YIG Oscillators: Is a Planar Geometry Better? (Short Papers)

Two yttrium-iron-garnet (YIG) oscillator technologies are compared: the more mature YIG sphere oscillator technology which is based on the uniform (resonant) precession of the electron spins in a small sphere of YIG, and the new planar YIG technology which utilizes the propagation of magnetostatic waves in an epitaxial film of YIG. The YIG sphere technology has been used for microwave oscillators for more than 25 years, but has two significant areas of difficulty in applications the alignment of the YIG sphere in the magnetic bias field coupling cavity requires great precision and the gain element requires a negative resistance element to sustain oscillation. The MSW technology is much newer and less well understood, but the resonator elements are fabricated using a 50- µm line width planar technology making it an appealing candidate. Both technologies are reviewed herein with regard to resonant element theory, temperature, and noise characteristics. New data and theory are presented on MSW resonator optimization.     

Dual-tunable hybrid wave ferrite-ferroelectric microwave resonator

A novel electric and magnetic field tunable microwave resonator with a yttrium iron garnet and barium strontium titanate layered structure is investigated. The measured characteristics at 3.6 GHz, corresponding to the proximity of magnetic and dielectric resonance modes, show a broadband electrical tunability. A tuning range of 1.5% of the central resonance frequency is obtained for nominal electric fields.     

A Proposal of a New Dielectric Resonator Construction for MIC's

A compact and high-temperature-stable dielectric resonator having no shielding metal walls nor a conventional frequency tuning screw is described. This resonator consists of a high epsilon/sub r/ dielectric resonator element mounted on a low-loss dielectric mount, a dielectric disk with thin metal film fixed on the resonator element, and a microstrip line substrate on which to mount the constituents. The resonant frequency tuning is made by trimming the metal film on the disk. The TE/sub 01delta/ -mode resonant frequencies are analyzed through dielectric waveguide model application. Less than 1-percent analytical error is presented in comparison with the experimental data for a practical resonator. The frequency tuning limit by metal film trimming is about 7 percent. The unfoaded Q value of 2700 at 8.8 GHz and a 4.4-ppm/deg frequency temperature coefficient are obtained.     

Temperature stabilization of spin-wave ferrite devices

A method for the self-compensation of the temperature drift of frequency in spin-wave ferrite devices using reversible thermal demagnetization of permanent magnets is proposed. The efficiency of the method is demonstrated for the normal magnetization of the yttrium-iron garnet (YIG) film. A configuration of the magnetic system with the built-in system for the thermal stabilization and electric frequency tuning is presented. The advantages of the system are demonstrated for the frequency stabilization of a YIG film cavity.     

Microwave binstability in a planar ferrite-piezoelectric resonator

Bistability in a planar resonator containing an iron-yttrium garnet ferrite film and a lead zirconate titanate (PZT) plate is studied. The characteristics of the bistable resonator are measured in a frequency band of 0.8–16 GHz at an excitation power level ranging from 1 to 20 mW. Magnetic and electric tuning of the resonator frequency and switching of the resonator between stable states with the use of weak magnetic (∼0.5 Oe) and electric (0.75 kV/cm) fields are demonstrated. It is shown that, as the excitation power increases, the resonator’s switching time decreases from ∼1.7 to ∼0.3 μs.     

Ferrite-dielectric resonators made of uniaxial ferrites in before-the-resonance region

Theeffect of splitting resonant frequencies of azimuthally heterogeneousHE _±11δ oscillations of a disc ferrite-dielectric resonator made of barium hexaferrite is studied in external magnetic field on frequencies below 47 GHz. Applicability of the developed earlier analytical theory of electromagnetic oscillations in magneto-gyrotropic resonators to mode identification and calculation of field dependencies of magnetic oscillations’ resonant frequencies in the before-the-resonance region is demonstrated. Hysteresis effect is discovered in the field dependencies of magneto-dynamic oscillations’ eigenfrequencies in resonators made of uniaxial ferrite. The influence of dielectric layer between the resonator and the metal screen on frequency splitting of HE _±11δ oscillations is studied. The possibility of using ferrite-dielectric resonators in the self-magnetization mode is discussed.     

Magnetic tuning of cylindrical H01δ-modedielectric resonators

The theory of magnetic tuning of cylindrical H_01δ dielectric resonators is developed. It is based on rigorous solutions to the dielectric resonator systems containing microwave ferrites. It is shown that the most effective magnetic tuning of H_01δ dielectric resonators can be accomplished by inserting a thin ferrite rod through an axial hole in the resonator. This kind of tuning utilizes the dependence of the parallel permeability tensor component μ_z on the magnetic field applied. Experiments have been performed which show that a 4% tuning range can be attained with a Q-factor of the resonant system of the order of 2000 at X -band. Using an appropriate DC magnetic field circuit, a 120 MHz tuning bandwidth has been obtained with a consumption of tuning power of about 75 mW     

YIG带阻滤波器的研究进展

随着通信与雷达系统在高频、宽带和小型化方面的高速发展,钇铁石榴石（YIG）带阻滤波器是其发展道路中不可缺少的磁调谐器件。该文针对YIG带阻滤波器阐述了YIG带阻滤波器设计原理,介绍了近年来几种典型谐振器结构的发展状况,并分析了这几种结构的优缺点。     

Tunable dielectric resonator with ferroelectric element

A method for electrical tuning of a dielectric resonator using a Ba_xSr_(1-x)TiO₃ thick film grown on a metal substrate is described. The results show that by incorporating a ferroelectric element, fast resonant frequency tuning of a dielectric resonator, while maintaining a useful Q-factor, is possible     

Magnetostatic wave resonators using microstrip disk

The authors propose a magnetostatic wave resonator using yttrium-iron-garnet (YIG) film with a microstrip disk. Assuming a magnetic wall at the edge of the disk, a dispersion relation is derived and solved numerically to obtain the resonant frequency. Resonant mode charts are given for various parameters of resonator. The quality factor is also given as a function of the resonator dimensions. Resonant characteristics are confirmed experimentally using 40-μm- and 13.5-μm-thick YIG films with 5-mm-diameter strip disk at S band     

双层YIG波导中静磁体波的传播特性

本文研究了在倾斜静磁场作用下,双层YIG薄膜波导结构中静磁体波的传播特性,得到了其色散的特征方程,计算了磁场倾角从5°到20°范围内双层波导结构中静磁体波传播的色散关系和延迟特性.结果表明,斜向场情况下在双层YIG薄膜结构中传播的静磁体波适合应用于高频范围,并且通过调节磁场倾角可以获得比单层膜波导结构更好的延迟率可调范围.斜向场情况下采用双层YIG薄膜结构,对于改进静磁波器件和磁光波导器件的性能具有十分重要的意义.     

Tunable Dielectric Resonator Bandpass Filter With Embedded MEMS Tuning Elements

This paper presents a novel approach for constructing a tunable dielectric resonator bandpass filter by using the microelectromechanical system (MEMS) technology. The tunability is achieved by unique MEMS tuning elements to perturb the electrical and magnetic fields surrounding the dielectric resonators. The use of such elements as a tuning mechanism results in a wide tuning range at a relatively low tuning voltage and fast tuning speed. A three-pole tunable dielectric resonator bandpass filter is designed, fabricated, and tested. The experimental filter has a center frequency of 15.6 GHz, a 1% relative bandwidth, and an unloaded Q of 1300. A tuning range of 400 MHz is obtained by using MEMS tuning elements with 2 mmtimes2 mm tuning disks. The measured results demonstrate the feasibility of the proposed concept     

Magnetostatic Wave Propagation in a Finite YIG-Loaded Rectangular Waveguide

The propagation of magnetostatic waves (MSW) in a waveguide partially loaded with a low-loss ferrite slab is investigated theoretically. The most common low-loss ferrite material used for MSW propagation is epitaxial yttrium iron garnet (YIG). A YIG slab is placed inside and along the guide and not in contact with the sidewalls of the wavegnide. The dc magnetic field is assumed to be parallel to the YIG slab and perpendicular to the direction of propagation. Using the integral equation method, the dispersion relation is found to be an infinitely large determinant equal to zero. Proper truncation of this determinant and numerical analysis to find its roots are carried out in this work. It is seen that in order to obtain high values of group time delay, the YIG slab must be narrow and placed at the bottom of the guide. On the other hand, to maximize the device bandwidth, a narrow YIG slab positioned at the top inside surface of the waveguide is preferred. It is also noticed that there exists a tradeoff between the time delay and the device bandwidth and that maximization of one property leads to a poor value in the other. Thus, some design compromises should be made. It is also observed that the frequency range of operation of the device can be adjusted by an external magnetic bias field. This property of tuning the device to operate in any frequency range adds an extra dimension of flexibility to the operation and also to the design of these devices.     

Magnetically Controlled Millimeter Waveband Filter Based on Disk Resonator Chain

Numerical calculation of transmission spectra of the chain of disk resonators has been executed by FDTD method. Two dielectric and the semiconductor disk resonators form the chain of disk resonators. The tensor constitutive parameters of semiconductor resonator can be varied with magnetic field. The optimal range of magnetic field, providing the most effective tuning the resonance frequency of the resonators chain, is defined. The numerical values of the tuning the frequency-selective parameters of structure under study are obtained.     

基于磁性介质棒的可调太赫兹波吸收器研究

设计了一种中心吸收频率可调的太赫兹波吸收器。在开口谐振环两侧引入磁性介质棒(钇铁石榴石),在改变外加磁场的条件下,通过影响开口谐振环周围环境的有效磁导率来控制中心吸收频率的大小。计算仿真结果表明,当磁感应强度从0 T变化到18 T时,该吸收器的中心吸收频率变化范围高达4 GHz(0.532~0.536 THz),而且吸收率均超过99%。     

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.     

Microwave resonators with dual-mode oscillations

Analysis of microwave resonators with dual-mode oscillations is conducted. A new type of resonators is discovered in which dual-node oscillations are observed. It represents a half-wave resonator with a short-circuit in the middle part. The length of such a resonator is twice less than the length of a widely used ring resonator. It is shown that in resonators of the loop type combined frequency tuning of dual-mode oscillations is accomplished using capacity and inductance. In the loop-type resonators with a stub frequency tuning of dual-mode oscillations is accomplishing with two capacities synchronously changing their values according to a specific law. Resonance equations are obtained.     

Dielectric resonator dual modes filter

In a shielded cylindrical dielectric resonator a number of degenerate modes with identical natural frequencies can be found. These degenerate modes can be coupled together to form coupled circuits by perturbating the geometrical configuration of the structure. The letter presents both TE01p mode resonant frequency perturbation by a tuning screw and a two modes dielectric filter using two perpendicularly polarised HE111 modes of the resonator.     

Rigorous Analysis of Rectangular Dielectric Resonator Antenna With a Finite Ground Plane

A probe-fed rectangular dielectric resonator antenna (RDRA) placed on a finite ground plane is numerically investigated using method of moments (MoM). The whole structure of the antenna is exactly modeled in our simulation. The feed probe, coaxial cable and ground plane are modeled as surface electric currents, while the dielectric resonator (DR) and the internal dielectric of coaxial cable is modeled as volume polarization currents. Each of the objects is treated as a set of combined field integral equations. The associated couplings are then formulated with sets of integral equations. The coupled integral equations are solved using MoM in spatial domain. The effects of ground plane size, air gap between dielectric resonator and ground plane, probe length, and position on the radiation performance of the antenna including resonant frequency, input impedance, radiation patterns, and bandwidth are investigated. The results obtained for the antenna parameters based on the MoM investigation shows that there is a close agreement with those obtained by measurement. Moreover it is shown that the MoM results are more accurate than other simulation results using software package such as High Frequency Structure Simulator (HFSS).