Fringe management for a T-shaped millimeter-wave imaging system

Two methods, the modulated scene method and modulated beam method, are proposed in this paper to manage the fringe in a T-shaped correlating millimeter-wave imaging system. The modulated scene method incorporates the fringe into the scene to form a fringe-modulated scene. The pencil beam that corresponds to the beam of the system with a zero baseline scans the modulated scene to form an image. To recover the image of the original scene, an algorithm that involves demodulation and spectrum patching is used to process the original image after deconvolution. The resulting image is a super-resolution image of the scene. The advantage of the modulated scene method is that a phase shifter is not required. The modulated beam method incorporates the fringe into the beam. By dynamically adjusting the phase of a local oscillator, the fringe scans together with the beam. The advantages of this method are that demodulation is unnecessary and only a single output (real or imaginary) from the complex correlator is necessary to generate a super-resolution image. A disadvantage is that a rapidly adjustable phase shifter is needed. The performance of these methods is theoretically analyzed and tested with simulated data.