Modelling arrays of circular horns with choke rings

Arrays of circular waveguides or horns are commonly used in directly radiating arrays or as feeds for reflectors. An application of the latter that holds continuing interest is the production of shaped beams with satellite antennas and the ability to design accurately arrays is vital for achieving high performance and reducing the design cycle time. In modelling arrays of circular horns for satellite antennas it is important to account for the following: different-sized horns; irregular element spacing; high-order modes; mutual coupling; arrays combining smooth, stepped and corrugated horns; coaxial-choke rings; finite flange effects; and gaps between horns. The paper outlines method used in computer software that has been developed to take these factors into account. Some results are presented to demonstrate the accuracy of the software and its application.