Characteristics of Millimeter-Wave Imaging Optics Using a Single Offset Paraboloidal Reflector

Abstract

ABSTRACT All-reflective systems with focal–plane arrays of monolithic elements promise major improvements in millimeter wave imaging applications. In this work high resolution, diffraction limited, wide–field imaging performance is investigated for a single offset paraboloidal reflector. Using accurate electromagnetic vector diffraction analysis, off-axis image degradation is computed for progressively larger field-of-view. Comparisons validate the estimates obtained from the closed-form expressions used to initiate the design process. As a practical example of the design process, a system with an unobstructed 500 wavelengths entrance aperture diameter is designed and its imaging performance, at various locations within a 6048 elements image plane, is computed. The offset reflector dimensions result in a less than 0.2 degree half-power beamwidth and about 50 percent directivity loss at the edges of a rectangular 13 × 6.5 degrees image field of view. Review of these results demonstrate the high–performance...