Quansi-optical mode converter for Ka-band application on a gyrotron
Abstract
A series of electron cyclotron masers (ECMs) has been designed and successfully operated in the frequency range of 6 to 200 GHz over the past 10 years at Strathclyde University. The current Mk. VI ECM operated between 35–200 GHz, the TE0 10 mode (35.2 GHz) being the lowest order cavity mode excited. Investigation of this ECM and quasi-optical converter combination was made to establish to what extent a Gaussian beam could be produced from the TE0 10 gyrotron cavity mode. An antenna of the Vlasov (step-cut radiator) configuration was chosen and successfully developed in a series of low-power experiments up to the W-band frequency regime. The low-power experiments demonstrated that such an antenna system could be constructed and operated in the Ka-band frequency region without resorting to high precision quasi-optical components. The final version of the quasi-optical antenna was externally coupled to the output window of the maser and a plane polarized pencil beam was successfully obtained from the combined maser/Vlasov antenna mode converter. A theoretical model involving a single TE0n0 input mode was chosen to analyse the output beam characteristics from the Vlasov antenna system. Comparison was made between the single mode theoretical model and the experimental results obtained from the maser.
- Publication:
-
International Journal of Infrared and Millimeter Waves
- Pub Date:
- June 1991
- DOI:
- 10.1007/BF01010381
- Bibcode:
- 1991IJIMW..12..629W
- Keywords:
-
- Antenna Radiation Patterns;
- Cyclotron Resonance Devices;
- Extremely High Frequencies;
- Mode Transformers;
- Reflector Antennas;
- Maser Outputs;
- Microwave Antennas;
- Vlasov Equations;
- Electronics and Electrical Engineering;
- Quasi-optical mode converter;
- gyrotron