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# IEE Proceedings - Microwaves, Antennas and Propagation

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Displaying Results 1 - 13 of 13
• ### Simulating 3D waveguide discontinuities using a combination of Prony's method and FDTD with improved absorbing boundary conditions

Publication Year: 1994, Page(s):127 - 132
Cited by:  Papers (4)
| | PDF (392 KB)

Two major problems usually arise when the finite-difference time-domain (FDTD) method is used for wideband characterisation of dielectric discontinuities with high permittivity in waveguides. First, reflections are provoked by imperfections in the absorbing boundary conditions. Secondly, many time steps are necessary to overcome the problems associated with the truncation error inherent in the dis... View full abstract»

• ### Simplified treatment of wire-to-plate junctions with magnetic-current frill excitation

Publication Year: 1994, Page(s):133 - 137
Cited by:  Papers (1)
| | PDF (308 KB)

A structure consisting of a flat metal plate and a wire joined to the plate and driven at the plate by a magnetic-current frill (approximating the coaxial-line excitation) occurs frequently. The electromagnetic analysis of such a structure poses considerable problems, the main one being due to discontinuous surface-charge density (i.e. to discontinuous surface-current derivative) on the plate near... View full abstract»

• ### Microstrip with dielectric overlay: variational analysis and validation

Publication Year: 1994, Page(s):138 - 140
Cited by:  Papers (10)
| | PDF (196 KB)

A variational technique for the analysis of microstrip with dielectric overlay/cover in the Fourier transform domain is investigated with special reference to the strip thickness dependence. The effective permittivity calculated for different overlay thicknesses and permittivities indicates a mode change from quasi-TEM to TEM as the effect of strip width disappears in agreement with full wave spec... View full abstract»

• ### Simplified Green's functions for calculating capacitance and inductance of multiconductor transmission lines in multilayered media

Publication Year: 1994, Page(s):141 - 144
Cited by:  Papers (3)
| | PDF (224 KB)

Using the impedance formula and the asymptotic property of the hyperbolic tangent function, the Green's function due to a line source embedded in a general layered medium has been analytically converted into a more suitable form for numerical calculation of capacitance and inductance. The new form is designed to eliminate slow convergence when the vertical distance of the source and field points i... View full abstract»

• ### Finite element analysis of propagating, evanescent, and complex modes in finlines

Publication Year: 1994, Page(s):65 - 69
Cited by:  Papers (5)
| | PDF (340 KB)

The finite element method is employed to analyse the characteristics of propagating, evanescent, and complex modes in finlines. The recently developed mixed-interpolation-type triangular elements are used, where no spurious solutions appear and consistency with the published results is obtained. The existence of the complex mode for both the even mode and the odd mode in finlines is found for part... View full abstract»

• ### Finite-difference time-domain field approximations for thin wires with a lossy coating

Publication Year: 1994, Page(s):107 - 113
Cited by:  Papers (12)
| | PDF (392 KB)

Computation of the scattering and radiation by thin wires with a nondispersive lossy coating using the finite-difference time-domain method is discussed. The time-domain relationship between the electric fields perpendicular to a lossy material boundary is derived and a subcell' approach is followed which allows the spatial grid size to be larger than the wire radius. Radiated and scattered time-... View full abstract»

• ### Electromagnetic fields interpolation from nonuniform samples over spherical and cylindrical surfaces

Publication Year: 1994, Page(s):77 - 84
Cited by:  Papers (10)
| | PDF (432 KB)

Algorithms for the interpolation of electromagnetic fields from nonuniformly spaced samples over a sphere and over a cylinder are presented. They use an iterative technique and are based on optimal sampling expansions of central type. The algorithms have been found to be convergent if the average sample's density is slightly higher than the Nyquist one and if it is possible to build a one-to-one c... View full abstract»

• ### Modelling of straight thin wires using time-domain electric field integral equations

Publication Year: 1994, Page(s):123 - 126
Cited by:  Papers (4)
| | PDF (228 KB)

The thin-wire time-domain electric field integral equation is formulated starting from the extended boundary condition theorem and including a first-order approximation for the charges at the end caps of the wire. The equation obtained is solved directly in the time domain by the moment method. The effects of this approximation and of changing the situation of the matching points on the segments o... View full abstract»

• ### Environmental coupling loss effects in superconducting HF loop antenna design

Publication Year: 1994, Page(s):94 - 100
| | PDF (420 KB)

Losses coupled into an electrically small HF loop receiving antenna system from its environment are investigated by analysis and computation using the NEC programme to assess the significance of such effects when superconducting technology is applied. Results are presented showing ground plane and terrain perturbations of the loop performance itself together with the effects of lossy supporting su... View full abstract»

• ### Symmetrical five-port waveguide junction with -20 dB residual mismatch over waveguide bandwidth

Publication Year: 1994, Page(s):101 - 106
Cited by:  Papers (3)
| | PDF (404 KB)

Current designs for the symmetrical five-port waveguide junction have residual mismatches that rise to -14 dB over parts of the waveguide bandwidth. The present paper describes the use of a computer model to search for a new design (based on a combination of metallic post, dielectric sleeve and five inductive diaphragms) which yields a residual mismatch that does not exceed -20 dB over the entire ... View full abstract»

• ### Measurements and predictions of attenuation and scatter of microwave signals by trees

Publication Year: 1994, Page(s):70 - 76
Cited by:  Papers (21)
| | PDF (492 KB)

A set of propagation measurements was conducted at a uniformly planted apple orchard to determine the attenuation of radio waves at 11.2 GHz with increasing foliage depth in the signal path. Measurements were also made to examine the level of scattered signals emerging from such media into free space (backscattering) and its dependence on the angular direction of the receiving antenna. Measurement... View full abstract»

• ### Diffraction effects of a tape covering the gaps of a panelled compact range' operating at millimetre waves

Publication Year: 1994, Page(s):114 - 122
Cited by:  Papers (1)
| | PDF (592 KB)

Diffraction which arises at the interpanel gap edges of a panelled reflector in a `compact antenna test range' clutters the measured radiation pattern with the formation of spurious lobes. The the approach of covering the gaps with a thin metallic tape is studied in terms of its effectiveness to suppress the spurious effects at frequencies mainly in the 180 GHz band. A ray GO/GTD like approach is ... View full abstract»

• ### Characterisation of electromagnetically coupled superquadric loop antennas for mobile communications applications

Publication Year: 1994, Page(s):85 - 93
Cited by:  Papers (5)
| | PDF (548 KB)

Analysis of two mutually coupled loop antennas with arbitrary relative orientation and position and possibly different geometries is presented. The antennas are represented by generalised superquadric curves, which include circular, elliptical, and rectangular loop geometries, and they may be located either in a homogeneous region or next to an infinite ground plane. A Galerkin-type moment method ... View full abstract»