A dual polarized suspended stripline fed open-ended waveguide antenna subarray for phased arrays

This paper presents the design and experiment of an antenna subarray for wideband and dual linear polarized phased arrays. The proposed antenna is a one-dimensional linear array which consists of two feeding networks for each polarization and radiating elements. The suspended stripline is used as the transmission line of the feeding network because of its low loss and low mutual coupling. The radiating element is an open-ended square waveguide antenna with a parasitic element inside and a transition from waveguide to two orthogonal suspended strip feed lines. In order to achieve a good transition performance of both polarizations, a compact transition, in which the waveguide between two feed lines is double ridged and the waveguide at the junction to the aperture waveguide is quadruply ridged, is proposed. The prototype subarrays with ten radiating elements have been fabricated and measured in 16 element array. The experimental results show a good impedance bandwidth of 18%, low cross polarization levels less than ™27 dB, and low losses with antenna efficiency above 70% in the frequency band of 14%.