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Analyse of one type of resonant cell is proposed. One to three cells are combined into a low pass filter. The filter design curves for various substrates and cut off frequencies are presented.
In this paper, a new structure with only one (first order) bandstop is reported. A simple trapezoid shape of the microstrip line is introduced instead of the more complicated pattern. It obtains simple simulation, optimization and fabrication.
For efficient EM modeling of real life structures it is very often needed to import these structures from CAD formats. Final step in this procedure is meshing of imported structure. Techniques and algorithms for meshing into triangles are much more developed than those into quadrilaterals. The paper presents novel and efficient technique for conversion of triangular mesh into quadrilateral mesh. Results...
The goal of this paper is to investigate how accuracy and efficiency of MLFMM of a given level depends on the order of approximation. We performed this investigation using a corner scatterer of side 20 lambda as a benchmark. We chose this model because its RCS results show several distinctive lobes in specific directions and at different levels, calculation of which is challenging even for direct...
In this paper, an accurate plate model of helical antenna is developed using WIPL-D Pro, a full wave 3D EM software. Realistic coaxial cable feed below PEC plane is used. All effects resulting from geometry and the principle of work for this type of antenna are fully taken into account, including proximity effect of helical turns and higher order propagation modes at coaxial cable aperture. Thus,...
Diakoptic surface integral-equation formulation is used to efficiently simulate large antenna arrays, modeled as 3D EM structures. The significant accelerations and storage reductions are achieved, when compared to the classical MoM-SIE. Both near field and far field (radiation pattern) of the arrays, calculated using DSIE, match the results calculated using MoM-SIE very well (the maximal relative...
In this paper,diakoptic approach was proposed and can be used to predict radiation pattern of a large array with practically no loss of accuracy compared to simulation of full array. On the other hand the simulation times are greatly reduced using diakoptic approach, which makes it a method of choice for simulation of large and complex structures such as antenna arrays.
The canonical particle swarm optimization (PSO) algorithm is known to be very good solution for EM optimization problems. In this paper we present results for a few modifications of the PSO algorithm (fully informed PSO algorithm and repeated PSO algorithm) when they are applied to the optimization of a broadside antenna array. The aim is to find out if and under what circumstances these modifications...
In this paper, we present an overview of parallelization of WIPL-D 3D EM solver and present examples of electrically large structures simulated on a small computer cluster. A helicopter up to 51 lambda long was used as a benchmark example for illustrating parallelization efficiency. Radar cross section from the 51 lambda long helicopter is calculated in 72 minutes on a low-cost 8-node cluster.
According to the uniqueness theorem for time-harmonic electromagnetic (EM) field, the field inside a finite domain v is uniquely determined by tangential electric (Et) or magnetic (Ht) field on the bounding surface S, except on resonant frequencies of the domain. This leads to solution methods that enforces either Et, or Ht, or both tangential components on S, e.g., in electric-, magnetic-, or combined-field...
The improvement of the efficiency of the time-domain analysis using frequency-domain response and the Fourier transform is achieved by adjusting the current expansion at each frequency and by interpolating the results in the frequency domain. The future work will include investigation of the minimal number of frequency samples needed for the interpolation, a non-uniform sampling in the frequency domain...
This paper presents the method for evaluation of reflectivity of RF absorber using 3D electromagnetic solver WIPL-D Pro. Absorber design using measurement and trial method is a tedious and time consuming task, and proposed method can be used to make it easier and faster. It has been investigated what is the minimum size of the sample needed for accurate results, how conductivity of the material affects...
We present an efficient and accurate approach for calculating time-domain responses of antennas mounted on electrically large platforms, such as airplanes, spacecrafts, ships, tanks, etc. The approach is based on the proficient frequency-domain analysis coupled with the inverse Fourier transform, in order to obtain time-domain responses. For the basic frequency-domain analysis we use method of moments...
When designing an anechoic chamber, it can be of particular advantage to develop a proper model of RF absorber. Using the model it is possible to calculate absorber reflectivity in magnitude and phase, for various angles of incidence, for parallel and perpendicular polarizations. Absorber data sheets commonly specify only the magnitude of the absorber reflectivity for normal incidence. For all other...
We present a numerically efficient technique for simulating RCS from trees and forests. Furthermore, we included other objects positioned (potentially hidden) in forests and the finite real ground below. The exploration of forest density, real finite ground plane, and operating frequency is done. The software tool WIPL-D Pro v6.0 is used for all simulations.
This paper introduces a PO-driven iterative Galerkin solution of field integral equations. The procedures can be applied in analysis of perfectly conducting bodies suited in incident electromagnetic field. Computer implementation of the procedures is memory efficient since it is no longer necessary to store matrix of dimension n times n, where n is the number of unknowns. Numerical examples show fast...
This paper presents the results for three different antenna optimization problems that are found using the particle swarm optimizer (PSO). The outcomes found with PSO are compared to the outcomes found with other optimization algorithms to estimate the efficiency of PSO. The first problem is finding the optimal position of the feeding probe in a radiating rectangular waveguide. The second problem...
Two general approaches to multiminima optimization are considered. The first approach is based on repetition of a single minima method (e.g., the Nelder-Mead simplex applied to the best solution in a set of random trials). The second approach is based on a coarse estimation of local minima using initial set of points and local optimization starting from these local minima (e.g., random search as a...
In the process of electromagnetic modeling and simulation, one encounters various limits imposed by the hardware capabilities of modern computers. As the complexity or the electrical size of the problem grows, so does the need for faster processors and more RAM in order to make the analysis of such projects feasible. With the era of 64 bit computing at our door step, 4 GB is no longer the theoretical...
The scattered field from reflector is usually evaluated by using a) GO (Geometrical Optics) combined with AF (Aperture Field) method, or b) PO (Physical Optics). Sophisticated methods includes a) GTD (Geometrical Theory of Diffraction) and PTD (Physical Theory of Diffraction) [1,2]. However, these techniques can not be used for analysis of feeds for such antennas. Precise analysis of feeds can be...
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