A Spherical Aberration Corrective Lens for Centimeter Through Submillimeter Wavelength Antennas

We present the design of a dielectric lens to correct the spherical aberration in spherical reflector antennas for use at centimeter through submillimeter wavelengths. A set of near-field measurements at a frequency of 100 GHz of a 30 cm diameter spherical antenna with 30 cm radius of curvature confirm improvement in illumination efficiency from 20.2% for the feed at the paraxial focus of the spherical primary to 42.4% with the feed position optimized as described by [M. Alonso-DelPino, P. Goldsmith, C. Elmaleh, T. Reck, and G. Chattopadhyay, 'Efficiency optimization of spherical reflectors by feed position adjustments,' IEEE Antennas and Wireless Propagation Letters, vol. 16, pp. 2865-2868, 2017] to 53.1% with the present TPX corrective lens. Further improvement should be possible by antireflection treatment of the lens surfaces, and by using both lens surfaces to optimize the amplitude in addition to the phase distribution of the antenna illumination. This technique offers advantages for antenna systems used for communication and for a variety of remote sensing applications.