Development of the Microstrip Circulator with a Magnetized Ferrite Sphere in Millimeter Wave Band

In this paper, a novel microstrip circulator with a magnetized ferrite sphere is proposed for various millimeter wave communications. A three-dimensional Finite-Difference Time-Domain (FDTD) approach for the analysis of this ferrite sphere based microstrip circulator is first presented. The electromagnetic fields inside the ferrite junction are calculated using special updating equations derived from the equation of motion of the magnetization vector and Maxwell's curl equations in consistency. Frequency dependent insertion loss, isolation and reflection loss of circulator are calculated over a wide band of frequencies with a single FDTD run. Experimental results at Ka band are presented and compared with theoretical simulations. As a result, a good agreement is found between them.     

A ferrite sphere Y-junction waveguide circular

A novel 4-mm waveguide circulator with a ferrite sphere is presented. The operation modes and frequency splits of the circulator are also discussed, and agreement between the predicted center frequencies and experiment values is obtained.     

Analysis of the H-Plane T-Junction Millimeter Wave Waveguide Circulator with a Ferrite Sphere

This paper presents an approximate but efficient field treatment of the new easy-to-fabricate ferrite sphere based H-plane waveguide circulator for potentially low-cost millimeter wave communication systems. A new three-dimension modeling strategy using a self-inconsistent mixed coordinates based mode matching technique is developed, i.e. the solutions of the Helmholz wave equations in the ferrite sphere and in the surrounding areas are deduced in the form of infinite summation of spherical, cylindrical and general Cartesian modes respectively. The point matching method is then used on the interface to numerically obtain the coefficients of different orders basis functions of the field. Therefore, the field distributions as well as the characteristics of the circulator are numerically calculated and the good agreement is observed between the numerical results and the measured data.     

Analysis of Millimeter Wave Microstrip Circulator with a Magnetized Ferrite Sphere by FDTD Method with Modified Matrix Pencil Method

In this paper, the modified matrix pencil (MMP) method is used in the finite difference time domain (FDTD) method to eliminate the late time instability of time domain responses when analyzing the novel microstrip circulator with a magnetized ferrite sphere. The frequency dependent scattering parameters: reflection, isolation and insertion parameters of the microstrip circulator calculated over a wide band of frequencies with this hybrid method are compared with that obtained by direct FDTD method which agree well with the experimental results.     

低温共烧陶瓷铁氧体环行器的设计与分析

基于叠层片式化结构对工作于S波段的低温共烧陶瓷(LTCC)铁氧体环行器进行设计和分析,模拟研究了器件制备中面临的关键问题对器件频率特性的影响。研究结果表明,采用微波铁氧体层与陶瓷介质层构成混合结构,匹配电路以三维方式进行布线和互联,器件可以获得优良的带内特性。在器件的三维电路布线中,当连接两节阻抗线的导体圆柱端口气隙高度达到20μm时,器件的传输特性和隔离特性急剧恶化。此外,研究还发现微波铁氧体层与陶瓷介质层出现分层时,形成的气隙高度不应大于20μm,否则将导致器件的传输特性和隔离特性显著降低。因此,在进行LTCC铁氧体环行器的制备时,导体圆柱与陶瓷介质层以及微波铁氧体层与陶瓷介质层的异质材料匹配共烧是保障器件优良性能的关键。     

On the Modified Resonance Theory of Waveguide Circulator with Various Ferrite Specimens

A modified resonance theory of waveguide circulator with ferrite specimen is presented. The kernal of this theory is a two-step analysis method of an H-plane Y-junction waveguide circulator. For the first step, the ferrite specimens of Y-junction waveguide circulators are treated as if it were dielectric resonators with no magnetic bias. This simplistic approach is used to design the ferrite specimens of the circulators. Simple formulas are developed for determining the center frequency of the circulators. For the second step, wave circulation is made possible when a pair of degenerate resonance modes experiences different changes when the ferrite specimens are being magnetized. A modified analysis of joint resonance theory and simple field theory is advanced to evaluate the performances of the circulators. Good agreements between the analytically obtained performance and experimental result of various MMW waveguide circulators are observed.     

Magnetically tunable silicon-ferrite photonic crystals for terahertz circulator

The gyromagnetic properties of ferrite materials and the nonreciprocal property of a silicon-ferrite photonic crystal cavity are investigated in the terahertz region. Through the structure optimization and analysis of defect mode coupling, we design a magnetically tunable circulator, of which central operating frequency can be tuned from 180 to 205 GHz and the maximum isolation is 65.2 dB. Moreover, the further study shows that the gyrotropy, dispersion, and ferromagnetic loss of ferrite materials under the different external magnetic fields greatly affect the transmission and isolation property of this device. This circulator is flexible to realize functions of controllable splitting, routing, filtering and isolation by changing the external magnetic field for the THz applications.     

Investigation of Waveguide Y-Junction Circulator with a Triangular Ferrite Post

An H-plane waveguide Y-junction circulator with a triangular ferrite post is investigated by a modified analysis of jointly resonance theory and simple field theory. Good agreement between the theoretical obtained performances and experimental results is observed. The circulator exhibits a very low insertion loss and a wide bandwidth.     

A broadband Ka-band microstrip circulator for integrated millimeter wave systems

A Ka-band microstrip circulator, using ferrite with 4 M=5000 G, have been developed. By optimizing the circulator configuration, broadband n=2 Chebyshev response performance are obtained over 7 GHz bandwidth. The circulator have isolation of greater than 15 dB, and insertion loss of less than 1.0 dB.     

双通道三端口反射式光环行器 结构与特性分析

为了降低广泛应用于光通信系统的光环行器的制造成本和占空比，增强系统中各器件的功能复用，提出一种功能复用反射式光环行器设计方案，利用透镜和反射镜组成光的空间交叉功能来实现功能复用以及光束方向传输引导，从而达到反射式光环行器输入 输出多尾纤之间的对应耦合。利用琼斯矩阵，从理论上对其主要性能进行了分析。分析结果表明，设计的光环行器在功能复用基础上具有低插入损耗、高隔离等特性，达到了光环行器的性能指标，在低插入损耗、高隔离的基础上具有功能复用效用。     

A new design method of H-plane waveguide circulator

A new method to design the partial height ferrite posts of H-plane waveguide circulator for given frequencies is presented. Agreements between calculated design results and experiment values in [1] and our MMW waveguide circulators are obtained.     

X波段叠层片式微带铁氧体环行器的设计

采用叠层片式化设计有望实现微波环形器与低温共烧陶瓷(LTCC)技术的结合。借助三维电磁仿真手段设计了一种X波段微带铁氧体环行器,基片采用具有不同饱和磁化强度的旋磁材料构成叠层片式结构。研究结果表明,叠片数目及其饱和磁化强度的搭配对环形器的回波损耗和隔离度特性影响显著,这与叠层结构引入的界面及叠片变化的饱和磁化强度影响了环形器的等效输入电路参数有关。通过优化设计,可以获得具有高回波损耗、高隔离度及低插入损耗等优良性能的器件,但带宽受叠片数目及其饱和磁化强度的搭配影响较小,难以通过优化进行拓展。     

Analysis and design of a new type NRD-guide E-plane Y-junction circulator

A new type of E-plane Y-junction circulator has been developed based on the nonradiative dielectric waveguide (NRD-guide) in Ka- band. First, the circulation principle has been analysed by the theory of polarization wave. The field components in the nonreciprocal Y-junction zone and the conclusion of 60° phase difference between clockwise and counterclockwise rotating polarization modes has been obtained. And then, the resonant frequency of the non-dc biased triangle ferrite sample has also been calculated. This kind of structure is benefit to enlarge the bandwidth of the Y-junction circulator. As an example, we had designed and fabricated a circulator in Ka-band. Its operating frequency is 35. 1GHz, the 1.5dB insertion loss and 20dB isolation bandwidth is about 1. 0GHz.     

FDTD Analysis of EW Wave Circulating by a Magnetized Ferrite Body in Free Space

An efficient numerical method has been devised for the study of wave circulating by a magnetised ferrite body of an arbitrary shape. It is a finite-difference time-domain formulation that incorporates Mur's absorbing boundary conditions and a perfectly matched layer. Several shapes of interest have been studied, including spheres, circular cylinders. The electromagnetic fields inside ferrite and the power-density distribution on the ferrite's surface normal to the bias external magnetic field are obtained. It is observed that an incident plane wave would circulate around the magnetised ferrite body in an open space as if the ferrite were placed inside a waveguide junction circulator.     

Application of Preconditioned GMRES Algorithm for Analysis of Millimeter Wave Ferrite Sphere Circulators

The generalized minimal residual (GMRES) iterative method is applied to solve such sparse large non-symmetric system of linear equations resulting from the use of edge-based finite element method. In order to speed up the convergence of GMRES, the symmetric successive overrelaxation (SSOR) preconditioning scheme is applied for the analysis of millimeter wave ferrite circulator. Consequently, this preconditioned GMRES (PGMRES) approach can reach convergence 19 times faster than GMRES. The isolation and insertion losses of millimeter wave waveguide circulator are compared with those obtained from literature.     

Application of Preconditioned GMRES Algorithm for Analysis of Millimeter Wave Ferrite Sphere Circulators

The generalized minimal residual (GMRES) iterative method is applied to solve such sparse large non-symmetric system of linear equations resulting from the use of edge-based finite element method. In order to speed up the convergence of GMRES, the symmetric successive overrelaxation (SSOR) preconditioning scheme is applied for the analysis of millimeter wave ferrite circulator. Consequently, this preconditioned GMRES (PGMRES) approach can reach convergence ten times faster than GMRES. The reflection and insertion losses of millimeter wave waveguide circulator are compared with those obtained from literature.     

A mm-wave four-port quasi-optical circulator

A four-port quasi-optical circulator has been designed, built and tested for operation in the millimetre wave band. The specific circulator reported here was investigated over a 20 GHz bandwidth, centred on 94 GHz. Good performance characteristics were obtained over this bandwidth. Isolations of better than 30 dB and insertion losses of around 0.5 dB were achieved. The input vswr was found to be less than 1.35 over the whole bandwidth investigated and vswr's of less than 1.1 were achieved for narrower bandwidths. It is possible of course to configure the 4-port circulator as a 3-port circulator or indeed as 2-port isolator. Further optimization and consequent improvements in performance are almost certainly obtainable.     

Autogenerator with Ferrite Circulator Powered Hybrid Electron Accelerator Characteristics Modeling

Physics of Atomic Nuclei - This paper considers the power supply scheme of a hybrid accelerator with standing and traveling wave sections, connected through a ferrite circulator from an...     

Efficient Analysis of Millimeter Wave Ferrite Circulators by the GMRES Iterative Algorithm

The finite element method (FEM) combined with the perfectly matched layers (PML) is given for simulation of waveguide ferrite circulators. The generalized minimal residual (GMRES) iterative method is applied to solve such sparse large non-symmetric system of linear equations resulting from the use of edge-based finite element method. The formulation of FEM and the algorithm of GMRES method are described in detail. The reflection and insertion losses of millimeter wave waveguide circulator are analyzed and the results are compared with those obtained from literature.     

Millimeter wave microstrip circulator

A new and unique microstrip drop-in type Y-junction circulator has been designed and developed for operation in the millimeter wave frequency region. This device utilizes NiZn ferrite as the gyromagnetic material which is mounted on a duroid substrate.