Multimodal propagation in multiconductor transmission lines

Abstract

This paper is devoted to the analysis of the multiconductor transmission line (MTL) – a type of structure that is encountered in very many applications ranging from power systems to microwave engineering. Our aim is to provide the reader with a self-contained presentation of the subject where MTL frequency-domain equations are formulated and their solution is established. Matrix techniques are made intense use in order to permit a compact analysis of the problem. Solutions to MTL equations are presented in two different useful formats; at first we consider a solution in the form of a superposition of natural modes of propagation, later, a relationship between voltages and currents at the MTL ports is established by employing the transmission matrix formalism. The presentation is not limited to the simple case of uniform MTL, the important problem of nonuniform MTL is also encompassed.

Keywords:

• matrix techniques
• modal analysis
• multiconductor transmission lines
• propagation modes
• transmission matrix
• uniform and nonuniform MTL

Acknowledgements

The Fundação para a Ciência e a Tecnologia (Project PEst-OE/EEI/LA0008/2013), and the Instituto de Telecomunicações (Project PC226), sponsored this work.