Gaussian vertex plate improves return loss and far-out sidelobes in prime-focus reflector antennas

Abstract

Vertex plates are commonly used to improve the return loss of primary-fed reflector antennas. We propose a new type of vertex plate with a Gaussian thickness profile that gives lower far-out sidelobes of the radiation pattern of the reflector antenna than the standard vertex plate with constant thickness. We derive the dimensions of this vertex plate needed to cancel the field at the focus of the reflector. We apply the design rules to improve the return loss (RL) of a primary-fed reflector with hat feed, and simulate it by using a computer code based on the finite-difference time-domain (FDTD) technique. The results verify the improvements of the radiation pattern obtained by using a Gaussian vertex plate rather than a standard one. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 125–129, 1999.