations even if measurement samples are located in the shadow region of the scatterer and the line of sight (LOS) contribution and the echo contribution are indistinguishable for the field probe. In contrast to conventional frequency domain methods, mutual coupling contributions of the AUT currents are identified and removed in the time domain representation of the reconstructed currents. Numerical examples show that, due to the sparse time domain representation of the currents, the free-space radiation of the AUT can be determined accurately even at the borders of the measured bandwidth.