In this letter, a two-material-filled ridge half-mode substrate integrated waveguide (2M-RHMSIW) is proposed for monomode bandwidth (MMB) enhancement. The cutoff frequency of the dominant mode decreases with the permittivity of the material filling in the bottom layer increasing. The cutoff frequency of the second mode increases as the permittivity of the material filled in the top layer decreases. Therefore, the proposed structure uses low-permittivity material for the top substrate layer and high-permittivity material for the bottom substrate layer, to widen the MMB. In addition, a series of air holes are drilled in the top substrate layer to reduce its effective permittivity, which further widens the MMB. A prototype of the proposed structure is fabricated under PCB process, which MMB is from 2 to 14 GHz.

中文翻译：

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用于单模带宽增强的两种材料填充脊半模基板集成波导

在这封信中，提出了一种填充两种材料的脊形半模基板集成波导 (2M-RHMSIW)，用于增强单模带宽 (MMB)。主模的截止频率随着填充在底层的材料的介电常数的增加而降低。第二模式的截止频率随着填充在顶层中的材料的介电常数降低而增加。因此，所提出的结构在顶部基板层使用低介电常数材料，在底部基板层使用高介电常数材料，以加宽 MMB。此外，在顶部基板层上钻了一系列气孔，以降低其有效介电常数，从而进一步加宽了 MMB。所提议结构的原型是在 PCB 工艺下制造的，其 MMB 为 2 至 14 GHz。