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Near-Field Microwave Imaging Utilizing Tapered Rectangular Waveguides

This paper is focused on utilizing tapered rectangular waveguides for near-field microwave-imaging purposes. Conventionally, the standard rectangular waveguides have been used as imaging probes to capture images of subsurface inclusions/defects in various dielectric media. The lateral resolution provided by the standard probes is inversely proportional to the waveguide's aperture size. Consequently, seeking high-resolution images dictates the operation in higher microwave frequency bands. For many applications, however, the probe's sensitivity is not optimum in these frequency bands, and hence, there is a tradeoff between sensitivity and resolution. In this paper, the authors propose the employment of tapered waveguides in the near-field imaging systems as an effort to attain higher resolution while maintaining an acceptable sensitivity. It will be shown that tapering the rectangular waveguide significantly enhances the spatial resolution of the obtained images as opposed to the standard waveguides operating at the same frequency