Ultra-Wideband Coplanar Vivaldi Antenna Array with Dielectric Patch Antenna for Grating Lobes Suppression

This paper details a new approach for enhancing the radiation characteristics of a coplanar Vivaldi antenna (CVA) array. First, the inter-element mutual coupling is reduced by introducing slots in the conventional CVA array. Then, a low-profile dielectric patch antenna (DPA) is situated between the CVA flares when it acts as a traveling wave radiator at the higher frequency band. The DPA is excited by the loop current at the radiation part of the CVA, and a set of TE modes with omnidirectional radiation patterns are excited. This combination enhances the directivity in the broadside direction of the CVA and suppresses the grating lobes by as much as 10 dB. The 4 x 1 linear array covers the frequency range of 2.77-13.6 GHz, with 132% fractional bandwidth. Then, four of the proposed linear arrays are connected to constitute an 8 x 2 planar array to achieve a gain of 15.2-24.6 dBi. The proposed arrays are fabricated, tested, and mounted on a small unmanned aerial system (sUAS) for radar measurements. The real-life field radar results with the proposed arrays are presented including an echogram of the scanned area.