从理论上分析了以理想磁导体(perfect magnetic conductor, PMC)为边界的手征负折射平板波导的模式特性及其磁场的具体分布. 利用PMC边界条件, 导出了手征负折射波导的色散方程和磁场各分量表达式. 通过波导的色散曲线发现, 当手征参数 κ>1时, 某些区域曲线出现下凹, 左旋圆极化(left circularly polarized, LCP)波的折射率为负值, 实现了负折射特性, 截止频率也不再是传播常数β=0所对应的频率. 根据传播常数β和k+, k−的关系, 将色散曲线分为3个区域, 给出了各区域一阶奇模和一阶偶模磁场的具体分布, 并与一般手征媒质平板波导的磁场分布作了比较. 结果发现, 切向分量场Hy,Hz 在上下边界处为零, 满足PMC边界条件. 而由于面磁流的存在, 法向分量Hx在边界处不为零.
The mode characteristics and magnetic distributions of a chiral negative refraction parallel-plate waveguide under perfect magnetic conductor (PMC) boundary are studied theoretically. With boundary conditions of PMC, dispersion relations and electromagnetic fields are obtained. Using the dispersion curves, if the chirality parameter κ >1, curves become concave-down in some regions and the refractive index of left circularly polarized (LCP) wave is negative. It imply that chiral medium can realize negative refraction. The cutoff frequency is no longer the conventionally defined frequency when propagation constant is zero. According to the relations between propagation constant β and wavenumbers k+ and k−, the dispersion curves are divided into three regions. Amplitudes of magnetic field components on the first-order even mode and first-order odd mode are plotted respectively. Chatacteristics of the magnetic field components are discussed and compared with the conventional chiral slab waveguide. It is shown that Hy and Hz are zero at x/d = ±0.5. It indicates that they satisfy the PMC boundary conditions and,due to the existence of magnetic current, Hx is not zero at the interface.
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