A Microwave Imager Implemented With a Space-Fed Randomized Aperture

Recently, microwave imaging based on randomized illuminations has demonstrated promising potentials. The key to realize such imaging is to implement an imager with a reconfigurable, randomized aperture. In this work, we discuss the theory and the guidelines for implementing such an imager and demonstrate an experimental prototype working in the 24-GHz ISM band. It is realized with a board-integrated, space-fed, 400-element phased array capable of realizing independent 1-bit phase modulations for each element. The fields transmitting through this aperture can be deterministically randomized by simply controlling direct current bias voltages. Assisted by optimized system calibration and standard
$\ell _{1}$
-norm regularization, experimental imaging with a notably improved quality can be obtained. The proposed solution can be used in wide applications, especially suitable for the massive personal security screenings in common public, government, and military areas.