A Pole-Extraction Algorithm for Wall Characterization in Through-the-Wall Imaging Systems

Estimation of wall parameters is critical for focused through-the-wall imaging (TWI). In this paper, a novel algorithm based on pole extraction and wall reflection coefficients is presented to accurately estimate the essential parameters of a multi-layered wall. The generalized pencil of function (GPOF) is applied to decompose the frequency-domain received signal into a summation of ordered exponential terms and phase delays. Matching the terms with the multiple wall reflections provides equations for extracting the parameters. A frequency-domain calibration process is proposed to remove the antenna response from the measured wall response. The formulation of the proposed parameter extraction and calibration algorithms is presented along with the simulated and measured results for validation. The efficacy of the method is demonstrated on a real TWI system.