Hughes Aircraft Company

Wilbur J Linhardt

Mon N Wong

Robert J Patin

An array of horn antennas with non-uniform aperture sizes is disclosed wherein the individual horns phase track over a wide frequency band. The horn with the smallest aperture is considered the reference horn, and its length defines the overall horn length of the other horn in the array. The flare lengths of the other horns of the array are less than the length of the reference horn, and lengths of waveguide are added to the other horns such that the respective combined flare lengths and waveguide lengths of each of the other horns equals the horn length of the reference horn. The respective lengths of the flare and the waveguide section are chosen such that the resultant horn antenna phase tracks the reference horn over the frequency band. Therefore, horn antennas of various aperture sizes, and restricted to a maximum length can be phase matched over a band of frequencies by reducing the flared length of each horn in relation to that of the smallest or reference horn, and making up the resulting length difference by a waveguide section.

Horn antenna array phase matched over large bandwidths

A phase compensated waveguide hybrid coupler is formed with a pair of waveguides of rectangular cross section and sharing a common short wall. An aperture in the short wall provides for the coupling of electromagnetic energy between a first of the waveguides and a second of the waveguides. Such coupling introduces a 90.degree. phase shift. An input terminal is located at an end of the first waveguide. Phase compensation is introduced by a set of capacitive irises located in the first waveguide and by a set of inductive irises located in the second waveguide. The capacitive and inductive irises are located on a side of said coupling aperture away from said input terminal.

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Hawthorne, CA, United States of America

Wilbur J Linhardt