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5.2.11. Parameter Reference

Parameter Name

Valid Entries

Description

Solve Type

Full, Ports Only

Solve on the full model or on the ports only.

Basis Set

h0.5, h1.5, h2.5, h3.5, h4.5, c1.5, c2.5, c3.5, c4.5

The basis set dictates the accuracy of the field representation within each mesh element. The higher the basis set order, the more functions are used, generally resulting in a more accurate result. For more information, see “Basis Set”.

Output Meshes

True, False

If false, the solver will not output the mesh to its dataset, thus reducing computation time and data set (and thus project) size. This can be useful in cases such as sweeps or optimizations, where mesh data is not necessary.

AMR Error Estimator

Local Error Estimate

Determines what quantity is used to determine where to refine the mesh during AMR.

Field Output File

Full path to optional field output file to be used by other simulators (e.g. PT3p).

Frequency Sweep Type

Automatic, Discrete, GAWE

The Discrete sweep solves for each frequency point independently. It is typically faster for simulations with fewer frequencies per active process, especially if the simulation includes many ports. The GAWE (Galerkin Asymptotic Wave Expansion) sweep uses an asymptotic method to approximate the solution in bands of frequencies around expansion points. This method is faster than a Discrete sweep for a large frequency count with a relatively small number of ports. When the Automatic sweep type is selected, the solver uses either a Discrete sweep or a GAWE sweep, depending on which is likely to be faster for the given frequency count, port count, and parallel configuration.

Drive Frequencies Specification

Linear Range Count, Linear Range Increment, “Custom List Specification”

Determines how the frequencies are specified.

Solve Inside Conductors

Per Material, Never, Always

This flag controls whether the solver will solve for the field inside metal conductors. This is sometimes necessary to achieve high accuracy solutions. Solving inside conductors generally increases the solution time and should not be done unless the skin-depth is comparable to the metal thickness over at least a portion of the frequency band. Otherwise, lossy metal will be approximated using impedance boundary conditions on the metal surface, which will yield sufficient accuracy in most cases without incurring the runtime performance penalty of solving inside the metal.

Minimum Solved Frequency (GHz)

Numerical frequency value. Any simulation below this frequency is treated as indicated by the choice in Extrapolate Toward DC.

Extrapolate Toward DC

Cubic Polynomial Fit, None

This flag controls solver behavior at frequencies below the minimum solved frequency. If Cubic Polynomial Fit, results at frequencies below the minimum solved frequency are extrapolated from the results above the minimum solved frequency, using a cubic polynomial fit. If None, results at frequencies below the minimum solved frequency are found by solving at the minimum solved frequency.

Fields/Output Frequency

None, AMR Frequencies Only, All Frequencies

Fields (E, H, and optionally surface current J) can be output at the AMR frequencies, at all frequencies, or not at all. Field output will slow the solution sequence somewhat, and will also inflate the size of the solution datasets.

Fields/Optional/Surface Current Density

True, False

If true, surface current density fields are generated.

Fields/Optional/Wall Losses

True, False

If true, the losses on conducting walls are generated as additional fields.

Antenna Far Fields/Output Frequency

None, AMR Frequencies Only, All Frequencies

Request far field output at the AMR frequencies, at all frequencies, or at no frequencies. If either AMR Frequencies Only or All Frequencies is selected, antenna patterns and related results such as gain and directivity are computed for the entire frequency spectrum.

Antenna Far Fields/Sphere Sampling Increment, Theta (deg)

Sampling increment of far field sphere in theta direction, in degrees.

Antenna Far Fields/Sphere Sampling Increment, Phi (deg)

Sampling increment of far field sphere in phi direction, in degrees.

Sphere X Axis

X axis direction in world coordinates. The far field sphere is most densely sampled on the Z axis. By adjusting the axes of the sphere, the dense-sampling region may be rotated to an area of known interest in the antenna pattern without incurring the computational cost of a smaller sphere sampling increment. This is a unitless vector and its magnitude is irrelevant.

Sphere Z Axis

Z axis direction in world coordinates. The far field sphere is most densely sampled on the Z axis. By adjusting the axes of the sphere, the dense-sampling region may be rotated to an area of known interest in the antenna pattern without incurring the computational cost of a smaller sphere sampling increment. This is a unitless vector and its magnitude is irrelevant.

Port Solver/Basis Set

Automatic, h0.5, h1.5, h2.5, h3.5, h4.5, c1.5, c2.5, c3.5, c4.5

The basis set dictates the accuracy of the field representation within each mesh element. The higher the basis set order, the more functions are used, generally resulting in a more accurate result. Automatic causes the use of a basis set one order higher than is used in the volumetric solve. For more information, see “Basis Set”.

Port Solver/Mode Degeneracy Tolerance

Used in the determination of mode degeneracies. If the Kz values of two modes are within this tolerance, the two modes are considered to be degenerate and single mode (formed by a linear combination) is output.

Port Solver/Eigensolver/Method

Automatic, Iterative, Direct

This flag controls whether the eigensolver uses a direct or iterative method. The Direct method identifies all of the eigenmodes and then selects the appropriate ones based upon sorting criteria. The Direct method is very robust, but it scales very poorly with mesh element count. The Iterative methods converge only one, to at most a few modes of interest, but do so quite rapidly and in a fashion that scales well as the port meshes increase in element count. Except possibly for very small problems, the Iterative methods are the best choice, and the Automatic selection is equivalent to Iterative.

Port Solver/Eigensolver/Iterative/Convergence Tolerance

Visible if Port Solver/Eigensolver/Method is "Iterative". The target residual for convergence of modes. A mode is considered converged if the corresponding eigenpair (mode field pattern and propagation constant) gives a matrix equation residual less than this value.

Port Solver/Eigensolver/Iterative/Maximum Iterations

Visible if Port Solver/Eigensolver/Method is "Iterative". This is the maximum number of iterations that the iterative eigensolvers will use to converge the number of modes requested at each port.

Port Solver/Eigensolver/Iterative/Method

Automatic, Port Arnoldi, Port Lanczos

Visible if Port Solver/Eigensolver/Method is "Iterative". The iterative methods include Port Arnoldi and Port Lanczos, which implement the asymmetric Arnoldi and Lanczos processes, respectively. The Automatic selection is equivalent to Port Arnoldi.

Port Solver/Eigensolver/Output Messages

True, False

If true, status messages from the port eigensolver are sent to the log.

Volumetric Linear Solver/Method

Automatic, Direct

This parameter controls the type of solver that is used to solve the matrix equation(s). The Direct solver performs an LU factorization of the matrix, and the iterative method uses a variant of the preconditioned conjugate gradient (PCG) method. The Automatic selection is equivalent to Direct, and this is almost always faster than the Iterative option.

Volumetric Linear Solver/Direct/Method

Automatic, HMLU, MFLU

Choosing “Direct” for the linear solver method parameter forces the solver to use one of two methods that rely on an LU factorization of the system matrix – “MFLU” and “HMLU”.

Volumetric Linear Solver/Direct/Method/HMLU/Factor Accuracy Level

Automatic, Low, Medium, High, Perfect

The HMLU linear solver produces an inexact LU factorization of the system matrix that is subsequently used in an iterative loop to determine the solution vectors for port/mode excitations. The accuracy of the factor can be controlled via the “Factor Accuracy Level” solver parameter. Options are “Low”, “Medium”, “High”, “Perfect”, and “Automatic”. The “Perfect” setting yields a factor with an accuracy equivalent to that obtained using the MFLU solver, and will result in the iterative loop converging in a single step. A lower factor accuracy is faster to compute and takes less system memory, as compared to higher accuracy settings, but it can also lead to more iterations being required in the iterative loop. If the “Automatic” setting is chosen, the solver will adjust the accuracy setting as necessary to minimize runtime and memory, starting with the “Low” setting. The “Automatic” setting also allows for fail-over to a different solver if the default solver cannot solve the problem.

Fast Frequency Sweep/Convergence Tolerance

Not visible if Frequency Sweep Type is "Discrete". The maximum value of the estimated matrix equation residual error. Used to determine the valid bounds of the expansion about a given frequency point. The actual value may be reset based upon actual residual at the expansion point (which may be higher because of linear solver errors).

Port Characteristic Impedance Method

Power Current, Power Voltage, Voltage Current, Wave

The characteristic impedance at a wave port can be computed using one of three expressions: P/I2 (called "Power Current"), PV2 (called "Power Voltage"), and V/I ("Voltage Current"). In homogeneous waveguides the wave impedance (called "Wave") is also available. For most single-moded transmission lines the three expressions will give similar values, while in waveguides all four options can be quite different and the proper one to use will be problem-dependent. When using either the Power Voltage or Voltage Current method in a waveguide port, the voltage is calculated in the direction given by the port's Orientation Up Vector, as defined in port properties.

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