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.

中文翻译：

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用于超宽带应用的具有回旋镖形分形的非对称 CPW 馈电六边形单极天线

最近几天，小型化天线由于其广泛的覆盖范围而在便携式超宽带 (UWB) 应用中获得了重要意义。由于具有自相似性、空间填充性和空隙性这三个特性，分形天线在这种情况下变得流行，从而产生了具有广谱的小型化。传统的分形天线实现了良好的阻抗带宽和相对较高的增益，代价是在紧凑的尺寸、辐射特性和广谱之间进行权衡。本文针对超宽带特性，提出了一种具有较高天线增益和较宽带宽的非对称共面波导馈电六边形单极天线，该天线具有回旋镖形分形。分形结构实现了天线的小型化。天线尺寸为0.287λ r× 0.287λ r× 0.009λ r， 在哪里λ r是 3.45 GHz 的谐振波长。建议的天线印刷在 0.8 毫米厚的 FR-4 基板上，相对介电常数为 4.4，损耗角正切为 0.02。从频域分析，实验结果表明，分数带宽为101.7%，检测到的峰值天线增益为5.1 dBi。天线的辐射性能几乎是全向的。从时域分析、群延迟和三个不同的保真系数，即保真系数（FF）、系统保真系数（SFF）和系统保真系数（FFS），发现所提出的天线具有可忽略的失真。由于带宽满足高达 20% 以上的部分带宽和大于 500 MHz 的绝对带宽，因此建议的天线适用于 3.45-10.6 GHz UWB 应用。