On planar Y-ring circulators

Single circulation frequency operation (SCFO) Y-ring circulators have been explored in earlier papers, where their inner circumference has been assumed to exhibit a magnetic wall (MW). In this paper, a new design is given using air in the center of the ring and treating the ring circulator as a composite dielectric-ferrite (DF) circulator. This DF circulator offers a wider bandwidth than the MW ring component     

Novel folding technique for planar ferrite-coupled-line circulators

A novel folding technique for a longitudinally magnetized ferrite-coupled-line (FCL) section is reported in this paper. The results from Ansoft HFSS simulations of a single-folded structure are presented for a 17-GHz folded stripline FCL section and the measurements on the 17-GHz folded stripline three-port FCL circulator confirm the folding concept and demonstrate that nonreciprocal behavior is retained.     

Synthesis of wide-band planar circulators using narrow couplingangles and undersized disk resonators

Circulators using radial/lumped-element resonators with narrow coupling angles that result in gyrator circuits that are as good as, if not better than, those obtained with the classic approach are presented. The form of the lumped element variable is not unique and can be realized by making use of the fringing capacitance at the interface between a dielectric resonator and a substrate with a higher relative dielectric constant than that of the resonator. The topology requires the adjustment of electromagnetic, electrostatic, and network conditions with common parameters, so that a solution that relies on fringing effects only is not generally ensured. The synthesis of octave-band circulators using two quarter-wave-long impedance transformers is reported. A 1-2-GHz circulator based on one such solution with an insertion loss of no more than 0.35 dB between any two ports and typical return loss of 20 dB is described     

Efficient full-wave analysis of stratified planar structures andunbiased TW-FET's

We have developed a rigorous full-wave analysis technique capable of characterizing quasiplanar travelling wave structures, consisting of multilayer dielectrics and conductors of finite thickness, also taking into account dielectric and conductor losses. We have studied boxed embedded microstrips and another complex passive structure, namely the T-gate TW-FET, devoting particular attention to the distribution of current inside the metallization. All structures considered were simulated by means of a desktop computer. We have tested our program by comparing our results with experimental data of embedded microstrips and employed it for the characterization of planar and T-type gates of the FET's without bias     

Efficient nonadiabatic planar waveguide tapers

We report taper designs with high transmission efficiencies and with lengths shorter than those needed for adiabatic operation. The tapering occurs between rectangular optical waveguides with the same vertical silicon-on-insulator layer structure, but with different horizontal widths, namely 0.5 and 2.0 /spl mu/m, and for taper lengths between 0.5 and 3.0 /spl mu/m. After a comparison between two different optimization methods in a two-dimensional calculation scheme, one of these is repeated using three-dimensional calculations. The results show that, also in the length region where conventional linear and parabolic tapers are not yet adiabatic, tapers with a high efficiency can be designed by applying complex taper structures with more degrees of freedom.     

The new method of time-domain analysis of a planar transmission line with discontinuity

In this paper, the new technique of time-domain analysis of discontinuities in a planar transmission line is presented. In the process of time-domain analysis, the analysis model of system and the concept of transfer function are employed and the frequency-domain method of lines and the technique of the fast Fourier transform are used. The results of time-domain data and frequency-domain characteristics for the shielded microstrip with step discontinuity are given and compared with the published results of other authors.     

Bent planar waveguides and whispering gallery modes: a new methodof analysis

A matrix method for analyzing bent planar optical waveguides is discussed. The method is a modification of an earlier method which yields bend loss directly, inasmuch as a nonuniform refractive index is approximated by a series of linear profiles rather than a series of uniform profiles. The method can be used with absorbing or leaky structures. The effect of whispering gallery modes has also been studied. It appears that a whispering gallery explanation given by H.J. Harris and P.F. Castle (1986) may not be adequate     

A new global finite element analysis of planar balanced mixers

A new global fullwave analysis of complex planar balanced mixers is presented. The proposed technique is based on a 3D finite element method using edge elements. The simulated results for the study of two planar balanced mixers - one in the X-band and the other in the millimetric band - are compared to those obtained by measurements.     

Efficient TM-pass multilayer planar optical waveguide polariser

A novel TM-pass polariser using the form birefringence of a stratified periodic medium is proposed. The mode-filter properties of a planar waveguiding structure with form birefringent buffer layer on a lossy substrate are investigated numerically. A structure with TM/sub 0/-mode attenuation of less than 3 dB/cm at lambda /sub 0/=633 nm and TE-mode losses exceeding 300 dB/cm has been demonstrated experimentally.<>     

Efficient and accurate modeling of planar anisotropic microwavestructures by the method of lines

A new algorithm for the analysis of planar microwave structures with anisotropic substrates is proposed and substantiated. This algorithm is based on generalized transmission-line (GTL) equations, which are developed here for numerical algorithms. For the purpose of analysis, two different modal matrices for the discretized transverse electric and magnetic fields are calculated. Furthermore, impedance/admittance transformation formulas are developed with the help of the GTL equations for longitudinal sections and general junctions. Crossed discretization lines are used in the latter case. The materials are assumed to be biaxial or specific anisotropic. Special algorithms are developed for junctions consisting of more than two waveguides in the cross section and for bends. The proposed algorithm is verified by numerical results     

金刚石薄膜与新一代平面显示器

场发射显示器是近年来发展很快的一种新型平面显示器，兼有阴极射线管及液晶显示器两者的优点，金刚石膜具有负的电子亲和力特性，利用它作为发射器的电子发射材料制成的金刚石膜场射器，有效功函数很小，因此工作电压可以大大降低，同时，由于金刚石具有良好的物理化学特性，发射器的工作寿命可以延长，同时对工作所需的真空度要求下降。     

Analysis and experimental evaluation of a new planar piezoelectricaccelerometer

The behavior of a new planar piezoelectric accelerometer is investigated, both theoretically and experimentally. The proposed accelerometer is composed of a piezoceramic ring filled, in its inner space, with a seismic mass. The theoretical analysis has been carried out by using a matrix model of the radial symmetric modes of the thin piezoceramic ring, proposed by the authors (1996). The numerical results obtained for the empty ring show that, with the response being constant, the bandwidth increases when the annulus radius increases. On the contrary, by inserting a high-density and stiffness seismic mass, both the response and the bandwidth increase by increasing the percent quantity of the seismic mass. The measurements of admittance and sensitivity, carried out on a test specimen, validate the computed results and demonstrate that the accelerometer is planar. Finally, an accelerometer composed of two of such elements, stacked and connected in parallel, has been realized     

铜厚膜环行器的研制

采用新型的在大气气氛中烧结的铜厚膜多层导电浆料,应用厚膜混合技术制作了2。2GHz和2.8GHz的环行器。其性能指标可与同类型采用薄膜贵金属制作的环行器相媲美,且工艺简单,成本低及生产周期短。     

Theoretical design of wideband waveguide circulators

This letter describes the procedure used in designing, by purely theoretical means, wideband waveguide 3-port circulators. An extension of earlier field analysis, together with the usual Polder expressions for ferrite permeability, enables a computer programme to give optimum wideband circulators for any size waveguide with any low-loss ferrite material. Experimental results are given of circulators so designed.     

Efficient analysis of planar microstrip geometries using aclosed-form asymptotic representation of the grounded dielectric slabGreen's function

A newly developed closed-form asymptotic representation of the grounded dielectric slab Green's function is used in a moment-method formulation to calculate the propagation constant of an infinite microstrip transmission line and the input impedance of a finite-length, center-fed printed dipole. In these problems, source and field points are laterally rather than vertically separated with respect to the substrate. The conventional Sommerfeld integral and the plane wave spectral integral (PWS) representations of the microstrip Green's function converge very slowly in this case. However, the asymptotic closed-form representation of the Green's function does not have this limitation, and it remains accurate even for very small lateral separation between source and observation points. A modified form of the Sommerfeld integral representation is used only for observation points in the immediate vicinity of the source, while the asymptotic form is used elsewhere. Some numerical results based on this approach are presented and are shown to compare very well with previous results based on the corresponding exact-integral or PWS forms of the Green's function     

Field analysis of a general chiral planar waveguide

The propagation characteristics of general chiral planar waveguides are presented. This is the first time the eigen equation is given in a simple formulation. The results indicate that there are two types of field distribution which is related to the working wavelength and chiral admittance. When the chiral admittance is larger than a certain value, the fields of one kind of circularly polarized wave in the core become exponentially damping in the transverse direction.     

Neurocomputational analysis of a multiband reconfigurable planar antenna

Procedures using neural networks are developed for characterizing multiband reconfigurable antennas. A multilayer perceptron (MLP) is used to locate the operational frequency bands of the antenna at different reconfigured conditions. Another self-organizing map (SOM) neural network accomplishes the task of locating the switches to be turned ON for a desired frequency response. The developed formulation is tested on a laboratory prototype antenna.     

多端口平面传输线连接器的数值研究

本文提出了研究多端口平面传输线连接器的数值方法；该方法首先将平面传输线等效为波导模型，然后采用边界元法对等效后的波导不连续情况进行了分析，计算了任意端口之间任意模式的散射参量，文中所述过程具有推导简单、计算量小，处理问题灵活等特点。     

一种新型探地天线的优化设计

设计了一种新型超宽带平面天线.用FDTD研究了近地面天线的模拟计算问题,给出了天线的近场辐射性能.通过与平面蝶形偶极天线对比,结果表明该天线具有波形保真度好,对称的辐射方向图及后向辐射小等特点,进一步通过加载集中电阻优化设计,改善了天线的驻波特性.此天线不仅适用于探地雷达,还可以广泛地用于宽带通信和冲激雷达等系统.     

Efficient analysis of quasi-optical filters by a hybrid MoM/BI-RMEmethod

This paper presents a novel algorithm for the analysis of quasi-optical filters, consisting of thick metal screens perforated periodically with arbitrarily shaped apertures. The algorithm is based on the widely used method of moments (MoM) in conjunction with entire domain basis functions. Its flexibility, accuracy, and rapidity depend on the use of the boundary integral-resonant mode expansion (BI-RME) method in the numerical determination of the basis functions. A computer code has been developed based on this algorithm. The analysis of two different quasi-optical filters operating at 8 GHz and 280 GHz is reported and compared with experimental data as well as with other simulations. In both cases, the whole analysis requires few seconds on a standard workstation and the theoretical results show a very good agreement with the measured data in a wide frequency band. The capability of the MoM/BI-RME approach to handle completely arbitrary shapes is highlighted in the second example. In this case, in fact, the fabrication process causes small deformations of the nominal shape of the apertures, which must be accounted for, since they play an important role in the frequency response of the filter