Boresight-gain loss and gore-related sidelobes of an umbrella reflector

It is shown that energy in the gore-related sidelobes of an umbrella reflector comes from energy lost from the main beam. Both boresight gore-loss and sidelobe level correlate directly with cyclic aperture phase error caused by the geometry. The gore-sidelobe peak is located near
\theta_{p}
, where
\sin \theta_{p} = 1.2N_{G} (\pi/D\lambda)
where
N_{G}
is the number of gores and
D
is the reflector diameter. An expression is also derived for the amplitude of the gore-related sidelobe.