A directivity enhanced structure for the Vivaldi antenna using coupling patches.

Abstract: A novel structure to improve the directivity of the Vivaldi antenna by adding three metal patches on the end‐fire is introduced. The two side patches that were close to the radiator change the E‐field distribution of the traveling wave, and the middle patch was a director. The strong coupling between the radiator and side patches led to the constraint of much E‐field energy between the side coupling patches, and this structure reduces the current on the end of radiation aperture. Compared with the other antennas, the Vivaldi antenna with the two side coupling patches did not compromise the frequency range, but decreased the radiation of the side lobes especially at high frequencies. The measured results showed that this proposed antenna operated in an ultra‐wide frequency range of 2 GHz to 18.7 GHz. The directivity of the proposed antenna has been greatly improved, with a maximum increment of 4 dB at 15 GHz. This enhanced structure showed good universality for the other Vivaldi antennas. [ABSTRACT FROM AUTHOR]