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Effective Antenna Simulations using CST MICROWAVE STUDIO

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Effective Antenna Simulations using CST MICROWAVE  STUDIO Powered By Docstoc
					    Effective Antenna
    Simulations using
     CST MICROWAVE
        STUDIO ®

                       Franz Hirtenfelder
              CST GmbH, Bad Nauheimer Strasse 19
                 D-64289 Darmstadt, Germany,
               E-Mail: franz.hirtenfelder@cst.com




1                                      www.cst.com
                             CST Worldwide
     CST Office                                   CST Europe
     CST Distributors and Reps
                            CST of America                            CST of Korea




                                                                             AET Japan




CST West Coast



                                                          CST China

       • Founded in 1992
       • Focus on 3D EM Field calculation
       • 100 Employees + Worldwide Distributors
       • Best in Class links: Cadence, Agilent,
 2               AWR, Sonnet, ....                                     www.cst.com
 FI - The Finite Integration Method
         Discretizing each Maxwell Equation

    ∫
    δA
      E d s = − ∫∫ B d A
                  A
                   &                       &
                                    Ce = − b

            ek

    el                ej                ⎡ei ⎤
             bn            ⎡ ⋅ ⋅ ⋅ ⋅ ⎤⎢ ⎥           ⎡⋅⎤
                           ⎢ 1 1 −1 −1⎥ ⎢ej ⎥ = − d ⎢b ⎥
            ei             ⎢          ⎥ ⎢e ⎥ dt ⎢ n ⎥
                           ⎢ ⋅ ⋅ ⋅ ⋅ ⎥ ⎢ k⎥
                           ⎣ 4 4 4 4 e 123
                                      ⎦             ⎢⋅⎥
                           1 42 43⎣ l ⎦ 4 ⎣4           ⎦
                                C       {         −b&
                      &
ei + e j − ek − el = −bn                 e

3                                              www.cst.com
       FI - The Finite Integration
                 Method
    Covering the whole frequency range
                  r r         ∂ r r                   Ce = − b &
                ∫ E ⋅ ds = − ∫∫ B ⋅ dA
                             ∂t A
              ∂A                                     ~      &
                  r r
                ∫ H ⋅ ds = ∫∫ ⎜
                                 r
                              ⎛ ∂D r⎞ r
                                   + J ⎟ ⋅ dA
                                                     Ch = d + j
              ∂A           A
                              ⎝ ∂t     ⎠               ~
               ∫∫
                  r r
                  B ⋅ dA = 0                           S d = q
              ∂V
                  r r
               ∫∫ D ⋅ dA = Q
                                                       Sb = 0
              ∂V

    Maxwell’s equations (1876)                  Grid equations (1977)

        div curl = 0                                 SC=0
                                                     ~    T
       curl grad = 0                                 CS=0
4                                                              www.cst.com
           Finite Integration + PBA
                    Statics to THz
               Maxwell Grid Equations

∂              ∂                           ∂
   = 0            a iω                        ≠ 0
∂t             ∂t                          ∂t


                Frequency Domain (j>0)      Implicit
    E-static

    M-static                                 Explicit
                Eigenvalue Problem (j=0)
                                             Time
    J-static                                 Domain
    Tracking    EMS              MWS
                                              PIC
                      MAFIA
5                                              www.cst.com
      CST MICROWAVE STUDIO®
    General purpose solver 3D-volume
                            • large problems
                Transient   • broadband
                            • arbitrary time signals
                            • narrow band / single frequency
        Frequency Domain    • small problems
                            • periodic structures with Floquet port modes


    Special solver 3D-volume: closed resonant structures
                            • strongly resonant structures, narrow band
              Eigenmode
                            • cavities
             FD Resonant    • strongly resonant, non radiating structures



    Special solver 3D-surface: large open metallic structures
          Integral Equation • large structures
       (based on MLFMM) • dominated by metal

6                                                                           www.cst.com
        Comparison of Simulation
               Methods
        Frequency Domain                      Time Domain
             Solvers                             Solvers




           FEM, MoM,
         FEM, MoM, FIT                      FIT, FDTD, TLM
          MLFMM, FIT



• Implicit Algorithm ( A x = b )    • Explicit Algorithm ( xn+1 = M xn )
• Steady State (single frequency)   • Transient Solution




7                                                            www.cst.com
Finite Integration in Time Domain
            Explicit Time integration

                  ()b
                              = M(
                                             b
                                               )
                          (n+1)                  (n)

                    e                        e




                                                       t


      en+1/ 2
                en −1 / 2 > bn −1 > e n +1/ 2 > bn
     No Matrix Inversion Required !
8                                                          www.cst.com
Meshes + Frequency / Time Domain
                          Numerical Effort

     Mx=r                                               x(n+1) = M x(n)
     Implicit Algorithm                                Explicit Time Integration




can be applied to tetrahedral meshes               very efficient for many mesh cells
               Typical effort    Frequency
                                                Frequency
                                 Domain
                                                Domain
                                 Direct
                                                Iterative
                                                       Time Domain



                                  N = Number of mesh cells
 9                                                                    www.cst.com
 Geometry Approximation Techniques
  Original Object              FEM Model              FDTD, TLM Model




                                               or




Finite Element Method                      Standard FDTD, TLM
+ good approximation of curved objects     - bad approximation of curved objects


                           Numerical Effort ?

 10                                                               www.cst.com
           Growth through technology



     FEM                  FDTD
                                                      CST



                                                    Competitors




                            FIT+PBA

                                      CST MWS 1.0
☺ Representation of rounded objects
☺ Efficiency / Speed / Accuracy

11                                                     www.cst.com
                            Accuracy: PBA
                           1. Adaptive mesh refinement   2. Tuning Step
                           of untuned filter             30 Lines/Lambda = 51000 cells
                                                         TD (AR) Solver time: 256 s
                                                         Resonant (MOR) Solver 91 s




3. Increased mesh density to 50 Lines/lambda


                                                                 slight readjustedment of
                                                                 only one parameter
                                                                 by 0.0125mm!!




     Resonant (MOR) Solver 414 s
12                                                                       www.cst.com
                        Accuracy: Staircase
                                                Mesh density was increased:
                                                Results did not converge to the PBA-results




89.000 Cells. 2.5 min   384.000 Cells. 27 min
  (1.7 GHz Laptop)




                                  1.050.000 Cells. 1h 15 min
     600.000 Cells. 46 min    (all MOR Solver, 1.7 GHz Laptop)        5Mio , 2.5 h
13                                                                          www.cst.com
     Accuracy: PBA




14                   www.cst.com
     Example of a Vivaldi Antenna




15                                  www.cst.com
     EM / Circuit Co-Simulation via
   APLAC for CST DESIGN STUDIO™
Example: Antenna including feeding network and filter


                                                Sub-model
                                                                     CST MWS model




       Circuit elements




   APLAC for CST DESIGN STUDIO™ is a subset of APLAC Simulator, APLAC Solutions‘ Circuit
   Simulation and Design Tool, featuring a selection of linear and nonlinear elements & methods
16 geared for EM / Circuit co-simulation tasks.                                        www.cst.com
      Subgrid: Spiral with phone and head
                          Here: Subgridding reduces
                          •     number of cells by factor > 13
                          •     computing time by factor 10




 No Subgridding                        Subgridding
 1987440 Meshcells                     148922 Meshcells
 Meshing: 294 s + Solver: 14322 s      Meshing: 607 s + Solver: 816 s
 Total: 14616 s                        Total: 1423 s
17                                                                      www.cst.com
                      Conformal YAGI Array




       Desing by FGAN, single YAGI elements based on:
  Noriaki Kaneda, W. R. Deal, Yongxi Qian, Rod Waterhouse,
 andTatsuo Itoh „A Broad-Band Planar Quasi-Yagi Antenna“
 IEEE TRANSACTIONS ON ANTENNAS AND ROPAGATION,               without sub grid (1.6 million mesh nodes)
               VOL. 50, NO. 8, AUGUST 2002




                                                             without sub grid (0.6 million mesh nodes)

18                                                                                     www.cst.com
                  Multilevel Subgridding




            Automatic
            Multilevel
           Subgridding




19   single Element      YAGI Array        www.cst.com
       Periodic Boundaries
     Unit Cell Model of an open Waveguide


                        For a simple waveguide with a phaseshift along x-
                        direction the powerflow and propagation
                        direction for the two existing plane waves are
                        investigated.
                        The phase-angle is set to a value where grating lobes
                        occur
     Dielectric sheet
          (λ/2)




20                                                          www.cst.com
     Electrical Phase Shift Angle = 45 deg




     Blind Spot occurs at an electrical
     Phase Shift Angle = 71 deg




     Grating lobes occur at electrical
     Phase Shift Angles > 150 deg


21                                       www.cst.com
     Portinformation: PlaneWave 1 and 2




22                                  www.cst.com
       New Unit Cell Boundary Condition

     honeycomb_02.zip




     S2


      60°

                        S1
S1 is always along Ox
S2 at an angle („grid angle“)
   with respect to Ox
23                                   www.cst.com
     New Unit Cell Boundary Condition




                           Slanted Ports


24                                         www.cst.com
       Periodic Boundaries
     Astrium Terra-SAR: “Complete Model”




25                                         www.cst.com
     Periodic Boundaries
      Astrium Terra-SAR: Unit Cell




26                                   www.cst.com
                                     LeftHanded Materials
                                                   Wedge Model




     Drude                               Lorentz
                             ω  2
                                                           ( μ s − μ ∞ )ω 0
                                                                          2
     ε eff (ω )= ε ∞ −          p
                                         μ eff (ω )= μ ∞ + 2
                         ω (ω − iν c )                    ω 0 + iωδ − ω 2
27                                                                            www.cst.com
     LeftHanded Materials
          Antenna Model




28                          www.cst.com
Integral Equation Solver
 • I-solver is based on…

              ∫    [                           ]
     E(r) =−iωμ g(r−r')J(r')+γ−2∇ (r−r')∇⋅J(r') dS
               S
                                 g       '        '




29                                                              www.cst.com
                                                      www.cst.com • Dec-07
I-solver – MLFMM idea




      MoM                   FMM                      MLFMM

Every element          Use boxes to
couples to all other                           Recursive
                       combine coupling
elements                                       scheme
                        → sparser matrices
 → dense matrices

30                                                     www.cst.com
                                             www.cst.com • Dec-07
            MLFMM Solver Example
7.30m x 6.10m x 2.30m        175λ x 147λ x 56λ at 7 GHz
880k Surface mesh cells, 1st order MLFMM
Plane wave illumination from front
The Helicopter requires at 7 GHz
approx. 72 h and 22GB RAM.




        7.30m x 6.10m x 2.30m      25λ x 21λ x 8λ α 1 GHz
        140.000 Surface Mesh cells, 1st order MLFMM algorithm
        Plane wave ilumination from front, 4 h CPU 16 GB
31                                                              www.cst.com
              MLFMM Solver Example




     540,000 surfaces ~2.7 million DOFs (1st order)
                at 4GHz 75 h requires 32GB RAM.
32                                                    www.cst.com
Applications – Antennas
 • Horn with dish at 30 GHz




            50λ




                          Radiation pattern




33                                                      www.cst.com
                                              www.cst.com • Dec-07
                                 Summary

     1) User Friendliness
             Intuitive Parametric CAD-Modeling
             Powerful Postprocessing
     2) Speed and Accuracy
             FI-Method + PBA
             Various Solvers, Hexa and Tetra Mesh
             Frequency dep. Materials
     3) Interoperability
             Powerful CAD-Import + Export
             Open Archicture  CST Design Studio
     4) Automation / Optimisation
             OLE + VBA-compatible Macro Language
             Word, Excel, Powerpoint, Matlab, Animations
     5) Support



34                                                         www.cst.com
     Effective Antenna
     Simulations using
      CST MICROWAVE
         STUDIO ®



         Thank you!


                   Franz Hirtenfelder
          CST GmbH, Bad Nauheimer Strasse 19
             D-64289 Darmstadt, Germany,
           E-Mail: franz.hirtenfelder@cst.com
35                                              www.cst.com

				
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posted:7/10/2011
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