Cavity backed microstrip patch array feed for multiple beam applications

Multiple beam antennas use reflectors with several feeds at offset locations in the focal plane, The complete feed array tends to be bulky and heavy, hence, to alleviate this, microstrip patch arrays have been used as feed elements. However, a power division circuit becomes necessary for the patches which increases losses. A patch array backed by a cylindrical cavity is proposed which eliminates this lossy circuit. An additional feature is that the beamwidths in various planes may be controlled to a certain extent by varying the interelement spacing. The test results of the proposed feed are presented and discussed; the feed seems suitable for use in multiple-beam applications.