Design and Experimental Verification of 0.34-THz Rectangular TE10 to TEn0 Mode Converters

A novel rectangular TE10 to rectangular TEn0 (
$n=2, 3, 4, \ldots $
) mode converter based on an
$E$
-plane Y-shaped branch waveguide power dividing network is proposed in this article. To obtain the desired high-order mode, the signal observed at the output end of each adjacent branch waveguide of the power dividing network is designed to possess the property of equal amplitude and reversed phase. Three terahertz-band (300–400 GHz) rectangular TE20/TE30/TE40 mode converters were designed and optimized, obtaining a 1-dB transmission bandwidth of 100.0 GHz (29.4%), 100.0 GHz (29.4%), and 67.2 GHz (19.8%), respectively. This kind of mode converter offers good flexibility to excite any TEn0 modes with good electrical performance, including high mode conversion efficiency and low port reflection over a wide frequency bandwidth. The prototype of two identical rectangular TE30 mode converters joined back-to-back was microfabricated and measured. The experimental measurement results were in good agreement with simulation predictions when the conductor ohmic loss, machining, and assembling errors were taken into account, which verifies the feasibility of the design methodology and manufacturing scheme for a mode converter operating above 300 GHz.