Wideband and High Cross-Polarization Discrimination 45° Linearly Polarized Slot Array Antenna Without Cavity-Backed Layer

This letter presents a wideband and high cross-polarization discrimination (XPD) 8×8-slot full corporate- feed 45° linearly polarized slot array antenna. A new vertical 1-to-4 power divider consisting of one H-plane T-junction and two E-plane T-junctions is employed to replace the 1-to-4 cavity-backed power divider in the conventional designs, which balances the amplitude and phase distributions among the output ports. By further bending the output ports of the 1-to-4 power dividers upward 90° along the diagonal plane, the TE 10 mode in the signal path is smoothly shifted along the intended E- and H- planes and directly excites the 45° tilted radiation slots. Combined these features, the grating lobe suppression and XPD improvement over a wide frequency band can be achieved without introducing additional metal structures. For demonstration, a prototype covering 24–33 GHz is implemented. The experimental results are in good agreement with the simulation ones, which verifies the design concept.