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The size reduction for resonant monopoles is an important issue for HF and VHF antennas. Unfortunately, size reduction results in degradation in both efficiency and bandwidth, as is well known from the fundamental limits on small antennas. This paper firstly introduces a MATLAB-controlled NEC2 simulation tool with genetic algorithm optimization, and uses this to find the optimal position of inductors...
This paper describes the axial ratio characteristics of an Archimedean spiral antenna placed on a thin magnetic material. The thin magnetic material having a high permittivity and some magnetic loss tangent is used. The outer circumference of the spiral antenna is chosen to be approximately one wavelength at 300 MHz. To obtain a unidirectional beam, the antenna is located above a ground plane. The...
This paper describes the design and numerical simulations of a switch system to launch fast (100 ps), high-voltage (>100 kV) spherical TEM waves from the first focal point of a prolate-spheroidal impulse-radiating antenna.
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....
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...
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...
The interest in the exploitation of wireless sensor networks in dissipative media (other than the free space) is nowadays growing in importance, thanks to the identification of ever newer fields of applications. This paper introduces an efficient design methodology for an easy definition of the characteristics of mobile sensors inserted in pipes filled with fluids. The proposed procedure takes into...
A compact reconfigurable four bands Planar Inverted-F Antenna (PIFA) is presented for Digital Video Broadcasting - Handheld (DVB-H), Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications (GSM800, 900, 1800 and 1900), Personal Communications System (PCS), Wireless Local Area Network and Bluetooth (WLAN), Worldwide Interoperability for Microwave Access (m-WiMAX)...
The main purpose of this paper is to compare the numerical simulation of the electromagnetic scattering by a sea surface using a MoM approach and Nodal Discontinuous Galerkin Methods (NDGM).
In Green's function diakoptics, wave-field interactions between disjoint domains in space are described in terms of interacting multi-port subsystems. In addition to integral-equation based Green's function diakoptics for time-harmonic fields, a demonstrably stable discrete space-time Green's function diakoptics scheme has been reported to be effective for proximate regions. For distant regions it...
Requirements to an antenna for thermal spot detection by a microwave radiometer are analyzed. A parasitic rectangular patch antenna has been designed and measured showing to meet the requirements.
In this paper an original acceleration scheme for the computation of periodic multilayered mixed-potential Green's functions is used to perform numerical dispersive analyses in bidimensional periodic structures embedded in a dielectric slab. The acceleration scheme is first described with reference to the various components of the dyadic and scalar potentials. The Green's functions are then implemented...
A new set of hierarchical vector basis functions that spans the curl-conforming reduced-gradient spaces of Nédélec on a triangular-prism cell is presented. These functions are constructed from orthogonal scalar polynomials to enhance their linear independence, which is a simpler process than an orthogonalization applied to the final vector functions. The new functions are compatible with those recently...
This paper describes the application of an efficient implicit finite-difference time-domain method (FDTD) based on the locally one-dimensional (LOD) scheme to the analysis of periodic band-gap structures. In particular, the technique of oblique incidence is introduced into the periodic LOD-FDTD method. To maintain a tridiagonal system of linear equations, we newly develop a three-step algorithm consistent...
The scheme of mono-pulse direction finding is well established. This paper uses a method of electromagnetic simulation to evaluate the direction finding performance of a number of common mono-pulse schemes. The mono-pulse variants include amplitude comparison of mechanically squinted beams, electronic squint and a linear interferometer. The advantage of simulation is that performance and other features...
It has been recently shown that in the case of scattering by a perfect electric conductor, it is possible to have a convergent Method of Auxiliary Sources (MAS) field due to divergent MAS currents. These conclusions are extended in the present paper for the case of the implementation of MAS to dielectric scattering problems. The main differences are pointed out, which regard the existence of two critical...
The ISM band at 60 GHz provides sufficient bandwidth for wireless transmission of data rates in the Gbps range. To fully utilize this unlicensed frequency range, the design of suitable antennas has to account for application-specific demands in terms of frequency bandwidth and antenna gain. We present a successful implementation, based on a compact patch array approach, meeting realistic requirements...
The integral equation (IE) method is commonly used to model time-harmonic electromagnetic (EM) phenomena. One of the major challenges in its application arises in the solution of the resulting ill-conditioned matrix equations. Here, we introduce a new domain decomposition (DD) based iterative method for the IE solution of time-harmonic electromagnetic problems. There are two major ingredients in the...
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