Wideband Dual Linearly Polarized Hollow- Waveguide Septum Antenna Array for Ku-Band Satellite Communications

This article presents a Ku-band full-corporate-feed dual linearly polarized (LP) hollow-waveguide (HW) septum antenna array. A modified low-profile septum polarizer, worked as the radiating element, is designed to push the radiation nulls out of the desired passband upon odd-mode excitation, which helps to achieve stable and consistent radiation performance for both H-pol and V-pol. Square coaxial lines are employed to realize two sets of full-corporate feeding networks with compact size, enabling close spacing between the two adjacent radiating elements. A magic-T based on the single-ridge waveguide is designed to provide in-phase and out-of-phase responses for the feeding networks so that the dual LPs can be achieved. A prototype covering 10.5-14.5 GHz is designed, fabricated, and measured for demonstration. Experimental results show that more than 17.3 dBi peak gain and better than 79% antenna efficiency for both polarizations are achieved within the desired frequency band. In addition, the antenna is free from grating lobes over the same frequency band.