Co array based aperture synthesis for microwave imaging applications

Abstract

Most of the RF imagers make use of scanning with real apertures. They are limited in their applications to static and stationary installations only due to large size and heavy weight of the equipment. Modern tactical defence applications, however, require the imager to be very compact in size, light weight, handy, portable and quick deployable at the time of emergency. We have carried out this study to explore the possibility of using co-array based aperture synthesis scheme and establish its suitability for practical microwave/ millimetre wave imaging applications. newline Simulation studies have been carried out on the process of co-array based aperture synthesis and post data acquisition beam forming to study the effect of varying various parameters of the co-array on the synthesized pattern. Basic process of image formation using co-arrays and post data acquisition beam forming has been extended for use in 2-D imaging in multi target scenario. Simulation of complete process of imaging was done in MATLAB in 3D coordinate system. Simulated images were formed for objects of different sizes/ shapes and for some simulated targets representing real life targets. Experimental systems were developed to collect scattered data from the targets placed in the scene using linear as well as circular co-arrays. We have conducted outdoor experiments to collect scattering data from some real life targets at millimetre wave frequencies. Validation of the method of imaging was done by comparing the images reconstructed using the experimental data with the simulated images. The targets could be detected in shape and size. The experimental images matched very well with the simulated images confirming the efficacy of this method of imaging at microwave frequencies. newlineWe expect this technique of imaging to be useful in many practical applications like, sensors for unmanned/ autonomous ground vehicles, sensors for concealed weapon detection, ground penetration radars, through the wall imaging and also in medical imaging. newline newline