A novel compact dual-band circular/linear polarization (CP/LP) switchable slot annular antenna with integrated filtering network is proposed in this paper. The feed network is composed of a couple of stepped impedance resonators (SIR) with favorable dual-band filtering characteristic. The SIR structure loaded with T-shape branches can adjust the center frequency more flexibly especially for dual band operating. A PIN diode is welded on the slot antenna to achieve the transform between the linear polarization and the circular polarization of the filtering antenna. The proposed dual-band CP antenna easily achieves 10 dB impedance bandwidth of 140/180 MHz and 3-dB axial-ratio bandwidth approximating 230/210 MHz at 2.6/4.8 GHz.

中文翻译：

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一种新型紧凑型带滤波网络的双频圆/线极化可切换缝隙环形天线

本文提出了一种具有集成滤波网络的新型紧凑型双频圆/线极化（CP/LP）可切换缝隙环形天线。馈电网络由一对具有良好双频带滤波特性的阶梯阻抗谐振器 (SIR) 组成。加载T形分支的SIR结构可以更灵活地调整中心频率，尤其是在双频段工作时。缝隙天线上焊接有PIN二极管，实现滤波天线的线极化和圆极化之间的转换。所提出的双频 CP 天线可轻松实现 140/180 MHz 的 10 dB 阻抗带宽和 2.6/4.8 GHz 时接近 230/210 MHz 的 3 dB 轴向比带宽。