An open-boundary quad-ridged guide horn antenna for use as a source in antenna pattern measurement anechoic chambers

The present paper introduces a new antenna design to be used in anechoic chambers. When measuring three-dimensional patterns, the receiving antenna in the anechoic chamber must be able to sense the two orthogonal components of the field that exist in the far field. This can be accomplished by mechanically rotating the source horn in the chamber. A better and faster approach is to use a dual-polarized antenna and to electronically switch between polarizations. This new design is a broadband (2-18 GHz) antenna with dual polarization. The antenna is a ridged guide horn. The novel part is that the sides have been omitted. Numerical analysis and measurements show that this open-sided or open-boundary horn provides a better and more stable pattern behavior for the entire band of operation, as well as good directivity for its compact design. The radiation and input parameters of the antenna are analyzed in this paper for the novel design as well as for some of the early prototypes to show some of the ill effects of bounded quad-ridge horn designs for broadband applications. Mechanically, the antenna is built so that it can be mounted onto the shield of an anechoic room without compromising the shield integrity of the chamber.