Development of Traveling
A W band folded waveguide Traveling Wave Tube that adopts horseshoe-shaped attenuator and a periodic step-tapering folded waveguide slow wave structure is reported in this paper. In this Traveling Wave Tube, Reflection from severability was effectively reduced and self-oscillation was depressed, and also electronic efficiency is raised by about 1.5~2% comparing with uniform periodic folded waveguide Traveling Wave Tube.
Because of the merits of all metal structure, simple coupling structure and compatibility with micro-fabrication technology, folded waveguide slow wave structure is widely used in millimeter and Terahertz Traveling Wave Tube, but suppression of self-oscillation and improvement of interaction efficiency have been the two most important questions[1-4]. Self-oscillation in W band folded waveguide Traveling Wave Tube commonly includes reflection oscillation, backward-wave oscillation and band-edge oscillation. Reflection oscillation is mainly caused by individual frequency mismatch in its wide frequency band due to machining error and welding deviation of TWT, backward wave oscillation will occur when resonant condition is satisfied between electrical parameters and interaction length, and the band-edge oscillation is due to the mismatch of slow wave structure’s ends. Therefore, it is verynecessary to improve processing precision of the folded waveguide and optimize concentrated attenuator and periodic distribution of folded waveguide slow wave structure to suppress the oscillation and improve the interaction efficiency. Sri Siva Sakthi Travels
This W-band folded waveguide Traveling Wave Tube adopts a horseshoe-shaped attenuator shown in Fig.1 and simulation result by HFSS is shown in Fig.2. From Fig.2, we can see that voltage standing wave ratio in wide range of 10GHz are less than 1.1. In order to improve interaction efficiency of the folded waveguide Traveling Wave Tube, a periodic step-tapering folded waveguide slow wave structure was designed in Fig.3. Compared with uniform periodic folded waveguide, interaction efficiency increased from 3% to 5%. Simulation results by CST are shown in Fig.4 and Fig.5, a stable output power and pure peak spectrum can be seen from above figures A low VSWR energy transfer system was fabricated and combined with the periodic step-tapering folded wave guide SWS for cold measurement. The test results are shown in Fig.6. From Fig.6, we can see that voltage standing wave ratio in 10GHz broadband range are less than 1.367.W-band folded wave guide periodic step-tapering Traveling Wave Tube is shown in Fig.7 and test electrical parameters are listed in table 1. Fig.8 shows that there is no oscillation power when input power is zero and Fig.9 shows that there are two peaks when input power is not zero, right peak is true power output point and left for its image produced by mixing. Fig.10 shows output power increases with input power and the maximum output power is 65W with electronic efficiency is about 4%.
A horseshoe shaped attenuator and a periodic step tapering folded waveguide slow wave structure can not only effectively suppress self-oscillation, but also raise interaction efficiency by 1.5~2%, which laid a good foundation for stable and efficient work of a W-band Traveling Wave Tube. https://srisivasakthitravels.com/
https://www.facebook.com/Sri-Siva-sakthi-Travels-102008227873939/
A W band folded waveguide Traveling Wave Tube that adopts horseshoe-shaped attenuator and a periodic step-tapering folded waveguide slow wave structure is reported in this paper. In this Traveling Wave Tube, Reflection from severability was effectively reduced and self-oscillation was depressed, and also electronic efficiency is raised by about 1.5~2% comparing with uniform periodic folded waveguide Traveling Wave Tube.
Because of the merits of all metal structure, simple coupling structure and compatibility with micro-fabrication technology, folded waveguide slow wave structure is widely used in millimeter and Terahertz Traveling Wave Tube, but suppression of self-oscillation and improvement of interaction efficiency have been the two most important questions[1-4]. Self-oscillation in W band folded waveguide Traveling Wave Tube commonly includes reflection oscillation, backward-wave oscillation and band-edge oscillation. Reflection oscillation is mainly caused by individual frequency mismatch in its wide frequency band due to machining error and welding deviation of TWT, backward wave oscillation will occur when resonant condition is satisfied between electrical parameters and interaction length, and the band-edge oscillation is due to the mismatch of slow wave structure’s ends. Therefore, it is verynecessary to improve processing precision of the folded waveguide and optimize concentrated attenuator and periodic distribution of folded waveguide slow wave structure to suppress the oscillation and improve the interaction efficiency. Sri Siva Sakthi Travels
This W-band folded waveguide Traveling Wave Tube adopts a horseshoe-shaped attenuator shown in Fig.1 and simulation result by HFSS is shown in Fig.2. From Fig.2, we can see that voltage standing wave ratio in wide range of 10GHz are less than 1.1. In order to improve interaction efficiency of the folded waveguide Traveling Wave Tube, a periodic step-tapering folded waveguide slow wave structure was designed in Fig.3. Compared with uniform periodic folded waveguide, interaction efficiency increased from 3% to 5%. Simulation results by CST are shown in Fig.4 and Fig.5, a stable output power and pure peak spectrum can be seen from above figures A low VSWR energy transfer system was fabricated and combined with the periodic step-tapering folded wave guide SWS for cold measurement. The test results are shown in Fig.6. From Fig.6, we can see that voltage standing wave ratio in 10GHz broadband range are less than 1.367.W-band folded wave guide periodic step-tapering Traveling Wave Tube is shown in Fig.7 and test electrical parameters are listed in table 1. Fig.8 shows that there is no oscillation power when input power is zero and Fig.9 shows that there are two peaks when input power is not zero, right peak is true power output point and left for its image produced by mixing. Fig.10 shows output power increases with input power and the maximum output power is 65W with electronic efficiency is about 4%.
A horseshoe shaped attenuator and a periodic step tapering folded waveguide slow wave structure can not only effectively suppress self-oscillation, but also raise interaction efficiency by 1.5~2%, which laid a good foundation for stable and efficient work of a W-band Traveling Wave Tube. https://srisivasakthitravels.com/
https://www.facebook.com/Sri-Siva-sakthi-Travels-102008227873939/
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