A novel single-feed ultrawideband cavity-backed slot antenna with a reconfigurable polarization capability is demonstrated in substrate-independent air-filled substrate integrated waveguide (AFSIW) technology for Internet-of-Things applications in the [5.15–5.85] GHz frequency band of the unlicensed national information infrastructure. The antenna achieves an ultrawide impedance bandwidth by exploiting a double ring of slots and supports four switchable linear polarization states ( $\pm$ $\text{45}^\circ$ , $0^\circ$ , $+\text{45}^\circ$ , and $\text{90}^\circ$ ) by leveraging four quartets of p-i-n diodes. By electrically shorting the slots at well-defined positions by these p-i-n diodes, dynamic polarization reconfiguration is achieved by switching their dc bias current, supplied at the antenna feed through an external bias tee and routed from the antenna's back to front cavity plane via the AFSIW sidewalls. This new simple, yet effective, bias network enables the integration of all polarization control electronics inside the antenna cavity to protect them from environmental effects. Finally, measurements prove that the prototype exhibits an overlapping impedance bandwidth of 29%, from 4.85 to 6.45 GHz, and a stable conically shaped radiation pattern across the operating bandwidth with a 3 dB beamwidth of 45 $^\circ$ and a peak gain of 6.5 dBi for all four states.

中文翻译：

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多极化可重构充气基板集成波导腔背隙式缝隙天线

一种新颖的具有可重配置极化能力的单馈源超宽带腔后隙缝隙天线，在不依赖于衬底的充气式衬底集成波导（AFSIW）技术中得到了证明，该技术可用于物联网应用，频率范围为[5.15–5.85] GHz，未经许可的国家信息基础架构。该天线通过利用双缝隙环实现超宽阻抗带宽，并支持四种可切换的线性极化状态（ $ \ pm $ $ \ text {45} ^ \ circ $ ， $ 0 ^ \ circ $ ， $ + \文本{45} ^ \ circ $ ， 和 $ \ text {90} ^ \ circ $ ）利用四个四极管的pin二极管。通过这些引脚二极管在确定位置上使狭缝电气短路，可以通过切换其直流偏置电流来实现动态极化重新配置，该偏置电流通过外部偏置T形天线馈入天线，并通过AFSIW从天线的背面引至前腔平面侧壁。这种新的简单但有效的偏置网络可将所有极化控制电子设备集成到天线腔内，以保护它们免受环境影响。最后，测量结果证明该原型在4.85 GHz至6.45 GHz范围内具有29％的重叠阻抗带宽，并且在整个工作带宽上具有稳定的圆锥形辐射方向图，其3 dB波束宽度为45 $ ^ \ circ $ 所有四个状态的峰值增益为6.5 dBi。