Advanced HFSS Training: The Field Calculator. Richard Remski Applications Engineer, Ansoft Corporation

Transcription

1 Advanced HFSS Training: The Field Calculator Richard Remski Applications Engineer, Ansoft Corporation 1

2 Designed for people who slept through Vector Calculus...just like ME! A REFERENCE for REST of US! Isosurface? What heck s an isosurface? Normal Vectors I have known and loved How not to Cross r Integrals, and or stories A Domain of r Own Integration by parts: It s not just a good idea: it s Law! *The For Dummies name, cover style, and cartoon figure are all trademarks of Hungry Minds, Inc. Their use here is whimsical and by no means represents an endorsement by Hungry Minds, Inc. of presentation to follow. by Richard Remski Ansoft Apps Engineer 2

3 Field Calculator Basics Synopsis Definition and Basic Lat Data Types and Indicators Detailed Lat Usage Field Calculator Usage Example: Scattering Computations Reflected magnitude computations at various incidence angles from a dielectric slab Problem setup Calculator Use Macro/Optimetrics Setup Additional Sources Calculator Cookbook and Macro Manual 3

4 HFSS Field Calculator: Definition A tool for performing mamatical operations on ALL saved field data in modeled geometry E, H, J, and Poynting data available Perform operations using drawing geometry or new geometry created in Post3 Perform operations at single frequency (interp. or discrete sweeps) or or frequencies (fast sweep) Generate numerical, graphical, geometrical, or exportable data Macro-enabled 4

5 HFSS Field Calculator: Basic Lat Data Data Stack: Stack: Contains Contains current current and and saved saved entries entries in in a a scrolling scrolling stack stack similar similar to to a a hand-held hand-held scientific scientific calculator. calculator. Name Name Field: Field: for for renaming renaming top top stack stack expression expression Stack Operations: Stack Operations: Buttons for Buttons for manipulating stack manipulating stack contents only. contents only. Degree/Radian Degree/Radian Selector Selector Calculator Calculator Functions: Functions: Organized Organized groupings groupings of of all all available available calculator calculator functions functions in in button button format. format. Some Some buttons buttons contain contain furr furr options options as as dropdown dropdown menus. menus. Status Status Bar Bar (not (not currently currently shown): shown): Some Some operations operations will will provide provide help help feedback feedback across across lower lower edge edge of of calculator calculator during during use. use. 5

6 Geometric Geometric surface surface generated generated along along E E field field iso-value iso-value contour contour Vector data output to a Vector data output to a plane geometry plane geometry Mag EY (Normalized) HFSS Field Calculator: Data Types The calculator can manipulate many different types of data Geometric Complex Vector Scalar Data types are indicated in calculator stack for each entry Most calculator operations are only available on appropriate data type(s) Scalar Scalar E-field E-field data data graphed graphed along along a a line line geometry geometry Location (Inches) FIG. 4. NORMALIZED E Y-FIELD MAGNITUDE, LOSSLESS WR-90 6

7 HFSS Field Calculator: Data Indicators CALCULATOR USAGE HINT: Most data CALCULATOR USAGE HINT: Most data input types will be self-explanatory, e.g. E and input types will be self-explanatory, e.g. E and H fields being Phasor quantities will be H fields being Phasor quantities will be Complex Vectors (CVc). The only exception Complex Vectors (CVc). The only exception to this rule is Poynting input, which will to this rule is Poynting input, which will show up as a CVc even though E H* show up as a CVc even though E H* should have no imaginary component. The should have no imaginary component. The calculator only knows that two complex calculator only knows that two complex vectors were crossed, and does not know vectors were crossed, and does not know ahead of time that imaginary component ahead of time that imaginary component has been zeroed. has been zeroed. Each stack entry will be preceded by a unique code denoting its data type Mamatical: CVc: Complex Vector Vec: Vector CSc: Complex Scalar Scl: Scalar Geometric: Pnt: Point Lin: Line Srf: Surface Vol: Volume Combinations can also exist e.g. SclSrf : Scalar data distributed on a Surface geometry 7

8 HFSS Field Calculator: Detail Lat - Stack As data is entered into calculator it appears at TOP of stack, pushing older entries DOWN. UNDO attempts to take back last operation between stack entries. It may not work for all data types (e.g. results of a pure math operation cannot be reversed) PUSH duplicates top stack entry CLEAR deletes ALL entries from stack upon confirmation POP deletes top entry off stack RLDN rolls stack downward, moving top entry to bottom EXCH exchanges or swaps top two stack entries RLUP rolls stack upward, moving bottom entry to top 8

9 HFSS Field Calculator: Detail Lat - Operations All calculator operations are organized into columns classifying m by type of operation and type of data upon which operation can be performed. SCALAR column operations can only be SCALAR column operations can only be performed on Scalar data (not complex or performed on Scalar data (not complex or vector data), such as finding Cosine of a vector data), such as finding Cosine of a value using Trig functions. value using Trig functions. The The INPUT INPUT column column contains contains all all operations operations which which input input new new data data into into stack stack (field (field data, data, constants, constants, user-entered user-entered vector or complex vector or complex numbers, etc.) numbers, etc.) The The GENERAL GENERAL column column contains contains operations operations which which can can be be performed performed on on many many data data types types (e.g. (e.g. adding adding scalar scalar values values or or adding adding vectors). vectors). OUTPUT OUTPUT column column operations operations result result in in generation generation of of calculator calculator outputs, outputs, in in eir eir numerical, numerical, graphical graphical (displayed (displayed as as 2D 2D graphs graphs or or in in 3D 3D view), view), or or exported exported form form The VECTOR The VECTOR column contains column contains operations to be operations to be performed on vector performed on vector data such as data such as converting to scalar, converting to scalar, Dot and Cross Dot and Cross products, and Unit products, and Unit Vector computations Vector computations 9

10 HFSS Field Calculator: Detail Lat Exploded View 10

11 HFSS Field Calculator: Usage Overview CALCULATOR CALCULATOR USAGE USAGE HINT: HINT: Any Any time time use use Fields Fields post-processor post-processor to to plot plot a a quantity quantity (Plot->Fields) (Plot->Fields) are are actually actually performing performing operations operations using using calculator! calculator! To To see see steps steps that that went went into into generating generating plot plot just just created, created, open open calculator calculator interface interface and and view view stack stack contents. contents. This This can can often often help help guide guide as as try try to to use use calculator calculator to to create create r r own own custom custom outputs. outputs. Use just like a scientific calculator Notation is RPN, similar to HP scientific calculators First Quantity, Second Quantity, n Operation Remember stack fills from top and pushes older contents below. General use progresses from left to right Input quantity or quantities at left Perform operations in middle Operate between quantities; apply quantities to geometries, etc. Define desired output type at right 11

12 HFSS Field Calculator: Usage Changing Data Types Always Always think think of of what what type type of of data data are are working working with with and and wher wher or or not not it it is is compatible compatible with with r r desired desired operation. operation. For For example, example, note note INTEGRAL INTEGRAL sign sign is is in in Scalar Scalar column, column, implying implying that that to to integrate integrate complex complex numbers numbers will will have have to to integrate integrate real real and and imaginary imaginary components components separately, separately, performing performing an an integration integration by by parts. parts. As discussed previously, many operations must be on correct data type Many operations result in a different data type than inputs Ex1: The Dot product of two vectors is a scalar. Ex2: Obtaining Unit Vec Normal to a Surf generates a Vector. Some calculator buttons exist primarily to assist in type conversion Vec? converts Scl to Vec data Scal? does reverse Cmplx Real or Cmplx Imag takes a Scl component from a CSc or CVc Cmplx CmplxR or Cmplx CmplxI take a Vec or Scl component and make it real or imaginary part of a complex value CVc or CSc, respectively 12

13 HFSS Field Calculator: Usage Input Types The available field inputs are E E and and H H are are Peak Peak Phasor Phasor representations representations of of steady-state steady-state fields. fields. Therefore Therefore current current representations representations J J derived derived from from n n H H or or se se are are also also Peak Peak Phasor Phasor quantities. quantities. The The Poynting Poynting Vector Vector input input is is a a time-averaged time-averaged quantity. quantity. E : The complex vector E field data everywhere in modeled geometry H : The complex vector H field data everywhere in modeled geometry Poynting : The time-average Poynting vector computed from above as ½ (E H*) Jvol: Current density in a volume, computed as (σ + jωε )E which contains both conduction and displacement currents) Jsurf: Net Surface current computed as n (H top tetrahedra H bottom tetrahedra ) Unlike or quantities, Jsurf can only be output on an object surface geometry 13

14 HFSS Field Calculator: Usage Output Types Different data outputs can be generated depending on selected Output column button and stack content(s) Draw provides graphical geometry output in post-processor Plot generates field graphical output (scalar or vector) depending on stack contents Anim generates animations with respect to a position or phase animation variable 2D Plot creates line-graphs of scalar quantities in a rectangular (XY) plot format Value is used to take value of a field stack entry on a specific geometry Eval turns stack placeholder text into final numerical answers Write and Export outputs stack data to output file formats for use outside calculator or current project 14

15 HFSS Field Calculator: Usage Possible Operations Ω Q u = 2 2 s 2 Γ n H H 2 dω dγ + tgδ Ω H d As long as can perform math using interface, re is no restriction on possible calculator operations available Ω Outputs derived can be or than electromagnetic in nature Pure geometric operations (vector and surface cross and dot products, generation of Iso-surface contours from any scalar data field imported into geometry, etc.) Thermal heating computations derived from field values combined with rmal mass characteristics and equations Integrations to obtain summary quantities such as Quality factors, power dissipation or flux, etc. 15

16 Field Calculator Example: Bistatic Scattering HFSS is capable of computing plane-wave scattering solutions Normal incidence can be computed using a waveguide simulation approach, with port excitations Off-normal incidence however requires fields post-processing for data extraction from plane-wave excited solutions Possible applications include radomes and radome filters, RCS analysis, and PBG analysis This example will illustrate computation techniques necessary to obtain reflected field magnitude from a dielectric slab 16

17 Bistatic Scattering Example: Model Construction PML slabs top and bottom sized at 1.2 µm height, material parameters determined with automatic PMLmatsetup macro. For incidence wave angle of arrival (0,θ), where θ=0-60, Master/Slave phase relation is set to (180,θ) to correspond to specular angle A 2 x 2 µm unit cell representing an infinite sheet of dielectric, ε r = 11.8, 2 µm thick Incident wave will be 25 THz, varying from normal to 60 incidence angles, TM polarization Linked boundary phase settings must vary with incidence angle. Use Optimetrics to automate parametric analysis.* The height of air on each side of dielectric must consider necessary evaluation planes for field calculator! The cutplane for magnitude (or phase) integration data cannot intersect dielectric itself, and should not be too close to very reactive near fields Min height to clear 60 angled plane is 2*tan(60), or 3.46, plus λ/10 clearance of 1.2 is Use 5 microns air. PML outer faces terminated with perfect_h *The simulations can be done without Optimetrics: one HFSS project per incidence angle. 17

18 Bistatic Scattering Example: Parametric Operation Cutplanes are easily generated from Cutplanes are easily generated from Geometry menu. The carat buttons permit Geometry menu. The carat buttons permit rotation of normal about X, Y, or Z axis by rotation of normal about X, Y, or Z axis by 10 degree increments per click. Cutplanes 10 degree increments per click. Cutplanes need to be created normal to both incident need to be created normal to both incident AND scattered ray directions. AND scattered ray directions. Optimetrics Nominal Project has one input variable taang will control incident wave s ta angle for a parametric sweep Same variable used in master/slave boundary setting Output from nominal project will be generated by macro-recording of operations in field calculator Cutplanes for post-processing will be generated before macro recording [Post-processor geometry is copied for parametric models with no geometry variations] Calculator Write operation permits exportation of computed values into Optimetrics-available outputs 18

19 Bistatic Scattering Example: Calculator Operations P inc = 2 1 S ( E H ) ds inc inc The calculator will be used to extract two quantities P ref = 2 1 S ( E H ) ds ref ref Incident magnitude, P inc Computed using Incident field solution S S is is evaluation evaluation surface surface used used for for each each calculation. calculation. Since Field Calculator already provides Since Field Calculator already provides RMS Poynting vector, we will be able to RMS Poynting vector, we will be able to select it directly and integrate it over select it directly and integrate it over desired surface rar than having to compute desired surface rar than having to compute it ourselves. it ourselves. Note however that if we were interested in Note however that if we were interested in reflection coefficient in a given polarization reflection coefficient in a given polarization (from some surface which might impart a (from some surface which might impart a polarization change relative to incident polarization change relative to incident wave) we would have to manually compute wave) we would have to manually compute Poynting vector using only E and H Poynting vector using only E and H field components of interest for reflected field components of interest for reflected case. case. Reflected magnitude,p ref Computed using Scattered field solution These quantities will n be used to compute reflection coefficient with Optimetrics ρ mag = (P ref / P inc ) 1/2 19

20 Bistatic Scattering Example: Magnitude Computation P ref = 2 1 S ( E H ) ds ref 1. Start Macro Recording ref 2. Data Edit Sources. Select Scattered Field for P ref calculation first Open Calculator interface 4. Qty Poynting (auto-computed RMS Poynting Vector) 5. Cmplx Real (eliminate unneeded imaginary) Geom Surface (select one of created evaluation surfaces) 7. Normal (The Normal button is a shortcut for take dot product of surface normal of this surface to prior stack entry) Eval (creates actual numerical output from symbolic) 10. Abs (absolute value) 11. Write Enter output variable name and save file name for reflected power 20

21 Bistatic Scattering Example: Mag. Computation, cont. P inc = Data Edit Sources. Select Incident field for P inc computation 13. Return to calculator interface. S ( E H ) ds inc inc Qty Poynting (auto-computed RMS Poynting Vector) Cmplx Real (eliminate unneeded imaginary) 16. Geom Surface (select one of created evaluation surfaces) Normal (The Normal button is a shortcut for take dot product of surface normal of this surface to prior stack entry) Eval (creates actual numerical output from symbolic) 20. Abs (absolute value) 21. Write Enter output variable name and save file name for incident power 22. Stop Macro Recording 21

22 Bistatic Scattering Example: Optimetrics Macro We now have a saved macro which is not yet universal across projects It explicitly calls out source name, which varies with angle It uses only one set of incidence and reflection evaluation cutplanes If are running individual projects, only need to fix first issue Can have macro ask for incidence angle for which cutplane will be selected Create all cutplanes in first project, n copy it to run subsequent incidence angles (Postprocessor geometry is copied automatically) 22

23 Bistatic Scattering Example: Opt. Macro Edit In macro recording: Insert lines to read in taang input variable Optimetrics knows this is a variable, but post-processor of each project does not Set up conditionals to assign an incident evaluation plane name and reflection evaluation plane name, as shown Replace occurrences of name used in recording original macro with appropriate variable entry Only one occurrence for each Comment out or delete command lines containing: SetPortSourceType, SetSourcePhase, or SetSourceMagnitude Should be two occurrences of each 23

24 Bistatic Scattering Example: Results Magnitude Reflection Reflection Coefficient Angle off Normal (deg) Rho (ory) Rho (HFSS) Bistatic Reflection Coefficient Angle (deg) Rho (ory) Rho (HFSS) Error (%) Calculated results agree well with oretical values Accuracy drops for higher incidence angles Can compensate with more convergence if necessary May also increase air height and evaluation plane elevation over reflection surface Remember, we analyzed only a λ/6 square sample! 24

25 HFSS Field Calculator: Closing Thru illustration, application of field calculator has been reviewed Although not covered herein, calculator s functionality extends its usefulness to many model applications Macro implementation permits generation of a user library of frequently-used computations 25

26 HFSS Field Calculator: Additional materials More computations in field calculator are outlined in Calculator Cookbook (on r CDs) Living Document under continual updating Macro language use is covered more in depth in Macro Manual A macro primer and additional macro presentation are also part of this workshop Furr questions: Check online help or call an AE! 26

27 HFSS Field Calculator: Future Expansion The author intends to expand this presentation to include a second computation example Suggestions welcome! Ideas so far include: Coupling coefficient between two cavities from an eigensolution project Evaluation of current along length of a monopole Plot of wave impedance along throat of a waveguide horn Isosurface computation for high power applications The Bistatic scattering example will be expanded to show a computation of relative phase of reflection to incidence as well as magnitude All projects associated with se examples will be made available (unsolved) from our technical support website along with this presentation 27