The design of linearly polarized slotted waveguide feeds for spherical reflectors

A procedure for the design of linearly polarized slotted waveguide line feeds for spherical reflector antennas is described. The necessary equations for determining the complex propagation constant
\alpha + j\beta
in a line source are given in terms of reflector parameters. Guide and slot dimensions that will yield the desired
\alpha
and
\beta
are then found by making use of experimental data, presented herein. These data consist of measured values of
\alpha
and
\beta
as functions of slot length for a number of slotted waveguide test sections of various widths. The technique is applicable over a wide range of frequencies and reflector sizes. An example is given in which a feed is designed at 1420 MHz to illuminate 700 ft of aperture in the Arecibo spherical reflector.