A comprehensive analysis of a TE₁₁ to HE₁₁ mode converter for an oversized F-band corrugated waveguide

Abstract

We have investigated the mode transition behavior from approximately half- to quarter-wavelength in typical F-band (90–140 GHz) TE₁₁ to HE₁₁ converters of varying corrugation depths. Simulations in which the number of slots in the corrugation is varied indicate that the optimal number of slots should be greater than two, which is in excellent agreement with the experimental results. The mode content was also analyzed with and without a quarter-wavelength depth-corrugated tapered section. The electric field pattern at the exit of a quarter-wavelength tapered transition connected to a half-wavelength to quarter-wavelength TE₁₁ to HE₁₁ mode converter is compared with that without a converter. Electric field patterns both with and without a half- to quarter-wavelength TE₁₁ to HE₁₁ mode converter show a highly Gaussian field pattern with less than 35 dB of cross-polarization. Simulated field patterns are in good agreement with the experimentally measured field patterns, with the measured and simulated electric field distributions matching approximately 96.5 and 97.5%, respectively, to a pure Gaussian distribution.

Keywords:

• corrugated waveguide
• horn antennas
• mode transition
• high power transmission
• gyrotrons

Acknowledgments

This research was supported by National R&D Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2011-0020575). Also, we acknowledge financial support by Korea Research Institute of Standards and Science (KRISS).