Asymmetric CPW-fed hexagonal monopole antenna with Boomerang-shaped Fractals for ultra-wideband applications

Abstract

Abstract In recent days, miniaturized antennas have gained significance in portable ultra-wideband (UWB) applications owing to its broad coverage spectrum. Fractal antennas have become popular in this context owing to the three properties: self-similarity, space-filling, and lacunarity, thereby producing miniaturization with a broad spectrum. Conventional Fractal antennas achieve a good impedance bandwidth, relatively high gain, at the cost of trade-off between compact size, radiation characteristics and broad spectrum. In this paper, an asymmetric coplanar waveguide–fed hexagonal monopole antenna with Boomerang-shaped Fractals is proposed for UWB characteristics with relatively high antenna gain and wide bandwidth. The miniaturization of the antenna is realized by the Fractal structure. The size of the antenna is to be 0.287 λ r × 0.287 λ r × 0.009 λ r, where λ r is the resonating wavelength at 3.45 GHz. The proposed antenna is printed on a 0.8-mm-thick FR-4 substrate with relative dielectric constant of 4.4 and a loss tangent of 0.02. From frequency-domain analysis, the experimental results reveal that the fractional bandwidth is 101.7% and the peak antenna gain detected is 5.1 dBi. The radiation performance of the antenna was nearly omnidirectional. From the time-domain analysis, group delay and three different Fidelity Factors i.e. Fidelity Factor (FF), System Fidelity Factor (SFF), and Fidelity Factor of System (FFS), the proposed antenna is found to have negligible distortion. As the bandwidth meets up to fractional bandwidth above 20% and absolute bandwidth greater than 500 MHz, the proposed antenna is suitable for 3.45–10.6 GHz UWB applications.