Eigenoscillations in waveguide junctions filled with an anisotropic dielectric

An electrodynamic model for calculation of the characteristics of waveguide junctions with an anisotropic filling is developed. Several dependences reflecting the relation between the resonance wavelengths of different oscillations and the geometric dimensions of the junction and the components of the filling permittivity tensor are found. These dependences can be used for measurements of the electric characteristics of anisotropic materials. The physics of resonance phenomena is studied.     

Group velocity of dielectric waveguide modes

The group velocity and dispersion of surface-wave modes propagating along a circular dielectric rod are computed and presented graphically in normalised form. The group velocity as each mode approaches the cutoff frequency is calculated approximately.     

Natural electromagnetic modes in cylindrical waveguide junctions and their use for nondestructive microwave measurements of electromagnetic characteristics of materials

On the basis of mathematical analysis of electromagetic modes in cylindrical and radial waveguide junction an automatic nondestructive complex allowing to measure electromagnetic parameters of materials (ferrites, leucosapphires, etc.) was developed. Complex is characterized by high sensitivity to variations of parameters and small error of measurements, confirmed by comparison of received data with ones of certified materials.     

Approximate solution for step discontinuity in dielectric slab waveguide

A simple method is presented for obtaining approximate expressions for the power reflection and transmission coefficients of surface waves scattered by a step discontinuity in a dielectric slab waveguide. The approximation is compared with Rozzi's exact solution. Agreement is quite good for a wide range of the relevant parameters.     

Hybrid modes in a dielectric lined conical waveguide

The letter presents a new conical structure which can support the spherical hybrid modes associated with a corrugated conical waveguide. The analysis closely follows that of hybrid modes in a corrugated conical waveguide. It is found that, to obtain hybrid modes in a dielectric lined conical waveguide, it is necessary to taper the dielectric constant of the lining.     

Computation of the dielectric rod waveguide radiation modes

The continuous mode spectrum of a dielectric rod waveguide is analysed in detail. The validity of the orthogonality relations is proved explicitly and the related normalization factors are computed and presented. The results are compared with existent literature and some discrepancies are noted. A full wave approach is pursued without making use of the “weak guidance” approximantion.     

Approximate approach to the design of shielded dielectric diskresonators with whispering-gallery modes

An analytical method is presented for calculating the resonant frequency and the Q-factor of shielded dielectric disk resonators excited in whispering-gallery modes. The method is based on a single-mode representation of electromagnetic fields in partial regions of the resonator. For high order modes with high degree of energy concentration in the dielectric this method gives a good agreement with experimental results obtained for different sapphire disks at both room temperature and cryogenic temperatures     

Approximate cutoff frequency of dielectric ridge waveguide, with application to travelling-wave masers

An approximate relation is obtained between the cutoff frequency and the geometry for dielectric ridge waveguide. This relation suggests that the cutoff frequency of rutile slab loaded rectangular waveguide will be substantially raised if the slab height does not exactly equal the waveguide height.     

Approximate analytical evaluation of the continuous spectrum in a substrate-superstrate dielectric waveguide

In this paper, an original closed-form approximate evaluation is performed for the continuous-spectrum field excited by an infinite line source in a dielectric substrate-superstrate configuration, optimized for leaky-wave radiation. By means of a suitable approximate asymptotic representation obtained via Watson's lemma, the continuous-spectrum field has been expressed as the sum of the contributions of two leaky-pole singularities, each weighted by a transition function that depends on both the frequency and observation distance. The validity of these results is shown in the near and far fields at different frequencies, including the frequency range in which the leaky wave is physical and the entire transition region through the spectral gap. This new closed-form result explicitly shows the nature of the continuous-spectrum field in the transition region, and provides insight into the nature of the fields on more complicated structures in microwave integrated circuits.     

Propagation of TM modes in a circular dielectric waveguide filled with a medium with Kerr nonlinearity

Eigenmodes propagating in a cylindrical dielectric waveguide of circular cross section filled with a nonlinear medium whose nonlinearity is described by the Kerr law are analyzed. The nonlinear eigenvalue boundary problem for the nonlinear Helmholtz equation is considered. An iterative numerical method for obtaining the approximate solutions is developed. Numerical results are presented.     

The theory of propagation of electromagnetic waves in a waveguide with a magnetoactive anisotropic modulated filling

Propagation of electromagnetic waves in a waveguide with an arbitrary cross section is considered. The waveguide is filled with a magnetoactive anisotropic medium periodically modulated in space and time. The wave equations for the potentials of transverse electric (TE) and transverse magnetic (TM) fields are derived. Expressions for the TE and TM waveguide fields observed in the region of weak interaction between the signal wave and the modulation wave are found in the first approximation for small modulation indexes of the filling. The frequency near which strong (resonance) interaction between the signal wave and the modulation wave develops is expressed in an analytic form. The propagation of TE and TM waves in the strong-interaction region is investigated.     

Slow propagation of electromagnetic waves in a dielectric slab waveguide with a left-handed material substrate

The dispersion properties of the guided modes propagating along a dielectric slab waveguide with a left-handed material substrate are studied. It is shown that both the oscillating and surface modes can propagate very slowly along such a waveguide if the thickness of the core layer is chosen appropriately. The propagation speed of the guided waves can even approach zero and this slow propagation is illustrated with an finite-difference time-domain simulation in a tapered waveguide. The influence of the material loss on the slow propagation is also discussed.     

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.     

Eigen Q-factor of electromagnetic oscillations of E-type in waveguide junction of plane waveguides with anisotropic dielectric

The electrodynamic and numerical analysis of eigen Q-factor of electromagnetic modes of E-type in waveguide junction of plain waveguides, fulfilled with anisotropic dielectric in depending on a permittivity tensor components and dielectric loss have been carried out in the paper. The recommendations on using of waveguide junctions for measurement of dielectric losses of the materials are given.     

Scattering of modes by the end of a diaphragm-loaded planar dielectric waveguide

A planar dielectric waveguide loaded with an infinitely thin perfectly conducting diaphragm is considered. The problem of the guided mode reflection from the end of such a waveguide is analyzed with the help of the integral equation method and the variational method. Dependences of the fundamental mode reflection coefficient on the waveguide parameters and on the dimension of the aperture are calculated.     

A novel design method for electromagnetic bandgap based waveguide filters with periodic dielectric loading

An extremely rapid, versatile prototyping methodology is developed for waveguide filters with periodic dielectric loading which enables direct dimensional synthesis of the unit cell starting from given design objectives. A prototype filter has been designed using a low dielectric constant material and built for the purposes of testing the feasibility of the proposed approach. Our numerical results are compared with an independent commercial software package and also with experimental measurements. Simulation results are also presented for a filter loaded high dielectric constant material. In both cases the results are in excellent agreement with the theory and demonstrate the validity and the applicability of the proposed method.     

Analysis of propagation characteristics of whispering gallery modes in a dielectric disk or a curved rectangular dielectric waveguide

The finite-element method is applied to the analysis of whispering gallery modes in curved optical waveguides. Numerical examples for whispering gallery modes in a dielectric disk with rough boundaries are given. It is demonstrated that the whispering gallery modes and the normal guided modes in a curved rectangular dielectric waveguide are analyzed consistently with this approach, and that the normal guided mode approaches the whispering gallery mode with the increase of waveguide width. The minimum width of the rectangular waveguide needed to support a whispering gallery mode is evaluated.<>     

Electrodynamics of waveguide junctions with anisotropic loading

An electrodynamic model for the calculation of waveguide junctions with anisotropic loading has been built in this study. A wave equation for longitudinal components of hybrid electromagnetic field and a system of linear algebraic equations (SLAE) were obtained. The conditions were found under which the SLAE for HE _mnp -oscillations (indexes indicate the number of variations of the field in terms of coordinates x, y, z, respectively) disintegrated into two independent systems corresponding to H _mno — and E _klo -oscillations. The developed algorithm and the software programs were used to carry out numerical analysis for these modes of oscillations that are of practical interest. The recommendations are given on the use of waveguide junctions for measuring components of the dielectric permittivity tensor of anisotropic crystals.     

Polarization of the electromagnetic field of modes propagating in an open circular ferrite waveguide

An open circular longitudinally magnetized ferrite waveguide is considered. Both the frequency-dependent rotation angle of the polarization plane of the HE ₁₁ mode propagating in a lossless waveguide and the effect of ferrite loss on the field polarization is studied.     

Explicit formulas for cutoff values of TE modes on symmetric dielectric slab waveguide with Kerr-like permittivity

Based on the perturbation method, very simple expressions are derived which give accurate approximations for the cutoff values of TE modes in the symmetric slab waveguide with a Kerr-like nonlinear thin film.<>