Propagation characteristics of a circular waveguide filled with a chiroferrite medium

A chiroferrite is made from chiral objects immersed in a magnetically biased ferrite. A waveguide including a chiroferrite is anticipated to possess some novel features due to the presence of chirality in combination with anisotropy. In this paper, the propagation characteristics of a circular metal waveguide filled with a chiroferrite medium are investigated by an analytical procedure. The equations of relations between the transverse components and the longitudinal ones of electromagnetic fields in general chiroferrite waveguides are derived in a cylindrical coordinate system. The coupled wave equations for the longitudinal electric and magnetic fields are decoupled into two Helmholtz equations which are then solved analytically. The characteristic equation is formulated for the circular chiroferrite waveguide. Propagation constants varying with the structural and material parameters have been calculated for several lower chiral modes. A number of interesting features have been revealed by the numerical results.     

Isoform modes in a ferrite filled waveguide

The conditions governing the propagation of electromagnetic fields in a ferrite filled waveguide when the longitudinal electric and the longitudinal magnetic fields have the same transverse behavior, i.e., are isoform, are discussed. In particular an exact solution for a rectangular waveguide is obtained.     

Propagation and radiation characteristics of the circular electric,circular magnetic and hybrid waveguide modes

The field distributions and propagation constants of the circular electric, circular magnetic and hybrid modes of oversized waveguides are expressed, taking the effects of walls into account. These effects are described by wall functions which depend on surface impedances of the wall, and are determined for different types of guides. The near and far field patterns are derived in the case of real wall functions. It is shown that, for very oversized waveguides, the terms containing wall functions can be ignored in the calculations, and it results that the expressions of fields and propagation constants become independent of the types of waveguides. An application to corrugated waveguides for Electron Cyclotron Resonance Heating experiments shows the variations of the radiation characteristics versus geometric parameters of the corrugations and determines the ranges of interest for these 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.     

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.     

Evanescent modes in ferrite-filled circular waveguide

The analysis by Suhl and Walker (SW) is extended to include the evanescent state. The technique has applications in the field analysis of waveguide ferrite-dielectric interfaces.     

Propagation and radiation characteristics of dielectric loaded corrugated dual-frequency circular waveguide horn feeds

Based on a systematic analysis the design and experimental studies on a composite dual-frequency feed with a single radiating aperture are presented. The criterion for selecting the ratio of the diameter of the corrugated guide excited at the lower frequency in the dominant mode to that of the dielectric rod, axially located within the guide and excited at the higher frequency in the dominant mode, is discussed. The constructional features of a typical dual-frequency feed designed for operation atSandXbands (with 2.68 GHz and 9.375 GHz as center frequencies, respectively) are outlined. The measured radiation patterns show good symmetry and sidelobe suppression over 20-percent bandwidth inSandXbands and are in good agreement with calculated patterns.     

Propagation characteristics of a circular waveguide coated inside with a metamaterial

The problem of guided wave propagation of a circular waveguide that is coated on the inside with a metamaterial coating is studied by a boundary value approach and the propagation features cylindrical waveguide are studied by solving the resultant characteristic equation numerically. The results are compared to those with an inside dielectric coating. The variation of the normalized phase constant is studied as a function of the parameters of the coating including the permittivity and permeability, the coating thickness expressed as a ratio of b/a, and frequency. The behavior of the cylindrical waveguide is shown to be significantly different from that with a dielectric coating.     

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.     

Design of slot arrays in waveguide partially filled with dielectric slab

The Elliot procedure for the design of a waveguide slot array is extended to the case of partially filled radiating waveguides. The dielectric slab lies on the top of the radiating waveguide, i.e. on the slotted wall. The proposed solution prevents some of the most common drawbacks of waveguide slot arrays. Results are validated against a commercial FEM software.     

Aperture matching of a dielectric loaded circular waveguide elementarray

An X-band phased array with dielectric-loaded circular waveguide elements was investigated. The aperture was designed to provide balanced scan characteristics for both the E- and H-planes. The results of an experimental study are presented in which the active impedance of the radiating element was matched by introducing a circumferential groove onto the dielectric plug. Both the aperture junction and the matching groove were measured to derive their respective equivalent circuits for `look-in' and `look-out' impedance transformations. The groove size and its location from the aperture were then optimized by a hybrid approach wherein the measured data and computer simulations were used to greatly reduce the shop time, lab tests, and the number of trials in the hardware development     

Field patterns of TM0 modes in a shielded dielectric resonator

The resonant modes in a cylindrical dielectric resonator located within a cylindrical shielding cavity are studied by means of the finite integral technique. The field patterns of five lowest transverse-magnetic modes are presented, and the controversies of the mode designations are discussed.     

A spherical scatterer inside a circular hollow dielectric waveguide

A theoretical investigation is presented of scattering characteristics of a perfectly conducting spherical object placed inside a quasi-optical transmission line of the millimeter and submillimeter waves in the form of a circular hollow dielectric waveguide (HDW). From the analytical expressions obtained, backscattering and extinction cross sections of this object are derived via the excitation coefficient of the dominantHE ₁₁ mode of the circular HDW and the HDW geometrical parameters. The agreement of the results with the corresponding data for the scattering of a plane homogeneous wave is shown.     

Propagation of lower-order modes in a radially anisotropiccylindrical waveguide with liquid crystal cladding

The propagation behavior of the four lower-order modes, HE₁₁ , TE₀₁, TM₀₁, and HE₂₁, in a radially anisotropic cylindrical waveguide with liquid crystal cladding is studied both theoretically and experimentally. The cylindrical waveguide is a doubly-clad fiber with an isotropic core and inner cladding and a radially anisotropic outer cladding made of nematic liquid crystal. Theoretically, the propagation and decay constants for the TE₀₁ and TM₀₁ modes are obtained by solving the wave equations exactly, while those for the HE₁₁ and HE ₂₁ modes are derived using perturbation techniques under the weakly guiding approximation. It is predicted that in such a structure the guided TE₀₁ mode can be separated from the leaky HE₁₁, TM₀₁, and HE₂₁ modes. The theoretical results show good agreement with the experimental observations for a 3 cm long fiber cell with a 5 μm inner cladding radius     

On the equivalent circuit representation of the slittedparallel-plate waveguide filled with a dielectric

An investigation of the equivalent π circuit representation for the transverse slit in the wall of a transverse electromagnetic (TEM) parallel-plate waveguide is presented. For the narrow slit, approximate analytic expressions for the equivalent circuit parameters are given in terms of the centerline representation and, for the arbitrarily width slit, the equivalent circuit parameters are considered by the method of moments in terms of both the centerline representation and edge representation, and various characteristics of the equivalent π admittance circuit representation are discussed. A critical look is taken at the validity of the previous model of th E-plane gap coupling between two rectangular microstrip patch antennas, and the improved model is considered for the narrow slit (gap) width case     

Difference between the TM11 mode in a circular and elliptical waveguide

The letter deals with the stability and field configuration of the TM11 mode in a circular and elliptical waveguide. Some numerical results illustrate the variation of the position and value of the maximum electric field in the longitudinal direction as a function of the eccentncity of the cross-section.     

90° dielectric polariser in circular waveguide

Experimental results for a 90° dielectric polariser in a circular waveguide are presented. A small slot notched into the circular waveguide wall, used for the accurate alignment of the dielectric plate, has led to a decrease in the relative phase shift by 15.7%. A new U-shape impedance matching structure results in bandwidth of 12.4%     

Scattering from a circular dielectric post embedded in a groundeddielectric sheet waveguide

A systematic method for obtaining the scattered electric field in a grounded dielectric sheet waveguide is presented. It is shown that the point-matching method can be used for an explicit calculation of the integral equation to estimate the scattering from a circular dielectric post embedded in the grounded sheet. The magnitude of the reflection coefficient as a function of dielectric constant is given     

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.