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FDTD (finite difference time domain) method is a well-known method for numerical solution of electromagnetic compatibility (EMC) problems. In this paper this method is used to calculate the shielding efficiency (SE) of enclosure with aperture. Transient fields related to indirect electrostatic discharge (ESD) are used as incident fields to investigate EMC problem of aperture penetration into cavities.

It is known that any wave field carrying the energy into infinity must have the centers of radiation, singularities in some area. Otherwise the wave fields value should be everywhere identically equal to zero. In this paper attention is paid to localization of these singularities under assumption that every wave field is determined by its own singularities in a unique fashion. Investigations have shown that these singularities are distributed as a bright centers. For localization of the wave fields singularities the functions describing the converging and diverging waves are used. Based on these concepts and with the help of the method of auxiliary sources (MAS) a simple numerical method for field reconstruction up to its singularities is suggested in order to solve the inverse problems.

A simple method for investigation of the scattered fields singularities is presented. It is shown how this technique can be applied to the synthesis problem of "well-matched" antenna with predefined pattern. The basic idea is that the wave field corresponding to the desired pattern must have a domain of singularities, and it is determined by these singularities in a unique way.

Usually metallic shields are used to protect equipment, sensitive electronic parts and systems which can be disturbed or even destroyed by transient EM fields. The propagation of energy into the enclosures occurs principally via transmission lines, transmission line-like structures and different kinds of apertures, realized for cooling purposes and cable connections. This paper presents a numerical study of the coupling of transient fields into a metallic enclosure with apertures. Cylinders with rectangular cross sections are investigated under the illumination of a transient plane wave having the same time-dependence and magnitude, as a Gaussian pulse. The method of investigation is the finite-difference time-domain method.

There are many publications concerning the inverse problems. It is known that such tasks have no unique solution. For example, in the given antenna problem there are different current distributions on the different surfaces. The main problem is to obtain the distribution of these currents that produce the minimum reactive field in the near zone so that the whole feeding energy is transmitted into the travelling wave. Such antenna is called a well matched antenna. On the other hand it is known that the travelling wave is analytical everywhere except in the area of singularities of the radiated field. This paper presents a method for visualisation of this area and the singularities in it. The suggestion is that the simple sources placed in the points of the singularities form a well matched antenna. The problem to be solved is as follows. Given the amplitude and phase distribution in far zone, find the corresponding current distribution and the best location that gives a well matched antenna.

A pear-shaped metallic antenna covered with a high-permittivity thin dielectric layer is presented. Such a geometry with the special structure of the presented antenna provides wideband radiation capabilities. On the other hand, the dielectric layer helps to keep the size of the antenna small. The layer is thin to avoid undesired increase of the Q-factor. which makes the antenna narrowband. The electrodynamic problem for the proposed structure is solved using the method of auxiliary sources (MAS). The user-friendly program package was created for numerical experiments. Electromagnetic characteristics of the antenna have been investigated and some numerical results of the conducted work presented. The main attention was paid to find out the optimal geometry of the antenna and the connection with feeding cable in order to get the best matching and efficient radiation.

Small metallic voluminous antenna covered with a high permittivity dielectric layer is presented. This is a drop-shaped antenna that is supposed to have a wideband radiation characteristics due to its geometry and special structure. The dielectric layer helps to keep the size of the antenna small. To avoid undesired increase of the Q-factor due to this layer its thickness is kept as small as possible. The structure was numerically simulated using the method of auxiliary sources (MAS). The field distributions for particular frequencies are presented together with the frequency response of the investigated structure.

A method of auxiliary sources (MAS) based method of determining the resonance frequencies of a high conductivity hollow metallic body is presented. As a working prototype a simplified closed car-shaped body is taken, and its eigenfrequencies and corresponding near fields are investigated. Numerical results are also presented.

The approach for solving diffraction problems upon the large conducting scatterers with apertures is presented in this paper. The solution is based on the method of auxiliary sources (MAS). The idea is to introduce the two domains, inside and outside the object where the field is calculated by two different sets of unknowns. Together with necessary boundary conditions the continuity of the electric and magnetic field is enforced on the surfaces representing the holes or apertures. This method allows the describing the large part of scatterer by fewer unknowns compared to conventional methods like MoM.

The Method of Auxiliary Sources (MAS) is implemented to solve the problem-of EM field diffraction upon an open metallic object such as a car body. The key idea of the MAS is to present the unknown scattered field by a superposition of fundamental solutions of the appropriate wave equation Auxiliary Sources (AS), whose radiating centers are located on some auxiliary surface, shifted outside the area, where the field is to be found. In the case of semi-open objects constructed by a thin metallic surface with cavities and partitions (like the car or other means of transportation), the imaginary surfaces covering the apertures presented in the investigated object are introduced to represent the separated domains that are applicable for the MAS algorithm. The efficiency of MAS is illustrated and some resonant properties of the described objects are investigated.

Summary form only given. The method of auxiliary sources (MAS) has been extensively used for solving the different type of applied EM problems. The key idea of the MAS is to represent the unknown scattered field by a sum of fundamental solutions of appropriate wave equation-auxiliary sources (AS), whose radiating centers are located on some auxiliary surface shifted outside the area where the unknown field is sought. The following applied EMC and other problems were solved by the MAS using different type of AS and are presented: (1) diffraction on a spherical body with an aperture, using the elemental dipoles for the AS; (2) diffraction on an open metal cube with non-symmetrical excitation using the piecewise-sinusoidal distribution of auxiliary current on the auxiliary surface which is modeled with a grid; and (3) modeling of a portable resonant antenna with dielectric substrate and metal back reflector using the piecewise-linear distribution of the auxiliary current. In all these problems the best choice of AS and the advantage of each type used is discussed.

Summary form only given. The method of auxiliary sources (MAS) was successfully applied at the numerous electrodynamical problems. There is a gap in the information available about some applications of the MAS, especially in the area of solution of inner problems of electrodynamics. This paper attempts to fill in the present gap and to describe in details the works, previously done by the authors of this paper, in the area of calculation of the propagation characteristics of complex waveguide structures, as well as to present the new applications of the method in this direction. The following areas are discussed: solution of the scattering problem for resonant frequencies; MAS formulation of the calculation of longitudinally homogeneous waveguides and coaxial cables having complex cross-sectional structure; calculation of eigen-frequencies and eigen-fields of some special waveguide structures; dielectric waveguides; and recommendations for optimization of the MAS for solution of inner problems.

Summary form only given. Much effort have been made in the study of the scattering, absorption and other diffraction properties of objects made of or coated by various composite and optically active materials (chiral, bi-isotropic, bianisotropic). To effectively solve the scattering problem of such objects in the case of a complex geometry and excitation type, the further development of the existing methods is needed. This may be done in the way of a proper formulation and solution of the scattering problem. In this article, a spinor formalism is suggested to state and solve the scattering problem upon the bi-isotropic (in particular, chiral) objects through the method of auxiliary sources (MAS), suitable for this aim. Some results of the study are demonstrated.

Summary form only given. A portable adaptive antenna made of linear sources imbedded in a screened dielectric was proposed by Zaridze et al. (see Proc. IEEE AP Int. Symp., Orlando, Florida, p.2524-27, 1999). In this article, based on the method of Zaridze, an adaptive antenna with improved polarization properties is suggested due to the use, instead of a dielectric, chiral medium. A software package for computation and visualization of characteristics of such an antenna is presented and demonstrated. The interaction of antenna with the outside lossy dielectric body is also simulated and evaluated. The antenna considered is represented as an aggregate of linear sources imbedded in partially screened chiral medium of the given shape, dimensions and material properties. The number of excitation sources, their amplitudes, phases and situations, as well as wavenumber of excitation are the input parameters for the user. One can also choose the shape of antenna, its dimensions, undercoat material parameters and percent of the screened boundary. The lossy dielectric body, simulating the human head attached to the antenna, is also included in this scheme. The user may specify dimensions and complex permittivity of dielectric body, as well as its disposition with respect to the antenna. The created software package has been tested in a wide frequency range and for different geometrical, material and excitation parameters. The efficiency of software package to compute and optimize parameters of adaptive antenna alone or in the presence of lossy dielectric body is also demonstrated.

Summary form only given. In the Laboratory of Applied Electrodynamics the holographic technique for visualization of the wave fields was developed. This method is based on the method of auxiliary sources and allows one to reconstruct the image of the object (target) illuminated by an ultrasonic or EM field source by processing the data of the amplitudes and phases distribution of the scattered field measured in the nearby zone. The numerical experiments were done to reconstruct the objects illuminated by EM and acoustic field using the near scattered field's value calculated by solving the direct scattering problem. In order to check and optimize the above mentioned method for 3-D problems and use it in practice the experimental setup was built that performs illumination of some objects by ultrasonic wave and records the values of the amplitudes and phases of the total (incident plus scattering) field in some nearby area. The investigated object is located in the water tank. The measured signal (amplitude and phase) is converted into digital form and is redirected to PC. The specially developed software processes the automatically recorded data. The processing algorithm is based on the above mentioned wave field visualization method and reconstructs the image of the object.

Compact adaptive volume-resonant antennas with beam-steering capability can be employed in wireless applications. The described antennas can radiate the energy in a desired direction within a certain range of angles by changing the amplitudes and phases of feeding currents of the dipoles printed on the dielectric substrate with a conductive back surface. The improved efficiency entails a lower RF exposure of the user for equal power emitted compared to conventional cellular phone antennas. The 3-D method of integrated auxiliary sources is employed to study the performance of the presented antenna.

The application of the method of auxiliary sources (MAS) for solving different types of electromagnetics and particularly EMC related problems is presented. Improvements of the MAS using the different types of auxiliary sources (AS) are demonstrated in several examples. These investigations have shown that the proper choice of the location and type of AS significantly reduce the total number of unknowns in the solved problems, improve the accuracy and convergence of the solution and lead to a highly efficient and fast solution algorithm.

Compact adaptive volume-resonant antennas with beam-steering capability could be employed in wireless applications. The described antenna can radiate the energy in desired direction within certain range of angles by changing the amplitudes and phases of feeding currents of the dipoles printed on the dielectric substrate with a conductive back surface. The improved efficiency entails a lower RF exposure of the user for equal power emitted compared to conventional linear antennas. The 3-D method of auxiliary sources (MAS) is employed to study the performance of the presented antenna.

This chapter proposes complex materials (anisotropic, chiral, Tellegen, and general biisotropic) as element base for Finite Photonic Crystal (FPC) devices, offers an effective method for their handling, illustrates possibilities of their numerical analysis and discusses results for FPC design. The approach is based on the Method of Auxiliary Sources (MAS) and its implementation to complex structures.

An efficient solution to the 3-D scattering problem for the complex material structure is presented. The computer code to calculate and visualize radiation, propagation, scattering and polarization properties of complicated structures is described. The numerical results, illustrating the electromagnetic properties of lossy dielectric, chiral, Tellegen and fully biisotropic structures are demonstrated.

In the Laboratory of Applied Electrodynamics a holographic technique for the visualization of wave fields has previously been developed. This method is based on the method of auxiliary sources (MAS) and allows to reconstruct an image of the object(s) illuminated by an ultrasonic or EM field source by processing the data of the scattered field, the amplitudes and phases measured in the nearby zone. The numerical experiments were done to verify this method and prove the proposed approach. Together with this, an experimental setup was constructed to measure the complex values of the ultrasonic field's scattered from the illuminated object(s). This data was used for the further numerical processing and the reconstruction of the wave field and object image.

An adaptive portable antenna with extended possibilities to control radiating, directional, polarisation and compatibility properties is proposed. A physical model of the antenna including the absorbing human head is analysed, and the program complex for calculating the antenna characteristics is demonstrated.

A finite difference time domain (FDTD) method in combination with the perfectly matched layer (PML) is used for dispersive media. The FDTD method is derived using the convolution relationship between the current density J and the electric field E. The high accuracy of the FDTD method is confirmed by computing the reflection and transmission coefficients for a one dimensional nonmagnetized plasma slab.

Publisher Summary A conventional Method of Auxiliary Sources (MAS) is a method of finding the solution of the boundary problem for a given differential equation by expanding it in terms of fundamental, or other singular solutions of this equation. This chapter describes the conventional method of auxiliary sources (MAS) in application to 2D and 3D scattering problems upon bodies of complicated shape and filling. It offers general recommendations for the proper implementation of the MAS with predesigned accuracy. Finally, the application of the MAS to particular problems is illustrated, including the problems of anisotropy, chirality, and those of multiply-connected boundaries. Far and near fields for different situations are analyzed through numerical simulations in a wide frequency band starting from the quasi-static up to the quasi-optics. The efficiency of the MAS to study complex scattering problems, as well as to visualize various physical phenomena in electromagnetic and light wave band is also demonstrated.

The role of scattered field singularities in the solution of EM scattering problems by the method of auxiliary sources is discussed. The example of a hyperbolic surface when the scattered field singularities are mainly located in a single point and the scattered field is represented by a single auxiliary source is presented.

The modification of the method of auxiliary sources (MAS) for solving the electromagnetic (EM) diffraction problems is discussed. The presented approach explores the integrated auxiliary sources reducing in may cases the number of unknowns of a particular problem. This is especially important for scattering problems on open structures, scatterers with thin geometry, dielectric scatterers with very high permittivity. The results of particular problems solution are presented to demonstrate the capabilities of the method (e.g. diffraction on thin dielectric parallelepiped and scattering by perfectly conducting cube with one open side).

The paper is devoted to a computer simulation of the electrostatic discharge (ESD) from cone. The numerical model is based on the electrodynamical consideration of the problem. The method of moments (MoM) in the time domain, coupled with a nonlinear model of the arc, is used to develop an efficient algorithm of the ESD simulation. The transient currents and fields are analysed from an EMC point of view. The results of numerical simulation are shown to be in a good agreement with experimental data.

The development of the method of auxiliary sources (MAS) to 2-D and 3-D scattering problems upon the objects of complicated shape and of complex materials is considered. Application of MAS to the problems of anisotropy, chirality and biisotropy is shown. The algorithm used to determine the solution in a general case is described, and the new numerical and physical results of investigating specific objects in a wide frequency range are presented. A program complex for studying the radiation, propagation, scattering and absorption processes in complex media is demonstrated.

A holographic technique based on the method of auxiliary sources (MAS) for microwave and ultrasonic imaging is presented. The essence of the method is the visualization of the scattered field singularities (SFS). The idea is that any discontinuity of the electromagnetic characteristics of the investigated media causes remission of the incident field and represents the SFS of the scattered field. The proposed imaging method is sensitive to such singularities and gives the possibility to visualize and detect the insertions in the area under investigation.

The problem of shielding sensitive measurement equipment, computers and control devices, against the influence of disturbing electromagnetic fields is by no means new. Usually, the metallic shields are used to protect equipment, the sensitive electronic parts of which can be disturbed or even destroyed by transient EM fields. Practical shielding enclosures always contain many apertures such as vents, cable feed-through and seams, which allow electromagnetic energy to couple into the structure. This paper presents a numerical study of the coupling of transient fields radiated during electrostatic discharge (ESD) into the metallic enclosure with an aperture. Computer simulation of the ESD is done using an electrodynamic method based on the method of moments (MoM) in the time domain for discharging bodies of revolution, located near the grounded plane. For a discharging structure like a spheroid the calculated currents and fields are compared with experimental data and are shown to be accurate for EMC applications. Such realistic fields are used in this paper as incident fields to investigate aperture penetration into cavities. The time domain analysis is done using the FDTD method.

The extension of the method of auxiliary sources (MAS) into time domain is presented. The MAS has been extensively applied to the wide class of steady electromagnetic processes problems as one of the efficient tools. It provides the faster algorithm for simulation and visualization of electromagnetic periodical and transient processes in real scale of time. Particular efficiency occurs for closed scatterers. With the help of MAS in the time domain it is easy to follow the formation of eigenfields of various structures. The transient scattering on a cylinder with a longitudinal slot is considered as an example.

The paper reports on an ongoing research about numerical calculations of transient fields from ESD. Results from a thin wire code which includes an arc model and preliminary results for scattering on voluminous objects are presented.

The electromagnetic compatibility (EMC) and estimation of specific absorption rate (SAR) problems are discussed in this paper together with interaction of the cellular telephone antenna field with the user's head considering the shape of the telephone housing and the model of the hand. The radiation characteristics of cellular handset antennas strongly depend on the objects in vicinity of the phone. When the wavelength of the radiated field is comparable with the dimensions of the objects located near the handset those objects disturb performance and change all electrodynamic properties of the antenna. The presented electromagnetic analysis is based on method of auxiliary sources (MAS) (R. Zaridze et al., IEEE Trans. Antennas and Propag., vol. 50, No. 1, pp. 50-58, 2002).

In this article a new methodology of remote exploration of buried bodies by means of pulse irradiation is presented. The ways to simplify the experimental evaluations are presented. The results of some software simulations of surface reconstruction are presented.

A new type of PCS antenna with optimal geometric size and shape for obtaining desirable electric and radiation characteristics presented together with a user-friendly program package for dielectric coatings antennas analysis. Investigated the user body interaction with the antenna radiation, also antenna with directed radiation and conducted necessary measurements for antenna properties. The method of auxiliary sources (MAS) used for obtaining accurate results at low computational costs. The electromagnetic compatibility (EMC) and estimation of specific absorption rate (SAR) problems discussed together with interaction of the cellular telephone antenna field with the user. Some numerical and experimental results are presented.

The variety of approaches for remote determination of shape and position of latent bodies is important in vast number of applications in different branches of science and technology, such as applied electrodynamics, tomography, medicine (for investigation of the internal organs), archeology (for the study of fragile archeological samples), military engineering (for detection of explosive substances) and so on. Moreover, such methods represent the only possibility of exploration, in case when a direct contact is undesirable, dangerous or simply impossible. Most of the currently existing methods reconstruct the body's shape by means of its direct exposure to the radiation of significantly less wavelength compared to its size. The proposed method can be used even when the wavelength is comparable to the body's sizes

Paper presents applications of the Method of Auxiliary Sources (MAS) for solving problems of electromagnetic wave's diffraction on the one and two periodic structures. The Method of Auxiliary Sources is expanded (MAS) for two-periodic problems. The numerical investigation of reflection\transmission properties of dielectrics with periodical shape is performed.

A pear-shape monopole Antenna with optimal geometric size and design for obtaining desirable electric and radiation characteristics presented together with a user-friendly program package for the analysis of antennas with dielectric coatings. Investigated the user body Interaction with the Antenna radiation, also Antenna with directed radiation is simulated. The Method of Auxiliary Sources (MAS) used for obtaining accurate results at low computational costs. The results of the simulation are verified by measurements.