Research On Terahertz Planar Integrated Slow Wave Structure

Terahertz science and technology is one of the most cutting-edge research fields.The terahertz wave has unique physical properties such as low energy,high permeability,fingerprint spectrum,broadband,transient and coherence.These excellent physical properties make terahertz waves suitable for many applications,such as satellite communications,remote sensing imaging,biomedical and basic scientific research.The bright future of terahertz science and technology has also stimulated research interests in academia and industry.At present,the development of Terahertz Science and technology is mainly limited by the immature terahertz sources.Vacuum electronic devices are the only practical devices for terahertz radiators with high power,high efficiency and long working life,which are small in size and can work at room temperature.Traveling wave tubes and backward wave tubes are the two most common vacuum electronic devices,its operating frequencies have been extended from KHz to THz,and the output power has also increased from mW to MW.Miniaturization and integration have become the development trend of vacuum electronic devices,and high power can be achieved by adopting multi-beam system and multi-stage cascaded structure.Firstly,the backward wave tube(BWT)and traveling wave tube(TWT)based on rectangular staggered double grating slow wave structure have been studied in detail.Secondly,a dual-channel rectangular staggered double grating slow-wave structure,based on the rectangular staggered double grating slow-wave structure,is proposed.The traveling wave tube composed of the new slow-wave structure was studied.Finally,three schemes of cascaded microwave tubes are proposed and the output characteristics of different schemes are simulated respectively.The dispersion characteristics of the rectangular staggered double grating slow-wave structure and the dual-channel rectangular staggered double grating slow-wave structure have been analyzed.The transmission characteristics of single-tube microwave tube and cascaded microwave tube composed of these two slow-wave structures also are studied.Finally,the wave-beam interaction of microwave tube is calculated and analyzed.The wave-beam interaction between the single-tube microwave tube and the cascaded microwave tube shows that: The output power of the backward-wave tube based on the rectangular staggered double-grating slow-wave structure can reach 13.47 W.The maximum gain of TWT based on rectangular staggered double grating slow-wave structure can reach 18.8dB.The maximum gain of TWT based on dual-channel rectangular staggered double-grating slow-wave structure can reach 30.8dB.Based on the cascade scheme of TWT and BWT,the output power of the whole tube is 2.7W.Based on the cascade scheme of two BWTs,the output power of the whole tube can reach 11.5W.Based on the cascade scheme of two TWTs,the output power can reach 13 W and the maximum gain can reach 31.1dB.