一种紧凑的准各向同性天线

A Compact Quasi-Isotropic Antenna

文中提出了一种具有准各向同性辐射能力的紧凑平面天线。为了实现良好的准各向同性辐射性能,首先基于理想且相互垂直的电偶极子和磁偶极子辐射源模型进行了理论分析。电小环加载的电偶极子工作于三次模时,长直金属条和电小环分别等效为电偶极子和磁偶极子,存在天然的90°相位差。由于电小环辐射能力弱,所以初始的全空间增益差远大于10 dB。因此,文中通过将长金属条弯折成有切口的长方形,降低电偶极子的辐射能力并提高等效磁偶极子的辐射能力,实现了准各向同性辐射方向图。为了验证设计的有效性,加工并测试了所提出的紧凑天线,其尺寸为0.28λ0×0.26λ0×0.01λ0,λ0是中心频率对应的自由空间中的波长。测试结果表明,该紧凑天线具有3.6%的-10 dB阻抗带宽和全空间内增益变化小于4.5 dB的辐射特性。

A compact planar antenna is proposed in this paper with a quasi-isotropic radiation pattern.To achieve quasi-isotropic radiation performance,an ideal model consisting of two mutually perpendicular and ideal electric and magnetic dipole radiation source is applied and analyzed.When the electric dipole with an electrically small loop(ESL)loaded operates at the 3rdmode,the straight metal strip and the ESL respectively work as an electric dipole and an equivalent magnetic dipole with natural quadrature phases.The initial full-space gain deviation is larger than 10 dB due to the weak radiation ability of the ESL.By bending the long metal into a segmented rectangle,the radiation ability of the electric dipole is reduced while that of the equivalent magnetic dipole is increased,resulting a quasi-isotropic radiation pattern.To validate the design strategy,a prototype with a compact size of 0.28λ0×0.26λ0×0.01λ0(λ0is the free-space wavelength at the center frequency)is fabricated and tested.The measured results show that the proposed compact antenna has a-10 dB impedance bandwidth of 3.6%and gain deviation less than 4.5 dB over the full space.