Effect of the Magnetic Perturbation on Magnetostatic Surface-Wave Propagation

This paper discusses the propagation of the magnetostatic surface wave in two ferrite slabs (namely, YIG and Ga-YIG) with different magnetic saturations, and considers a weak coupling in between them. The theoretical results are obtained by using the conventional perturbation technique which is subsequently supported by experiment. Further, the time delay in group velocity affected by the magnetic perturbation is treated theoretically.     

Design of Unapodized Surface-Wave Transducers with Spectral Weighting

The technique commonly employed to provide a wide-band surface-wave transducer with a specific conversion loss as a function of frequency uses the linear frequency-modulation (LFM) (quadratic-phase) design. This provides the necessary dispersion, and anodization is then employed to obtain the required conversion loss. In some applications the anodization presents complications in that the beam generated has nonuniform width, and diffraction and phase-front problems can result. An alternate technique is described that relies on varying the number of effective transducer elements as a function of frequency to provide the conversion-loss variation. As examples of this technique, a flat bandpass filter for a nonlinear convolver and a very large fractional-bandwidth transducer (with spectral weighting to provide sidelobe control) for a memory application are described.     

Analysis and Design of Dispersive Interdigital Surface-Wave Transducers

A comprehensive circuit model characterization of dispersive interdigital transducers with nonuniform electrode spacing is presented. The model is an extension of a three-port circuit which has been useful for representing periodic transducers. The extended model includes the effects of strong piezoelectric coupling whereby the acoustic waves and electric circuits interact, and it also accounts for reflections of acoustic waves which result from perturbations of the crystal surface by the metal electrodes. The inclusion of the latter effect is shown to be essential for explaining observed levels of triple-transit echos in filters and delay lines. The circuit model is used to derive a transducer design procedure which determines the electrode positions and the anodization function (acoustic aperture taper) required to reproduce a desired waveform. This procedure is applicable to the design of weighted dispersive filters and broad-band nondispersive delay lines. In order to verify the theory a low-loss octave-bandwidth nondispersive delay line was designed using linear FM dispersive transducers on YZ LiNbO/sub 3/. The performance of this device was found to be in good agreement with the circuit model predictions.     

Bandpass Filters Using Nonlinear FM Surface-Wave Transducers (Short Papers)

A generalized FM method of obtaining bandpass filters using surface-wave delay lines is discussed. Two identical FM transducers are used as input and output. The FM function of the transducers is determined by the required passband.     

Magnetostatic Surface-Wave Propagation in Ferrite Thin Films with Arbitrary Variations of the Magnetization Through the Film Thickness

A variational formulation for the magnetostatic problem in an anisotropic and inhomogeneous region bounded by perfect conductors is described. The method is applied to the special case of magnetostatic surface-wave (MSSW) modes propagating in a ferrite thin film with arbitrary variations of the saturation magnetization through the film thickness. Methods for calculating dispersion relations, delay characteristics, and magnetostatic potential functions are discussed. The functional that is minimized is interpreted in terms of contributions to the mode energy. Also, concepts pertaining to homogeneous films such as mode bandwidth and dimensional scaling effects are extended to the general inhomogeneous case. Calculations for a two-layer film with a gradual transition region and an ion-implanted film are presented as numerical examples.     

Acoustic Surface-Wave Recirculating Memory

An acoustic surface-wave memory is described, operating at a bit rate of 220 MHz and storage capcity of 1280 bit-per recirculation loop. The transducers are coded using orthogonal pairs of Golay complementary sequences to obtain pulse-in pulse-out behavior. The shape of the delayed pulse is analyzed and compared with the pulse shape that is obtained using a simple single finger pair transducer. The recirculation electronics uses standard MECL-III logic for both the amplifier and the write, read, inhibit, and reclocking functions. The cost of the recirculating memory and the feasibility of constructing larger capacity stores are also discussed.     

Higher-Order Cylindrical Surface-Wave Modes

A general theory of the propagation of higher-order modes on cylindrical surface-wave structures is examined and applied to the dielectric-clad rod. A theory is developed in which the boundary conditions at the guide are specified by an impedance dyadic. The characteristic equation for the structure is then obtained in terms of the elements of the dyadic. The equation is solved and yields a set of conditions which are satisfied by the values of the dyadic elements at the cutoff points for each of the higher-order modes. A mode without a cutoff frequency is shown to exist on the structure used. The relationship between the guide wavelength and frequency has been verified experimentally.     

Magnetostatic wave mixer

A new element, allowing the mixing of signals in the microwave frequency range is described. Excitation of magnetostatic waves (MSW) in the non-stationary medium has been used to modulate the carrier harmonic signal. The proper choice of the working point allows the higher harmonic products of the output frequency spectrum to be suppressed.<>     

Magnetostatic wave convolvers

The present paper reviews recent theoretical results, and reports initial experimental results, on the convolution of contra-propagating magnetostatic forward volume waves (MSFVWs), in the form of cw signals or time-limited cw pulses, in an epitaxial yttrium iron garnet (YIG) film. Computations of the convolver bilinearity factorF _int indicate an efficient convolution process over a wide bandwidth, with values ofF _int that are of the same order as, or better than, the reported experimental results for MSW convolution in a YIG cylindrical or plate geometry. The values of F_int determined experimentally are in excellent agreement with theory. These results are of interest to microwave system developers particularly if bandwidths of 1 GHz or larger can be realized in practice. A limiting feature of magnetostatic wave (MSW) convolvers is that the maximum delay time of a delay line that is realizable without excessive insertion loss is in the order of 0.5s. The advantage of MSW convolvers, of course, lies in their ability to perform signal processing directly at microwave frequencies, and in applications such as electronic warfare the advantageously large bandwidths would mitigate the limitations in delay time.This work was supported in part by a contract from the AIL Division of the Eaton Corporation.     

岸-舰双基地地波超视距雷达技术

岸-舰双基地地波超视距雷达是一种在海边利用大型天线阵列发射、在舰船上接收的双基地多输入、单/多输出雷达。该雷达通过多个天线同时发射多个相互正交的信号,在接收端对各路发射信号分离后,利用发射阵列孔径通过信号处理综合形成发射方向图。概述该雷达的工作原理和主要特点,计算其威力覆盖范围,分析需要解决在运动平台上的时频同步、基于直达波的幅相校正、直达波抑制、电离层杂波与射频干扰的抑制等关键技术,介绍该雷达原理性试验系统及其试验结果。     

A Dielectric Surface-Wave Structure: The V-Line

Properties of the V-line, a wedge-shaped surface-wave structure comprising a cylindrical dielectric binding medium of sectorial cross section supported by two conducting plates, are considered in terms of its higher-order hybrid modes of propagation. Practical modifications of the ideal structure are emphasized. Design curves and equations are presented to determine various propagation parameters and their significance is discussed. Experimental verification of the theory is described.     

Nondegenerate Surface-Wave Mode Coupling Between Dielectric Waveguides

A new variational derivation of the coupling coefficient is given for the problem of nondegenerate surface-wave modes on parallel dielectric waveguides. The results coincide with those of a number of different methods in the literature on the degenerate case, but all give distinct results in the nondegenerate case. These differences are examined and compared with the exact solution, whereby the approximations involved can be evaluated for the case of two parallel slab waveguides.     

Magnetostatic wave resonators and oscillators

The purpose of this paper is to describe the current status of magnetostatic wave tunable resonators operating between 2 and 12GHz and their applications to microwave oscillators, the wave propagating in a pure yttrium-iron-garnet epi-layer. The first section deals with magnetostatic surface wave (MSSW) resonators consisting of a pair of reflective grooved gratings and two microstrip-transducers set between the gratings. Results on insertion loss, off-resonance frequency rejection andQ value are presented. However MSSW cavities suffer several disadvantages such as the small saturation power level at low frequencies and the difficulty to temperature compensate MSSW devices. These problems are overcome with magnetostatic forward volume waves (MSFVW). Then the second section is devoted to MSFVW resonators. A peculiar folded geometry made of five grooved gratings and two microstrip-transducers has been designed to provide a sufficient out-of-band rejection. The experimental characteristics of these resonators are given. In the last section of this paper are reported the features of tunable oscillators implemented with MSSW and MSFVW resonators in a hybrid configuration. Results about tunability, output power,FM phase noise are reported. MSFVW resonator stabilized oscillators are very promising and magnetostatic wave resonators seem a challenge to YIG spheres.This work was supported by the Direction des Recherches, Etudes et Techniques (France).     

Magnetostatic surface wave straight-edge resonators

The performance of the magnetostatic surface wave straight-edge resonator (MSSW-SER) is presented. The resonator uses a rectangular YIG film to propagate MSSWs where the straight edge serves as a reflector. Problems arising from coupling to width mode resonances and their effect on the main resonance are investigated. Through a careful choice of YIG and transducer parameters, the interference effects of the width mode resonances with the main resonance are minimized. As a result, highQ tunable microwave resonators with a tuning range from 2–20 GHz, insertion loss less than 10 dB, and spurious rejection better than 10 dB could be designed and fabricated. This MSSW resonator could be used to construct a tunable low-phase-noise feedback oscillator. However, the tuning range of this MSW feedback oscillator is limited by the phase change of the external amplifier circuit.     

静磁微执行器模型研究进展

磁驱动微执行器是一种重要的微执行器.与静电驱动相比,磁驱动具有一些无可替代的优点.静磁驱动是磁驱动方式中重要的一种,具有广阔的应用前景.综述了国内外静磁微执行器模型的最新进展,分析了各类模型的优缺点,特别强调了在微观领域,不能通过简单的电-磁类比得到相应的磁微执行器的各类模型.讨论了磁微执行器的各种典型的pull-in模型.这些模型对磁微执行器的设计、分析与优化具有重要的参考和实用价值.     

Linear Signal Processing by Acoustic Surface-Wave Transversal Filters

The impulse response of acoustic surface-wave (ASW) filters is determined by the configuration of an array of planar transducers tapping the acoustic signal propagated in the piezoelectric substrate. The transducer configuration is derived here by applying the generaI procedure used for the synthesis of linear transversal filters, which consists in time sampling the required impulse response and arranging the spacing and weights of the taps according to the time intervals and amplitudes of the impulse-response samples. The design of the tapping structure that synthesizes the impulse response of ASW transversal filters is based on a nonuniform sampling procedure, previously developed by the authors, that meets the particular requirements of ASW device operation. The features of this design procedure are presented, and several geometries of tapping transducers corresponding to impulse responses of different characteristics are discussed. The application of the procedure to the design of typical ASW filters is illustrated by the results of experimental models.     

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     

静磁波技术及其应用

本文论述了静磁波的基本特点,静磁波技术的发展及其应用现状,并提出了静磁波器件的研究及其发展方向。