太赫兹矩形波导与共面波导耦合结构设计

太赫兹（THz）波位于微波与红外光波之间，现有微波和光波段波导技术应用正在向THz波段拓展。但是，由于水汽对THz波的强吸收及制造工艺等原因，THz器件主要是平面结构，而THz源及其传输需要用矩形波导。因此，矩形波导与共面波导之间的转换结构成为决定元件和系统性能的关键部分。该设计利用脊波导进行阻抗匹配及电磁场模式转换，实现THz波矩形波导到共面波导的高效率耦合。结果表明，在0.2~0.4 THz频段内，该转换结构的传输系数(S₂₁)高于?3 dB，可以对THz电磁场进行高效率转换。该结果可用于太赫兹分子探测、太赫兹通信等领域，为0.2 THz以上太赫兹的模式转换提供了一种可行方案。

Design of coupled structure of terahertz rectangular waveguide and coplanar waveguide

Terahertz (THz) wavelength lies in between millimeter waves and infrared waves in the electromagnetic spectrum. The existing optical waveguide and microwave millimeter waves waveguide technologies can be applied to the THz band. Because of the strong absorption of THz waves by water vapour and the limitation of manufacturing processes, THz devices were mainly planar structures and rectangular waveguides were commonly used for THz source and transmission. Therefore, the conversion structure between rectangular waveguides and coplanar waveguides has plays an indispensable role in determining the performance of components and systems. In recent research, the ridge waveguide has been used for impedance matching and electromagnetic field mode conversion to accomplish the high-efficiency coupling between THz wave rectangular waveguides and the coplanar waveguides. According to the simulation of CST microwave studio, the results show that the transmission coefficient (S₂₁) of the conversion structure is higher than ?3 dB in 0.2-0.4 THz frequency band, which show that the ridge waveguide converts the THz electromagnetic field with high efficiency. The performance of the conversion structure breaks the restriction of frequency which is below 0.2 THz before. This designed structure can be used in various fields, such as terahertz molecular detection and terahertz communication, and it also provides a feasible solution for terahertz mode conversion above 0.2 THz.