CST

Periodic Eigenmode Simulation of a Travelling Wave Tube

This example demonstrates an eigenmode calculation using periodic boundaries in z-direction. The phase shift of the periodic boundary is defined as a parameter which is swept from 5 degrees to 175 degrees with a step size of ten degrees. CST MWS's Eigenmode solver is ideal for this task.


Geometry reduced to a single helix turn
Figure 1: Geometry reduced to a single helix turn

The frequency range is defined up to 10 GHz. The boundary conditions are set to "electric" except for the two boundary conditions in the z direction, which are defined as "periodic" in order to model the periodicity of the helix. A parameter "phase" is assigned to the periodic boundary, so that the phase shift can be used in a parameter sweep.


E, H fields and surface currents obtained from the periodic eigenmode solution
Figure 2: E, H fields and surface currents obtained from the periodic eigenmode solution

All Fields for periodic phase shift may be plotted as in figure 2 where the E and H Fields are shown.


Dispersion characteristics obtained from parameter sweep of the phase
Figure 3: Dispersion characteristics obtained from parameter sweep of the phase

Figure 3 shows the dispersion curves obtained from the parameter sweep via post-processing templates. The phase velocity is shown here as a function of  frequency. The eigenmode solver delivers any aribitrary number of desired modes, 3 of which are shown in the plot.


Pierce Impedance extracted via template-based post-processing of the parameter sweep results
Figure 4: Pierce Impedance extracted via template-based post-processing of the parameter sweep results

Figure 4 shows the Pierce Impedance obtained as a post-processing step. The powerflow in the tube is also an additional post-processing quantity that may be calculated.


CST Article "Periodic Eigenmode Simulation of a Travelling Wave Tube"
last modified 30. Apr 2013 9:56
printed 25. Sep 2016 9:07, Article ID 123
URL:

All rights reserved.
Without prior written permission of CST, no part of this publication may be reproduced by any method, be stored or transferred into an electronic data processing system, neither mechanical or by any other method.

Feedback

10 of 14 people found this article useful

Did you find this article useful?

Other Articles

CST HPC Flyer

CST HPC Flyer Document type
CST® STUDIO SUITE® offers a broad range of hardware based acceleration methods. The systems that are supported range from single off-the-shelf workstations to high-end cluster based solutions. A critical measure in determining the feasibility of a simulation is the computational time needed to complete the simulation to a particular level of accuracy. Although this time can be reduced by choosing an appropriate solver and solver settings that are well suited to the problem, many simulation tasks still require a high level of computational resources. This could be because of extensive parameter studies, a high model complexity, or simply a large number of mesh cells needed for the discretization. In these cases it is impractical or even impossible to handle the simulations using a standard workstation computer. High Performance Computing (HPC) techniques help reduce the computational time of such simulations, and make the handling of complex models possible. Read full article..

EMC Simulation in the Design Flow of Modern Electronics

EMC Simulation in the Design Flow of Modern Electronics
EMC compliance is a necessary condition for releasing products to market. National and international standards bodies such as the IEC2 and the FCC3 define limits on the emissions a device is allowed to produce, and automotive and aerospace manufacturers can set even stricter standards for their OEM suppliers. If these standards are not met, the product cannot be sold. Read full article..

The use of CST Microwave Studio in the Design of an X-Band Circularly Polarised Splashplate Antenna

The use of CST Microwave Studio in the Design of an X-Band Circularly Polarised Splashplate Antenna Document type
Richard Roberts, Astrium Ltd This presentation describes how CST Microwave Studio (MWS) has been used in conjunction with POS 5 and GRASP 8 to design an X-Band circularly polarised Splashplate Antenna. The antenna essentially consists of a centre fed reflector (17 wavelengths in diameter), the Splashplate feed (~2 wavelengths in diameter), and a septum polariser to allow the Tx and Rx bands to operate in opposite polarisations. A significant factor in the design is that a short circuit had to be assumed at the other port of the septum polariser meaning that the return loss of the Splashplate feed and the reflector were critical to the axial ratio performance. CST MWS enabled this aspect of the design to be modelled and analysed using the T-solver. Comparison of the measured and predicted antenna performance has validated the design process. Although a compliant performance has been achieved, it is evident that some modelling improvements could be sought in order to get a better convergence between prediction and measurement. Read full article..

eASIC Reduces Multi-Level Package Design Times with CST MICROWAVE STUDIO

eASIC Reduces Multi-Level Package Design Times with CST MICROWAVE STUDIO Document type
eASIC is a fabless semiconductor company specializing in Single Mask Adaptable ASIC™ (application-specific integrated circuits). They produce custom integrated circuits for a wide range of applications, designed with the specific needs of the customers in mind. Supporting customers effectively, especially during the development stage of a new product, requires a rapid, cost-effective design and manufacturing process. Read full article..

Train Signaling System Interference Estimation by CST MWS

Train Signaling System Interference Estimation by CST MWS
This webinar presents results of the TREND project, that aims to define the conditions to control EM emissions that affect the signaling and communication systems on board of trains. We focus on the EM simulation of the interferences received by BTM antennas (Balise Transmission Module). The BTM loop-antenna is placed beneath the locomotive floor and operates as a Radio Frequency Identification (RFID) reader that interrogates balises that are distributed along the railway track as part of the European Rail Traffic Management System (ERMTS). The BTM loop is victim of radiated and conducted EM interference generated by the main current path of the train’s engine: from pantograph to the tracks. We make use of TLM solver for wire modeling and combine a high resolution mesh for the BTM antenna embedded into a model that represents Oaris, a train manufactured by CAF. This work is supported in the context of FP7 European project TREND (Test of Rolling Stock Electromagnetic Compatibility for cross-Domain Interoperability, contract number 285259). Read full article..
Back Back  

Your session has expired. Redirecting you to the login page...