Electrically tunable microwave phase shifter based on layeredferrite-ferroelectric structure

Based on surface spin wave propagation in a layered structure containing ferrite and ferroelectric materials. Operating characteristics of the phase shifter are investigated theoretically. It is shown that waveguiding elements from planar layered ferrite-ferroelectric structures allow the construction of compact devices with high electrical tunability achieving 10°/V     

Effect of a magnetic wall and a conducting plane on the characteristics of magnetostatic waves in an in-plane-magnetized ferrite plate

The dispersion relations for an in-plane-magnetized ferrite plate with an arbitrary combination of magnetic-wall or perfectly conducting plane boundary conditions imposed at a distance from the plate’s surfaces are compared. A rule is formulated so that a dispersion relation for one of the structures can be used to derive the equation for any other structure. The isofrequency and dispersion characteristics of magnetostatic waves in a metal/ferrite/magnetic-wall structure are investigated. It is found that, in this case, the waves are characterized not only by a unidirectional propagation over the entire range of their existence (～5 GHz) but also by the presence of a nearly straight section of the dispersion curve (～2 GHz). In this structure, volume waves, surface waves, and waves with an amplitude that is constant over the plate thickness are seen to exist within the same frequency interval.     

Analysis of step discontinuities on planar dielectric waveguidecontaining a gyrotropic layer

Nonreciprocal wave propagation characteristics through step discontinuities on planar dielectric waveguides with a gyrotropic layer such as ferrite are presented. In the proposed nonreciprocal structures, the wave propagates from a dielectric waveguide to a ferrite and dielectric waveguide or vice versa, where two structures are connected to create abrupt discontinuities. Nonreciprocal scattering coefficients for TE excitation are calculated at 35 GHz using the well-known mode-matching method     

Propagation model for ultrafast signals on superconductingdispersive striplines

The algorithm suitable for the computer-aided design of transmission lines is used to model the propagation of picosecond and subpicosecond electrical signals on superconducting planar transmission lines. Included in the computation of a complex propagation factor are geometry-dependent modal dispersion and the frequency-dependent attenuation and phase velocity which arise as a result of the presence of a superconductor in the structure. The results of calculations are presented along with a comparison to experimental data. The effects of modal dispersion and the complex surface conductivity of the superconductor are demonstrated, with the conclusion that it is necessary to incorporate both phenomena for accurate modeling of transient propagation in strip transmission lines     

Stacked superconductor structure for microwave transmission

Propagation characteristics of microwaves along a stacked superconductor microstrip structure are investigated. The suitability of such a structure for practical applications is discussed. A rigorous integral equation formulation has been used for the analysis of such structure. The effect of thickness of superconducting strip on propagation characteristics has been studied. Results presented show that the slow wave propagation and low dispersive coupling are possible in a realistic stacked multi-dielectric and superconducting layers microstrip line package.     

Millimeter-wave three-port finline circulator using distributedcoupling effect

The design and experimental results for a novel three-port finline circulator are presented for the frequency range 26-40 GHz. The circulator consists of a T^E-junction cascaded with the section of ferrite coupled slot finlines magnetized in the propagation direction. The T^E-junction structure refers to a transition from a unilateral single slot finline taper to a coplanar line region via a tapered center conductor. The design procedure for the structure is described and confirmed by experimental results. The proposed structure belongs to the family of the distributed coupled ferrite line nonreciprocal devices suitable for application in the millimeter-wave range     

Complex media microstrip ridge structures: formulation and basiccharacteristics of ferrite structures

Microstrip transmission lines residing on bianisotropic material ridges embedded in a multilayered environment are studied using a coupled set of integral equations (IE's). The full-wave IE formulation accounts for general linear media in the ridge region using equivalent polarization currents residing in a multilayered bianisotropic background. Numerical results showing basic propagation characteristics are presented for a variety of single and coupled ferrite ridge structures. It is shown that the use of finite width ferrite ridges as either substrates or superstrates can produce nonreciprocity while confining the ferrite material to a small area in the vicinity of the transmission line     

Double semiconductor substrate in overlay shielded superconducting microstrip lines

The Transverse Transmission Line (TTL) is used in the theory of the overlay shielded microstrip lines considering the superconductor strip on two semiconductor regions. The superconductor effect is included with the boundary condition of the surface impedance, that is related to the complex conductivity of the material, calculated from the advanced two-fluid model. Applying the moment method the complex propagation constant of the structure, including the phase constant and the attenuation constant, is obtained. Results are presented for the complex propagation constant, versus the frequency and the temperature, of this overlay superconducting microstrip lines.     

尖晶石型铁氧体/TiO2复合材料的水热法制备及性能研究进展

综述了尖晶石型铁氧体/TiO₂复合材料的水热法制备与性能研究进展,包括零维、一维结构的尖晶石型铁氧体/TiO₂复合材料和特殊形貌的尖晶石型铁氧体/TiO₂/石墨烯复合材料的水热法制备研究现状,以及复合材料电化学性能、光催化性能、吸波性能的研究进展。总结了二元或三元复合材料由于充分发挥了各组分材料间的协同作用以及复合材料具有的独特结构,使复合材料具有优异的电化学性能、光催化性能和吸波性能。指明未来应以水热法制备尖晶石型铁氧体/TiO₂/石墨烯三元复合材料为目标,向着引入中空过渡层以及制备具有特殊结构的三元复合材料方向发展。     

Phase and Loss Characteristics of High Average Power Ferrite Phasers (Short Papers)

An analysis is presented of the propagation characteristics of some waveguide latching ferrite phaser structures useful for high average power applications. Calculated results show the effects on the loss and differential phase shift of adding vertical slab or T-shaped cooling structures of dielectrics, such as beryllium oxide and boron nitride. Typical design data are presented.     

Cerenkov Radiation in Anisotropic Ferrites

A numerical analysis and an experimental study of Cerenkov radiation from an anisotropic ferrite are reported in this paper. Extensive curves of the interaction resistance R/spl lambda/, measured per unit wavelength of interaction distance, are presented as functions of the several ferrite and geometric parameters. Values in excess of 10/sup 3/ ohms per wavelength of interaction distance are noted. The conditions for Cerenkov radiation in the ferrite are derived from consideration of plane-wave propagation through the ferrite. X-band output powers of approximately one watt were observed using a 0.88 Mev bunched electron-beam with a peak current of 18 ma.     

Propagation Constant of a Rectangular Waveguides Completely Full of Ferrite Magnetized Longitudinally

This paper is an analysis of rectangular waveguide completely full of ferrite magnetized longitudinally. The analysis is based on the formulation of the transverse operator method (TOM), followed by the application of the Galerkin method. We obtain an eigenvalue equation system. The propagation constant of some homogenous and anisotropic waveguide structures with ferrite has been obtained. The results presented here show that the transverse operator formulation is not only an elegant theoretical form, but also a powerful and efficient analysis method, it is useful to solve a number of the propagation problems in electromagnetic. One advantage of this method is that it presents a fast convergence. Numerical examples are given for different cases and compared with the published results. A good agreement is obtained.     

Measurements of a leaky-wave ferrite isolator

A single ferrite/dielectric image line is analyzed using the effective permittivity method adapted for ferrites. E/sub pq//sup x/ modes are used in association with a transverse bias direction to obtain nonreciprocal behavior. It is shown that the required conditions can be obtained that enable the composite image line to guide in one direction and leak in the other. Thus, the structure behaves as a "leaky-wave isolator." Dispersion diagrams showing this behavior in the frequency range of 14-30 GHz are obtained for a 2 /spl times/ 2 mm/sup 2/ ferrite (type TT1-390) rod with adjacent dielectric loading with /spl epsiv/r=10. The structure is built and the bias is applied externally in a direction transverse to and in the plane of the direction of propagation. The required modes are excited and probed by semirigid coaxial cables mounted on vernier mechanisms. The S-parameters indicating the nonreciprocal behavior in the frequency range expected are shown.     

Propagation of the Quasi-TEM Mode in Ferrite-Filled Coaxial Line

The Suhl and Walker approximation for the propagation constant of the quasi-TEM mode in ferrite-filled parallel plane waveguide has been applied to the ferrite-filled coaxial line. The approximation is compared to exact solutions for a coaxial line filled with a lossless ferrite with close agreement. The propagation constant of the quasi-TEM mode is determined by measuring the complex reflection coefficient of a plane ferrite-air interface. The /spl alpha/ and (/spl beta/ are compared to the Suhl and Walker approximation with losses, and qualitative agreement is found. In order to relate the measured values to the propagation constants, the boundary value problem of the reflection from a plane ferrite-air interface is investigated. Expressions are derived which relate the real and imaginary parts of the propagation constant in the ferrite to an approximation to the complex reflection coefficient of the TEM mode in the empty line.     

Scattering parameters measurement of a nonreciprocal couplingstructure

A novel ferrite image guide was designed and tested from 26.5 to 40 GHz. The nonreciprocal structure consisted of two dielectric image guides separated by a ferrite slab. M-type hexagonal ferrite was used with its C-axis oriented parallel and perpendicular to the direction of propagation. The S-parameters of the device were measured for a nonuniform external biasing magnetic field applied parallel to the C-axis of the ferrite slab. Nonreciprocal effects were observed for all cases considered above. The results imply applications for ferrite devices operating at millimeter wavelength frequencies, such as isolators, filters, modulators, switches, phase shifters, etc     

Millimetric Nonreciprocal Coupled-Slot Finline Components

Promising preliminary results are presented for isolators and a four-port circulator in novel finline structures in the frequency range 26.5-40.0 GHz. The basic configuration is a ferrite-loaded coupled-slot finline with the ferrite magnetized parallel with the direction of propagation. The nonreciprocal effects of the odd mode propagating alone and of the odd and even modes propagating are described. All structures exhibit a 20-dB isolation bandwidth greater than 3.6 GHz. It is suggested that such structures would also be suitable for higher frequencies.     

Analysis of partial-height ferrite-slab differential phase-shiftsections

Rectangular waveguide loaded with transversely magnetized ferrite slabs is a classic arrangement used in the construction of high-power differential phase-shift circulators. The characterization of this structure is extended in this paper by using a combined magnetostatic/microwave finite-element method to evaluate propagation characteristics in terms of material parameters, frequency, and bias field. Magnetic flux density was found to vary by typically 20% across a partial-height ferrite slab. Experimental phase-shift data agreed to within 5% of numerical calculations for a 9.25-GHz device. Supplementary design data are presented for the first higher order mode in the cutoff plane, the effect of material properties on phase shift, and to compare below and above resonance operation     

Longitudinal Section Mode Analysis of Dielectrically Loaded Rectangular Waveguides with Application to Phase Shifter Design

The structure consisting of an E-plane dielectric slab partially filling a rectangular waveguide is examined with attention on those higher order mode propagation characteristics that are relevant to the design of nonreciprocal remanence ferrite phase shifters. The validity of the model is established by introducing experimental comparison in the form of VSWR measurements for both pure dielectric loading and an actual composite ferrite phase shifter. Emphasis is placed on the consideration of possible mechanisms for the elimination of LSE/sub 11/, LSM/sub 11/, and LSE/sub 12/ modes, since certainly the first, most probably the second, and quite possibly the third will propagate in a practical device. Experimental verification of theoretical predictions is established and phaser design guidelines are drawn. Some additional topics, such as slabcorner chamfering and the effect of the switching wire, are included for completeness.     

Coupled-slot fin-line isolators

Preliminary results are presented for novel isolators in the frequency range 26.5?40.0 GHz. The structure is a ferrite-loaded coupled-slot fin-line with the ferrite magnetised parallel to the direction of propagation. The results suggest applications at higher frequencies.     

A photonic bandgap microstrip filter based on YBCO superconducting film

Photonic bandgap (PBG) structures can stop propagation of electromagnetic waves of certain frequencies and hence can be applied to construction of microstrip filters. In this paper, a novel PBG microstrip filter based on YBa/sub 2/Cu/sub 3/O/sub 7/ high-temperature superconductor films is presented. The PBG patterns forming the filters were etched on a 0.3- and a 0.7-/spl mu/m-thick film. Experimental results showed that the transmission coefficient S/sub 21/ of the filter is dependent on the thickness of the YBa/sub 2/Cu/sub 3/O/sub 7-x/ film. The thinner PBG filter exhibits an effective stopband of a center frequency of 20 GHz, a bandwidth of 4.7 GHz (at -40 dB), an attenuation of -55 dB, and a rolloff rate of 38 dB/GHz, while the thicker structure exhibits narrow notches only in the S/sub 21/ characteristics.