Research On The Wideband Dual-Frequency Planar Slow-Wave Structure For Traveling Wave Tube

Modern communication technology has achieved rapid development in the past two decades.The era of 5^th generation(5G)communication is coming,which will lead a new round of technological innovation.Furthermore,6G and beyond 6G technologies will use higher frequency bands,where solid-state devices(SSD)have been unable to meet the requirements of signal transmission power at base station.Meanwhile,satellite communication,as an important communication technology,carries more and more information capacities,where the requirements of spectrum are becoming higher.Therefore,it can be considered to use SSD as signal sources and traveling wave tubes(TWT)as power amplifiers to meet the requirements of high-power transmission.As one of the candidates for high-frequency SWS,the new planar meander line SWS(ML-SWS)has a wide bandwidth and can be fabricated by a mature manufacturing process,which can be mass-produced and is easy to miniaturize.However,the bandwidth of the ML-SWS is insufficient compares to that of helix SWS.This thesis proposes to use a double-layer asymmetric ML-SWS to expand the bandwidth and construct a broadband TWT.In this thesis,the high-frequency characteristics of the ML-SWS are analyzed theoretically in chapter II.The dispersion characteristics and coupling impedance formula of the ML-SWS are introduced.The structure parameters of the ML-SWS are analyzed,and two ML-SWSs with different working frequency are designed.Following this work,a double-layer asymmetric ML-SWS(DLA ML-SWS)with dual-electron beams is designed on chapter IV.On the basis of the single-layer ML-SWS,the DLA ML-SWS is presented.The center frequency of the upper layer ML-SWS is designed at 38 GHz and that of the lower layer ML-SWS is designed at 30GHz.Two electron beams are used for wave-beam interaction and dual-mode operation.The simulation results show that this structure achieves an output signal with large bandwidth,which covers the entire Ka band.Furthermore,based on the design on chapter IV,the DLA ML-SWS with single-electron beam is designed to optimize the wave-beam interaction on chapter V.This structure has compact spacing and reduces the size of the overall device.Using an electron beam improves spacing efficiency and achieves gain balance by adding an attenuator.The simulation results show that this structure can also cover the entire Ka band.However,the output power has decreased compared to that of DLA ML-SWS with dual electron beams.The reason of this is discussed in this chapter.Finally,a conclusion is drawn at the end of this thesis.