2.5维模拟中时域有限差分近-远场变换方法

Finite-difference time-domain method for near-to-far-field transformation in 2.5-dimensional simulation

为进行从高功率微波源到天线辐射整个系统的2.5维模拟,在近场模拟的基础上对2.5维模拟中时域有限差分(FDTD)的近-远场变换方法进行了研究。先将2.5维近场模拟区的输出边界绕对称轴旋转一周,得到封闭的3维圆柱面;然后根据等效原理由该封闭面上的FDTD近场求得等效电磁流;再根据自由空间中电流及磁流的时域辐射场公式计算出电磁流的远区辐射场。给出了2.5维模拟中TM01模式及TE01模式激励下圆锥喇叭远区辐射算例,所得计算结果与3维全电磁模拟软件CST的计算结果符合较好。

For the 2.5-dimensional simulation of the whole system from HPM（high power microwave） source to antennas＇ radiation, a scheme of finite-difference time-domain（FDTD） nea-to far-field transformation in 2.5-dimensional simulation is proposed based on the simulation of near fields. The closed three-dimensional column surface is got through rotating the output- boundary in the 2.5-dimensional simulation domain about the symmetry axis. The equivalent electric and magnetic currents can be obtained from FDTD near fields on the dosed surface with equivalence principle： The far-fields radiated by these currents are then calculated using the radiation field expressions. The examples about far fields of conical-horns excited by circular waveguide TM01 mode or TE01 mode are given. And the results agree well with those obtained by using 3D electromagnetic simulation software