In this paper, a novel technology based on double-layer metasurfaces is proposed in order to broaden the bandwidth of microstrip antennas, which has been verified in X-band linearly polarised and circularly polarised antennas. Referring to the conventional metasurface antenna that employs slot-coupled feeding, these designs add an extra metasurface between the radiation patch and the ground plane so as to establish dual resonance modes, TM10 and TM20. Following the adoption of the composite right/left-handed transmission lines principle, this technique aims to adjust the propagation constant in the right-hand region by introducing parallel inductors and capacitors to widen the dual resonant frequencies' interval, thereby realising a broadband antenna. In addition, the interlayer metasurface may also be utilised as a director to balance the E-field of the radiation patch. A linearly polarised double-layer metasurface antenna with a size of 0.8 0.8 0.058 (wavelength in free space at the centre frequency) is filled with F4B substrate with a dielectric constant of 2.2. It finally realises an impedance matching bandwidth (VSWR 2) from 8.41 to 11.67 GHz, occupying about 32.47 of the centre frequency. This circularly polarised antenna attains both an impedance matching bandwidth of 32.44 (i.e. 8.29–11.5 GHz) and an axial-ratio bandwidth of 19.72 (i.e. 9.6–11.7 GHz).

中文翻译：

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双层基于超表面的薄型宽带X波段微带天线

为了加宽微带天线的带宽，本文提出了一种基于双层超表面的新颖技术，该技术已在X波段线性极化和圆极化天线中得到验证。参照采用缝隙耦合馈电的常规超表面天线，这些设计在辐射贴片和接地平面之间增加了一个额外的超表面，以建立双共振模式TM10和TM20。在采用右手/左手复合传输线原理之后，该技术旨在通过引入并联的电感器和电容器来加宽双谐振频率的间隔，从而调整右手区域的传播常数，从而实现宽带天线。此外，层间超表面也可以用作指向矢，以平衡辐射斑片的电场。尺寸为0.8的线性极化双层超表面天线 0.8 0.058 （中心频率处的自由空间中的波长）（F4B衬底）填充有介电常数为2.2。最终实现了阻抗匹配带宽（VSWR 2）从8.41到11.67 GHz，约占32.47 中心频率的 此圆极化天线的阻抗匹配带宽均为32.44 （即8.29–11.5 GHz）和19.72的轴向比率带宽 （即9.6–11.7 GHz）。