Abstract Recently, the asymmetric transmission has been employed to enhance the cooling power of daytime radiative cooler [Wong et al., Solar Energy Materials and Solar Cells 2018, 186: 330–339]. we argue here that the radiative cooling power cannot be improved by integrating the radiative cooler with an asymmetric electromagnetic transmission device. The reason is that the equivalence between the absorption and emission of the whole structure cannot be broken by adding the asymmetric transmission device. The theoretical analyses are provided to tackle this problem. The scattering matrix method is used to prove that the asymmetric transmission can be realized in reciprocal materials only when there is mode-to-mode conversion. However, the ray tracing method did not take the mode-to-mode conversion into account in Wong's paper, thus the absorption and emission of the whole structure could not be accurately calculated. We believe this work can prevent researchers from advancing in the improper way.

中文翻译：

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非对称传输在白天辐射冷却中的应用不能增加冷却功率

摘要 最近，非对称传输已被用于增强日间辐射冷却器的冷却能力 [Wong 等人，太阳能材料和太阳能电池 2018, 186: 330–339]。我们在此认为不能通过将辐射冷却器与非对称电磁传输装置集成来提高辐射冷却能力。原因是增加非对称传输装置不能打破整个结构吸收和发射之间的等效性。提供了理论分析来解决这个问题。散射矩阵法被用来证明只有当存在模到模转换时，才能在互易材料中实现非对称传输。然而，Wong 的论文中光线追踪方法并没有考虑到模式到模式的转换，因此无法准确计算整个结构的吸收和发射。我们相信这项工作可以防止研究人员以不正当的方式前进。