Jacques Citerne

Theoretical of and Experimental Investigation Finline Discontinuities

The dominant and the first-five higher order modes in a unilateral finline are precisely described from a thorough spectral-domain approach. Then, using the modal analysis, coupling coefficients between eigenmodes at a discontinuity that have to be introduced into the scattering matrix formulation are directly computed in the spectral-domain, and, consequently, the equivalent circuit parameters of the discontinuity are determined. Finafly, finline discontinuities often used for impedance transformation are investigated and a good agreement between theoretical and experimental results is reported.

Theoretical and Experimental Investigation of Open Microstrip Gap Discontinuities

A theoretical analysis of open discontinuities in microwave planar circuits using integral equations technique solved by the moment method is described. Characterization of the dicontinuity by an equival ent scattering matrix is then accurately evaluated from the determnation of the current distribution along the line containing the discontinuity under different load conditions. An experimental method, which is capable to determine directly the discontinuity equivalent circuit parameters, is proposed. A good agreement between theoretical and experimental results is reported.

An efficient analysis of planar microwave circuits using a DWT-based Haar MRTD scheme

A new wavelet-based technique to generate multiresolution time-domain schemes is presented in this paper. By using symbolic calculus, a rigorous and general formulation of subgridding at every level of multiresolution is obtained. As it is rigorously equivalent to a finer finite-difference time-domain (FDTD) scheme, it does not require any particular treatments for boundary conditions. This technique has been successfully applied to the study of microstrip structures. The near- and the far-field computation can be both improved in terms of CPU time and memory storage, while maintaining the same accuracy as the classical FDTD computation.

Methodology to interpolate and extrapolate SAR measurements in a volume in dosimetric experiment

There has been an explosive growth in the area of wireless communication. Over the world, hundreds of millions of subscribers are using mobile phones. International and national organizations have recommended limits for the protection of mobile phone users and standards are going to be established to certify the compliance of mobile phones with these limits. To ensure this conformity, numerical and experimental dosimetric analyzes are essential to evaluate the electric fields inside the users head. These fields can not be measured near the mobile phone- the phantom interferes where they are a maximum and the use of interpolation and extrapolation is then necessary to evaluate the electric field components. This paper describes the interpolation and extrapolation methodologies, of the experimental sampled data in three dimensions, of the power absorbed in the whole volume of the head phantom. A new method to interpolate and extrapolate SAR measurements is presented. This technique, which is very fast and not very expensive in terms of required memory, is compared with other interpolation techniques which use splines or wavelets.

Multi-carrier CDMA using interference cancelation

In this paper, various detection techniques in the synchronous case of a multiuser MC-CDMA system operating in frequency selective Rayleigh channel are compared with respect to the achievable spectral efficiency. It is shown that a parallel interference cancellation MMSE scheme with two stages could be a good compromise between performance and complexity.

On the EMC dipole feed-line parasitic radiation

A rigorous analysis of the electromagnetically coupled microstrip dipole based on potential integral equations, Greens functions, and the moment method is presented. The computations of the antennas radiated field using the steepest descent technique is then detailed, and the theoretical results are compared with experimental measurements in the X-band. By considering the feed as an antenna part, the excitation line parasitic radiation is shown clearly. Two possibilities to reduce this parasitic phenomenon are proposed. Also, it is shown that in any microstrip structure (one or two layers) excited by a microstripline, the feed parasitic radiation is nonnegligible. >

Exact Calculation of Scattering Parameters of the Coplanar-Slot Transition in Unilateral Finline Technology

The dominant and higher order modes, in both a unilateral finline and coupled unilateral finlines in the even and odd modes, are accurately described from a thorough spectral-domain approach. Then, coupling coefficients between eigenmodes at a coplanar-slot transition in unilateral finline technology, which are to be used in the generalized scattering matrix formulation, are directly computed in the spectral domain. Scattering parameters of the dominant mode in the Ka -band are presented for both even- and odd-mode excitation of the coupled unilateral finlines.

Series form of space domain Green's function on the conductor plane of microstrip antennas

A procedure is shown which yields a closed analytic series form in the space domain for the Greens functions for microstrip antennas. An explicit formulation is reported for the expression of the scalar Greens function at the air-dielectric interface of a single-layered medium, which can be represented in closed form in the space of Legendre polynomials as well as the contribution of the singularity at the origin and of the surface wave at infinity.<<ETX>>

Theoretical and experimental investigation of smooth and discrete microstrip ring antennas

A rigorous full wave analysis of ring antennas using the integral equation technique is presented. The input impedance and the radiation patterns of both smooth and discrete microstrip ring antennas are calculated for the first two resonance modes (TM/sub 11/ and TM/sub 12/). A full wave analysis using the integral equation technique associated with the method of moments is shown to be a powerful tool for characterizing microstrip ring antennas. It is shown also that the second TM/sub 12/ resonance mode of the ring has a greater bandwidth than that obtained for the first TM/sub 11/ mode. Good agreement is reported between theoretical and experimental results.<<ETX>>

Analysis of radiating end effects of symmetric and asymmetric coplanar waveguide using integral equations technique

An integral equation technique solved by the moment method associated with the single one-port model is used to analyze radiating end effects of symmetric and asymmetric coplanar waveguides (CPWs). Theoretical results obtained on a short-circuit end of a CPW are compared with those obtained experimentally using series-gap-coupled straight CPW resonators. The experimental data confirm the accuracy of the theoretical results.<<ETX>>