Software Calibration of a Frequency-Diverse, Multistatic, Computational Imaging System.

We demonstrate a technique for calibrating a frequency-diverse, multistatic, computational imaging system. A frequency-diverse aperture enables an image to be reconstructed primarily from a set of scattered field measurements taken over a band of frequencies, avoiding mechanical scanning and active components. Since computational imaging systems crucially rely on the accuracy of a forward model that relates the measured and transmitted fields, deviations of the actual system from that model will rapidly degrade imaging performance. Here, we study the performance of a computational imaging system at microwave frequencies based on a set of frequency-diverse aperture antennas, or panels. We propose a calibration scheme that compares the measured versus simulated scattered field from a cylinder, and calculates a compensating phase difference to be applied at each of the panels comprising the system. The calibration of the entire system needs be performed only once, avoiding a more laborious manual calibration step for each transmitting and receiving path. Imaging measurements performed using the system confirm the efficacy and importance of the calibration step.