QW-Editor - graphical editor for definition of geometry, media, I/O parameters and postprocessing. It comprises a library of parameterised objects and a capability for generating further objects and libraries. Conversion to and from CAD formats is also facilitated.
In QW-Editor, shape and filling of arbitrary 3D or V2D circuits can be defined by picking up parameterised objects from object libraries. Moreover, the user can create his own objects by writing scripts in a simple UDO language. Manual operation with mouse and keyboard is also possible. QW-Editor provides an intuitive user interface with various kinds of visualisation windows, convenient dialogues, menu commands, and toolbar buttons.
Although QW-Editor automatically generates the FDTD mesh, the user is equipped with many means of controlling the meshing process, including the enforcement of global and local maximum cell size, mesh snapping planes, and mesh refinement in regions of expected rapid field variation.
Using predefined parameterised library objects from libraries provided by QWED or building the desired structures with the use of these objects as blocks.
Defining new such objects in the UDO language developed by QWED. The list of available UDO language commands contains calls to the library objects, commands for direct creation of individual elements as well as a variety of classical programming language commands to define variables, programming loops or arithmetical operations.
Importing CAD files created in external modellers and exported in the commonly known *.sat and *.dxf formats.
Drawing shapes directly in QW-Editor using elements as building blocks. This way of proceeding may be convenient and fast for some relatively simple structures. However, compared to other ways, it becomes less effective for more complicated structures. Nevertheless, in many practical cases manual operation on elements is useful for modifying or supplementing the structures defined by operations on objects.
Fig. 1. Ridged horn antenna with teflon lens in QW-Editor - QW-3D example
The most important element of the new QW-Editor is the AMIGO system. AMIGO formally stands for the Advanced Mesh Intelligent Generation Option but it really plays a very friendly role, in accordance with the abbreviated name. It serves two purposes. Firstly, it optimises the meshing so as to provide requested wavelength resolution in all media while avoiding small cells. Secondly, it allows fast setting of frequency ranges for all ports as well as S-parameter and FD-Probing postprocessings. Additionally, it shows useful information about: details of structure definition that cannot be modelled within requested mesh constraints, time step forced by the current mesh, expected duration of the analysis, and allows setting automatic stop criteria.
General view of QW-Editor
Fig. 2. Axisymmetrical corrugated horn in QW-Editor - QW-V2D example
Fig. 3. Coax line constructed with 19 sections in QW-Editor - QW-V2D example
AMIGO - Advanced Mesh Intelligent Generation Option
Processing / Postprocessing
Time-domain data, such as time evolution of fields or currents and voltages at lumped ports, can be accessed in QW-Simulator at any time and any location within the structure. Data in the frequency domain, such as S-parameters, is produced by means of the Fourier transform, which must be performed on selected time-domain quantities throughout the simulation. Additional memory must also be allocated at the beginning of the simulation process. For these reasons, the user must indicate the required frequency domain results before starting QW-Simulator. This is done in the Parameters- Processing/Postprocessing dialogue.
The following media types are supported by the software:
PEC, PMC - perfect electric conductor, perfect magnetic conductor
Metallic - lossy metal. Magnetic permeability and electric conductivity can be declared.
Dielectric isotropic - electric permittivity, magnetic permeability, electric conductivity and magnetic loss can be declared
Dielectric anisotropic - it uses the same parameters as dielectric isotropic, but different values can be set in different directions
Ferrite - ferrite medium magnetised with a static z-oriented magnetic field. It has all the parameters of dielectric isotropic, and additionally the parameters of the ferrite model: damping constant, saturation magnetisation and static biasing z-directed magnetic field.
Dielectric dispersive has magnetic permeability, electric conductivity and magnetic loss defined analogously as for dielectric isotropic. Its complex relative permittivity (including series losses) is given by Debye, Drude or Lorentz dispersion model with user-specified parameters.
Metamaterial has electric conductivity and magnetic loss defined analogously as for dielectric isotropic. Its complex permittivity (including series loss) and complex permeability (including series magnetic loss) are given by Debye, Drude or Lorentz dispersion model with user-specified parameters.
Input / Output Port Parameters
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The I/O Ports Parameters dialogue allows defining the parameters of wave simulation and absorbing walls. This dialogue changes, depending on the type of port. It allows to set parameters for the following types of ports:
transmission lines (waveguides, TEM, Multi TEM, Plane TEM)
absorbing walls (Mur with superabsorption, PML)
lumped sources/probes or lumped impedances
plane wave or a Gaussian beam
The Heating details dialogue allows defining the parameters for microwave heating applications, i.e. heat transfer analysis, rotation or movement of a load, heating time etc.
Read more about Basic Heating Module.
QW-Editor includes QW-ObjectGenerator. QW-ObjectGenerator is essentially an interpreter for source programs provided by QWED in a form of library UDOs or prepared by the user in a specially developed UDO (User Defined Object) language. These source programs are stored in files with *.udo extension. It is recommended that each *.udo file contain a description of one User Defined Object. The UDO language is simple and yet gives the user the possibility to create his own arbitrarily complicated parametric objects, best suited for his particular requirements. The UDOs system contains about 400 UDOs grouped into libraries focusing on particular applications.
Fig. 1. Meshing of a coaxial line (inner/outer radii equal 1.521 mm/3.5 mm, basic cell size a=0.8 mm):
classical stair-case mesh versus conformal mesh generated by QW-3D.
Conformal approximations for irregular geometries
Advantages of conformal QW-FDTD have been demonstrated by the authors in a number of scientific papers. Economies in computer resources by over an order in magnitude have been reported, in comparison with standard stair-case FDTD.
There are two main types of windows displayed the structure:
2D - describes a chosen section of the structure. In the case of Fig. 1 the lower left one describes a section in XZ plane and the upper left window describes a section in the XY plane, which is a natural base for investigating, introducing and correcting the elements of which the project is composed.
3D - shows the structure in OpenGL. It allows project visualisation but do not allow any kind of project editing. In the case of Fig. 1 the lower right windows show the structure in solid display without ports and boxes, and the upper right window shows the structure in wire display with ports and boxes.
There are four basic ways of defining geometries in QW-Editor:
discover accurate EM modelling