J.J. Gustincic

Bio: J.J. Gustincic is an academic researcher from Case Western Reserve University. The author has contributed to research in topics: Degenerate energy levels. The author has an hindex of 1, co-authored 1 publications receiving 21 citations.

A General Power Loss Method for Attenuation of Cavities and Waveguides

Abstract: The usual power loss method of evaluating the damping constant and Q of cavities and the attenuation constant of waveguides, as caused by finite wall conductivity, breaks down in the case of degenerate modes and fails to predict the coupling between degenerate modes. By means of variational formulations for the lossy case it is shown how the usual power loss method maybe generalized to treat the case when there are degenerate modes present. The generalized method turns out to be a particularly simple extension of the usual procedure.

Electromagnetic Field Computation by Network Methods

Abstract: In this monograph, the authors propose a systematic and rigorous treatment of electromagnetic field representations in complex structures. The architecture suggested in this book accommodates use of different numerical methods as well as alternative Green's function representations in each of the subdomains resulting from a partitioning of the overall problem. The subdomains are regions of space where electromagnetic energy is stored and are described in terms of equivalent circuit representations based either on lumped element circuits or on transmission lines. Connection networks connect the subcircuits representing the subdomains. The connection networks are lossless, don't store energy and represent the overall problem topology. This is similar to what is done in circuit theory and permits a phrasing of the solution of EM field problems in complex structures by Network-oriented methods.

Discrete-Time Network and State Equation Methods Applied to Computational Electromagnetics

Abstract: The representation of electromagnetic structures by lumped element circuits is revisited. Net- work models can be established by a subsequent ap- plication of system identification and circuit synthesis methods to data obtained by numerical simulation or from measurement. Network models provide a com- pact description of electromagnetic structures and can contribute significantly to the formulation of electro- magnetic field problems and their efficient solution. On the field level network methods are introduced by seg- mentation of the electromagnetic structures and appli- cation of the field form of Tellegen's theorem. Methods for synthesis of lumped element models for lossless as well as lossy linear reciprocal multiports and for ra- diating structures are discussed. The state equation method as a general framework for lumped element network description is presented. Discrete time repre- sentations on the basis of Richards transformation and wave digital filter formulation are introduced. I. Introduction The design of modern high-speed analog and digital elec- tronics makes use of distributed passive circuit struc- tures. The modeling of distributed circuits requires full- wave electromagnetic analysis. Usually the whole circuitry contains lumped as well as distributed subcircuits con- nected via interconnects or transmission lines such that each interconnect or connecting transmission line carries a single transverse mode only. This allows the segmen- tation of the circuits by cutting through the connecting transmission lines. The circuit segments obtained in this way, exhibiting a number of n open transmission lines each of them carrying a single transverse mode only in the considered frequency band, is called a multiport or n-port, respectively (1). Whereas lumped element multi- ports can be treated by methods of network theory (2) distributed circuits require electromagnetic full-wave mod-

Conservation of complex power technique for waveguide junctions with finite wall conductivity

Abstract: Scattering at the junction of two waveguides with finite wall conductivity is rigorously treated using E-field mode matching and the conservation of complex power technique. At the transverse junction discontinuity between the two waveguides, the complex power absorbed by the junction wall is taken into account along with the usual transfer of complex power from one guide to the other. This leads to a generalized form of the scattering matrix (S) of the lossy junction which incorporates the surface impedance Z/sub m/ of the transverse metallic wall, assumed to be a good conductor. The specific case of a copper transverse diaphragm with centered circular iris in an X-band guide is considered and the equivalent TE/sub 10/ shunt admittance is computed. Numerical results are also given for lossy X-band cavity resonators with circular coupling holes. >

Attenuation in Rectangular Waveguides with Finite Conductivity Walls

Abstract: We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E) and the magnetic field (H) at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity e, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion.

Cavity Resonator Measurement of Dielectric Materials Accounting for Wall Losses and a Filling Hole

Abstract: A cavity resonator technique for the measurement of isotropic homogeneous nonmagnetic dielectric materials is addressed. The materials to be measured are placed in a well-defined position inside a circular cylindrical cavity resonator through a filling hole in the head end cap of the resonator. The measurement procedure solves the inverse problem based on a variational formulation in terms of the magnetic field in the resonator. The effects of lossy walls and of the filling hole are taken into account by using inhomogeneous surface impedance boundary conditions. In order to reduce the problem to matrix form, the magnetic field in the variational formulation is expanded in terms of undamped eigenmodes of the lossless cavity. The resulting equation is a generalized eigenvalue problem for the unknown material parameters. It is solved by using standard techniques such as the generalized Schur decomposition. The proposed method is tested against experimental data, including measurements at various temperatures, in order to show its capabilities as well as to see the effect of the filling hole on the results.