Theory Of Coupled Transmission Lines Research Articles

Differential Lines for Common-Mode Suppression Based in Hybrid Microstrip/CPW Technology

A symmetrical pair of differential microstrip lines implemented in hybrid microstrip/coplanar waveguide (CPW) technology is proposed. Transmission-line models are used to analyze differential- and common-mode responses, allowing efficient design with minimal optimization effort. The structure behaves as a conventional transmission line pair under differential-mode excitation, whereas asymmetrical coupled transmission line theory has to be applied to characterize common-mode operation. The common mode is strongly suppressed thanks to the introduction of a controllable transmission zero. A two-stage version of the structure is used to increase the common-mode rejection bandwidth. All the electrical parameters of the transmission lines have been obtained using an in-house fast quasi-TEM code. The good agreement between transmission-line models, full-wave simulations and measurements confirms the benefits of the structure and the design procedure.

Experimental Validation of Slow-Wave Phenomena in Curved Ring-Bar Slow-Wave Structure

Curved ring-bar (CRB) slow-wave structure (SWS) has been presented before in order to design an SWS for high-power and wideband traveling-wave tube in S-band. It was analyzed using the coupled transmission line theory and predicted to deliver 1-MW output power across 1.8–2.4-GHz bandwidth. However, the slow-wave characteristics were not experimentally validated through measurements. In this paper, we present $\omega -\beta $ measurement results to experimentally demonstrate that the CRB structure is providing the predicted slow-wave characteristics at the S-band. A novel synthetic technique is used to determine the $\omega -\beta $ relation using a six-period fabricated CRB structure. The measurement results exhibit a phase velocity of $0.7c$ – $0.75c$ across 2–2.5 GHz with a maximum error of less than 5%. In addition, the measured on-axis interaction impedance was $>43\Omega $ across the specified frequencies implying satisfactory agreement with theoretical predictions.

결합 전송선로 이론을 이용한 적층 세라믹 커패시터의 임피던스 특성 예측

결합 전송선로 이론을 이용한 적층 세라믹 커패시터의 임피던스 특성 예측

Equivalent-Circuit Modeling for Multilayer Capacitors Based on Coupled Transmission-Line Theory

This paper provides a novel modeling methodology for multilayer capacitors (MLCs) based on the coupled transmission-line theory. From an analytical solution of a single-layer capacitor, first- and second-order equivalent-circuit models for an N-layer capacitor are introduced using an infinite series approximation. The models demonstrated accurate prediction of the behavior of MLCs up to the first and second self-resonant frequencies. In addition, distributed physical parameters for the models were extracted directly from S-parameter measurements without an optimization process. High-frequency MLCs were measured up to 20 GHz using a vector network analyzer and compared with models from 1 to 47 pF.

Crosstalk Prediction for Three Conductors Nonuniform Transmission Lines: Theoretical Approach & Numerical Simulation

In this paper the crosstalk between nonuniform transmission lines is examined. Firstly, methods for prediction of crosstalk between microstrip transmission lines are reviewed. Classical coupled transmission line theory is used for uniform lines and cannot be used for nonuniform transmission lines. Secondly, equations are derived which can be solved to obtain formulas for the near-end and far-end crosstalk for nonuniform transmission lines. Finally, an example is worked which illustrates the crosstalk between three conductor nonuniform transmission lines. Obtained theoretical results were compared with simulations data. Comparison results shown that theoretical and simulation results are approximately the same.

Crosstalk between microstrip transmission lines

Methods for prediction of crosstalk between microstrip transmission lines are reviewed and simplified for the weak-coupling case. Classical coupled transmission line theory is used for uniform lines, and potential and induced EMF methods are used for crosstalk between nonuniform lines. It is shown that the potential method is equivalent to classical coupled transmission line theory for the case of uniform lines. An experiment was performed for uniform coupled microstrip lines for frequencies from 50 MHz to 5 GHz, and good agreement between theory and measurement was obtained for both near- and far-end crosstalk. >