Design and simulation study of Helix Traveling Wave Amplifier for Ku-Band applications

The purpose of this investigation is to present a Ku-Band Helix Traveling Wave Tube Amplifier (TWTA) design and simulation procedure with considering initial design assumptions. The design process which consists of four critical steps is stated. Firstly, required input parameters such as dc beam current (Io), dc beam voltage (Vo) and frequency band of operation are chosen. Determination of the design objectives such as gain and output power constitutes the second stage of the design procedure. For this purpose, overall gain in considered frequency range is specified as over 20 dB. The output power is aimed to 100 W. To obtain design objectives mentioned in the second step, it is necessary to have optimum helix slow wave structure (SWS) design parameters such as helix pitch, radius and pitch angle. Therefore, the optimized design parameters of the SWS are determined by using Eigen Mode Solver (EMS) (cold (beam absent) analysis) of Computer Simulation Technology (CST) Microwave Studio (MWS) for acquiring the beam-wave synchronization. Particle in Cell (PIC) simulation (hot (beam present) analysis) is carried out by assuming the uniform electron beam flow. The length of the interaction structure of the designed TWT is nearly 110 mm and all design objectives are nearly achieved as it is expected. Many crucial figures related to gain, power and beam wave interaction are depicted with detailed explanations. Furthermore, the design limitations of this proposed design due to assumptions are also clarified.