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During magnetic resonance imaging (MRI), an implanted lead present in a patient's body scatters the radiofrquency (RF) field used for magnetic resonance. The resultant RF field can achieve very high values in the vicinity of the implant structure. The conduction currents flowing in tissue can cause dangerous resistive heating. Therefore scattering by implanted devices is an important safety issue...
To calculate the scattering from thin dielectric-coated perfect electric conductor (PEC) surfaces, the impedance boundary conditions (IBC) and thin dielectric sheet (TDS) approximation are quite powerful in integral equation method because both remove the need to solve the field in dielectric layer. However, the rigid validation criteria restrict the application scope of IBC method. Although the TDS...
Electric Field Integral Equation (EFIE) is widely used for solving three dimensional electromagnetic scattering and radiation from complicated structures because it is effective for both open and closed surface. But the convergence of EFIE is not as good as the magnetic field integral equation. In this paper, an efficient iterative technique for accelerating the convergence of EFIE is introduced....
The printed compound air-fed array (PCAFA) is an improved Fabry-Perot resonator (FPR) antenna, which exhibits better performance than traditional FPR antenna, by means of the non-uniform phase and magnitude of field distribution on aperture are partly compensated in design. In this paper a kind of circularly polarized (CP) PCAFA antenna is proposed and studied, in which the FSS cover is composed of...
A new magnetic quasi-particle called a chiral soliton is described in multilayered magnetic nanostructures. This quasi-particle exhibits many of the features exhibit by domain walls but is better suited to 3-dimensional device architectures.
If the RCS of a target is measured in measurement facility which is not a Faraday cage, this RCS might be corrupted by eventual outside transmissions which fill the same spectral band than measurement. In this situation, outside radiations are going to pollute the value of the measured RCS and as a consequence their level must be reduced in order to be able to get correct values of RCS. This article...
This paper introduces how to design the software of EMC test based on object-oriented programming idea. According to main functions, this software is divided into five objects, which are test template object, instrument object, apparatus object, graph object, and report object. Test template object is the core of this software, and information of test item, frequency band, test procedure and parameters...
Decoupling and matching feeding networks are considerably interested for small wireless terminals to enhance their abilities in the application for MIMO systems. This paper describes various kinds of decoupling and matching feeding networks and derives the formulas for determining the network elements explicitly. Numerical results are presented to ensure the formula for each decoupling and matching...
Manifestation of magnetospheric disturbances in the Earth's ionosphere has a very complex character. Magnetospheric storms and substorms cause drastic violation of the ionosphere structure. As a result, there are some difficulties in operation of different radio systems: communications, navigation, over-horizon radiolocation and so on. The specific regularities in variations of both frequency range...
In this paper, near field radiation characteristics of HF antenna on platform and typical microwave reflector antenna are analyzed by MLFMA. In the full wave computation, interactions among current on patches are performed by MLFMA, which are the most time and memory consuming, the other operations are still computed by MoM. Numerical results prove the precision of the method.
This paper investigates the pulsed fields waveform dependent characteristics of NEMP simulation. The termination impedance, the absorbing impedance of NEMP (nuclear electromagnetic pulse) simulator and the structures of simulator's influence on waveform of test region of NEMP simulator have investigate intensively. The conclusions of this paper can provide guidance to the design of NEMP simulator.
We present effective medium approximation (EMA) that provides an homogeneous equivalent for the top layer of on-chip interconnects in an integrated circuit. An empirical mixing model for straightforward and fast extraction of the effective dielectric constant of a slab of integrated circuit wiring and its analytical formulation based on Maxwell-Garnett rule is presented for a range of aspect ratios,...
Most of magnetic nano-structures today are ultrathin or nanostructured films and multilayers. The main challenge is to find a suitable technology to integrate and to contact nanostructures in a reliable manner. Here, we investigate the problem of contact integration into functional 3-D devices and evaluate the influence of 3-D magnetic layer geometry on performance of magneto-electronic devices. Real...
Modelling multiple reflections inside materials, using ray-tracing technique and Geometrical Optics (GO), is very important when deterministic propagation modelling is used in indoor environments. Indeed, when an electromagnetic wave undergoes a transmission or a reflection, the thickness of the interacting material has to be taken into account to model the wave propagation in an accurate way. Most...
This paper presents a procedure of numerical code hybridization. It can be effectively used in a fast analysis and synthesis of the field patterns radiated from a phased array antenna. In particular, both low and high frequency methods are employed to simulate simultaneously the strong coupling within an antenna structure and its interactions with electrically large structure existed in its vicinity...
Boundary integral equations for bodies of revolution have a Green's function kernel that can be written as the azimuthal integral over the free-space Green's function. We show that existing approximation methods for computing this integral suffer from efficiency or stability problems. Improvement of one of these methods leads to controllable accuracy while retaining efficiency.
GNSS meteorology is the remote sensing of the atmosphere (particularly troposphere) using Global Navigation Satellite Systems (GNSS) to derive information about its state. Over past five years the studies on GNSS tomography were performed in the Wroclaw University of Environmental and Life Sciences on the GNSS tomography. The results for epoch wise researches, allows to develop stable tomography numerical...
This paper presents a hybrid combination of the generalized ray expansion (GRE) method and high-frequency methods for analyzing the scattering and radiation problems incorporating electrically large and complex structures. A dense grid of ray tubes are launched from the phase centers of the subapertures making up the equivalent surface which encloses the target in the scattering problem, or the antenna...
We propose the use of inverse scattering for the design of filters, in microstrip technology, with a specified reflective group delay response. The inverse scattering is performed using the layer peeling algorithm. The method is simple and easily implemented numerically. To validate the method, filters with a reflective linear group delay were designed and implemented. The simulation and measurement...
The Dirichlet problem for Laplace's equation in an area between two arbitrary profiled infinitely long cylinders is rigorously solved by the Method of Regularization. The obtained solution is applied to the accurate analysis of the shielded microstrip line with homogeneous dielectric filling and thick conductor - the structure supporting the transmission of an ideal TEM-wave. Capacitance and characteristic...
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