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newFASANT

Frequently Asked Questions

General

What is newFASANT?

The newFASANT Suite is an EM Simulation software for the analysis, study and/or design of a wide range of cases. It can be used both for academic and professional purposes, within the fields of aerospatiale/aeronautic applications, automotive industry, communications, radar and others.

How can I obtain newFASANT?

You can contact us through e-mail or the contact form and we will get in touch with you. We will happily address any questions and provide an updated price list. If you are located in any of the countries with an official newFASANT distributor you can contact our distributor and request the price list.

How do I install newFASANT?

We provide a self-contained installer that should make all the process transparent for you. If you have any difficulty with the installation we will be glad to help you.

Which platforms do you support?

At the present time we support x64 Windows and GNU/Linux platforms. Please contact us for other options.

Do I need to purchase the full Suite, even if I do not need all the functionality?

No. It is possible to purchase separate modules in order to address the kind of applications that you need. We maintain a wide list of modules for this exact reason: to provide just the functionality that the customer needs. If you need to expand your range of applications in the future you can purchase additional modules.

Do you provide any support with the purchase?

Yes, we provide technical support with every purchase, and will send updated releases including bug fixes and other improvements. We will also address any inquiry regarding hands-on use of any of the functionalities of our software.

How do I start using this software?

We are trying to make newFASANT as user-friendly as possible, even considering that it is a very powerful EM simulator. We provide extensive documentation in our web site that can also be downloaded as pdf files. These documents are also included with every release of our software. We have video tutorials in our YouTube channel and training examples inside the documentation. Finally, we are always happy to help our customers with any technical questions, and are willing to set up videoconference demonstrations if any point is not clear to them.

I have very special needs that are not covered by the modules you provide. Is there any solution for this?

Yes. We are very flexible and willing to provide customized solutions. Please contact us and give details of the applications you need to simulate and we will get in touch with you.

Can I take the results out of newFASANT?

All the results obtained with newFASANT can be exported as text files to be processed and/or visualized using external tools.

What do you mean by hybridization, and what are the methods for it?

Hybridization is the combination of two or more EM approaches, for instance the following combinations:

  • MoM-GTD
  • MOM-PO
  • GTD-PO

We have several hybridizations in newFASANT: for instance, we can compute the radiation pattern of an antenna using MoM and later import this radiation pattern in the GTD module to obtain the radiation pattern considering the interaction of the antenna with the platform. The GTD-PO module hybridizes GTD and PO. This module automatically classifies the surface to be treated using PO or using GTD.

Why do I get the “Can’t load result files” error?

This message appears when the results have not been generated due to some reason, for instance the solver stopped suddenly due to some error.

What is full wave analysis?

A full wave analysis does not use assumptions for the shape and amplitudes of currents and fields. MoM and FDTD are methods for full wave analyses. GTD and PO are asymptotic methods (non a full wave analysis)

Also, the development of architectures and paradigms for the parallelization of computer codes are playing a very important role in the expansion of the scope of rigorous analysis methods.

Yes, that is absolutely true.

Where is Ground plane exactly required?

Ground plane is required when you want to analyze the monostatic and/or bistatic radar cross section of a target on or over an infinite perfect electric conductor or dielectric ground plane, such as land, sea, etc., for instance: a ship over the sea.

Modeling

Can I generate my full geometrical model using newFASANT?

Probably. We include many general CAD features, primitives and geometric operations in order to generate and manipulate geometries. However, it is also possible to generate the geometry using external tools and import them in newFASANT.

MoM Solver

What is the Difference between GMRES and GMRES(k)?

GMRES(k) does some kind of initialization every k iterations, reducing the need of memory compared to GMRES. However GMRES(k) has a slower convergence. GMRES(k) behaves like GMRES when k is very high (for example, several thousands). GMRES(k) in newFASANT uses a default value of 300 for k. The user can change this value.

How can I know which solver to use for which problems (GMRES & BICGSTAB)

No rules. In our experience BICGSTAB works better than GMRES for most cases. For some few cases, with near closed surfaces GMRES can be better than BICGSTAB. The recommendation is try to use first BICGSTAB and if it does not present good convergence use GMRES.

Document for preconditioners

There is not any general rule to use preconditioners. Sometimes is better not to use preconditioner. In my experience for problems with only conductors or with conductors plus thin layer dielectric diagonal preconditioner improves the convergence for mesh densities of 8 div/wavelength or higher. The SAI preconditioner work fine for more cases but it only works with OPENMP.

In problems with volumetric dielectric is better not to use preconditioner.

Sometimes we shall explore the convenience of using or not preconditioners running with and without preconditioners.

Is CBF+MLFMA implemented in the newFASANT software?

Yes, it is implemented. By default we use always MLFMA when applying CBF

How do we define block size (lambda) in CBF?

With the present versions and in our experience the block size in CBF shall be 1 or 2 wavelengths to obtain the best efficiency with CBF for monostatic RCS. Now we are improving CBF in order to use larger block sizes (4 or 8 lambdas), which will represent a noticeable increase in efficiency.

When should I choose EFIE, MFIE or CFIE?

CFIE and MFIE can be applied only to closed surfaces. EFIE can be applied to all kinds of surfaces (open and closed). EFIE is more accurate than the others, however can suffer bad convergence and therefore can require much more CPU-time than the others.

For fast computations in which the accuracy is not the absolute priority we recommend to use CFIE for closed surfaces. Given a geometry composed by open and closed surfaces newFASANT allows to apply CFIE to closed surfaces and EFIE to open surfaces.

Since in the MoM the unknowns are distributed over the surface of the objects, it is widely used for the analysis of scattering or radiation problems involving geometries with one or several layers of homogeneous materials.

MoM can be apply also to full volumetric problems, on which a volumetric mesh shall be done into the volume and we need to solve unknowns to obtain the current in this mesh. MoM can be applied successfully to treats problems with one or more homogenous dielectric volumes.

However when MoM becomes more efficient is when solves problems involving geometries with metallic surfaces or with one or several layers of homogeneous materials.

The use of these approaches entails the storage of only the near-field terms of the coupling matrix and computing the far-field interactions efficiently via fast matrix-vector products in the iterative solution process.

That is right.

There are a number of techniques that also take advantage of the efficient evaluation of these products in the iterative solution of large problems, such as the Complex Multipole Beam Approach (CMBA), the Impedance Matrix localization (IML) technique or the Adaptive Integral Method (AIM).

That is right.

The submatrices that contain the coupling between moderately distant blocks (about a few wavelengths, usually) can be compressed using some of the techniques available in the literature, like those based on the Modified Gram-Schmidt procedure (MGS), the Adaptive Cross Approximation (ACA) or the Matrix Decomposition Algorithm. It is worthwhile to remark that these approaches make use of purely algebraic manipulations of the original matrices.

That is right. These approaches depend on purely algebraic manipulations of the original matrices and can be applied most cases than MLFMM because they do not depend on the behavior of the Green function.

A third group of methods, is based on a strategy that utilizes a domain-decomposition scheme and reduces the number of unknowns by replacing the subdomain-type basis functions with a set of macro-basis functions.

That is right. There are many domain-decomposition techniques. They are well suited for some special geometrical shapes but are difficult to apply to general geometries.

Instead of being limited to a predetermined and/or fixed shape, the CBFs are generated taking into account the physics of the problem, so they are tailored to the geometrical properties of each block, and their use leads to a “reduced” matrix whose size is considerably smaller than that of the original impedance matrix based on subdomain functions (e.g. Rao-Wilton-Glisson functions or rooftops).

That is right.

Each CBF, in turn, can be seen as an aggregation of low-level basis functions whose weights are fixed when each CBF is generated.

That is right.

The reduction in matrix size achieved by the CBFM enables us to use direct solvers for some problems where, previously, an iterative solver represented the only possible choice because of the size of the impedance matrix. However, for very large problems the reduction achieved in the number of unknowns may still be insufficient as to resort to a direct solver. In this situation, an iterative solution process can be utilized by combining the CBFM with the MLFMA approach.

That is right. For this reason we have combined CBFM with the MLFMA approach.

The CBFs are represented in terms of modified rooftop functions defined along the u or v directions over a parametric domain, totally conformed to the NURBS patches, so the discretization error is minimized.

That is right.

In CBFs the low-level basis functions employed are modified rooftops placed over the parametric domain of NURBS patched and totally conformed to the surface.

That is right.

The total number of resulting CBFs can be minimized by setting a threshold γ, relative to the largest singular value, and retaining only the singular vectors corresponding to the singular values above the threshold.

That is right.

Meshing

What are the mesh elements for different methods?

For MoM: curved conformed quadrangles with sporadic curved conformed triangles.

For PO and IR: flat triangles

GTD works directly with the NURBS surfaces without any meshing. In this case, the meshing step that the user sees running the module only indicates that the matrix visualization between surfaces is being processed.

What are the differences between meshing options?

In the User Guides you can find a description of the different parameters that can be used in the meshing process. Regarding recommendation for setting the mesh density on MOM:

  • Electrically large and smooth surfaces (RCS applications, reflectors antennas) can be analyzed using a low sampling density for instance 6 div/wavelength or less for combining enough accuracy and efficiency.
  • In most problems a sampling density of 10 div/wavelength gives enough accuracy.
  • In some problems with geometrical with details very small compared with the wavelength high sampling densities (20, 40, 100 ....) could be required.
What is the application for Curvature Meshing in PO-Module?

This technique provides a non-regular mesh with patches generated to discretize the curvatures and edges of the geometry with a quasi-adaptive method. The generated meshes usually are lesser dense than the ones provide with the Regular Meshing strategy.

PO Solver

What is the difference between PO in the MOM module and PO in the PO module?

PO in MOM does not consider multiple bounces and shading between the parts of a body. It uses the mesh of MoM. PO in the PO, GTD-PO and ISAR-PO modules can consider multiple bounces if the user selects 2 or more bounces in the parameters settings. These modules consider the shading between the parts of the target and use their own mesh based on flat triangles.

Is PO Method same in both PO-Module & in GTD-PO Module?

There are small differences. In PO-module always the PO is computed in the far field. However in GTD-PO the PO can be computed in both near and far field

In PO Module what is the use of Duplicate Normal option and the application

In the PO module, the surfaces are only considered on the region pointed by its normal vectors. This option is used to consider both sides (according with the normal vector directions) of the selected objects. It is recommended for use with open surfaces that contribute to the results in the two normal vector possible directions.

GTD Solver

In GTD-Module, RCS is not available & in PO-Module Antenna (Source) is not available Why?

GTD-Module has its own limitations when you want to compute the RCS. This limitations are due to the existence of caustics, therefore not RCS computation is included in this module.

In PO-Module only can feed with a plane wave because for RCS we only need feeding by plane waves.

GTD-PO Solver

What is the difference between PO in GTD-PO module and GTD-PO?

When in the GTD-PO module the user selects GTD-PO the program analyzes the surfaces and source position and classifies automatically the surfaces to be simulated using GTD or PO. When in the GTD-PO module the user selects (in the setting parameters) PO the program uses PO for all the facets.

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