单极天线和偶极子天线辐射特性数值计算*

采用时域有限差分法(FDTD)在柱坐标系下对同轴线馈电单极天线辐射特性进行数值计算,推导了二维扩展柱坐标下修正的Maxwell方程,应用辅助微分方程FDTD法对修正的Maxwell方程进行了差分离散,以TM波在自由空间中的传播为例,仿真了电磁波在自由空间中传播过程并分析了坐标伸缩完全匹配层的性能,建立了单极同轴线馈电天线仿真模型,仿真分析了同轴线馈电单极天线的近场、远场及阻抗特性。在三维直角坐标系下建立了偶极子天线仿真空间模型,数值计算了偶极子天线不同切面的远场方向图,仿真结果与客观实际相同,验证了空间模型及相关理论的正确性。

Numerical Calculation of Radiation Characteristicof Monopole and Dipole Antenna

The radiation characteristics of monopole fed by coaxial line are simulated by finite-difference time-domainmethod under cylindrical coordinate. The modified Maxwell equations are derived under 2D cylindrical coordinate. And theupdating equations of these equation are obtained by applying auxiliary difference equation FDTD (ADE-FDTD) approach.Taking the propagation of TM wave in free space as an example, the propagation process of electromagnetic wave is simulatedand the performance of coordinate stretched PML(CS-PML)is also analysed. The simulation model of monopole fed by coaxial line is established. By using this model, the near field, far field and impedance characteristic of this kind of antenna are simulated numerically. The simulation space model of dipole antenna is established under 3D Cartesian coordinate. The far field patterns in different planes are calculated. The simulation results show agreement with the objective reality. The correctness of the model and relative theory is validated.