Coupled Transmission Line Networks Research Articles

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In this study, we propose the design and fabrication of a compact ultra-wideband high-efficiency rectifier based on a coupled transmission-line network. The proposed rectifier consists of a coupled transmission-line network and a voltage multiplier that increases the rectified peak voltage. The coupled transmission-line network was optimized to match the input impedance of the voltage multiplier without additional matching components, thus achieving a high power conversion efficiency of over 50 % in the ultra-wideband of 0.2-4.3 GHz. To verify its performance, the proposed rectifier was implemented and measurements were conducted. The dimensions of the implemented rectifier were 16.1 mm × 19.4 mm. The measurement results indicated that the proposed rectifier obtained a PCE of over 70 % in the ultra-wideband of 0.6-2.6 GHz. Furthermore, it achieved a maximum PCE of 74.9 % at 2.45 GHz.

Group-Delay Engineered Noncommensurate Transmission Line All-Pass Network for Analog Signal Processing

A group-delay engineered noncommensurate transmission line two-port all-pass network for analog signal-processing applications is presented, analytically modeled, and experimentally demonstrated. This network consists of transversally cascaded C-sections, which are distributed implementations of the bridged-T equalizer lumped circuit. It is obtained by interconnecting the alternate ports of adjacent lines of a 2N -port coupled transmission line network with transmission line sections, and it is modeled using multiconductor transmission line theory with per-unit-length capacitance matrix C and inductance matrix L. By allowing the different C-sections of the network to exhibit different lengths, a generalized group-delay engineering procedure is proposed, where quasi-arbitrary group-delay responses are achieved by combining the group-delay responses of C-sections with different lengths. A computer design approach based on genetic algorithms is applied for synthesis, which consists of determining the structural parameters of the different C-section groups. Using this approach, noncommensurate networks are group-delay engineered in edge-coupled stripline technology, and Gaussian, linear and quadratic group-delay responses are realized. The theoretical results are validated by experiment. Finally, two application examples of analog signal processing-a tunable impulse delay line and a real-time frequency discriminator-using the proposed dispersive noncommensurate all-pass networks are presented.

Transient Simulation Model for a Lightning Protection System Using the Approach of a Coupled Transmission Line Network

In this paper, a simulation model is proposed to evaluate the electromagnetic transient surge current distribution in a lightning protection system (LPS) due to a direct lightning stroke. The model is based on the coupled transmission line network in the frequency domain combined with the Fourier transform technique. The conductor of the LPS is described using the coupled transmission line model, and can be reduced to an active two-port equivalent circuit. The unknown quantities are the node voltages of the LPS at the physical junction, which leads to a fast solver at each frequency. The validation of the proposed approach is performed by comparing the results with those in the technical literature. The numerical examples show the flexibility, efficiency, and accuracy of the model in the range of practical application of LPS.

Minimization of delay and crosstalk in high-speed VLSI interconnects

Design optimization of time responses of high-speed VLSI interconnects modeled by distributed coupled transmission line networks is presented. The problem of simultaneous minimization of crosstalk, delay and reflection is formulated into minimax optimization. Design variables include physical/geometrical parameters of the interconnects and parameters in terminating/matching networks. A recently published simulation and sensitivity analysis technique for multiconductor transmission lines is expanded to directly address the VLSI interconnect environment. The new approach permits efficient physical/geometrical oriented interconnect design using exact gradient based minimax optimization. Examples of interconnect optimization demonstrate significant reductions of crosstalk, delay, distortion and reflection at all vital connection ports. The technique developed is an important step towards optimal design of circuit interconnects for high-speed digital computers and communication systems. >

Analysis of lossy multiconductor transmission lines using the asymptotic waveform evaluation technique

A method is described for the transient analysis of lossy coupled transmission line networks with nonlinear elements. The method combines the asymptotic waveform evaluation technique with a piecewise decomposition algorithm. Two to three orders of magnitude speedup can be achieved relative to previously published methods with comparable accuracy. The method is useful for delay and crosstalk simulation of high speed VLSI interconnects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Graph Transformations of Nonuniform Coupled Transmission Line Networks and Their Application (Short Paper)

The graph transformation method of [5] has been extended to apply for a class of coupled nonuniform transmission lines whose self and mutual line constants have the same functional dependence along the direction of propagation, and it is assumed that the mode of propagation is TEM. First, the graph representation of such nonuniform coupled two-wire transmission lines is derived by decomposition of the 4 X 4 admittance matrix. This leads to three-port equivalent circuits of nonuniform coupled two-wire line networks. Then, the multiport graph transformations of networks consisting of nonuniform transmission lines and nonuniform stubs are shown. By using the graph transformation of n-wire nonuniform coupled lines, the equivalent circuits for the nonuniform interdigital line and the nonuniform meander line are given. Finally, a meander-line low-pass filter consisting of parabolic tapered coupled transmission lines designed on this equivalent circuit is shown.

Simplified Analysis of Coupled Transmission-Line Networks

A relatively simple method is presented for analyzing coupled transmission-line networks by using network graphs and graph transformations. The network graph symbolism is easy to draw and to manipulate. All the graphs consist only of inductor, capacitor, and transformer symbols, and straight lines, which represent unit elements. The method of analysis is illustrated by several two-wire-line and multiwire-line examples. Also presented are several new useful transmission-line transformations and a graph equivalent for the general coupled transmission-line network. The graph-transformation method has four principal advantages: 1) explicit open-wire-line equivalent circuits of coupled line networks can be obtained relatively easily and without knowledge of network synthesis techniques; 2) the form of equivalent circuits can often be obtained without using any algebra; 3) at each step of the analysis, a positive-real network in graph form is available; consequently, in many analysis problems several equivalent circuits for the same network are derived; and 4) multiport networks are as easily dealt with as two-port networks.

Coupled Transmission Line Networks in an Inhomogeneous Dielectric Medium

In this paper, two-port networks composed of two identical, coupled transmission lines embedded in an inhomogeneous dielectric (e.g., suspended substrate, microstrip) are investigated. The ABCD parameters of circuit configurations, considered by Jones and Bolljahn, are obtained for the case of inhomogeneous dielectilc. Equivalent circuits of these networks are also given. It is shown that the characteristics of such circuits differ markedly from those embedded in a homogeneous medium. In addition, experimental results are presented for three types of circuits which have been constructed and tested. There is excellent agreement between the experimental results and those predicted theoretically on the basis of the equivalent circuits.