Multi-Mode Millimeter-Wave Near-Field Imaging

The use of a higher-order, TM
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mode is proposed for short-distance near-field imaging of planar metal pattern. Using a properly designed multi-mode dielectric probe tip, the conventional TEM-like mode (in two linear polarizations) can be used for sensing, together with the higher-order mode. Experiments, conducted at a frequency of 31 GHz, are showing improved resolution for metallic strips using the higher-order mode. Uniquely, mode coupling can also be used for sensing, as it is demonstrated for the detection of a metal edge.