Millimeter-Wave Dual Linearly Polarized Endfire Antenna Fed by 180° Hybrid Coupler

A dual linearly polarized endfire antenna, excited by an E-plane 180° 3 dB hybrid coupler, is reported for millimeter-wave applications. The radiator is constructed by two stacked open-ended substrate integrated waveguides (SIWs). A slope-shaped slot is employed to the common metallic layer of the two SIWs, operating as a polarizer. Experimentally, the proposed antenna achieves an impedance bandwidth (SWR <; 2) from 32 to 40 GHz for both the vertical and horizontal polarizations. The port isolation keeps above 14.5 dB over almost the whole operating band. Besides, the proposed antenna is compact and obtains symmetrical radiation patterns, therefore being suitable for array designs.