Spectral domain analysis of coupled microstrip lines on magnetized ferrite substrates

Dispersion characteristics of coupled microstrip lines on ferrimagnetic substrates are presented and their features discussed. The Hertz vector potentials in the spectral domain method are used to calculate the dyadic Green's functions in an impedance matrix form. The behavior of the propagation constants is obtained by using the spectral Galerkin's technique. Numerical results are found as a function of various geometrical parameters and of the externally applied static magnetic field. Nonreciprocal behavior is mainly observed when the static magnetic field is applied in the transverse direction, parallel to the ground plane.     

Suspended stripline on magnetized ferrite and anisotropic dielectric substrates

Suspended stripline on magnetized ferrite and anisotropic dielectric substrates are examined here. The spectral domain immittance approach was used for obtaining the dyadic Green's functions in the Fourier transform domain. Galerkin's method was used to obtain the dispersion characteristics of the dominant mode, and the curves for a few cases are shown as examples which could be used in designing isolators, phase shifters, and directional couplers.     

Characteristics of aperture coupled microstrip antennas on magnetized ferrite substrates

The method of moments in the spectral domain is applied to the full-wave analysis of aperture coupled microstrip antennas in the case where the substrate of the antennas is a layered medium containing magnetized ferrites. The subsectional basis functions used in the analysis make it possible to handle patch antennas and coupling apertures with right angle corners of arbitrary shape. The numerical results obtained show that antennas on ferrite substrates fed by single microstrip lines can radiate both circular and linear polarization, the polarization state being dependent on the orientation of the ferrites bias magnetic field. For a given polarization state, the matching frequency band of the antennas can be tuned over a wide frequency range by adjusting the magnitude of the bias magnetic field. Also, the polarization state can be continuously tuned from circular to linear within the same frequency band by adjusting both the magnitude and the orientation of the bias magnetic field. Some measurements are presented in order to check the validity of the numerical algorithm developed.     

The dispersion characteristics of shielded microstrip lines on magnetized ferrite and anisotropic dielectric substrates

The dispersion characteristics of the dominant mode in shielded microstrip lines on magnetized ferrite and anisotropic dielectric substrates have been obtained. The solution is obtained by applying the transverse equivalent transmission line in the spectral domain and Galerkin's method. Numerical results for the frequency-dependent propagation constants are presented which could be used in designing directional couplers and isolators.     

Mode charts for magnetized ferrite cylinders

Waveguide junction circulators using the E- and H-plane technique usually employ height-dependence ferrite modes. The most crucial parameter is the frequency splitting between two angle-dependent modes. It rises with the magnetic bias field until there is a maximum at about saturation. Mode charts are given to help the designer look up the resonance frequencies of the most important modes as a function of the external, measurable field. The unsaturated state of the ferrite material is also covered. These diagrams are in good accordance with experimental experience and have been helpful in interpreting circulator performance, especially for the identification of spurious resonances     

Application of Brillouin diagram for a magnetized ferrite

The construction and the applications of the Brillouin diagram for a magnetized ferrite are discussed. It is pointed out that the application of the principle of limiting absorption for the determination of the proper solution in an unbounded ferrite is readily carried out with the help of the Brillouin diagram.     

Fundamental investigation on a weakly magnetized ferrite absorber

Investigated are the matching characteristics of a magnetized ferrite absorber, which applies a weakly static magnetic field H_dc perpendicular to the sintered ferrite surface. Applying a static magnetic field to the ferrite enables the matching thickness of the absorber to be reduced from 8 mm in the absence of H_dc to 3 mm under 750 gauss. The matching frequency can also be changed broadly from 0.1 to 0.9 GHz by controlling ferrite thickness and H_dc, simultaneously. These are well explained in terns of an nonsaturated permeability rather than tensor permeability. A thin magnetized ferrite absorber is realized using a ferrite with a large value of imaginary part of permeability when real part takes the value near 1.0. Matching frequency characteristics, whether broad or narrow, correlates closely with the slant of the curve for real part of permeability taking the value near 1.0 in the present frequency     

Multiscale modelling of multilayer substrates

A multiscale (global-local) numerical method for the assessment of reliabilty issues in substrates is presented. The method allows for the calculation of accurate local quantities, without the need for heavy calculations. A global step is performed by first subdividing the substrate into cells. Next, the structure (circuit) of each cell is analysed and quantified and, based on the result, appropriate effective properties are assigned. In this way a homogenised finite element model of the substrate is constructed which is used to determine its global response. A local step is subsequently performed, where only a small ‘region of interest’ of the substrate is modelled in detail. The loading is accomplished by describing boundary conditions extracted from the global simulation.     

Plane electromagnetic wave scattering by transversely magnetized ferrite cylinder

The paper is devoted to the problem of scattering of plane electromagnetic wave by transversely magnetized ferrite cylinder. Exact analytical expressions for all partial cylindrical modes are obtained by solving Maxwell’s equations for transversely magnetized ferrite medium in cylindrical coordinate system. They are represented as the power series expansion and then are used to formulate and to solve the boundary problem. Numerical calculations of scattering patterns are also presented. Particular attention is paid to the possibility to control the scattering pattern by the external magnetic field.     

Analysis of double-layered nonradiative dielectric waveguide containing a magnetized ferrite

The propagation characteristics of the dominant mode in magnetized-ferrite-loaded double-layered nonradiative dielectric waveguide are studied. The analysis is based on mode-matching method. Numerical results are presented for various values of structure and material parameters.     

Dispersion characteristics of cylindrical coplanar waveguides

A full-wave analysis of the coplanar waveguide (CPW) printed on a cylindrical substrate is presented, and the dispersion characteristics of the cylindrical CPW are studied. Numerical results of the effective relative permittivity are calculated using a Galerkin's moment-method calculation. Experiment is also conducted, and the measured data are in good agreement with the theory     

Dispersion characteristics of planar multilayer dielectric structures

Shifts in frequency of the dispersion characteristics of orthogonally polarized modes propagating in planar dielectric structures containing a wave-guiding substrate and layers of low-loss dielectric film are calculated. The influence of the geometric and real-valued parameters of thin semiconductor films located on the surfaces of the substrate or between two substrates on the mode’s phase shifts is studied.     

Dispersion characteristics of cylindrical metal-clad opticalwaveguides

A study of the dispersion characteristics of cylindrical metal-clad optical waveguides indicates that: (1) the propagation of electromagnetic energy in metal-clad optical waveguides differs in principal from that of dielectric step-index waveguides and ideal metallic waveguides; (2) hybrid modes exist in this structure, and the cutoff frequency of the HE₁₁ mode does not equal zero; (3) TM and HE(EH) modes have attenuation higher at least by an order of magnitude than that of TE modes; and (4) the surface plasma wave can propagate in this structure. Thus, the lowest order mode is TE₀₁      

A quantitative analysis of the stress relaxation effect ofthermoplastics in multilayer substrates

All plastics can be divided into two groups called thermoplastics and thermosets, and each group exhibits very different behaviors. Unlike thermosets, thermoplastics are empirically known by the viscoelastic behavior of the thermoplastic layers; the stress generated by building subsequent layers can be significantly relieved in a multilayer structure. In this study, we quantitatively investigated the stress relaxation effect of thermoplastics in lamination-based multilayer substrates. As an increasing number of layers were laminated using either thermoplastic or thermoset adhesives, the maximum bow values were measured layer-by-layer using a laser profilometry during thermal cycling. When analyzed through an analytical model, the measured thermal behavior of thermoplastics exhibited as much as 70% stress relaxation in the multilayer structures, and highly contrasted with that of thermoset adhesives. The result provides an important design guideline that thermoplastics can be used as a stress relaxation layer in lamination-based multilayer substrates     

Wave diffraction by a finite set of azimuthally magnetized ferrite cylinders

The article is devoted to the problem of scattering of plane linear and circular electromagnetic waves by a set of ferrite-coated cylinders. Particular attention is paid to the possibility of controlling the scattering pattern by the azimuthal magnetic field induced in the ferrite by the dc current in metal core of cylinders. It is shown that the best sensitivity can be obtained for the magnetic field, which provides the magnetic resonance inside ferrite layer. Relevant scattering patterns are also presented.     

A coaxial-to-microstrip transition for multilayer substrates

Described is a right-angle coaxial-to-microstrip transition suitable for multilayer substrates. Electrically, it transforms the transmission mode from coaxial (TEM) to microstrip (quasi-TEM). Physically, this transformation occurs in two ways. First, strips of the ground plane are incrementally removed from each metal layer. At the same time, the coaxial line is gradually shifted off-center (i.e., made eccentric) toward the microstrip line. The theory supporting the technique is briefly discussed. To demonstrate, a coaxial transition is designed on a six-metal-layer laminate board. Measurements are compared to a conventional coaxial transition design.     

Walker mode of a ferrite column magnetized in an arbitrary direction

The Walker mode of an infinitely long ferrite column is analyzed using the magnetostatic approximation for the case of the magnetostatic field oriented arbitrarily with respect to the axis of the ferrite column. A simple expression for the only existing resonant frequency is obtained in terms of the physical parameters and the orientation of the magnetostatic field.     

Em wave diffraction by a finite set of magnetized ferrite cylinders

The paper presents a rigorous solution of the diffraction problem by a finite set of magnetized ferrite cylinders. The main purpose of the research is to determine the steerability of scattering diagram of diffraction by several longitudinally magnetized ferrite cylinders. A plane wave scattering as well as main mode scattering by cylinders in the open end of rectangular waveguide are considered and numerical investigations are presented.