Near-field microwave imaging using open-ended circular waveguides

Abstract

Near-field microwave imaging has shown great potential for wide range of subsurface sensing and imaging applications including corrosion mapping and composite structure inspection. Most of the systems developed so far use an antenna (probe) scanned over the structure-under-test (SUT). The near-field interaction between the microwave signal and the SUT reveals the sought-after information about the interior of the irradiated structure. Almost entirely, previous systems used open-end waveguides as the imaging sensor. In this paper, the utility of circular waveguides for near-field imaging will be discussed in detail. Herein, both the sensitivity and spatial resolution of such a near-field probe will be investigated using simulations and measurements.