Phase-corrected E plane horns

A method is described of phase-correcting a rectangular horn, whose H plane aperture is of the order of a wavelength or less, to obtain a uniform phase at the aperture. This is achieved by varying the guide wavelength within the horn, resulting in a slight taper in the H plane, and the shape so obtained is very suitable for electroforming. Results are given for an X band horn and show a great improvement in radiation pattern compared with an uncompensated horn.