O. Picon

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.

Analysis and design of slot-coupled directional couplers between double-sided substrate microstrip lines

The characteristics of a slot-coupled directional coupler between two microstrip lines coupled through a rectangular slot in the common ground plane are studied. First, conformal mapping techniques are used to obtain analytic closed-form expressions for the coupler even and odd mode impedances and propagation constants for any coupler configuration. Secondly, a full-wave analysis is performed using the spectral domain approach to determine the dispersion properties of the coupler parameters. Theoretical and experimental results for a 10 dB coupler at 10 GHz are presented.<<ETX>>

Three dimensional finite element analysis of N-port waveguide junctions using edge-elements

The finite element method is formulated in such a way that the electromagnetic solution of an excited cavity formed from an N-port waveguide junction leads directly and naturally to circuit characteristics of this junction. The use of edge elements eliminates nonphysical solutions. The reliability of the solution is assured compared to a penalty method. Accuracy of the method is demonstrated through the presentation of results for a waveguide T-junction while its efficiency is proven through the presentation of results for a case study of a finline step discontinuity.<<ETX>>

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.

Solution of Fin-Line Discontinuities through the Identification of its First Four Higher Order Modes

The dominant and the first four higher order modes in a unilateral fin-line are accurately described from a thorough Spectral Domain Approach. Then, coupling coefficients between eigenmodes at a discontinuity that have to be introduced into the scattering matrix formulation, are directly computed in the Spectral Domain. Finally, fin-line discontinuities often used for impedance transformation are investigated and comparison with measurements in K/sub a/ band are given .

A numerical TRL de-embedding technique for the extraction of S-parameters in a 2/sup 1/2/D planar electromagnetic simulator

A numerical application of the TRL calibration for a planar discontinuity is proposed to be used in electromagnetic simulators in order to calculate its scattering matrix without the need of either defining the port characteristic impedance as in the slotted line numerical simulation or of normalising with respect to a specified value of reference impedance as in other known de-embedding methods. The proposed technique is applied, in a 2/sup 1/2/D planar electromagnetic simulator using integral equations technique solved by the moment method, on a case study of a step in width coplanar waveguide discontinuity and the authors have demonstrated how many numerical problems encountered previously when using other techniques were eliminated.<<ETX>>

Three Dimensional Finite - Element Formulation for Finline Discontinuity Problems

A three dimensional finite - element formulation is proposed for finding directly the electric or magnetic field at a given frequency of excitation inside a general multiaxial finline discontinuity. It is shown that this formulation can be used to find the scattering parameters of a general finline bend discontinuity problem. Results are presented for a case study of a finline step discontinuity problem.

The impact of Whitney forms on computational electromagnetics

Edge elements are now known to be appropriate basis functions for the finite element method (FEM) applied to many microwave applications. Bossavit (1988, 1989) has presented edge elements as belonging to Whitney forms. In fact, he has argued for an approach based on differential forms from which the Whitney forms come out naturally when the discretization is concerned. We emphasize the role that the Whitney forms could play in computational electromagnetics by pointing out some direct consequences of their use. Considering the Whitney forms is well beyond just providing adequate basis functions in the Galerkin procedure. It allows one to fully understand why and how edge elements work so well and further sheds light on the discretization not only of the FEM but also of other numerical methods. First, we recall the elementary properties of Whitney forms. Then the discretization of Maxwell equations is tackled in this context. A possible analogy with circuit laws and the similarity with other methods are shown.

Elimination of non physical finite-element solutions for Maxwell equations: applications to three dimensional waveguide junctions

Maxwells equations can be naturally solved by the finite-element method in either two- or three-dimensional formulations for scattering or guided-wave problems. However, the well-known appearance of nonphysical modes has limited their use. In the present work, this problem has been overcome by using suitable basis functions, i.e. edge elements, which give accurate and reliable approximations of the fields. A general three-dimensional waveguide junction problem is formulated. Numerical results for the S-parameters for two test cases are provided and compared to experimental data and spectral domain approach results. These test cases are a rectangular waveguide T-junction and a finline step discontinuity. Field patterns in cut planes are also shown.<<ETX>>

Exact Calculation of Scattering Parameters of the Coplanar-Slot Transition in a 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 a 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.