Factorization of Antenna Efficiency of Aperture-Type Antenna: Beam Coupling and Two Spillovers

Antenna efficiency is one of the most important figures merit a radio telescope for observations, especially at millimeter wavelengths or shorter wavelengths, even multibeam telescope. To analyze system with beam waveguide, lossless antenna consisting two apertures in series considered frame scalar wave approximation. We found that can be evaluated field distribution over second aperture, and factorized into three factors: efficiencies coupling, transmission spillover, reception spillover. The factorization applicable to general aperture-type antennas waveguides relate aperture pupil function. numerically confirmed our an optical simulation. This evaluation enables us manage aberrations useful design telescopes.