Design of Vivaldi like antenna using fourier series approach

Abstract

Antenna designed for ultra wide band (UWB) applications should offer a wider bandwidth with minimum distortion of radiated and received pulses. One such antenna which satisfies these requirements is the Vivaldi antenna. Conventional exponentially tapered slot Vivaldi antenna offers only a small gain at lower microwave frequencies. This paper presents the design of the complex flare geometry of a Vivaldi like antenna, using fourier series approach. In general, the radiating flare of a Vivaldi antenna is a closed contour and any complex closed structure can be represented using finite fourier series. Fourier coefficients and hence the antenna shape is selected so as to achieve the objective of maximum gain and minimum reflection coefficient (S11). Designed antenna structure using FR4_epoxy dielectric (εr=4.4, h=4.5 mm, tanδ=0.002) as substrate has a dimension of 79×126 mm and it can be operated over a band of spectrum from 2.1 to 9.2 GHz. At a frequency of 2.6 GHz it offers a peak gain of 6.1226 dB. Simulations were performed in high frequency structure simulator (HFSS) and antenna parameters like return loss (S11), radiation patterns, gain and directivity are studied. Simulation results and measurements made from prototype agrees well, which verifies the proposed design concepts.