A compact and broadband omnidirectional antenna is proposed for quad-polarization diversity. Novel reconfigurable structures of omnidirectional vertical polarization (VP) and horizontal polarization (HP) elements based on embedded design are put forward to achieve low-profile. A simplified equivalent LC cascaded circuit is modeled to better understand the broadband VP element and guide its design. In order to realize quad-polarization diversity, an advanced switchable feed network, which contains ten p-i-n diodes with four output states are carefully designed. Measured results show that the overlapped bandwidth for all operation modes is 20.5% (2.28–2.8 GHz) within a compact size of 0.69 λ₀ × 0.69 λ₀ × 0.064 λ₀, where λ₀ is the free-space wavelength at the center frequency 2.5 GHz.

中文翻译：

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四极化分集紧凑型宽带全向天线的嵌入式设计

提出了一种用于四极化分集的紧凑型宽带全向天线。提出了基于嵌入式设计的全向垂直极化（VP）和水平极化（HP）元件的新型可重构结构，以实现低剖面。简化的等价物液晶显示器级联电路被建模以更好地理解宽带 VP 元件并指导其设计。为了实现四极化分集，精心设计了一个先进的可切换馈电网络，其中包含十个具有四种输出状态的 pin 二极管。测量结果表明，在 0.69 的紧凑尺寸内，所有操作模式的重叠带宽为 20.5% (2.28–2.8 GHz)λ₀ × 0.69λ₀ × 0.064λ₀，其中λ₀是中心频率 2.5 GHz 处的自由空间波长。