1-M W Four-Port E-Plane Junction Circulator (Correspondence)

An S-band four-port E-plane waveguide junction circulator has been developed that has a power-handling capability of 1-MW peak and 1-kW average. Improved ferrite materials and dielectric matching techniques have resulted in a device having a high-power insertion loss of 0.5 dB and a biasing magnetic field of 400 G. The E-plane configuration lends itself to a compact lightweight circulator design having a high-power capability greater than the H-plane configuration, since RF breakdown problems are alleviated by locating the ferrite in the region of minimum RF electric field. The final device requires approximately one-tenth the amount of ferrite and permanent magnet material used in comparable differential phase-shift circulators. The size and weight are reduced by a factor of approximately 5.     

Integrated self-biased hexaferrite microstrip circulators formillimeter-wavelength applications

Planar microstrip Y-junction circulators have been fabricated from metallized 130-μm-thick self-biased strontium hexaferrite ceramic die, and then bonded onto silicon die to yield integrated circulator circuits. The impedance matching networks needed to transform the low-impedance circulator outputs were deployed on low-loss alumina or glass dielectrics to minimize circuit losses. These magnetically self-biased circulators show a normalized isolation and insertion loss of 33 and 2.8 dB, respectively, and a 1% bandwidth for an isolation of 20 dB. Application of small (H<1.5 kOe) magnetic bias fields improved the isolation and insertion loss values to 50 and 1.6 dB, respectively. This design may form the basis for future monolithic millimeter-wave integrated circulator circuits that do not require magnets     

基于磁性光子晶体的多端口环行器设计

基于二维三角晶格和正方晶格光子晶体分别设计了六端口和八端口光子晶体环行器.环行器由硅介质柱光子晶体波导和铁氧体介质柱缺陷构成.所设计的六端口环行器每个波导连接处只有一个铁氧体材料,能够有效降低损耗;八端口环行器波导连接处添加了多个铁氧体材料可有效提高隔离度.使用有限元法对电磁波在环行器中的传输进行了仿真验证.计算结果表明,六端口环行器各端口的隔离度达到22～38 dB;八端口环行器各端口的隔离度达到21.7～40.5 dB.设计的多端口环行器具有结构简单紧凑、隔离度高、损耗低的优点.     

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.     

94-GHz 4-Port E-Plane Junction Circulator (Short Paper)

A 4-port junction circulator for use in 94-GHz E-plane integrated circuits is investigated. The design incorporates an E-plane X-junction of standard metal waveguides with a single ferrite disk on one of the narrow walls of the junction plus a metal plunger extending into the junction from the opposite side. The plunger is used to tune the n = 0 mode to the circulator center frequency and additionally can be used to tune the circulator center frequency over several gigahertz without critically degrading circulator performance, Minimum insertion loss of 0.65 dB was typical in a series of 12 plunger-tuned circulators with adjacent port isolation better than 20 dB, and crossport isolation better than 15 dB over nearly a 1-GHz bandwidth.     

CPW Circulators with Barium Ferrite Thin Films

A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.     

New lumped element circulator by ceramic integrated circuittechnology

A broadband and a compact lumped element circulator was developed by a co-firing method of a ferrite and inner conductor. A circulator fabricated by this method with the dimensions of 6×6×3 (mm) showed a 20 dB isolation bandwidth of 7% and an insertion loss of 0.7 dB at 800 MHz. The gyromagnetic inductance of this circulator was compared to that of a conventional circulator. The former always showed a higher inductance than the latter. This measurement and additional measurement of the inductance for non-magnetized ferrite disks with and without a gap have shown that a great portion of permeability increase came from the elimination of the demagnetizing field in the element. Although a broadbanding was obtained, the insertion loss of 0.7 dB could be improved by using a more conductive material. To optimize the isolation bandwidth, a refinement of the design method based on the gyromagnetic inductance measurement should also be established. In spite of these problems, the magnetically closed circuit circulator, mC³, seems to be the ultimate lumped element circulator from its broadband characteristics, compact size and simplified structure, to reduce production costs. Furthermore, the broadband characteristics decrease the loaded Q-factor causing an increase in the handling power of the circulator which is a useful feature in broadcasting equipment     

A 50-kW CW Ferrite Circulator in S Band

A 50-kW CW differential phase-shift circulator at 2450 MHz has been developed. Its insertion loss and isolation are 0.18 dB and 20 dB, respectively, over a bandwidth of 25 MHz at 2450 MHz. It is useful for protecting the microwave source of a high-power system from reflected power. The design and experimental results of the circulator are presented.     

The Frequency Behavior of Stripline Circulator Junctions

The frequency dependence of the circulation equations for Y-junction stripline and microstrip circulators is investigated, and a new set of design curves is generated for the frequency-independent forms of the circulation condition's roots for both below- and above-resonance cases. Using this new set of curves, the wide-band design predicted by Wu and Rosenbaum and Bosma's narrow-band design are analyzed and compared. Quantitative arguments for the effect of the junction parameters on the bandwidth are given. To support the arguments, the theoretical junction performance of the 7-15 GHz "continuous tracking" circulator reported by Wu and Rosenbaum is calculated and compared with the theoretical performance of a 24 GHz circulator junction designed using the same method. Experimental results also are presented for the 24 GHz design. An analysis for the effect of the ferrite thickness on impedance matching is also included.     

The Synthesis of Symmetrical Waveguide Circulators

A method for synthesizing symmetrical waveguide circulators by adjusting the eigenvalues of the scattering matrix is described. This procedure is particularly useful for the design of very compact circulators in the form of waveguide junctions containing ferrite obstacles. Permissible structural symmetries for a circulator are listed, and a standard form for the scattering matrix of a symmetrical circulator is defined. The synthesis procedure is then described in detail, stating the conditions to be imposed on the scattering matrix eigenvalues, and an expression is obtained for the changes in the eigenvalues due to the placing of anisotropic material within the junction. By applying the theory to Allen's 4-port turnstile circulator, it is shown that the use of a matched turnstile junction and a reflectionless Faraday rotator is not essential. The theory is also applied to the design of novel 3- and 4-port circulators, and two 6-port circulators, one of which may be used as a 5-position waveguide switch, are described. Some experimental results are presented for a compact 3-port circulator in the form of an H-plane Y junction, in 1 inch by 1/2 inch waveguide, containing a ferrite post obstacle. This circulator, which operates with a bias field of approximately 25 oersted, has a useful bandwidth of 3 per cent. Greater bandwidths would be expected in a Stripline or a fin-line version of this device.     

Integrated metal magnetic film coupled line circulators for monolithic microwaveintegrated circuits

A new structure of integrated planar metal magnetic film coupled line (MMFCL) circulators is presented, in which a metal magnetic film is used instead of ferrite materials. Simulation was performed with HFSS based on coupled-mode theory. An insertion loss of 4 dB and isolation of -13.5 dB between S₂₁ and S₁₂ over a frequency band of 3 GHz (from 36.5 to 39.5 GHz) were realised for a three-port MMFCL circulator     

High-Power S-Band Junction Circulator (Short Papers)

The design of a high-power air-cooled microwave Y-junction circulator which is capable of operation at peak and average power levels of 800 kW and 800 W, respectively, is described. The unit is an H-plane waveguide circulator which is externally air cooled. The circulator design employs a full-height substituted YIG rod with a center metal pin together with boron nitride matching transformers. The circulator exhibits an insertion loss of less than 0.4 dB, isolation greater than 22 dB, and a VSWR <1.26:1 over a 400-MHz bandwidth centered at 3.3 GHz. At high-power levels, the device exhibits insertion loss of less than 0.9 dB, isolation greater than 20 dB, and VSWR <1.25:1 at an indicative frequency within the operating bandwidth.     

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.     

Finite-difference analysis of cyclic H-plane waveguide three-port circulators with an arbitrary-shape lossy ferrite post

A finite difference method (FDM) with an analytical truncation boundary condition is developed for the analysis of cyclic H-plane waveguide three-port circulators with an arbitrary shape ferrite post. The method is based on scalar wave equations and the analytical field distribution in the rectangular waveguides. A general boundary field equation for an arbitrarily shaped ferrite or dielectric interface is derived. To verify the validity of the present method, the eigenvalue phases of the cyclic three-port empty junctions and the characteristics of H-plane waveguide Y-junction circulators with lossless, lossy cylindrical, composite and triangular ferrite post are calculated. Good agreements with previously published experimental and theoretical results have been achieved. The performance of a Y-junction circulator with a hexagonal ferrite post and the characteristics of a cyclic three-port circulator with a ferrite rod are also investigated.     

A Latching Ring-And-Post Ferrite Waveguide Circulator

This paper presents the performance and normalized design parameters for a latching ring-and-post ferrite circulator in waveguide. A C-band circulator has provided an insertion loss of 0.35 dB and a 20-dB isolation bandwidth of 17 percent. When the circulator was matched for higher maximum isolation (50 dB) but narrower bandwidth (10 percent) at room temperature, the 20-dB isolation bandwidth was 7.8 percent across the -40/spl deg/ to +75/spl deg/C temperature range. Low-loss operation was obtained at pulsed powers up to 7.5 kilowatts, and at least 20 dB of isolation was maintained up to 100 kilowatts. This performance, in conjunction with a switching speed of a fraction of a microsecond, permits the use of these circulators for transmitting-receiving functions in high-reliability RADARs.     

宽带X波段波导结环行器的研究

为了满足某系统的要求,需研制带宽在X波段达4GHz（40％）的宽带波导结环行器。文中采用Y形脊波导中心结形式,采用三阶等宽切比雪夫阶梯阻抗匹配器实现环行器宽带阻抗匹配,并利用HFSS软件优化环行器结构。设计的环行器实验结果为：在8．4GHz至12．4GHz范围内,插损不大于0．3dB,隔离不小于20dB,驻波不大于1．2。环行器设计结果与实验结果基本一致,表明该设计方法正确,设计的环行器满足系统宽带要求。     

差分环行器的研究进展

基于时空调制(STM)的单端环行器因其输入信号和调制信号的混合,在接近所需频带处将受到互调产物(IMP)的影响,这些IMP不仅会对相邻通道造成干扰,还会限制调制参数。差分环行器通过匹配两个单端环行器,以180°相位差的调制信号分别调制两个单端环行器,从而消除IMP,有效地改善了环行器的插入损耗、带宽及功率容量等指标,提高了环行器的性能,并降低了对调制信号的要求。该文描述了差分环行器的基本原理,对差分环行器的电路结构、调制方式及测试方法进行了总结。对比分析表明,差分体声波(BAW)环行器在插入损耗、隔离度及功耗等方面表现出优异的性能,有望取代大多数商业系统中的铁氧体环行器。     

Computer-Aided Junctions Design of H-Plane Waveguide with Full-Height Ferrites of Arbitrary Shape

A method for solving the problem of H-plane waveguide junctions with a full-height ferrite post of arbitrary shape is proposed. The junctions are allowed to have arbitrary cross section and arbitrary number of ports. The method is based on the integral equations derived from the reciprocity theorems in both the ferrite region and the air region ranging from the reference planes of connecting waveguides to the inside of the junction. For comparison with the previously published experimental and theoretical results, Y junctions with a circular ferrite post are first treated. Excellent agreement has been found between the experimental data and the numerical results obtained by the present method. The performance of a Y-junction circulator with a triangular ferrite post having rounded angles is next investigated. Both the ferrite geometry and the internal dc magnetic field are examined in detail. For this geometry the calculated 20-dB bandwidth has been found to become greater as the cross section of the ferrite approaches a regular triangle from a circle.     

Finite-Element Analysis of H-Plane Waveguide Junction with Arbitrarily Shaped Ferrite Post

A numerical approach for solving the problem of H-plane waveguide junctions with Iossy ferrite posts of arbitrary shape is proposed. The junctions are allowed to have arbitrary cross section. The approach is a combination of the finite-element method and the analytical method. To show the validity and usefulness of tbe method, Y-junction circulators with a circular ferrite post are considered. Our results agree well with earlier experimental and theoretical results. The performances of Y-junction circulators with a triangular equilateral ferrite post or a triangular ferrite post having depressed sides are investigated. The influences of the ferrite losses on the performance are examined.