Magneto-electric dipole antenna array for 77 GHz automotive radar

A 1 x 4 magneto-electric dipole (ME dipole) antenna array for 77 GHz automotive radar is proposed. The ME dipole is fed by a fork-shaped microstrip line coupling through a dog-bone slot. To meet the requirements aimed at automotive radar applications, the beamwidths of the proposed antenna are well-designed. Specially, a method of adding passive elements on both sides of the array is proposed to increase the 3 dB beamwidth from +/- 34 degrees to +/- 52 degrees in azimuth. Additionally, in elevation, a 3 dB beamwidth of +/- 10 degrees is achieved by designing the spacing between array elements. Moreover, based on low-loss printed circuit board substrates, radiation efficiency of the proposed array can reach approximately 90% at 77 GHz. Furthermore, a 4 x 4 array is established by arranging four 1 x 4 subarrays spacing 1.95 mm (half a free-space wavelength at 77 GHz) to study the interactions between subarrays for multiple input multiple output scenarios. A 1 x 4 and a 4 x 4 antenna prototypes are fabricated and measured to validate the correctness of this design. The results show that the proposed antenna is an eligible candidate for the medium- and short-range automotive radars. A 1 x 4 magneto-electric dipole antenna array for 77 GHz automotive radar is proposed. A method of adding and adjusting short-circuited passive elements is proposed to enhance the 3 dB beamwidth in azimuth. Based on the 1 x 4 subarrays, a 4 x 4 array is studied for the multiple input multiple output scenarios.image