A Cavity-Backed Endfire Dipole Antenna Array Using Substrate-Integrated Suspended Line Technology for 24 GHz Band Applications

This paper presents a 1 × 4 cavity-backed endfire dipole antenna array based on substrate-integrated suspended line (SISL) platform. A double-side SISL (DSISL) self-packaged feeding network with irregular boundaries is designed for the array. By utilizing the DSISL feeding network, the radiation loss and substrate loss of the feed line are effectively decreased, thus efficiency of better than 91% is achieved. Instead of the conventional metallic cavity, the proposed cavity structure is realized by multiple substrate layers. A predominantly TE10aperture field is obtained by adjusting the sizes of the backing cavity. Measured results show that the proposed dipole antenna array has narrow beam widths in the E-plane and obtained 10 dB impedance bandwidth of 19.7%, i.e., from 22.77 to 27.75 GHz which can cover the 24 GHz automotive radar band (24.25-26.65 GHz). Moreover, front-to-back ratio of better than 26 dB, high gain of better than 14.1 dBi, and low sidelobe level of better than -15 dB are achieved over the automotive radar frequency band.