Optical ray technique versus finite-difference method in the design of novel microwave horn antennas with low side-lobe level

Two distinct design methods for producing a tapered amplitude distribution across the E-plane aperture of a sectoral horn antenna are described and compared. The first system studied is essentially a lens in which the refractive index varies in a direction orthogonal to the axis. The authors refer to the horn as a `HYSEC´ horn. The design lends itself to a ray-optic approach which is undertaken at a specified frequency. The second system is a sectoral horn with rectangular corner inserts. The problem of finding its field is solved numerically using a finite-difference method