摘要:

Anarbitrarily shaped microstrip patch antenna excited by a three-dimensional electric point-source is examined. The metallic patch resides on a biisotropic chiral grounded slab. The analysis is based on the integral equation approach. The Green functions for the layered medium are used to formulate a coupled set of integral equations for the patch induced current. The layered medium Green dyadic function is expressed in terms of spectral TE and TM waves and of Sommerfeld-type integrals. The Sommerfeld-type integrals are expressed in a new and original way which greatly reduces the computational effort. Simulation results for structures in various high frequency configurations are presented.

ISSN:0920-5071    

DOI:10.1163/156939397X00846

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Frequency selective surfaces (FSS) have numerous applications in microwave and optical systems. In this work, instead of traditional dielectric substrates, ferrite substrates are used. By using ferrite materials, one can change the spectral properties of these structures without physically altering them. The transmission matrices for the ferrite substrate and the air, above and below the ferrite substrate, are derived here. By combining these transmission matrices along with the boundary conditions, the spectral domain Green's function is obtained. This process can be carried out for both the in-plane and perpendicular bias of the ferrite. Several results are presented to show the tunability of frequency selective surfaces with ferrite substrates as a function of the applied dc bias. Some special treatment is used in the transmission matrix to avoid its singularity for some evanescent modes.

ISSN:0920-5071    

DOI:10.1163/156939397X00855

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The influence of transversal density nonuniformity on the propagation of electromagnetic surface waves along plasma slabs and columns in the presence of collisions is analysed and illustrated by numerical evaluations for phase diagrams of axially homogeneous plasmas. Moreover, the changes in dispersion and damping caused by the occurence of plasma resonances in the transversal/radial density profile are studied. In addition, complex modes and backward waves in the collisionless dispersion curves of isotropic plasmas are treated.

ISSN:0920-5071    

DOI:10.1163/156939397X00864

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Wave-splitting is applied to the scattering problem of a time-harmonic plane wave obliquely incident on a laterally periodic inhomogeneous structure. An invariant imbedding approach and an Green function approach are used (and compared) to calculate the scattering fields as well as the internal fields. Numerical results for the reflection and transmission at diffraction angles are presented.

ISSN:0920-5071    

DOI:10.1163/156939397X00873

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Electromagnetic-field TE/TM decomposition theory, well known for fields in isotropic and uniaxially anisotropic media and their extension to uniaxial bi-anisotropic media is generalized to cover all bi-anisotropic media. General conditions for the medium parameter dyadics are derived for the decomposition to be possible. Some decomposable special bi-anisotropic media are considered as examples of applying the general conditions. Previously known cases are seen to fall under the conditions derived. The decomposition theory can be applied to splitting an electromagnetic problem in two simpler problems.

ISSN:0920-5071    

DOI:10.1163/156939397X00882

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Since circular polarimetric radars can be used to assess the relative contribution of odd-bounce and even-bounce scattering to the response of targets and to implement novel schemes for adaptive rain clutter suppression and radar pulse compression, they are increasingly used in applications such as radar meteorology, biophysical and geophysical remote sensing, and radar navigation. Although methods for calibrating linear polarimetric radars are widely known, they cannot be used to calibrate circular polarimetric radars until account is taken for the different form of the response of calibration targets when measured with respect to a circularly polarized basis. The response of three standard targets used to calibrate linear polarimetric radars (an odd-bounce-reflector and two even-bounce reflectors with different angles of rotation about the radar line-of-sight) does not yield a unique solution to the calibration equations. If, however, the odd-bounce reflector is replaced by either a circularly polarizing or linear polarization selective target, the calibration equations can be solved.

ISSN:0920-5071    

DOI:10.1163/156939397X00891

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The problem of diffraction by perfectly conducting plane complementary sectors assumes canonical form when conical geometry is used. This allows us to express the diffracted fields like spectra of E and H -modes and to unify the two problems simply invoking complementary limit conditions in the Sturm-Liouville problems for the pertaining Debye potentials. In particular, from the unification properties relative to the fundamental E and H modes it follows that the electric/magnetic singular behaviours by the tip conductor are identical to the magnetic/electric singular behaviours by the complementary tip conductor. For utility in printed circuit analysis, the former singular behaviours are formulated as simple weighting functions and the problem of EM singularities excitation along the conductor edge of any printed circuit is discussed.

ISSN:0920-5071    

DOI:10.1163/156939397X00909

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A closed form, high-frequency solution is presented for the field radiated by an electric dipole located upon a rectangular, ground- ed dielectric slab. This solution, which is based on a physical optics formulation, is given in terms of the geometrical optics field plus ray-diffracted field contributions from the four edges. These ray-diffracted fields are decomposed into space waves, surface waves and leaky waves contributions. By superimposing the effects of elementary dipoles, the radiation of a current distribution is obtained, that simulates the effects of a patch radiating on a finite grounded substrate. Also, a closed-form solution is derived in the case when the current distribution exhibits an analytical expression of its Fourier transform. Comparisons with measurements are presented to validate the asymptotic solution.

ISSN:0920-5071    

DOI:10.1163/156939397X00918

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939397X00927

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor