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

Vertex lates are commonly used to improve the return loss of primary-fed re flector antennas. We propose a new type of vertex plate with a Gaussian thi ckness profile that gives lower far-out sidelobes of the radiation pattern of the reflector antenna than the standard vertex plate with constant thick ness. We derive the dimensions of this vertex plate needed to cancel the fi eld 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 b y using a computer code based on the finite-difference time-domain (FDTD) t echnique. The results verify the improvements of the radiation pattern obta ined by using a Gaussian vertex plate rather than a standard one. (C) 1999 John Wiley & Sons, Inc.