1       Introduction

QuickWave^TM 3D, further in this manual also referred to by an abbreviation QW-3D, is a universal user-friendly electromagnetic simulator based on the conformal FDTD method and supplemented with a range of unique models for curved boundaries, media interfaces, modal excitation, and parameter extraction. It can be applied to a variety of microwave and millimetre-wave problems including:

·       accurate S-parameter calculations of shielded and open microwave and millimetre-wave circuits, also in cases involving dispersion, multimodal propagation, and evanescent modes, covering in particular the circuits manufactured in microstrip, coplanar, coaxial, cylindrical waveguide, and dielectric guide technologies,

·       calculations of radiation patterns, gain, radiation efficiency, radiation resistance, and return loss of antennas of various types (patch, horn, rod), rigorously taking into account irregular geometry, complicated corrugations, and inhomogeneous filling,

·       calculations of input impedance of mobile phone antennas and of specific absorption rate in human tissues,

·       calculations of heating patterns for microwave power applications, with accurate and fast display of instantaneous, time-maximum, and time-averaged patterns of fields, dissipated power, temperature, and enthalpy,

·       determination of eigenfrequencies, Q-factors, and pure modal field patterns for shielded and open inhomogeneous resonators, also in cases involving closely-spaced modes,

·       calculations of embedding impedance for lumped elements,

·       calculation of scattering patterns with free space incident wave (plane wave and Gaussian beam).

QW-3D comprises two main functional blocks:

·       QW-Editor, which permits graphical definition of 3D structures, mesh generation, and specification of simulation parameters via a convenient system of dialogues,

·       QW-Simulator, which conducts the FDTD calculations, extracts the desired frequency-domain parameters, displays all the computed fields and results, and allows saves them on disk.

In QW-Editor, shape and filling of arbitrary 3D 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, ribbons, toolbar buttons, and menu commands.

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.

QW-Simulator utilises state-of-the-art FDTD algorithms as well as many original models and procedures developed by the authors of the program during over two decades of intensive research on the time-domain electromagnetic modelling. These specialised features are well represented by the publications listed in Bibliography chapter. The following features should be emphasised:

·       accurate and stable conformal representation of curved metal boundaries [1] [3] [5],

·       higher-order modelling of media interfaces [4] [6],

·       wide-band modelling of skin effect in lossy metals [32],

·       guaranteed spurious-free behaviour of the algorithm, also in the presence of strong spatial irregularities [35],

·       matched modal excitation based on the field and impedance template [2] [11], with user-controlled available power and various waveforms,

·       lumped ports with user controlled available power or injected current,

·       S-parameter extraction incorporating differential decomposition of fields into incident and reflected waves [9], template filtering for desired mode extraction [11], compensation for imperfect absorbing boundaries [9] [10],

·       extraction of S-parameters between transmission line ports, which support propagating and/or evanescent modes [44], and lumped ports,

·       a variable source impedance technique for emulation of pure eigenmodes in inhomogeneous resonators [26],

·       anisotropic boundary conditions (wire grids).

QW-Simulator also offers many ways of visualisation of simulated fields and calculated circuit characteristics, including:

·       hilltop, thermal, and vector display of instantaneous field values in any plane perpendicular to any of the coordinate axes,

·       hilltop, thermal, and vector display of two-dimensional field envelopes in any plane perpendicular to any of the coordinate axes,

·       hilltop, thermal, and vector display of SAR and dissipative power – instantaneous, maximum, and average values,

·       3D vector display of electric field, magnetic field, and Poynting vector,

·       field envelopes along any line parallel to one of the coordinate axes, with a possibility of virtual measurements of attenuation and SWR, or along a user-defined contour,

·       field variation in time at any point, for TDR applications in particular, with possibility of virtual measurements of reflection coefficient and location of the discontinuity,

·       S-parameters versus frequency in linear, quadratic or decibel scale, on Smith chart and in polar coordinates,

·       radiation patterns versus angle accompanied by antenna efficiency, radiation resistance, and radiated power for a set of frequencies,

·       scattering patterns,

·       maximum, minimum, and average values of power dissipated in electric and/or magnetic field, and energy stored in electric and/or magnetic field, in the whole circuit or its selected subregions, and the resultant Q-factors.

QuickWave-3D permits to store calculated fields and results on the disk. The available options include:

·       exporting S-parameters in Super Compact and Touchstone formats,

·       saving S-parameters, eigenvalue charts, and antenna characteristics in text files of either QW or pure data formats,

·       dumping instantaneous field values of all field components, in the whole circuit, in text files,

·       dumping 2D patterns of selected field components and in selected layers in text files,

·       dumping 1D envelopes of selected field components along a selected line in text files.

A powerful feature of QW-Simulator is freeze of state. It permits to interrupt the simulation and store the simulator state with all its variables on disk. At any convenient time the user can resume the simulation at the broken point.

QW-3D may cooperate with optional modules: QProny and QW-OptimiserPlus, S-Converter and QW‑BHM. QProny performs signal postprocessing by a modified Prony method, extracting resonant frequencies and loaded Q-factors. It is recommended for faster analysis of high-Q devices such as narrow-band filters, resonators etc.. QW-OptimiserPlus acts as a master program, sequentially calling QW-Editor and QW-Simulator. It modifies user-selected variables to minimise the goal function. Currently it can work with goal functions based on S-parameters, FD-Probing, radiation patterns and also it can invoke an external software module, export selected QW results to this module, and import a user-defined goal function calculated by the module. Its graphical interface is fully integrated with QW-Simulator. S‑Converter performs cascading/de-cascading or embedding/de-embedding operations on several S-parameter files [36] [44]. QW‑BHM is a specialised module for microwave heating applications, which modifies media parameters of heated loads as a function of enthalpy [46] [48].

QW-MultiSim module is essentially a multithread implementation of QW-Simulator for faster analysis on multiprocessor PCs [38] [43].

Detailed description of QProny, S-Converter, QW-MultiSim, and QW-BHM module is given in separate manuals. All modules are distributed by QWED.