A Phase Confocal Method for Near-Field Microwave Imaging

A new fast imaging algorithm only using the phase information of electromagnetic fields for near-field microwave imaging is presented. This algorithm first compensates the phase shift as the wave back-propagates to the source, and then calculates the variance of phase of the shifted signals in terms of unit vector. This process is repeated at all focal points in the interested domain to form an image. The algorithm was validated by simulation and experiments; acceptable results were seen in both methods. To carry out the experimental test, we developed a fully automated microwave detection system containing a twin-antenna system whose movement can be controlled to form a synthetic aperture. Experiments were fully controlled by our self-developed software supporting remote operations. Although only 2-D imaging tests are discussed in this paper, the algorithm and the measurement system are able to fulfill 3-D rapid microwave scans.