A novel ultra-wideband antipodal Vivaldi antenna with trapezoidal dielectric substrate

An ultra-wideband Vivaldi antenna is designed in this article, its frequency band is 3.3-40 GHz. Based on the traditional antipodal Vivaldi antenna, a trapezoidal dielectric substrate is loaded in the direction of major axis, which not only eliminates the antenna gain peak shifting problem, but also improves the directional radiation performance. The dimension of the antenna is 57.5 mm x 60.7 mm. The substrate of the antenna is Rogers RO4003C with relative dielectric constant (epsilon(r)) of 3.38, loss tangent of 0.0027, and thickness of 0.508 mm. The simulation and measured results show that bandwidth of the antenna is 3.3-40 GHz, and it also has many advantages such as good radiation direction, high gain, narrow main lobe width, and low cross-polarization ratio.