Compact Wide-Angle Scanning Multibeam Antenna Array for V2X Communications

This letter presents a wide-angle scanning multibeam planar inverted-E antenna (PIEA) array for vehicle-to-everything communication. The compact four-element PIEA array is designed with 0.3λ
_o
spacing, which achieves 90
$^{\circ}$
wide-angle scanning when a 135
$^{\circ}$
phase shift is applied obtained using a 4 × 4 Butler matrix (BM). The closeness of the array elements causes high mutual coupling and high cross polarization at wider scan angles. Therefore, three novel techniques are employed to overcome the high cross polarization and mutual coupling between the antenna elements in this array. To feed the antenna array, a low-cost miniaturized beamforming 4 × 4 BM circuit is designed without the use of phase shifters and conventional crossovers. The total dimensions of the compact PIEA array are just 0.456λ
₀
× 1.12λ
₀
× 0.036λ
₀
, while the overall dimensions of the multibeam array, including BM, are 2.731λ
₀
× 2.2λ
₀
× 0.046 λ
₀
. This multibeam array achieves for the first time the wide-angle scanning angles of ±87
$^{\circ}$
with a 3 dB beam scanning range of ±120
$^{\circ}$
along with the scanning angles of ±20
$^{\circ}$
. This array design can be scaled to use as an antenna array for millimeter-wave applications.