Abstract
Two-step high-power TE03-to-TE01 mode transducers (TE02 is the intermediate mode) were designed to transform the TE03 output mode of the 150 GHz KfK gyrotron into the fundamental circular symmetric TE01 mode for low-loss propagation and further conversion into the linearly polarized quasioptical HE11 mode. The advanced perturbation structures of the ruppled-wall mode converters (with input- and output-diameter D=27.8 mm) were optimized by numerically solving the proper coupled-wave differential equations. The overall TE03-to-TE01 conversion efficiency at 150 GHz was calculated to be η0=99.1% for a long converter (total length L=2.67 m) and η0=97.8% for a short converter (L=1.07 m); ohmic attenuation is included. The corresponding theoretical bandwidth (for η≧95%) is ±1.4 GHz and ±2 GHz, respectively. Low-power experimental data are in excellent agreement with these computed values.
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Thumm, M., Kumric, H. & Stickel, H. TE03 to TE01 mode converters for use with a 150 GHz gyrotron. Int J Infrared Milli Waves 8, 227–240 (1987). https://doi.org/10.1007/BF01014556
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DOI: https://doi.org/10.1007/BF01014556