Magnetostatic Wave Devices Research Articles

Solution of Some Problems oOf Single-Scale Wavelet Transform Processor Using a Magnetostatic Surface Wave Device

Abstract In this paper, we investigate the implementation schemes of a single-scale wavelet transform processor using magnetostatic surface wave (MSSW) devices. There are three implementation schemes: the interdigital transducer, the meander line transducer and the grating transducer. Because the interdigital transducer has excellent properties, namely, good frequency characteristic and low insertion loss, we use the interdigital transducer as the implementation scheme of a single-scale wavelet transform processor using MSSW device. In the paper, we also present the solutions to the three key problems: the direct coupling between the input transducer and the output transducer, the insertion loss, and the loss characteristics of the gyromagnetic film having an influence on the wavelet transform processor. There are two methods of reducing the direct coupling between the input transducer and the output transducer: increasing the distance between the input transducer and the output transducer, and placing a metal “wall” between the input transducer and the output transducer. There also are two methods of reducing the insertion loss of a single-scale wavelet transform processor using a MSSW device for scale: the appropriate thickness of the yttrium iron garnet (YIG) film and the uniform magnetic field.The smaller the ferromagnetic resonance linewidth of the gyromagnetic film , the smaller the magnetostatic wave propagation loss.

Dissipative Soliton Oscillator With a Nonlinear Spin Wave Transmission Line and a Signal-to-Noise Enhancer in the Feedback Loop

This study reports on a dissipative soliton oscillator utilizing two nonlinear magnetostatic spin wave (MSW) devices in a feedback loop. Both nonlinear MSW devices [a spin wave transmission line (TL) and a signal-to-noise enhancer (SNE)] operate in the frequency band where three-wave parametric processes are allowed. Self-generation of a complex-modulated MW signal is caused by nonlinearity of the spin wave TL. The SNE carries out a passive locking of the spin wave self-modulation frequencies and forms the dissipative soliton trains. It is shown, that electronic control of a repetition interval and pulse ratio of dissipative solitons is realized by the change of a klystron beam current.

Implementing single-scale wavelet transform processor with magnetostatic surface wave device

When the envelope of the conducting strips for the input transducer of magnetostatic surface wave (MSSW) device is designed according to the wavelet-function envelope, the impulse-response function of the input transducer for MSSW device is equal to the wavelet function, so that single-scale wavelet-transform processor of MSSW type is fabricated. First, according to the envelope function of the wavelet, the length function of the conducting strips is defined, then, the lengths of the conducting strips can be calculated from the length function of the conducting strips, finally, the input transducer can be designed according to the lengths and widths for the conducting strips. The compensation method of the insertion loss for single-scale wavelet transform processor of MSSW type is also given in the paper. When the output end of single-scale wavelet transform processor of MSSW type is connected to the amplifier, its insertion loss can be compensated.

Electrodynamic theory of multiport structures using magnetostatic waves in ferrite films and its applications

The paper presents an electrodynamic analysis of tunable multiport ferrite-dielectric structures with parallel transmission lines of an arbitrary type, coupled through propagating magnetostatic modes of magnetized multilayered ferrite films. The structures are supposed to be excited at one port by an incident electromagnetic wave, and amplitudes and phases of electromagnetic waves at other ports are obtained by an analytical procedure. The model holds for an arbitrary direction of a magnetizing field and describes the interaction of magnetostatic modes in ferrite films of a finite width. The solution is obtained in a self-consistent approach, i.e., a reaction of magnetostatic waves (MSWs) on transducers, which excite them, is taken into account. Derived closed-form expressions for response functions of multiports provide the base for the modeling of a wide class of MSW devices: multichannel adjustable filters and delay lines, directional couplers, frequency-selective power dividers, tunable oscillators and active filters, and multiport resonators. The theory is also valid for the analysis of multi-element, interdigital, and meander MSW transducers. Applications of a general theory are demonstrated for numerical calculations of frequency responses of surface and forward volume MSW filters, delay lines with new types of strip-line transducers (two-port and T-type), and for the analysis of a phenomenon of mutual coupling of transducers in conventional devices.

Superconducting magnetostatic wave devices using HTS/perovskite-type manganite PCMO heterostructure

Pr1−xCaxMnO3 (PCMO) (x = 0.15∼0.30) has good dielectric and magnetic properties at the microwave band. High-Tc superconductor (HTS)/ferromagnetic PCMO heterostructure has a high potential for superconducting tunable microwave filters and superconducting magnetostatic wave (MSW) devices. In order to demonstrate the preparation possibility of superconducting MSW devices, we investigated the microwave behaviour of YBa2Cu3O7−δ(YBCO)/PCMO heterostructures fabricated by a pulsed laser deposition technique on (La0.3Sr0.7)(Al0.65Ta0.35)O3 (100) substrate. We also fabricated superconducting MSW-band elimination filter (BEF) with YBCO/PCMO structure. The MSW-BEF exhibited notch characteristic that is caused by the energy conversion due to the coupling between the MSW mode and the transverse electromagnetic mode. These results suggest that the HTS/PCMO heterostructure is effective for the superconducting MSW application.

Microwave Ferrite Devices

Ferrite based components are essential and critical elements in microwave systems. The seemingly mundane technology of these components finds widespread application in the form of phase shifters, circulators, magnetostatic wave devices, etc. The article reviews briefly the developments in the field of microwave ferrite devices. The progress, application and current levels of performance are discussed. Achievements in this field particularly in phase shifter development in our country are also highlighted.

Yttrium iron garnet films for magnetostatic wave devices having a small resonance frequency drift over a wide temperature range

Yttrium iron garnet films for magnetostatic wave devices having a small resonance frequency drift over a wide temperature range

温度による共鳴周波数の変動が極めて小さな静磁波素子用YIG薄膜

温度による共鳴周波数の変動が極めて小さな静磁波素子用YIG薄膜

End reflections and triple transit contribution to the band shape of magnetostatic volume wave delay lines

An analysis of the signal reflections originating at the garnet film ends and of the triple transit between the microstrip transducers in magnetostatic volume wave delay lines has been performed. The influence of those effects on the band shape and on the insertion loss of magnetostatic wave devices has been inferred and compared with experimental results. In this framework, the possible utilization of the reflections for filterbank applications is also proposed.

Equivalent circuit analysis for magnetostatic wave devices

Magnetostatic wave (MSW) devices are potentially very promising for carrying out signal processing directly at microwave frequencies, and recently have been receiving much attention. Although the development of a general design theory is essential for significant progress in the signal processing capabilities of the MSW devices, relatively few design theories have been discussed in the past. This paper extends and improves the general equivalent circuit approach to the magnetostatic wave devices proposed and discussed earlier. Based on the definitions of the purely magnetostatic terminal parameters and the magnetostatic characteristic impedance, the electromagnetostatic energy conversion is discussed and the appropriate general equivalent circuit models for the MSW devices are developed. Calculated insertion losses for various MSW devices are in excellent agreement with experimental results.

Excitation theory of propagating spin waves for anisotropic ferrite film (abstract)

The purpose of this work is to elaborate an excitation theory of spin waves (SW) in anisotropic ferromagnetic films (FF). The theory takes into account both dipole–dipole and exchange interactions and also crystallographic anisotropy of a FF. An arbitrary value and type of anisotropy are considered in terms based on effective demagnetizing factors of anisotropy. Two cases of exchange boundary conditions, namely pinned and unpinned surface spins, are analyzed. Using earlier elaborated normal mode technique1 spin-wave Green functions described linear response of spin-system of a anisotropic FF to the inhomogeneous microwave magnetic field are obtained. Owing to the explicit Green functions these forms are convenient for use in various problems of radiation and scattering of SW. As an example, we use these Green functions to calculate radiation resistance (RR) of a microstrip transducer. Analysis shows that ‘‘anisotropic’’ features of RR are connected with the peculiarities of dipole-exchange SW spectrum of anisotropic films. Normal uniaxial and cubic anisotropy in perpendicularly magnetized films [for (111)and (100)-oriented films] causes the shift of RR frequency dependences only. In all other cases dependence of RR on propagation direction of SW takes place. Normal uniaxial and cubic anisotropy in the tangentially magnetized films [e.g., for (111)and (100)-oriented films] causes unusual behavior of RR as frequency function owing to the new ‘‘anisotropic’’ branches of SW spectrum. It should be noted that expressions obtained for RR are convenient for practical calculations of characteristics of magnetostatic wave devices based on FF with large anisotropy.

静磁波デバイスの等価回路解析

Magnetostatic wave (MSW) devices are potentially very promising for carrying out signal processing directly at microwave frequencies, and recently have been receiving much attention. Although the development of a general design theory is essential for significant progress in the signal processing capabilities of the MSW devices, relatively few design theories have been discussed in the past. This paper extends and improves the general equivalent circuit approach to the magnetostatic wave devices proposed and discussed earlier. Based on the definitions of the purely magnetostatic terminal parameters and the magnetostatic characteristic impedance, the electromagnetostatic energy conversion is discussed and the appropriate general equivalent circuit models for the MSW devices are developed. Calculated insertion losses for various MSW devices are in excellent agreement with experimental results.

Improved Equivalent Circuit Analysis for Magnetostatic Wave Devices

We extended and improved the general equivalent circuit approach to the magnetostatic wave (MSW) devices we proposed and discussed earlier. In the theory we analyzed various possibilities of general equivalent circuit models for the MSW devices (MSSW, MSFVW and MSBVW). Appropriate general equivalent circuit models for all the MSW devices have been developed. The insertion losses of these devices based on the equivalent circuit models were calculated and excellent agreement with experimental results was obtained.

Characteristics of Magnetostatic Surface Wave Waveguides for Optical Devices

In magnetostatic wave devices, the thickness of a transmission path becomes between 10 and 20 µm due to the excitation of magnetostatic wave. However, the waveguide does not become a single mode for the optical wavelength when it acts as a magneto-optic device, with MO effect by magnetostatic wave. Such a waveguide is undesirable because the performance is diminished due to coupling between higher modes. Then the waveguide in which only the fundamental mode propagates can be constructed with the double magnetic layers. We discussed the configuration of such a waveguide in MSSW-optical devices.

Analysis of Magnetostatic Wave Transducers by a New Equivalent Circuit Model

A new equivalent circuit analysis for magnetostatic wave (MSW) devices, which is constructed in a different way from that given previously by the author, is discussed. As before, a magnetomotive force F, a magnetostatic current l, and a magnetostatic characteristic impedance z0 are so defined that the power carried by the MSW through the cross-section of the sample is correctly described. The validity of the model is examined by calculating the frequency dependence of radiation admittance of parallel-strip (grating) transducers.

Study of the excitation of magnetostatic modes in yttrium-iron-garnet films by a microstrip line

Magnetostatic modes in a rectangular yttrium-iron-garnet film, magnetized by a normal or parallel magnetic field, were excited using a microstrip line. The modes spectra are used to investigate the coupling between the microstrip and the magnetostatic waves in the film and to examine the theory of the dispersion of these waves. It is shown that when the microstrip is lifted off the film it excites magnetostatic waves in all directions whereas when it is close to the film waves are emitted only in the directions close to the normal to the microstrip line. These results are discussed in view of their implications to magnetostatic wave devices.

ChemInform Abstract: Ferrite Films for Microwave and Millimeter‐Wave Devices

For microwave and millimeter-wave applications, there is increasing interest in using films rather than bulk ferrites. In some cases, such as magnetostatic wave devices, films provide definite performance advantages. In other cases, films may provide lower cost, smaller size, and enhanced compatibility with planar circuit designs such as monolithic microwave integrated circuits (MMIC). The author reviews some of the progress that has been made in development of single-crystal and polycrystalline ferrite films. He describes some of the ideas that are currently being considered for making these ferrites compatible with MMICs. The materials considered include garnets, spinels, and hexagonal ferrites. >

Propagation of an extraordinary wave in a thin ferrite film in the absence of an external magnetic field

The propagation of an extraordinary wave in a unbiased ferrite film of (Bi,Lu) yttrium iron garnet is discussed. This, to our knowledge, is the first reported observation of this type of magnetostatic wave propagation. Two separate modes were observed to propagate in the material, with the mode selection resulting from the initial preparation of the film prior to measurement. These modes propagate in different ranges, 4.2–5.1 GHz and 2.63–3.13 GHz, and exhibit different propagation characteristics. The effect of an external magnetic field on the two modes is also reported for three mutually perpendicular direction-of-bias fields. Two of these directions are in-plane and the third is normal to the plane of the ferrite. This material has potential applications for microwave signal processing devices in that they do not require an external magnetic bias field for proper operation. This can greatly reduce the size of present magnetostatic wave devices, as well as allow these devices to acquire a more planar geometry.

Ferrite films for microwave and millimeter-wave devices

For microwave and millimeter-wave applications, there is increasing interest in using films rather than bulk ferrites. In some cases, such as magnetostatic wave devices, films provide definite performance advantages. In other cases, films may provide lower cost, smaller size, and enhanced compatibility with planar circuit designs such as monolithic microwave integrated circuits (MMIC). The author reviews some of the progress that has been made in development of single-crystal and polycrystalline ferrite films. He describes some of the ideas that are currently being considered for making these ferrites compatible with MMICs. The materials considered include garnets, spinels, and hexagonal ferrites. >

Magnetostatic wave technology: a review

Magnetostatic wave (MSW) technology has been under investigation for more than a decade. Using ferrimagnetic films such as liquid-phase epitaxial (LPE) yttrium iron garnet (YIG) films, MSW devices and subsystems offer instantaneous bandwidths of up to 1 GHz at operating frequencies in the microwave bands (0.5-26.5 GHz). Because MSWs travel with velocities two-to-four orders of magnitude slower than electromagnetic waves, compact devices can be built using hybrid and monolithic microwave integrated circuit (MMIC) techniques. These devices include delay lines, dispersive delay lines, filters, resonators, and directional couplers. Subsystems using these devices, such as electronically tunable delay lines channelized filter banks, delay-line discriminators, oscillators, and frequency multipliers can be used for applications in signal identification, control and processing directly at microwave frequencies. An overview of the MSW technology is presented and an assessment of the various devices and subsystems that can be built using thin and thick LPE-YIG films is provided. >