In this article, broadband gain enhancement of an ultra-wide band (UWB) antenna is achieved by using 4 × 4 array of a wideband negative refractive index (NRI) metamaterial as a reflector layer. A novel shaped metamaterial sized 14.8 × 14.8 mm 2 with double negative (DNG) characteristics in three frequency regions has been fabricated on a flexible FR4 with 0.25 mm thickness. The proposed metamaterial gives a continuous NRI bandwidth of 10 GHz (2–12 GHz). The effective parameters of the unit cell cover S, C, X, and Ku-band independently and show DNG region of 6.1 GHz at C (4–8 GHz) and X band (8.8–10.5 GHz, 11.2–11.6 GHz). The unit cell structure is also found to be feed insensitive. The unit cell has small volume of 54.76 mm 3 along with flexible nature which makes it suitable for wearable applications. For a 4 × 4 array the metamaterial still exhibits DNG characteristics. To understand the physical behavior of the unit cell, the circuit analysis along with the study of magnetic and electric field distribution at three resonance frequencies (2.2, 8.2 and 14.2 GHz) is done. Both simulation and measured results indicate that the gain and bandwidth of metamaterial antenna are enhanced by 2 dB and 0.8 GHz.

中文翻译：

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使用保形宽带NRI超材料提高UWB天线的宽带增益

在本文中，通过使用宽带负折射率（NRI）超材料的4×4阵列作为反射层来实现超宽带（UWB）天线的宽带增益增强。在厚度为0.25 mm的柔性FR4上，制造了一种新型异形材料，尺寸为14.8×14.8 mm 2，在三个频率区域具有双负（DNG）特性。拟议的超材料可提供10 GHz（2–12 GHz）的连续NRI带宽。晶胞的有效参数分别覆盖S，C，X和Ku频段，并显示在C（4–8 GHz）和X频段（8.8–10.5 GHz，11.2–11.6 GHz）时6.1 GHz的DNG区域。还发现晶胞结构对进料不敏感。单元电池的体积小至54.76 mm 3，并且具有柔韧性，使其适用于可穿戴应用。对于4×4阵列，超材料仍然具有DNG特性。为了了解晶胞的物理行为，进行了电路分析，并研究了三个共振频率（2.2、8.2和14.2 GHz）下的磁场和电场分布。仿真和测量结果均表明，超材料天线的增益和带宽分别提高了2 dB和0.8 GHz。