Multimode Network Theory Research Articles

Improved mode-matching and network analysis of E-plane waveguide branch directional couplers

The E-plane waveguide branch directional counplers are analyzed by a method which combines the multimode network theory with rigorous mode-matching approach. The electromagnetic field componenents are expanded by the superposition of LSE x modes rather than TE and TM modes in the mode-matching procedure. Meanwhile, the electromagnetic problem is transferred into the network problem through the mode-matching treatment. It is shown that the present method has the advantages of simplicity and less computation without affecting the accuracy of the calculation.

Mode matching analysis of the dielectric waveguide 3-D discontinuity problem

In this paper, the dielectric waveguide 3-D discontinuity problem is investigated by the method which combines the multimode network theory with the rigorous mode matching procedure both in the transverse cross section and in the longitudinal direction. Good agreement has been found between the numerical results and the experimental data in the literature, and the effectiveness and accuracy of the present method are justified. Some numerical results are given to establish useful guidelines for the design of dielectric waveguide components in the millimeter and optical wave integrated circuits.

Scattering characteristics of rectangular coaxial line discontinuities

The scattering characteristics of rectangular coaxial line discontinuities are investigated by an accurate and efficient approach, which combines the finite-element method with a rigorous mode-matching procedure. The impedance transform technique of the multimode network theory is used in the mode matching treatment so that the whole analysis of the 3-D discontinuity problem is significantly simplified. The accuracy and effectiveness of the present method are verified by experimental data.

Multimode network representation of multiple inductive and capacitive obstacles in parallel plate waveguides

In this paper the multimode network formulation is used to characterize a multiple obstacle or aperture discontinuity in parallel plate waveguide. The procedure leads to a frequency-independent integral equation. This equation is solved numerically by using the method of moments, allowing for the implementation of a very general and efficient code. The frequency-independent integral equation formulation and its numerical solution are first outlined. Then, we discuss the convergency properties of the procedure, and compare its results with other theoretical results available.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Rigorous multimode network representation of capacitive steps

Capacitive steps discontinuities are the basic components of many waveguide devices of common use, and several models have been developed for their characterizations. The multimode equivalent network formulation presented in this paper provides a new, simpler and more flexible representation of the step. The method leads to a frequency independent integral equation that is solved numerically by using the Method of Moments. From the solution, a frequency independent multimode impedance coupling matrix is computed. The coupling matrices of a number of cascaded steps can then be combined in a global matrix, so that a wide class of waveguide devices can be analyzed with only one inversion per frequency point. The results obtained from the method presented here are compared with measured data, showing very good agreement. A comparison of the runtimes of the code developed with a typical mode-matching solution is performed, showing that the code based on the multimode network formulation is substantially more efficient.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Scattering properties of discontinuities in NRD guide

The scattering characteristics of a guided wave by a class of discontinuities in a nonradiative dielectric (NRD) guide are systematically investigated by a method which combines the building block approach of multimode network theory with a rigorous mode-matching procedure. Some experimental data justify the effectiveness and accuracy of the present method. Extensive numerical results are obtained to develop useful guidelines for the design of NRD guide components.< >

Scattering characteristics of 3-D discontinuity consisting of semiconductor sample filled in waveguide with gaps

The scattering characteristics of 3-D discontinuity consisting of II-VI-epitaxial layer grown on lossy dielectric substrate inserted in the waveguide with gaps are investigated in detail by the method which combines the multimode network theory with the rigorous mode matching procedure. The experimental data verify the accuracy and the effectiveness of the present method.

Scattering characteristics of rectangular coaxial line branching directional coupler

The scattering characteristics of a rectangular coaxial line branching directional coupler are investigated by an accurate approach that combines the finite-element method with a rigorous mode matching procedure. The impedance transform technique of the multimode network theory is used in the mode matching treatment so that the whole analysis of the 3-D discontinuity problem is significantly simplified. The accuracy and effectiveness of the present method are verified by experimental data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Microwave transmission and reflection of stratified lossy dielectric segments partially filling waveguide

The microwave transmission and reflection is evaluated for stratified lossy dielectric segments partially filling the rectangular waveguide by the method which combines the multimode network theory with the rigorous mode matching procedure. As an example, we investigate in detail the microwave scattering properties of II-VI-epitaxial layer on a lossy dielectric substrate inserted in the rectangular waveguide. The experimental data verify the accuracy and the effectiveness of the present method. Extensive numerical results are presented to establish useful guidelines for the contactless microwave measurement of the conductivity of the epitaxial layer.

Radiation characteristics of multilayer periodic dielectric structures

Radiation characteristics of multilayer periodic dielectric structures are investigated by the method which combines the building block approach of multimode network theory with the rigorous mode matching procedure. The multilayer periodic structure is composed of uniform dielectric layers and single periodic layers. Two examples are given in this paper; first, radiation property of the double dielectric grating antenna is analyzed. The results indicate that the double dielectric grating antenna has relatively smaller dimensions than that of the single one. It is undoubtly of great importance in the case that the limitation of the weight and the volume of the system is strictly required. Secondly, some curved profile grating antennas are analyzed by combining the present method with the staircase approximation. In such a way, the effects of groove profile on the performance of the grating antennas are systemetically studied and some useful guidelines for the design of the dielectric grating antennas are thereby suggested.

Analysis of closed dielectric waveguides —Multimode network appoach

The dispersion characteristics of a class of closed dielectric waveguides are investigated by the method which combines the building-block approach of multimode network theory with the rigorous mode matching procedure. Several numerical examples for different guiding structures have been given by the approach. The same structures are also analyzed with the finite element method and the EDC method for comparison. The calculations show that the present approach yields as highly accurate results as the finite element method while almost retaining the simplicity of the EDC method, and justify the utility of the present method.

Effect of transition waveguides on dielectric waveguide directional couplers

The coupling of energy between two curved dielectric waveguides is investigated by the staircase approximation method, which combines the building-block approach of multimode network theory with a rigorous mode-matching procedure. Particular attention is directed toward two major effects of transition waveguides on the performance of directional couplers composed of dielectric waveguides: one is the change in the coupling length, the other is the radiation loss. The coupling problem is analyzed in terms of the scattering of an incident guided mode by the coupler structure as a whole. Numerical results are given to illustrate the coupling characteristics of various structures and to establish useful guidelines for the design of directional couplers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new approach for analysis of closed dielectric waveguides

The dispersion characteristics of a class of closed dielectric waveguides are investigated by the method which combines the building-block approach of mul timode network theory with rigorous mode matching procedure. Several numerical examples for different guiding structures have been given by the approach. The same structures are also analyzed with the finite element method and the EDC method for comparison. The calculations show that the present approach yields as highly accurate results as the finite element method while almost retaining the simplicity of the EDC method, and justify the utility of the present method

Technical memorandum: Dielectric-waveguide branching directional coupler

A dielectric waveguide branching directional coupler with curved transtion is presented, and is investigated by the use of a staircase approximation, which combines the building block approach of multimode network theory with a rigorus mode matching procedures. The coupling problem is analysed from the view point of the scattering of incident surface waves by the nonuniform dielectric structure as a whole. Particular attention is given to establishing the effect of radiatioin due to bending of the curved transtion wave guides and other discontinuties on the performance of the coupler. Numerical Results are given, from which guidelies for the design of bidirectional couples are derived