Vivaldi Antenna Array Using Defected Ground Structure for Edge Effect Restraint and Back Radiation Suppression

A compact printed planar antipodal Vivaldi antenna (AVA) array with high gain is presented. First, a novel method based on adding line-type defected ground structures (DGSs) between adjacent antenna elements is utilized to reduce the mutual coupling in the AVA array. It is accompanied by the reduced cutoff frequency and improved gain simultaneously. Second, inconsistent performance between edge and center elements can be decreased by adding a pair of semiring-shaped DGSs to the edges of the AVA array. Thus, the directivity of antenna array can be improved. Third, to reduce antenna array impact on back-end systems, multiple gradual semicircle-shaped DGSs are etched into the back end of the AVA array. The frequency band of the proposed AVA array is 24.37-28.5 GHz, and the gain is improved from 7.78-8.9 dB to 9.7-11.6 dB in the frequency band of 5G millimeter-wave communication when compared with the original AVA array. Finally, to verify the designed methods, the proposed AVA array was successfully fabricated and measured, and the measured results are in good agreement with the simulations.