1. Introduction to CST MWS
EKT 341 By
Dr Soh Ping Jack
Muhammad Ezanuddin bin Abdul Aziz
Cheor Wai Loon
Universiti Malaysia Perlis (UniMAP)

2. Introduction to CST MWS
OUTLINE
Introduction to CST MWS
Why 3D electromagnetic simulation tools are needed?
3D simulation methods
CST MWS – Simulation example
Summary

3. Why 3D electromagnetic simulation tools are needed?
INTRODUCTION
Why 3D electromagnetic simulation tools are needed?
Radiating electric & magnetic fields are described by Maxwell´s equations
Analytical calculation by solving the Maxwell´s equations
> exact or approximation
Analytical equations are derived for simple antenna structures
> dipole, monopole, microstrip antennas

4. Why 3D electromagnetic simulation tools are needed?
INTRODUCTION
Why 3D electromagnetic simulation tools are needed?
Present-day antennas are not simple structures
> Complex antenna shapes
> Dielectric material (phone covers, antenna radome)
> User close to antenna –> absorption
Exact solutions do not exist
Solution is approximated by using computational electromagnetic tools
• Numerical solution for the Maxwell´s equations
• Do not give exact solution, accuracy depends on the calculation capacity
• Arbitrary antenna shapes and materials can be solved

5. Why 3D electromagnetic simulation tools are needed?
INTRODUCTION
Why 3D electromagnetic simulation tools are needed?
User / environment / phone material influence on antenna performance
Specific Absorption Rate (SAR) [W/kg]
Hearing Aid Compatibility (HAC)
Optimized antenna solution for every situation
• Location
• Size
• Form

6. Why 3D electromagnetic simulation tools are needed?
INTRODUCTION
Why 3D electromagnetic simulation tools are needed?
Solution is visualized for the designer
• Impedance matching
• Radiation properties
• Surface currents
• SAR
Prototype manufacturing and measurement rounds
are replaced by simulations
Speeds up the design flow
Final goal is an efficient antenna for a specific application

7. 3D simulation methods INTRODUCTION
Excitation signal in a certain location of the 3-dimensional
space.
• This is typically antenna feed assuming 50Ω impedance
• Can be also plane wave e.g. In radar cross section simulations
Structure is surrounded by boundaries
• Open, electric, magnetic
• Antenna simulations are typically made with open boundaries -> radiation goes through boundary -> far field approximations are based on the power through boundary
Time or frequency domain calculation is made for the
excitation
• Idea is to calculate wave propagation in simulated structure
• When steady-state situation is met -> solver stopped
• Criteria can be e.g. The energy of back-reflected signal

8. 3D simulation methods Mesh
INTRODUCTION
3D simulation methods
Mesh
Simulated structure is meshed = divided in small subdomains (cubes) or triangular parts
Mesh type depends on the solver type (time or frequency domain)
Mesh is dense in critical points
• Surface of the conductors
• Feed area
• Small details
• High permittivity material
• High loss material

9. 3D simulation methods Method of Moments, MoM
INTRODUCTION
3D simulation methods
Method of Moments, MoM
• Full wave solution of Maxwell's integral equations in the frequency domain.
• Well suited for models including conductive materials only. One famous simulator is IE3D by Zeland
Finite Element Method, FEM
• Frequency domain calculation, ideal for low loss and resonance –type structures. Commercial simulator HFSS by Ansoft
Finite Difference Time Domain, FDTD
• Time domain simulation, good for broadband antennas. Commercial simulators SEMCAD-X by Speag and MWS by CST.
Nowadays trend is toward simulation tools with different solvers for different simulation problems !!!

10. CST MWS Computer Simulation Technology CST
INTRODUCTION
CST MWS
Computer Simulation Technology CST
• Several products for 3D simulation
• Microwave Studio is for electromagnetic high frequency problems
• FDTD method -> large simulations are relatively fast
• Not ideal for high Q resonators
• Lately included also frequency domain solver
• Widely used by antenna manufacturer and academia

11. INTRODUCTION

12. INTRODUCTION

13. INTRODUCTION

14. INTRODUCTION

15. INTRODUCTION

16. INTRODUCTION

17. INTRODUCTION

18. SUMMARY

19. References http://cst-simulation.blogspot.com/
spx.
Swanson D.G., Hoefer W. J. R. “Microwave circuit modeling using electromagnetic field simulation

20. QA
Question and answer?