45° Polarized slot array antenna with differential dual-end feeding network for vehicle applications

A 45° linearly polarized slot array antenna with differential dual-end feeding network is proposed in this paper, using substrate integrated waveguide (SIW) technology and single layer printed circuit board (PCB) process. Conventional radiation unit with one 45° inclined slot and two reflection cancelling vias is adopted in the proposed array, with its dual-end feeding potential exploited. Differential dual-end feeding network is applied to the one dimensional subarrays, in order to obtain a stable broadside radiation and a wide operating bandwidth. A simple filtering structure is integrated in the feeding network to reduce out-of-band monopulse radiation. A prototype array antenna with 4×4 radiation units at 24 GHz for vehicle applications is designed and fabricated to validate the design. Experimental results on reflection coefficient, gain, and radiation patterns are consistent well with simulation predictions. The prototype array antenna can operate from 23.9 GHz to 24.9 GHz (4%) with its reflection coefficient under -10 dB and its gain varied from 14.5 dBi to 16.5 dBi. The main beam is stable at broadside with a maximum gain of 16.4 dBi at 24.5 GHz.