A Planar Differential Wide Fan-Beam Antenna Array Architecture: Modular high-gain array for 79-GHz multiple-input, multiple-output radar applications

Abstract

This article proposes a planar, wide fan-beam differential, corporate-fed patch antenna array architecture for automotive radar applications that mitigates the multipath and multiple reflections effects of its conventional series-fed counterpart. The proposed array architecture offers the merits of wide beamwidth in azimuth, high gain, yet, is applicable in multiple-input, multiple-output (MIMO) configurations. Two 8 × 1 arrays were developed, built, and measured at the 77-81-GHz band. In design 1, the width of driven 50-Ω patch is optimized for the widest beamwidth and the array feeding network employs impedance transformers for matching. The experimental verification showed an azimuthal half-power beamwidth (HPBW) of 70° with a 15-dBi gain. In design 2, the interelement spacing is increased for wider beamwidth and less mutual coupling, and the feeding network transformers were eliminated to mitigate scattering and radar cross section (RCS) in turn. A 130° azimuthal HPBW was measured. A 2 × 2 MIMO radar hardware was built, employing the proposed array architecture on a scalable radar platform to validate its applicability in MIMO radars. For the sake of comparison, another reference demonstrator with conventional series-fed arrays was built. Frequency-modulated continuous-wave (FMCW) radar range and angle measurements were performed where multiple reflections and multipath effects were mitigated.