Broad-band uniplanar hybrid-ring and branch-line couplers

Novel uniplanar 180° and 190° hybrids suitable for MIC and MMIC applications are described. The uniplanar crossover hybrid-ring coupler using a coplanar waveguide (CPW) and slotline provides substantially improved amplitude and phase characteristics over a broad bandwidth compared to conventional microstrip hybrid-ring couplers. Experimental results show that the new coupler has a bandwidth of more than one octave from 2 GHz to 4 GHz with a ±0.4-dB power dividing balance and a ±1° phase balance. A uniplanar two-branch directional coupler using a coupled rectangular slotline ring has also been developed. CPW-to-slotline transitions using uniform and nonuniform CPWs or slotlines are also discussed. These transitions are uniplanar and simple to fabricate. No via-holes are needed for ground connections, and integration with solid-state devices is easy. A pair of broadband transitions using CPW shorts and slotline radial stubs is demonstrated with a 1-dB bandwidth of more than 5.2:1     

Microstrip directional coupler with flat coupling and high isolation

Based on the open-circuited slotline to realise capacitive compensation, a microstrip directional coupler with high isolation is investigated. Meanwhile, by adding external matching networks at the input/output ports, bandwidth is enhanced and a flat coupling is obtained. Centred at 2.4 GHz, a 3 dB directional coupler is designed, fabricated and examined. Both simulated results and measured data are presented, and good agreement between them is observed     

Analysis of slotlines and microstrip lines on anisotropicsubstrates

The propagation characteristics of the dominant mode in slotlines as well as in microstrip lines on anisotropic substrates are studied. The dielectric tensor in the substrate may have nondiagonal elements which represent misalignment, on the substrate surface, between the material coordinate system and the waveguide coordinate system. The analysis is devoted to the slotline and is based on Galerkin's method applied in the spectral domain. Numerical results are presented for a sapphire substrate and a boron nitride substrate. It is found that the coordinate misalignment on the substrate surface has a significant influence on the propagation characteristics of the slotline     

A dynamic model for microstrip-slotline transition and relatedstructures

An analysis of microstrip-to-slotline transition is presented. The method of moments is applied to the coupled integral equations. In the formulation, the Green's function for the grounded dielectric substrate, which takes into account all the radiation, surface wave, and substrate effects, is used. Meanwhile, all the mutual coupling effects are included in the method of moments solution. Certain related structures, such as slotline and microstrip discontinuities, a slot fed by a microstrip line, and a printed strip dipole fed by a slotline, can also be solved with this analysis. This approach may find applications to other related transitions in MIC (microwave integrated circuit) design     

Spectral domain analysis of coupled microstrip lines on magnetized ferrite substrates

Dispersion characteristics of coupled microstrip lines on ferrimagnetic substrates are presented and their features discussed. The Hertz vector potentials in the spectral domain method are used to calculate the dyadic Green's functions in an impedance matrix form. The behavior of the propagation constants is obtained by using the spectral Galerkin's technique. Numerical results are found as a function of various geometrical parameters and of the externally applied static magnetic field. Nonreciprocal behavior is mainly observed when the static magnetic field is applied in the transverse direction, parallel to the ground plane.     

A new analytic design technique for two- and three-way warped modecombine directional couplers

An analytic technique of designing ultra-wideband warped-mode two way and three-way microwave directional couplers is presented. With this matrix method it is possible to design couplers for any level of coupling by choosing a warping angle appropriate to the desired output amplitudes. The design technique involves obtaining a wave propagation matrix in analytical form as a function of the taper parameter, which in turn is a function of distance along the coupler length. The line parameters and the forward scattering matrix are then determined from the wave propagation matrix at any distance from the beginning of the coupler. The method is demonstrated for couplers using microstrip coupled comblines. The computed and the measured performances of a two-way and a three-way microstrip combline are presented for equal power splitting. These couplers were found to work between 1.5 and 8.5 GHz     

Backward directional coupler for weak coupling of double-sided microstrip lines using longitudinal double-slots

A backward directional coupler for double-sided microstrip lines is presented. Aligned microstrip lines are coupled via two parallel slots in the common ground plane. This design works well for weak coupling smaller than 20 dB and has some advantages over the single-slot coupler. Geometrical dimensions of the proposed coupler design are presented for coupling values of 20, 25 and 30 dB, together with measurements for a 30 dB coupler.     

Transient Analysis of the Electromagnetic Field for a Wave Absorber in Three-Dimensional Space

In recent years, large-scale structures such as tall buildings, large bridges, and towers cause severe reflection and diffraction in the propagation of electromagnetic waves. The most effective means for improvement of these characteristics is coating an electromagnetic wave absorber on the surfaces of structures. At the present time, determination of the performance of a coating and the estimation of its effects are carried out on a practical basis. Beforehand, however, theoretical clarification of absorbing characteristics is necessary for better design of a structure. This analysis demands the unified treatment involving both characteristics of absorber materials and the shapes in three-dimensional space of structures to which they are applied. Also, the analysis of propagation characteristics of a pulse wave in the time domain will be important. In this paper, we report the fundamental treatment of absorbing characteristics, including boundary conditions of the structure. The method of time-domain analysis in three-dimensional space and time is used. This method is formulated by Bergeron's method and based upon the equivalent circuit of both Maxwell's equation and characteristics of the medium. As an example, the performance of a very thin coating of absorber with magnetic loss is presented. The variations of field distribution for changes of magnetic-loss term including permeability and the frequency of incident wave, are shown. The absorbing characteristics for a pulse wave in the time domain are also given as a parameter of incidence angle.     

差分无源器件的设计

在现代无线通信系统中,差分电路相比单端电路而言具有更强的抗干扰能力,因此受到了国内外学者的广泛关注。文章介绍了混合模散射参数、差分器件设计中常用的微带线和缝隙线及两种传输线之间的相互转化,并介绍了基于微带线和缝隙线转换结构的两种全差分带通滤波器。两种滤波器分别实现了多频段和宽带的差模传输特性以及宽带的共模抑制特性。文章还给出了差分耦合器、差分功分器和差分天线等差分器件的设计。仿真与实测结果吻合较好,验证了设计方法的正确性。     

一种宽带高方向性微带定向耦合器

文中设计了一种小型化的具有高方向性的多节微带线定向耦合器。通过将耦合微带线分段处理,得到由一节1/4波长段和两节1/8波长段组合的多段耦合器。非均匀介质微带耦合线中奇偶模相速度的差异导致微带定向耦合器的方向性较差。文中通过在耦合器馈线拐角处采用1/4圆弧提高了方向性。通过优化仿真设计实现了10 GHz耦合器,耦合度为25 dB,并且从6~14 GHz的方向性优于30 dB。与传统的并联耦合线耦合器相比,文中所提出的耦合器具有更小尺寸和更加出色的方向性,且实测和模拟仿真基本一致。     

An integrated optic frequency translator for microwave lightwavesystems

A novel integrated optic component that performs a microwave frequency translation of an optical wave is presented. Its principle of operation and characteristics are derived from a perturbation analysis of the supermode propagation in a Y-fed directional coupler subjected to an electrooptic effect associated with a propagating microwave field. It is found that under appropriate values of the microwave field amplitude and interaction length, a very efficient conversion of optical power can be achieved. The optimum frequency shift of this transfer is controlled through the coupling length of the directional coupler. An approximate analytical solution of the coupled mode equations, which considers only the coupling between the two spectral components of the supermodes that are phase matched, has been performed     

Slow-wave directional coupler and its applications

The directional coupler and the traveling-wave directional filter made of coupled slow-wave microstrip lines are proposed and their characteristics discussed. These structures exhibit interesting characteristics not readily available in conventional transmission lines.     

一种宽带矢量调制器的设计及其应用

矢量调制器是一种可以同时控制微波信号幅度和相位的器件。本文介绍了一种基于新型微带定向耦合器的宽带矢量调制器。新的耦合器结构克服了传统微带耦合器耦合度低、方向性差的问题,也不需要Lange耦合器复杂的加工工艺,在平衡放大器、移相器和衰减器等场合具有广泛的应用。其次,研究了用串联电感对衰减器中PIN二极管的寄生参数进行补偿的一种简单方法,以改善衰减器衰减量变化时的相位性能。该方法原理简单,可在一定带宽内替代复杂的平衡结构,并给出相近的性能。最后给出了矢量调制器的测试结果和它在自适应天线阵等实际系统中的应用情况,并讨论了用于提高载波和边带抑制、满足高精度要求的校准方法。     

一种宽带微带线耦合器的设计

根据微带线理论,设计了一种新型的微带线定向耦合器。通过将耦合微带线分段处理,合理地设计每段耦合微带线的尺寸参数,扩展了耦合器的工作带宽。同时通过加载电容,以补偿耦合器奇模与偶模之间相速度的差异,并抵消不连续性所带来的寄生参数的影响,从而提高了定向耦合器的方向性。在设计过程中,借助ADS软件进行初步仿真优化,最后使用HFSS软件对设计结果进行进一步验证。     

L波段小体积微带监测耦合器设计研究

提出了一种用于1/8监测网络的微带线定向耦合器,该微带线定向耦合器结构在传统的微带线定向耦合器两端加入补偿电容,具有高定向性,给出了物理模型,对该结构进行了理论分析,并设计制作和测量了该种耦合器。测量结果表明,该定向耦合器的耦合度为26dB,工作频带为1.2～1.4GHz,隔离度超过-53dB,性能指标明显优于传统结构的微带线定向耦合器。同时减小了微带线定向耦合器的尺寸。     

A planar-lumped model for coupled microstrip lines anddiscontinuities

A convenient model for analyzing coupled microstrip line discontinuities is presented. A planar-lumped model similar to the planar waveguide model for single microstrip lines is developed for coupled microstrip lines. Fields underneath the two strips and those fringing at the outer edge are modeled by two equivalent planar waveguides. Electric and magnetic field coupling in the gap region is modeled by a lumped network. The lumped network parameters are evaluated such that [C] and [L] matrices for the model are identical with those for coupled lines. The model is verified by comparing coupler characteristics with those obtained by the conventional coupled line analysis. Just as the planar model of a single microstrip has been used for characterizing microstrip discontinuities, the planar-lumped model developed is used for coupled line discontinuities. Examples given include coupled microstrip sections with chamfered bends located at right angles to single microstrip lines, for which the results are in good agreement with experimental values     

一种基于微带均衡器结构的定向耦合器的研究

提出了一种新颖的基于微带均衡器结构的宽频带高定向性微带线定向耦合器,并对该结构进行了理论分析、设计、制作和测量。该结构的新颖之处是通过对耦合度随频率的变化曲线进行均衡得到宽频带特性。该结构采用三电容补偿的微带线定向耦合器结构,并通过在耦合端集成微带均衡器结构实现。测量结果显示,该结构在2.5～3.5GHz工作频带内的耦合度随频率的变化范围约为1dB,隔离度低于-34dB,较之传统结构的微带线定向耦合器均有大幅的提高。测量结果很好地验证了设计方法的正确性。     

Suspended Coupled Slotline Using Double Layer Dielectric

This paper presents a rigorous analysis of coupled slotline a) on a double-layer dielectric substrate, and b) sandwiched between two dielectric substrates. The dielectric substrates are of arbitrary thickness and permittivity and the structure is assumed to be suspended inside a conducting enclosure of arbitrary dimensions. The odd- and even-mode dispersion and characteristics impedance, along with the effect of shielding on these, are illustrated. These structures should find extensive applications in the fabrication of MIC components, such as directional couplers, phase shifters, and mixers.     

An Accurate Determination of Dielectric Loss Effect in Monolithic Microwave Integrated Circuits Including Microstrip and Coupled Microstrip Lines

For the first time, by a rigorous analysis, the performance of MIC planar transmission lines with Iossy substrates can be studied accurately. The generaf structural shape chosen for the analysis includes infinitely thin metallic strips embedded within the layers of homogeneous dielectric substrates. The rigor of the analysis was guaranteed by the assumption of the propagation of an electromagnetic hybrid wave (i.e., TE+TM) along tbe planar transmission lines. An efficient computation was, however, achieved by implementing the spectral domain approach as the basis for the analysis. To test the analysis, phase constants, characteristic impedances, and attenuations, due to dielectric losses, were computed for microstrip and coupled microstrip lines. The results obtained were compared with those given previously by the spectral domain analysis in which dielectric losses were not included directly [1]. The comparison showed an excellent agreement between the two theories for low-loss substrates. However, for Iossy substrates the present method is more accurate.     

Complex modes in shielded suspended coupled microstrip lines

The existence of complex modes in electrically shielded suspended coupled microstrip lines has been studied extensively, and the results are presented. A rigorous full-wave spectral-domain approach (SDA) with a newly proposed and tested set of basis functions can efficiently and accurately determine the propagation characteristics of the dominant, higher-order, and complex modes for planar or quasi-planar transmission lines. These basis functions are validated by comparing the convergence study of field solutions with those obtained by various sets of preconditioned bases and by the unconditioned subdomain ones. Excellent agreement is obtained for the propagation constants and the normalized complex longitudinal and transverse current distributions on conducting strips for the strongly coupled microstrip lines. For all the particular case studies discussed, it is shown that the complex modes may exist in all the shielded suspended coupled microstrip lines, even when the substrate dielectric constant is low. Theoretical results for the fundamental, higher-order, evanescent, and complex modes are presented for suspended coupled microstrip lines