摘要:

Plane wave reflection from a planar rectangular array of C-shaped wire elements placed over or on a (metal-backed) Dallenbach absorbing layer is considered. An explicit method is introduced after approximating each C-particle as a pair of electric and magnetic dipoles. Unlike our previous method, the present explicit method is valid even when the wire elements are near or on the dielectric-air interface of the Dallenbach absorbing layer. Such an explicit method is very useful for optimal design of thin and low profile anti-reflection structure involving array of C-shaped wire elements. Numerical results are presented to illustrate the anti-reflection effect, in particular, when the C-shaped wire elements touch the dielectric-air interface of the Dallenbach absorbing layer.

ISSN:0920-5071    

DOI:10.1163/156939300X00112

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The general solution of the 2D electromagnetic scattering problem may be expressed in terms of the so called Cylindrical Waves [4]. In the presence of a plane discontinuity, the solution of the electromagnetic problem may be found by means of the plane-wave expansion of the Cylindrical Waves and by characterizing the discontinuity by means of the reflection coefficient. In this way a numerical solution implies the quadrature of 2D radiation integrals with a highly oscillating kernel, to be solved by means of special quadrature algorithms. In

ISSN:0920-5071    

DOI:10.1163/156939300X00121

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Recently a general framework has been proposed for constitutive relations. This theoretical approach attempted to represent constitutive relations as spatiotemporal differential operators acting on the physically observable fields. The general statement is sufficiently broad to embrace linear and nonlinear systems, and dispersive as well as inhomogeneous systems. The present study investigates specific examples related to polarizable and chiral media. It was immediately realized that prior to working out the examples, we have to better understand the relation of the kinematics of particles to field concepts. Throughout, the Minkowski space notation and related relativistic ideas are exploited for simpler notation and deeper understanding.

ISSN:0920-5071    

DOI:10.1163/156939300X00130

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper, an efficient algorithm is developed to analyze the steady state response of a nonlinearly loaded antenna array under multitones excitation. The problem is equivalent to a multiport nonlinear microwave network problem with the network parameters of antenna array obtained by the moment method. The antenna array mutual coupling effects are included in the equivalent multiport network. This resulting equivalent network is then solved using an efficient successive over-relaxation algorithm. Numerical examples are shown to illustrate the capability of the proposed method and the intermodulation effect of the nonlinear loads. The proposed method is suitable for nonlinearly loaded antenna array under multitones excitation.

ISSN:0920-5071    

DOI:10.1163/156939300X00149

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The inhomogeneous dielectric configuration of the microstrip line supports only Quasi-TEM hybrid modes. The mode-coupling efficiency between the longitudinal section electric (LSE) and longitudinal section magnetic (LSM) modes increases with frequency. Microstrip circuits can be analyzed assuming TEM modes but only below a frequency fstat. Theoretical formulas predict that undesirably strong coupling between the Quasi-TEM and TM0modes, and the onset of the lowest-order surface wave TE0mode occur at frequencies fTEMand fc,TEo'respectively. In this paper, the full-wave FDTD method shows the existence of the longitudinal field components, and verifies to a certain extent the validity of the operating frequency range as predicted by the theoretical formulas.

ISSN:0920-5071    

DOI:10.1163/156939300X00158

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Groove guides have sharp corners in the guide proper so are not low loss and high power carrying wave guides. Proposed has been a groove rectangular waveguide with rounded internal angles [1]. However, the latter is not practical in having the infinite arms. Let us try the Conchoid of Nicomedes and Limacon of Pascal to see how can they be boundaries of static fields or high frequency waves. Also has been proposed the pentagon waveguide [2] for the high power transmission in high frequency. Yet we feel that we have very limited forms of waveguides, so we study the existing curves to see whether we can find some better guides such as rounded corner rectangular waveguide and others by starting from the boundary curves of p = a/ cos φ + l and p = a cos φ + l.

ISSN:0920-5071    

DOI:10.1163/156939300X00167

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Analysis of frequency selective surface with gridded square element using accurate integral equation technique is considered in this paper. An improved subsectional current approximation model is proposed. Two more terms of basis function, the downward half triangle (DHT) term and the upward half triangle (UHT) term, besides the commonly adopted rooftop function, are included to expand the induced current. The additional terms are used to account for the effect of the induced currents at the corners of the outer square of the unit cell. Green's functions are derived by using spectral domain immittance approach and the incident fields are derived by using the z-directed potential. The computed results are in good agreement with the measured results.

ISSN:0920-5071    

DOI:10.1163/156939300X00176

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Inthis paper, two dimensional transmission line circuits are used to determine cutoff wavenumbers of homogeneous arbitrarily shaped cylindrical waveguides. The derived circuits depend mainly on long transmission line (LTL) circuits. The resonance frequencies of these circuits are the required cutoff frequencies of the guide. The problem is reduced to a simple eigenvalue problem, which is solved to get the required solution. Numerical results are given to compare results with available analytical solutions and results given by other reported methods.

ISSN:0920-5071    

DOI:10.1163/156939300X00185

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The well-known decomposition of vector fields to solenoidal and irrotational parts, known as the Helmholtz decomposition, is generalized in terms of more general linear operators involving two arbitrary symmetric, positive-definite and complete (non-singular) dyadics. It is seen that, in terms of the generalized decomposition, potential expansions for the static electric and magnetic fields in anisotropic media can be formed in a straightforward manner. The decomposition theorem is further generalized in a form applicable to the static electromagnetic fields in the most general linear medium (bi-anisotropic medium) characterized by four medium dyadics. In this case, the decomposition theorem and potential expressions are presented in a compact form in terms of six-vectors.

ISSN:0920-5071    

DOI:10.1163/156939300X00194

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Boththe penetrated and the scattered fields in the presence of a non-uniform cold magnetized plasma column are investigated in this work, and the direct integral equation is formulated for describing the currents on the surrounded multiple perfectly conducting strips on the outer boundary of plasma column due to a normally incident TMwave. In order to formulate such an integral equation, two-dimensional dyadic Green's functions in multi-layered cylindrical shells are derived at first in terms of the cylindrical vector wave functions. Furthermore, by using the Galerkin's method, the surface current of the strips is expanded in the form of a series of Chebyshev polynomials of the first kind. Parameter studies are performed to show the variation of the near- and far-zone fields with the operating frequency, the effective collision frequency, as well as the angular width and the number of surrounded strips.

ISSN:0920-5071    

DOI:10.1163/156939300X00202

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor