Optimized TE01-to-TM11 mode conversion in highly overmoded circular waveguide at 70 and 140 GHz
Abstract
Mode coupling in bent, oversized, smoothly walled circular waveguides was studied by numerical integration of coupled-mode equations, to optimize high power TE01-to-TM11 mode transducers at 70 and 140 GHZ. Such transducers are used in the mode conversion sequence TE on to TE01 to TM11 to HE11 to generate the linearly polarized HE11 (Gaussianlike) mode from the circular electric TE on gyrotron mode. The balanced HE11 hydrid mode is ideal for electron cyclotron plasma heating in thermonuclear fusion research and for other technical applications. The lowest level of unwanted spurious modes is achieved with sinusoidal curvature distribution instead of constant curvature. The calculated efficiencies of 98.0% at 70 GHZ and 95.2% at 140 GHZ (inner diameter 27.79 mm, ohmic attenuation included) are in excellent agreement with the measured values (97.6% and 95%) respectively.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- June 1985
- Bibcode:
- 1985STIN...8628319S
- Keywords:
-
- Circular Waveguides;
- Millimeter Waves;
- Mode Transformers;
- Coupled Modes;
- Cyclotron Resonance Devices;
- Electron Cyclotron Heating;
- Numerical Integration;
- Optimization;
- Product Development;
- Transverse Waves;
- Utilization;
- Communications and Radar