A physically compact quad ridge horn design

The electrical and mechanical constraints placed on the element design for a very small dual linear polarized broadband phased array has resulted in the development of a physically compact quad-ridge horn antenna. Using its lowest operating frequency, this antenna has an aperture size of1/4\lambda \times 1/4\lambdaand an axial length of1/3\lambda. These dimensions represent a reduction in size of approximately 50% over conventional quad ridge horn antenna designs. With this size reduction however, there was no significant degradation in antenna performance. Specifically, a 3 to 1 operational bandwidth with a maximum VSWR of 3.5 to 1 in the operating band was achieved. Other antenna characteristics are dual polarization, 17 dB minimum isolation between ports, extremely broad pattern shape, and a coaxial feed system which originates from the rear of the antenna. This paper presents both the theoretical and empirical techniques employed throughout the development cycle. Also included are measured data for the original physically compact antenna and a second antenna based on a scaled version of this design.