Experimental test of a stepped zone mirror for microwaves

This paper is concerned with the construction and the experimental test of a stepped zone mirror, whose theory has been previously developed. According to the theory, this mirror is free from spherical aberration for any value of the angular aperture and at the same time is corrected for coma. The only monochromatic aberration which cannot be eliminated is astigmatism. A model of the mirror has been built to operate with \lambda=3.2 cm. The focal length is 86.4 cm and the angular aperture 120\deg . The test has given results in perfect agreement with the theory within a total field of about 40\deg . Special astigmatic receivers have been designed and built to eliminate the effect of the astigmatism. It is believed that the mirror may be used as a fixed antenna for radio astronomy.