Comparison Study of Hilbert Sierpinski and Koch Fractal Structure on Coplanar Vivaldi Antenna for L/S band Application

Abstract

This article presents the comparison study of fractal structure on the Coplanar Vivaldi antenna that operated at L/S-band application. We compare three types of fractal structure i.e: Hilbert, Sierpinski, and Koch to the Coplanar Vivaldi element. By keeping the dimension for all types of elements, we compare the performance of return loss, directivity, and sidelobe level at 0.5 to 5.5 GHz of frequency. From the simulation, we found that by adding the fractal structure, the performance of return loss and radiation pattern can be improved. The best return lost in the lowest frequency is grasped for Koch fractal at 0.92 GHz while in conventional at 1.3 GHz. The directivity improvement is achieved for Hilbert, Koch, Sierpinski, and conventional as 10,02 dBi, 8.62 dBi, 7.79 dBi, and 7,02 dBi respectively at 5 GHz. While at 3.5 GHz by adding a Sierpinski structure, the directivity of the antenna improves as 4 dBi, if it is compared to conventional ones. At 3 GHz the increases of SLL also observed for Hilbert structure as -13.28 dB while conventional element as -5.6 dB. The fractal structure can enhance return loss and radiation pattern performance on Coplanar Vivaldi antenna