A nonreciprocal left-handed transmission line is proposed and investigated, which is composed of a normally magnetized ferrite microstrip line periodically loaded with inductive stubs but without capacitive loading. The circuit configuration becomes simpler than that of a nonreciprocal left-handed transmission line with both shunt inductive and series capacitive loadings. In the proposed structure, ferrite medium is employed as the substrate not only for the nonreciprocal characteristics but also for negative effective permeability that is essential to establish the left-handedness. After calculations of dispersion curves using equivalent circuit model, scattering parameters along with field patterns are estimated numerically with the help of electromagnetic simulation, and the experiments are also carried out. It is found that the band width of the proposed left-handed transmission line is relatively narrow but the structure still has the high isolation ratio of more than 30 dB.

This paper investigates characteristics of periodic structure of ferrite and dielectric slabs in cutoff waveguide which include left-handed operation. Transmission line model and finite element simulation are used to get dispersion characteristics and scattering parameters. Band pass response of left-handed ferrite mode at negative permeability region are discussed with backward wave phenomenon. Theoretical results show that by choosing appropriate ratio of (1) ferrite width and dielectric width, and (2) ferrite length and dielectric length, band pass response with steep edge characteristics can be obtained by the LH ferrite mode, which are confirmed with experiments using single crystal of yttrium iron garnet ferrite. Good band pass and phase shift responses are observed in S band.

A variational formula is presented for magnetostatic wave resonators. The formula is applied to the magnetized ferrite disk and ring resonators. The resonant mode charts are shown, and it is found that if the aspect of the resonator is optimized, a single mode resonance can be realized on a wide frequency range.

This paper describes a new approach to analyze nonlinear characteristics of propagating waves in a ferrite material. As to the formulation of the wave in a ferrite medium, the analysis in this paper is not taken under the assumption of a sinusoidal steady state using Polder tensor permeability, but taken by directly differentiating the gyromagnetic equation in time domain without any linear approximations. Then it is combined with Maxwell equation in FDTD procedure. As a result, intensity-dependent nonlinear responses of the propagating wave are confirmed, and the nonlinearity is seen in only the right-hand polarization wave. It is also found that an effect of the damping term in the equation of the motion of the magnetization has nonlinear characteristics for wave propagation.

Nonlinear behavior of electromagnetic surface waves propagating along a tangentially magnetized ferrite slab is investigated. The nonlinear Schrodinger equation (NLSE) which describes the temporal evolution of the electromagnetic wave pulses has been derived directly from the Maxwell equations and the equation of precessional motion for the magnetization in the ferrite slab with the aid of the reductive perturbation method without magnetostatic approximation. Based on the formula derived, we have numerically evaluated the frequency-dependence of the nonlinear coefficient in the NLSE for both a magnetostatic surface wave mode and a dynamic mode. As a result, we have confirmed the possibility of the propagation of solitons in the waveguide.

This paper describes the properties of a TE10 metal waveguide filter using two polycrystalline ferrite chips at millimeter wave frequencies. The frequency response of the filter has been analyzed using the mode-matching technique, and optimized by the computer technique. The bandpass filter characteristics with high dynamic range more than 30dB was obtained with insertion loss of 1.5dB and good magnetically tunable response is observed with a quality factor of 200, which agrees considerably well with predicted values.

This letter discusses a microstrip line with an open-end termination in which the reflected microwaves can be optically controlled by a laser illumination. The frequency characteristics are emphasized rather than the time domain ones. The reflection characteristics have been demonstrated experimentally and theoretically for the frequency range of 24 GHz. In the theoretical treatment both the conductance and the capacitance are considered in the equivalent circuit model of the open end of the strip.

The various propagation characteristics of millimeter waves in silicon rib and image guides containing the optically induced plasma region have been investigated. Phase shift and attenuation properties resulting from the presence of plasma are evaluated using the effective dielectric constant method. Experiments have been carried out to demonstrate the optical control of millimeter waves at frequencies ranging from 3350 GHz using high-resistivity silicon illuminated by a high-power Xenon arc lamp and light emitting diodes. Optical control of millimeter wave attenuation of 20dB has been confirmed for a guide of length 90 mm and plasma density of 1021/m3 with average plasma thickness of 20 µm. To increase the sensitivity of optical control, Bragg reflection filter characteristics are studied and its stop band characteristics have been calculated using the transmission line model, and confirmed experimentally. To further develop the Bragg reflection filter, a Mach-Zehnder interferometer guide with one of the arms periodically corrugated is newly proposed and its optical control performance is confirmed by experiments. Finally the field distributions of the Mach-Zehnder configuration of rib waveguides are measured by a simple optical probing technique using the focused laser spot.

The filter characteristics of electromagnetic TM waves in a dielectric slab waveguide having a sinusoidal variation of its permittivity in the propagation direction are investigated. With the aid of a singular perturbation procedure, the coupled-mode equations governing the nature of TM waves interactions are deduced for both symmetric and asymmetric first-order Bragg interactions. Omitting the end effects, an expression describing the characteristics of reflection of TM wave is derived from the boundary value problem in the propagation direction. Experiments on reflection characteristics have been performed in the millimeter wave region where the dielectric slab created by arranging an Aflon slab in periodic fashion in a Teflon slab is tested as a permittivity-modulated slab waveguide. Return loss data and observed stopband responses are reasonably consistent with theory.

The degeneracy of TE and TM modes in a transversely magnetized ferrite slab is investigated from the dispersion diagram. The Bragg reflection phenomena in the periodic structures are employed to measure the propagation characteristics of both modes in the vicinity of the degenerate point. A theoretical study of the Bragg reflection phenomena in a surface-corrugated polycrystalline YIG slab is carried out on the basis of an equivalent-circuit model, and then experiments are performed. Existence of the degeneracy of TE and TM modes in the millimeter wave frequencies is confirmed experimentally.

In this paper, we report the simulation studies on MSW solitons based on numerical solution of nonlinear schrodinger equation by Split Step Fourier Transform method. We have studied both magnetostatic forward volume and surface modes that satisfy opposite nonlinear conditions. The parameters used for the simulation are obtained from experiments on nonlinear characteristics of both the modes. Important soliton properties such as nonlinear power dependence, pulse shaping, formation of multisolitons are studied and compared qualitatively with the experiments.

The time delay of magnetostatic wave in a YIG slab has been studied experimentally, where the nonuniform dc magnetic field is applied normal to a slab surface by using the artificially sharpened magnetic pole piece. The non-dispersive group delay characteristics are found, and the effect of nonuniform magnetic field on the propagation loss is also investigated.

This paper proposes a multisegment dielectric resonator (MSDR) placed on a slotline for millimeter-wave filter applications. The MSDR structure, including a rectangular dielectric lump and a thin low-dielectric insert, is quite useful for adjusting the coupling between the slotline mode and the resonant mode, leading to improve the filter performances. In addition, by tuning dimensions of the MSDR, a sharp and clear notch response can be designed in the transmission parameter. We have demonstrated the filter characteristics both theoretically and experimentally, and showed the practical procedure for the design of MSDR filters.

So far, a lot of analyses have been performed on the edge-guide mode isolator with one short edge. However, the detailed characteristics such as the influence of shape of a metal strip and the thickness of a ferrite substrate have not been revealed. This paper clarifies the influence of the structure on the frequency response both experimentally and numerically. The numerical analysis is performed by the FDTD method. The numerical results indicate that the frequency response does not depend on the thickness of ferrite substrate but does on the shape of the metal strip. Furthermore, based on the numerical results, the experiment is carried out on the prototype isolator. All the results provide a theory of the optimum design on the isolator.

This paper newly proposes a hollow ferrite waveguide which consists of a microstrip line loaded on two ferrite slabs with adjacent air gap. Dispersion relation of magnetostatic surface wave in the waveguide is derived by the two dimensional analysis, and reciprocal behavior for parallel bias magnetic field and nonreciprocal behavior for antiparallel bias magnetic field are shown. Propagation characteristic of magnetostatic surface wave in the hollow ferrite waveguide are experimentally demonstrated under both parallel and antiparallel bias magnetic field directions. Strong nonreciprocal behavior in the hollow guide was found for case of antiparallel bias field configuration. These experimental results are mostly in agreement with the dispersion diagram. A nonreciprocal four port junction is demonstrated as an application of the hollow ferrite waveguide.

Recently optical-microwave interactions in the yttrium iron garnet (YIG) film have been extensively studied due to its importance in the new, high speed optical signal processing devices. In this work, we present the experimental results on the simultaneous operation of optical isolator and optical modulator in a microstrip line on YIG single crystal. Optical isolation of more than 20 dB has been observed experimentally together with optical modulation by magnetostatic backward volume wave (MSBVW) in the frequency range from 1.5 GHz to 4.5 GHz. Theoretical results on the combined isolator-modulator in magneto-optic media based on the tensor form of dielectric constant are also discussed.

In this paper, the dispersion characteristics of magnetostatic surface waves (MSSW) in a nonlinear gyromagnetic medium are analytically investigated. Assuming the nonlinearity as the first order perturbation in permeability tensor of the gyromagnetic medium, the perturbation technique based on the multiple scale method is used to deduce the nonlinear dispersion relations for the MSSW. It is observed that for a given propagation constant of the MSSW the frequency decreases with microwave power. It is also observed that group velocity decreases, and as a consequence, delay time increases with power of the microwave. By evaluating the dependence of frequency on power and variation of group velocity on propagation constant within the accuracy of the perturbation theory, it is confirmed that the conditions for formation of bright soliton are not satisfied for the MSSW.

Transmission characteristics of a left-handed (LH) ferrite microstrip line are significantly affected by the nonuniform DC bias magnetic field in the ferrite substrate (internal magnetic field Hin) caused by the inhomogeneous demagnetizing effect because the strip conductors of these devices must be mounted at the edge of the ferrite substrate. Three dimensional analyses on the LH ferrite microstrip line are performed taking into account the nonuniform internal magnetic field Hin. The analytical results show that the nonuniform internal magnetic field under the strip conductor near the edge of the ferrite substrate is useful for spreading the frequency band of negative permeability and nonreciprocal operation, and for improvement of both the insertion and return losses of the LH ferrite microstrip line. Measured results of more than 20 dB isolation with 2.2 dB insertion loss and 1.33 GHz bandwidth are corresponding well to the analytical results.

This paper presents the scattering characteristics of a TE electromagnetic plane wave by metallic strip gratings on an optically plasma-induced silicon slab at millimeter wave frequencies. The characteristics were analyzed by using the spectral domain Galerkin method and estimated numerically. We examined to control the resonance anomaly by changing the optically induced plasma density, and the metallic strip grating structures were fabricated on highly resistive silicon. The optical control characteristics of the reflection, and the forward scattering pattern by the grating structures, were measured at Q band and are discussed briefly with theory.

This paper treats transmission characteristics of periodic structure of ferrite gyrator circuit with both theory and experiment, which is loaded into usual distributed constant line with and without lumped capacitor. Following three types of periodic structure of gyrator circuit are proposed: basic structure of periodic gyrator circuit, quasi-LH gyrator circuit with series capacitance loading, and quasi-LH gyrator circuit with parallel capacitance loading. Moreover, replacing the parallel capacitance with a resistance, a periodic structure of isolator circuit is proposed. Scattering parameters of gyrator circuit are derived with help of equivalent circuit model. Left handed transmission behavior of backward wave is discussed from dispersion curves. Experiments were undertaken using periodic structure of dielectric microstrip line and gyrator circuit fabricated on the ferrite substrate. Experimental results having wide band nonreciprocal characteristics are discussed with theory.