Wideband Rectangular TE10 to TE \text}} Mode Converters for Terahertz-Band High-Order Overmoded Planar Slow-Wave Structures

• Published in: IEEE transactions on electron devices Vol. 67; no. 3; pp. 1259 - 1265
• Main Authors: Shu, Guoxiang, Cai, Zhirong, Li, Yuchen, Liu, Guo, He, Wenlong
• Format: Journal Article
• Language: English
• Published: IEEE 01-03-2020
• Subjects: High-order overmoded (HOOM); rectangular mode converter; septum loaded; slow wave structures (SWSs); terahertz band
• ISSN: 0018-9383
• DOI: 10.1109/TED.2020.2968167

The technique of mode conversion between rectangular TE 10 and TE<inline-formula> <tex-math notation="LaTeX">_{n{0}} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">{n}= {2}, {3}, \ldots </tex-math></inline-formula>) modes is studied in this article. The mode conversion was mainly realized by coupling apertures. To compensate for the junction discontinuity and, thus, enhance the performances, rectangular septa were introduced in the mode converters. Rectangular recesses were added to suppress the potential competing modes. As two examples, the design of rectangular TE 20 and TE 50 mode converters operating in the terahertz band is presented in this article. To verify the design, two identical rectangular TE 20 mode converters joined back-to-back were manufactured by nanocomputer numerical control (CNC) machining and the performances of the converters were characterized by using a vector network analyzer. The measured transmission coefficients were in good agreement with the simulated ones and showed a good flatness response with a 3-dB bandwidth of ~70.7 GHz (220.0-290.7 GHz). The average measured value of <inline-formula> <tex-math notation="LaTeX">{S}_{{21}} </tex-math></inline-formula> was about −2.0 dB and the in-band port reflection <inline-formula> <tex-math notation="LaTeX">{S}_{{11}} </tex-math></inline-formula> was around −10.0 dB.