Experimental characterization of a wide angle lens for millimeter-wave imaging

The field of view of wide angle dielectric lens antennas for focal plane arrays is mainly limited due to astigmatic aberrations which are often not taken into consideration even in more complex coma-corrected lens designs with two aspheric surfaces. The paper describes an efficient compact range setup for the measurement of high-gain lens antennas in small antenna chambers and presents a thorough experimental study of the effects of astigmatism and feed displacement/misalignment on the pattern degradation for large scanning angles. An experimentally derived method to minimize these aberrations is explained, resulting in a fairly constant beam quality with a maximized gain over a large field of view of 40°.