Study of a Terahertz-Band Rectangular TE30/TE40/TE50 Mode Converter With the Same Exciting Topology

• Published in: IEEE transactions on microwave theory and techniques Vol. 71; no. 3; pp. 1216 - 1226
• Main Authors: Lin, Jujian, Shu, Guoxiang, Lin, Guangxin, Li, Qi, Liao, Jiacai, He, Jingcong, Ren, Junchen, Deng, Junzhe, Chang, Zhiwei, Xu, Biaogang, Yin, Huabi, Ruan, Cunjun, He, Wenlong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Apertures; Bandwidth; Conversion; Coupling apertures; Couplings; Errors; Machining; Magnetic analysis; Magnetic moments; Microwave theory and techniques; mode converter; same exciting topology; Terahertz frequencies; terahertz-band; Topology; Waveguides
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2022.3217562

A novel methodology of mode conversion from rectangular TE10 mode to TE30/TE40/TE50 modes with the same exciting topology is proposed in this article. The proposed mode converter compromises an <inline-formula> <tex-math notation="LaTeX">H </tex-math></inline-formula>-plane T-junction power dividing network and a mode exciting structure based on two coupling apertures. One of the most significant highlights of this geometry is that various TE<inline-formula> <tex-math notation="LaTeX">_{m0} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">m = 3, 4, 5, 6, 7, \ldots </tex-math></inline-formula>) high-order modes could be excited just by adjusting the width of the overmoded output waveguide. Terahertz-band (230-300 GHz) rectangular TE30/TE40/TE50 mode converters were optimized and 1 dB transmission bandwidths of 49.4, 32.5, and 29.0 GHz were obtained, respectively. Within these bandwidths, the port reflections were lower than −15 dB. Two kinds of back-to-back joined rectangular TE30 mode converter prototypes with different cutting planes were fabricated and measured. The measured <inline-formula> <tex-math notation="LaTeX">S </tex-math></inline-formula>-parameters are in good agreement with the simulated ones having considered the conductor loss, machining errors, and assembling errors, which verifies the feasibility of the proposed mode conversion methodology.