Extremely Broad Bandwidth Input/Output Coupling Structure Design for a $Q$ -Band Sheet-Beam Traveling-Wave Tube

In this paper, a new type input/output (i/o) structure, adopting the multiaperture coupler, for broadband sheet-beam traveling-wave tube was designed and analyzed. This novel coupling structure not only can get a larger electron passway, which will greatly benefit the transmission of the electron beam, without deteriorating electromagnetic transmission characteristics, but also work over an extremely broad bandwidth. The transmission characteristics of this coupling i/o structure are investigated by Ansoft's high-frequency structure simulator (HFSS). Operating at TE
₁₀
mode, the maximum insertion loss and isolation of the i/o structure over 36-52 GHz, which equals to 36.4% bandwidth, are -25 and -20 dB, the transmission coefficient is above -0.3 dB. The results of HFSS were verified by Computer Simulation Technology Microwave Studio.