Reduced sidelobe switched beam antenna array for driver´s fatigue level Doppler sensor

An innovative approach to the design of a three-beam antenna array having reduced sidelobes has been presented. A modified Butler matrix has been utilized to ensure a broadside beam together with two beams symmetrically located with respect to the broadside beam. Moreover, to ensure sidelobe reduction for all three-beams a recently developed method has been used, in which the number of radiating elements is increased and additional power dividers are added. Furthermore, an innovative arrangement of the feeding network has been proposed which allows for achieving an integrated antenna structure without any crossovers. The developed antenna array has been successfully applied in Doppler sensor designated for driver´s fatigue assessment.