Computer-aided Design Of Stripline Ferrite Junction Circulators

A general design procedure is presented for stripline Y-junction circulators employing solid dielectric between ground planes. The resonator design and impedance matching are derived in a form suitable for computer evaluation. The procedure is applicable to cases where either the circulator bandwidth or the ground plane spacing is specified. An experimental S-band switching circulator illustrates the technique.     

A Finite Element Analysis of Planar Circulators Using Arbitrarily Shaped Resonators

A planar circulator consists, in general, of three transmission tines, connected through suitable matching networks to a magnetized ferrite resonator having three-fold symmetry. This paper describes a finite element analysis which enables the Z-matrix of a planar circulator using arbitrary shaped resonators to be calculated. This technique allows quite general computer programs to be written which permit tables of circulation solutions to be calculated. Results for junctions using disk, triangular, and irregular hexagonal resonators are included in the text. The frequency response of junction circulators using various configurations whose magnetic variables have been chosen so that they operate over the widely used tracking interval has also been evaluated. The optimum response is in each case associated with a unique coupling angle.     

Equivalent Circuit Representation for the E-Plane Circulator

The resonator structure employed in an E-plane circulator may be described by a series-resonant circuit as opposed to a parallel circuit in the case of comparable H-plane devices. This is shown to result in a change of the direction of circulation at the edges of the circulator passband. Employing the equivalent circuit representation methods to increase the bandwidth of the E-plane circulator are discussed.     

Circulators Using Planar WYE Resonators

An important class of commercial three-port circulator relies for its operation on a junction resonator consisting of the symmetrical connection of three open-circuited transmission lines. A feature of this resonator is that it may be quarter-wave coupled to form a circulator with a moderate specification (25-percent bandwidth to 25-dB return loss points) and physical dimensions of the order of directly coupled conventional circulators (using a disk resonator). For circulators for which the in-phase eigennetwork may be represented by an ideal short-circuit, the equivalent circuit is a one-port network which may be formed from a characterization of the constituent resonator. This feature is used in this paper to study the equivalent circuit of junction circulators using planar WYE resonators. The derivation of the equivalent circuit parameters is supported with the design of a 4-GHz quarter-wave-coupled stripline circulator.     

Cutoff space of cloverleaf resonators with electric and magneticwalls

A planar resonator that has the symmetry of a junction circulator is the cloverleaf resonator. The isotropic cutoff space of this class of resonator is described using the finite-element approach. Circuits with threefold and fourfold symmetries and with a magnetic or an electric sidewall are separately dealt with. Standing-wave solutions are included for completeness. The gyromagnetic problem is separately investigated     

A substrate integrated waveguide degree-2 circulator

A substrate integrated waveguide (SIW) circulator is proposed and demonstrated in this work that can facilitate the integration of planar active components with high-Q passive components. Very satisfactory experimental and theoretical results are provided, at 22 GHz, for a degree-2 junction circulator using a post resonator. It also includes experimental results on the classic gyrator circuit of this type of junction.     

基于耦合模理论的体声波环行器设计

体声波(BAW)环行器是基于角动量偏置的一类新型无磁环行器,为了能准确地预测BAW环行器的性能,该文给出了一种基于耦合模理论(CMT)的设计方法。首先由CMT推导出BAW环行器的解析模型;然后利用Matlab绘制出归一化调制参数与环行器性能指标之间的关系图,并从图中选择环行器综合性能较好的调制参数点;接着以串联谐振频率1.752 GHz、品质因数1 593的体声波谐振器(BAWR)为例,计算出解析模型中的系数,同时确定调制信号频率和调制深度;再利用Matlab编程绘制出BAW环行器的S参数完成设计;最后将基于CMT计算的结果和基于ADS软件谐波平衡(HB)仿真结果进行对比。对比分析结果表明,基于CMT设计的BAW环行器插入损耗、端口隔离度、回波损耗与HB仿真结果基本吻合,验证了CMT设计方法的可行性。     

The Measurement of the Equivalent Admittance of 3-Port Circulators Via an Automated Measurement System (Short Papers)

A derivation of the equivalent admittance of symmetrical 3-port circulators is given which is based on the requirement that the S-matrix eigenvalues be separated by 120/spl deg/ on the unit circle for perfect circulation. This quantity has the property that if a 2-port matching network is found which matches into this admittance, then the same matching network connected in each circulator arm will match the circulator. It was used in conjunction with a computerized measurement system to determine the optimal single-step transformer matching of a stripline 3.7-4.2-GHz circulator and resulted in a device with performance better than 30 dB over this band.     

Verification of first circulation conditions of turnstile waveguide circulators using a finite-element solver

One means of adjusting the first circulation condition of any waveguide circulator is to have recourse to a finite-element (FE) solver. The purpose of this paper is to do so for each of the three possible geometries of the turnstile waveguide circulator. A complete statement of the first circulation condition also requires one of the susceptance slope parameter of the junction. This quantity is separately evaluated. The resonators under consideration are the side and apex coupled half-wave-long prism structures open circuited at each flat face and the conventional cylindrical geometry. The classic E-plane turnstile circulator using a prism resonator is also dealt with. The agreement between the existing literature and the FE adjustment is excellent.     

Synthesis of Quarter-Wave Coupled Circulators with Chebyshev Characteristics (Short Papers)

The purpose of this short paper is to give an exact theory of quarter-wave coupled circulators with Chebyshev characteristics. The synthesis starts by replacing the lumped-element equivalent shunt resonator of the circulator by a distributed one that has the same susceptance slope parameter as the original circuit. In this way the overall network involves commensurate transmission lines only. The bandwidth over which the assumed form of the equivalent circuit applies is carefully discussed in terms of the two split frequencies of the magnetized junction. Tables for the required circulator parameters and transformer admittances for one and two transformer sections as a function of VSWR and bandwidth are included. The realizable solution for the latter arrangement is severely restricted by the equivalent circuit of the basic junction. Experimental results on an octave-band stripline circulator, with a two-section transformer, are also included.     

Bandwidth optimization of an integrated microstrip circulator and antenna assembly. 1

A methodology for integrating a wideband circulator with a wideband antenna is considered herein. To accomplish this integration effectively, the conditions for perfect circulation are examined, whereby the port impedances of the circulator are allowed to be complex, treated as part of the design of the circulator, and couched in terms of network-scattering parameters. This approach allows for the design of a single matching network that interfaces between the circulator and the antenna, and effects a complex-to-complex impedance match for maximum power transfer. Simulation and experimental data for a stand-alone circulator and a compact circulator/antenna assembly are presented to validate the design methodology. The data shows that return loss and isolation on the order of 20 dB over a 4 GHz bandwidth about a 14 GHz center frequency was achievable, without the need of any post-fabrication adjustments     

Input impedance of a circulator with an inphase eigen-excitation resonator

The input impedance of a circulator with an inphase eigen excitation resonator can be expressed by that of a 2-stage bandpass filter. The external Q factor of an inphase eigenexcitation resonator should be three-quarters that of rotational-phase eigen-excitation resonators to obtain a maximally fiat performance.     

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。     

八毫米波段微带集成环行器

本文介绍我们研制成功的8毫米波段微带Y结环行器.说明了设计制作步骤,给出了测试结果.将其一端接匹配负载可构成Y结隔离器.该器件已用于毫米波集成前端中.     

Ferrite Coupled-Line Circulator With Reduced Length

A method to design a circulator based on a ferrite coupled line (FCL) with reduced length is presented. This is achieved by appropriate matching networks. Using ferrite perturbation theory, we derive closed-form expressions for the required matching impedances and the resulting bandwidth of the matched device. Based on this analysis, a realistic design for a stripline FCL circulator is obtained, whose length is shorted by a factor of three. A microstrip FCL circulator with only half of the optimum length is designed and fabricated. Both simulation data and measurement results clearly demonstrate the feasibility of a circulator based on an FCL with reduced length.     

Complex Gyrator Circuits of Planar Circulators Using Higher Order Modes in a Disk Resonator

Tire use of resonators or waveguides utilizing higher order modes is often an attractive solution to the design of millimeter microwave networks. This paper investigates the complex gyrator circuit of a planar junction circulator employing higher order solntions in a disk resonator. The first such solution displays many of the features of weakly magnetized junctions using the dominant mode in a disk resonator, but its loaded Q-factor is incompatible with the realization of quarter-wave coupled devices. Although the second one exhibits more useful equivalent circuits, it requires a relatively large magnetization, which is not altogether practical at millimeter frequencies. A circulator configuration that has a frequency response akin to that of a quarter-wave coupled one is one where the in-phase eigennetwork is degenerate with those of the demagnetized counter-rotating eigennetworks. The degeneracy between the in-phase limit, TM/sub 2, 0, -2/ and the second-order counter-rotating limit, TM/sub 1, 1, -2/ modes, in an oversized irregular hexagonal resonator, is used in this paper to construct such a device.     

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.     

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。     

Electromagnetic Wave Propagation Along a Ferrite Loaded Wire

The dispersion relation for axially symmetric modes propagating on a surface waveguide composed of a central conductor surrounded by an axially magnetized ferrite tube has been obtained. Tuning curves for an open boundary post resonator are calculated and compared with experimental results for an X-band tunable filter. The modes of circulation of a three-port waveguide circulator utilizing this geometry have also been studied and experimentally verified.