Setting subreflector edge taper in a satcom dual-reflector antenna [antenna designer's notebook]

Direct spillover from the feed past the edge of the subreflector can create sidelobes that exceed the sidelobe template requirements for typical SATCOM ground-terminal dual-reflector antennas. Some “rules of thumb” are given to the antenna designer for choosing the subreflector edge-illumination taper, to ensure that the design of the dual-reflector optics shaping does not create spillover past the subreflector that would be above the required sidelobe mask for transmitting operations.