Broadband gap-coupled unidirectional dielectric radiator (UDR) in the millimeter wave band

A gap-coupled unidirectional dielectric radiator (UDR) is proposed. Especially, a multi-pole gap-coupled UDR is employed to obtain a broadband characteristic. Design parameters of the UDR, such as the length of the resonator and the gap distance, are determined using an equivalent circuit model of an evanescent nonradiative dielectric (NRD) guide. The proposed UDR has advantages of planar integration due to a good union between the antenna and NRD guide, simple structure, easy design procedure, and low cost. Prototypes of the gap-coupled UDR were designed and measured at around 38 GHz. The measured result shows a good agreement with simulation data.