Title :
Broadband linearly polarized beat-wave TEm1/TE11 mode converters
Author :
McDermott, D.B. ; Pretterebner, J. ; Chong, C.K. ; Kinney, C.F. ; Razeghi, M.M. ; Luhmann, N.C., Jr.
Author_Institution :
Dept. of Appl. Sci., California Univ., Davis, CA, USA
fDate :
2/1/1996 12:00:00 AM
Abstract :
Broadband linearly polarized waveguide mode converters have been developed to transform the high-order cylindrical TEm1 output wave from harmonic gyrotron amplifiers into the more useful TE11 fundamental waveguide mode. The converter´s corrugation period is equal to the beat between the two waves and the bandwidth is predicted to be inversely proportional to the number of periods. Four-period TE 31/TE11 and TE41/TE11 converters with an azimuthal perturbation of mc=4 and mc =5, respectively, have yielded a peak conversion efficiency of 98% with a bandwidth greater than 3% and a one-period beat-wave converter has been designed to yield 12% bandwidth. However, it has been observed in measurements that the strong coupling in a short converter can lead to a shift of the center-frequency with an accompanying reduction of the efficiency and bandwidth. A two-period TE41/TE11 converter with 5% bandwidth displayed a 5% frequency shift and a conversion efficiency of only 86%
Keywords :
electromagnetic wave polarisation; gyrotrons; microwave amplifiers; waveguide components; 86 to 98 percent; azimuthal perturbation; beat-wave TEm1/TE11 mode converters; conversion efficiency; corrugation period; fundamental waveguide mode; harmonic gyrotron amplifiers; linearly polarized convertors; one-period beat-wave converter; peak conversion efficiency; short converter; strong coupling; two-period TE41/TE11 converter; Bandwidth; Electromagnetic waveguides; Frequency conversion; Fusion power generation; Gyrotrons; Magnetic resonance; Microwave technology; Polarization; Radiofrequency amplifiers; Tellurium;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
