Microwave Subsurface Imaging: Methodologies and Applications

Over the years, microwave subsurface imaging has gained widespread attention in many fields such as concealed weapon detection at security checkpoints, landmine detection, biomedical imaging, structural health monitoring, quality inspection of composite structures etc. The strategy of microwave imaging is to illuminate the object under investigation using a known electromagnetic source, and from the reflection and transmission parameters received in response, information regarding the electromagnetic signature of the target is derived using suitable inverse process. Of the various measurement techniques available, the criteria for selecting a particular scheme for microwave imaging would be primarily based on factors such as the ease of imaging, frequency of operation, imaging accuracy etc. In recent years, real-time imaging of objects has garnered interest where the imaging scheme does not involve complex iterative inverse solutions or time-consuming calibration procedures [1]. Accordingly, the focus has been shifted from theoretical studies to the development of sophisticated practical arrangements where one can acquire information about objects in real time.