The incremental inductance rule in quasi-TEM coupled transmissionlines

The application of the incremental inductance rule is described for the computation of losses in quasi-TEM coupled transmission lines. It is shown that the well-known formula valid for the single-line case can be extended to the case of normal modes travelling in general coupled structures providing one uses the power-current modal characteristic impedance definition. Numerical results are shown for several coupled lines systems     

Theory of large-signal direct modulation of extended cavitysemiconductor lasers with dispersive loss

We present a model of coupled semiconductor diode-dispersive extended cavity lasers that describes arbitrarily large current modulation, does not assume uniform photon and carrier densities within the semiconductor diode gain medium, and is simple to implement numerically. In particular, we look at the fiber grating laser, an example of such a coupled system that has been studied as a possible optical communications source. We find simple expressions for the instantaneous frequency and intensity in terms of a few parameters characterizing the dispersion, allowing for the design of the system to minimize chirp. From these expressions we also recover Kazarinov and Henry's adiabatic chirp formula in the limit of slow modulation and Petermann's dynamical chirp formula in the limit of uniform carrier and photon densities. We show that in typical cases, where nonuniformity is important, the instantaneous frequency modulation is quantitatively and qualitatively different than is predicted by previous models     

Revision, extension, and validation of Jordan's formula to calculate the surge impedance of vertical conductors

Jordan's formula to calculate the surge impedance of vertical conductors is revised and extended to take into account systems with multiple conductors. Experimental data and the hybrid electromagnetic model are applied in order to validate the derived expressions. Additionally, Jordan's formula is successfully used in the representation of an actual tower as a multiconductor vertical system. The obtained results indicate the usefulness of the derived expressions if an engineering analysis of direct strikes over elevated strike objects is required.     

Computing consecutive-type reliabilities nonrecursively

The reliability of consecutive-type systems has been approached from various angles. A new method is presented for deriving exact expressions for the generating functions and the reliabilities of various consecutive-type systems. This method, based on Feller's run theory, is easy to implement, and leads to both recursive and nonrecursive formulas for the reliability. The nonrecursive expression is especially advantageous for systems with numerous components. In comparison to the n (number of components) computations that the recursive formulas require, the nonrecursive formula only requires the computation of the roots of a polynomial of order k. The method is extended for computing generating functions and reliabilities of systems with multi-state components as well as systems with s-dependent components.     

Bounding the Blocking Probabilities in Multirate CDMA Networks Supporting Elastic Services

Several previous contributions have proposed calculation methods that can be used to determine the steady state (and from it the blocking probabilities) of code-division multiple-access (CDMA) systems. This present work extends the classical Kaufman-Roberts formula such that it becomes applicable in CDMA systems in which elastic services with state-dependent instantaneous bit rate and average-bit-rate-dependent residency time are supported. Our model captures the effect of soft blocking, that is, an arriving session may be blocked in virtually all system states but with a state dependent probability. The core of this method is to approximate the original irreversible Markov chain with a reversible one and to give lower and upper bounds on the so-called partially blocking macro states of the state space. We employ this extended formula to establish lower and upper bounds on the steady state and the classwise blocking probabilities.     

含状态等式约束的分布式估计融合

在假设各传感器间观测噪声不相关的基础上,将最优线性无偏估计意义下的分布式最优估计融合公式推广至含状态等式约束的分布式估计融合问题中,并在此约束条件下,先将该约束系统直接转换为投影系统,再利用投影系统中的Kalman滤波估计,分别讨论了两种信息融合方式:中心式与分布式融合。进一步地指出中心式估计融合优于分布式估计融合,并在分布式融合结构下,得到了约束的Kalman滤波估计优于投影的Kalman滤波估计的结论。通过数值模拟论证了两种融合方式下的性能差异。     

Coupled mode theory of optical resonant cavities

This paper presents a theory describing coupled optical resonant cavities by means of systems of time-dependent coupled equations for the field amplitudes of standing waves in each resonator. The coupling coefficients entering the theory are derived from first principles. To the author's knowledge, this theory is new. The coupling coefficients can approximately be related to the amplitude transmission coefficients of traveling waves passing between the two resonant cavities. This relationship is checked for an example. Finally, we show that the mode amplitudes of one cavity can be eliminated so that the field in the other cavity becomes coupled to samples of itself taken at earlier times. The coupled-cavity theory applies to cavities with loss or gain. It is here expressed in scalar approximation, but it can easily be extended to vector fields.     

Reverse-Link Capacity of Multiband Overlaid DS-CDMA Systems

In the future deployment of wideband DS-CDMA mobile communication systems, spectrum overlay among sub-bands with different bandwidths is probably inevitable. In this paper we present an approach to estimate the reverse-link capacity of overlaid multiband DS-CDMA systems in terms of the maximum number of users in each sub-band. We will derive the general capacity formula, and present a decomposition method for the capacity analysis to reduce the computational complexity. Based on this decomposition method the conditions for maximum bandwidth utilization are obtained. These results are then extended to account for realistic constraints such as the maximum received power and imperfect power control.     

On the Coding Gain for Degraded Channels

This correspondence deals with the coding gain for harddecisioned codes used over realistic channels. A simulation-based procedure is described, by which the performance (BER) curve of a coded system can be straightforwardly determined. The coding gain for real, i.e., "degraded" channels is discussed, vis-a-vis that for idealized channels. A formula for asymptotic coding gain for the latter type of channel is extended to channels with degradation. Finally, the coding gain for multiple-hop systems is briefly discussed.     

DD1滤波及其在非线性系统识别中的应用

DD1滤波是一种基于多元插值计算，将函数按多项式近似展开的非线性滤波方法，相对于扩展卡尔曼滤波而言，它不需要对函数进行微分运算，使得计算大为简化，且具有与扩展卡尔曼滤波相当甚至优于它的估计性能，适用范围较广。对DD1滤波及其在非线性系统识别中的应用进行了分析，给出了计算实例，计算结果表明了该方法的有效性和实用性。     

g-Representations and differential equations

This paper extends earlier results concerningg- andh-representations for nonlinear input-output maps so that vector-valued inputs and outputs can be treated. It establishes that the range of applicability of the extended results is very wide, and it illustrates how they can be used, within the context of systems governed by differential equations. In particular, it is shown that the nonlinear variation of constants formula is a special case of our main representation theorem.     

Distribution function of the ground clutter and generalization of the Westerfield formula for calculation of the clutter power in spatially multichannel MIMO radar systems

On the basis of a phenomenological model of the Earth surface in the form of a set of statistically independent elementary scatterers, signals scattered by an extended random surface in spatially multichannel MIMO systems on moving carriers have been described. Generalizations of the clutter distribution function and the Westerfield formula for calculation of the clutter power in the considered case of linear motion of transmitting and receiving system elements for signals with large time–frequency product have been obtained.     

Optical control of microwave signals using GaAs FETs

The distinct advantages of optical transmission systems and the increasing use of microwave frequencies within general communication systems, coupled with the ability to integrate microwave and optical components onto a single slice of gallium arsenide have stimulated considerable interest in the development of microwave optoelectronic systems. The paper reviews the electro-optic techniques for achieving direct optical control of microwave signals, and provides some insight into the historical development of the subject. The physical mechanisms involved in the interaction of optical and microwave signals are described through the consideration of photo-effects within microwave GaAs FETs. Current applications relevant to hybrid and monolithic constructions are given and the discussion extended to potential future developments     

Phase noise in externally injection-locked oscillator arrays

Previous investigations of noise in mutually synchronized coupled-oscillator systems are extended to include the effects of phase noise introduced by externally injected signals. The analysis is developed for arbitrarily coupled arrays and an arbitrary collection of coherent injected signals, and is illustrated with the specific case of linear chains of nearest neighbor coupled oscillators either globally locked (locking signal applied to each array element) or with the locking signal applied to a single-array element. It is shown that the general behavior is qualitatively similar to a single injection-locked oscillator, with the output noise tracking the injected noise near the carrier, and returning to the free-running array noise far from the carrier, with intermediate behavior significantly influenced by the number of array elements and injection strength. The theory is validated using a five-element GaAs MESFET oscillator array operating at S-band     

Solution of PDEs-electrically coupled systems with electrical analogy

This paper presents an approach to solve coupled systems where electrical/mechanical devices, whose behaviour is governed by a PDE or a system of PDEs, are connected together through an electrical circuit. In an earlier paper [1], it had been shown that PDEs can be modeled by an electrical equivalent circuit generated from the complete set of equations arising from the Finite Element Method (FEM). In this paper, the approach is extended to solve a system of PDEs. The approach allows the simulation of coupled systems with circuit simulation tools alone since the resultant system becomes an electrical circuit after an application of electrical analogy. The coupled system is solved by directly replacing PDE devices with the equivalent circuits. Further, a special circuit simulation technique, viz. multiport decomposition is used in order to solve a large coupled system. A sequential as well as a parallel simulator is built for coupled problems based on the proposed approach. A circuit with 100 linear PDE devices (the equivalent circuit contains 8 million nodes) has been simulated using the parallel simulator in less than 1 h. We have achieved a speedup of 5 over the sequential simulator using 8 processors on distributed memory architecture. The characteristic of p–n junction diode (drift–diffusion equation) is analyzed by our circuit simulator to show that the proposed approach can be used to build a circuit-cum-device simulator.     

Coupled multiple waveguide systems

The coupled-mode equations for systems of four and five planar coupled waveguides are investigated to determine transmission characteristics of interest. By proper selection of the coupling coefficients in a system of "synchronous" waveguides, full transfer can be achieved from one outermost guide to the guide on the opposite side. In the five-waveguide system, an excitation of the center guide can be fully transferred to a symmetric excitation of the outer guides. Sinusoidal modulation of the propagation constants leads to transfer functions with desirable properties for sampling applications. The analysis for synchronous waveguides is extended to waveguide systems of arbitrary order. Expressions for the coupling coefficients of anNth order system are given for each of the two types of transfer characteristics described above.     

受光阑约束的离轴厄米余弦高斯光束的传输

采用将光阑函数表示为复高斯函数叠加的方法,从理论上给出了离轴厄米余弦高斯光束通过受光阑约束的傍轴ABCD轴对称光学系统传输后的解析表达式,并可退化为无光阑约束时的情形。用同样方法分析得到了离轴余弦高斯光束通过受光阑约束的傍轴ABCD轴对称光学系统传输后的解析式。该方法比直接运用衍射积分公式可节省机时,其结果也可直接推广到二维情形。     

Band-Stop Filters For High-Power Applications

There are several advantages to the use of band-stop filters, rather than band-pass filters, in many systems. This is shown to be particularly true when signals at high-power levels must be transmitted or rejected. A formula has been derived which expresses the external Q of each resonator in a band-stop filter in terms of the element values of the normalized low-pass prototype and the parameters of the frequency transformation. The peak power capacity of iris-coupled waveguide cavity filters and TEM filters using capacitively coupled inductive stubs is then determined in terms of the external Q of the first resonator and the dimensions of the resonator. Experimental results given for a waveguide band-stop filter show good agreement with theory.     

Characteristic Impedances of Four-Conductor Transmission Line

A general formula for calculation of the characteristic impedance of four conductor transmission line in a rectangular shield is derived. A number of coupled and single strip transmission lines are considered by simplifying the general formula. Numerical results for a line in a square shield are presented graphically.