Wide-angle sectoral horns using leaky-wave wall structures

A lensless method of phase correction for wide-angle sectoral horns is presented. It consists of supplying the narrow walls of the horn with a leaky-wave interface corresponding to a fast phase velocity. An analytical expression of the radiated field is derived by operating the Fourier transform of the theoretical distribution, and a set of theoretical radiation patterns are presented. The limitations of this type of correction, as far as bandwidth is concerned, are also examined theoretically. Two horn antennas illustrating this method of correction are described: an
E
-plane sectoral horn and an
H
-plane sectoral horn. Both have a flare angle of
120\deg
and an aperture of
6\lambda
. The
H
-plane horn uses a longitudinal
U
-shaped section, and the
E
-plane horn a transversely slotted rectangular waveguide. Both of them are measured with and without correction, and the experimental results are compared with the theoretical predictions.