In this study, a compact configuration of frequency reconfigurable filtenna, designed by integrating a bandpass filter and with a monopole radiator, is demonstrated for achieving high-frequency selectivity along with compact size. The proposed filtenna can be efficiently tuned between ultra-wideband (UWB) and C-band states of operation. A bandpass filter, based on rectangular stepped impedance stub loaded multiple-mode resonator (MMR), is embedded to an elliptical monopole radiator to construct the filtenna circuit. The filtenna design approach leaves out the necessity of cascading an additional 50 Ω microstrip feed line in between the antenna and filter elements which makes the system more compact. The designed filtenna occupies 3.6–10.6 GHz band in its UWB state of operation and 3.63–4.70 GHz band in its C-band state of operation, respectively. The UWB operating state is intended for spectrum sensing application whereas the C-band operating state can be implemented for communication in a cognitive radio environment. The shifting between two operating states is controlled by appropriately switching the PIN diodes. An average peak gain of 2 dBi is observed within the passband. The overall size of the filtenna is optimised to 1.35 λ ₀ × 0.96 λ ₀ × 0.04 λ ₀ ( λ ₀ is calculated at 6.85 GHz). For validation purpose, the filtenna prototype is fabricated and characterised. A very close agreement is achieved with the suggested configuration.

中文翻译：

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基于集成了带通滤波器的椭圆单极天线的紧凑型UWB-to-C频段可重构滤波器天线，用于认知无线电系统

在这项研究中，通过集成带通滤波器和单极辐射器，设计出了频率可重构的紧凑型天线，可以实现高频选择性和紧凑的尺寸。所提议的天线可以在超宽带（UWB）和C波段工作状态之间有效地进行调谐。一个基于矩形步进阻抗短截线负载多模谐振器（MMR）的带通滤波器被嵌入到椭圆单极辐射器中，以构建天线天线电路。filtenna设计方法省去了在天线和滤波器元件之间级联额外的50Ω微带馈线的必要，这使系统更加紧凑。设计的天线在其UWB操作状态下分别占据3.6–10.6 GHz频带，在其C频段操作状态下分别占据3.63–4.70 GHz频带。UWB工作状态旨在用于频谱感测应用，而C波段工作状态可用于认知无线电环境中的通信。通过适当地切换PIN二极管，可以控制两个工作状态之间的转换。在通带内观察到平均峰值增益为2 dBi。filtenna的整体尺寸已优化为1.35 λ ₀ ×0.96 λ ₀ ×0.04 λ ₀（ λ ₀是在6.85 GHz时计算得出的）。为了验证的目的，制造并表征了filtenna原型。使用建议的配置可以达成非常紧密的协议。