A large L-band rectangular corrugated horn

A lightweight, rectangular, corrugated-horn antenna constructed from sheet metal is described. Over a 1.3-1.7 GHz operating band, its half-power beamwidth is approximately
20\deg
in the
E
-plane and varies from
17\deg
to
13\deg
in the
H
-plane. Quarter-wave choke slots at the aperture help to reduce the
E
-plane sidelobes below -55 dB at angles greater than
90\deg
, while the
H
-plane sidelobes lie in that range both with and without choke slots. Return loss throughout the operating band is -25 dB or below. Critical dimensions are provided, together with useful guidelines for designing similar antennas.