Eigenwaves in the structure of coupled EBG waveguides with a sparse lattice of coupling elements, as well as characteristics of directional couplers based on them, are investigated. The propagation constants of even and odd waves in a system of two coupled triple waveguides the common wall of which is a sparse lattice of metal cylinders with a period twice the period of the crystal. It is shown that a 3 dB directional coupler, in which the waveguides are coupled through a sparse grating in a common wall, has a rather weak frequency dependence of the transmission coefficients and the matching is no worse than –20 dB in a frequency band up to 30%.

中文翻译：

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具有耦合元件稀疏晶格的 EBG 波导的分布式耦合

研究了耦合元件稀疏晶格的耦合 EBG 波导结构中的本征波，以及基于它们的定向耦合器的特性。偶数波和奇数波在两个耦合的三波导系统中的传播常数，其公共壁是金属圆柱的稀疏晶格，其周期是晶体周期的两倍。结果表明，一个 3 dB 定向耦合器，其中波导通过公共壁中的稀疏光栅耦合，传输系数的频率依赖性相当弱，匹配度不低于 –20 dB 在一个频段到 30%。