Loss Analysis in the Trackside RF Chain of a Radio-Based CBTC System

A key assumption in the process of optimized design of RF systems is the efficient transfer of power from the transmitter source to the load (i.e., the end antenna). Unless the transmitter is located directly next to the load, a transmission circuit comprised of multiple cascaded or forked segments connects one to the other. An example of such transmission network is the RF transmission chain of the Communication-Based Train Control (CBTC) trackside antenna system. The system design requirement and validation process necessitates development of means for realistic evaluation and analysis of the reflection and insertion loss values offered by the trackside RF chains of a radio-based CBTC system. The aim of this research is to present a comparative study of three different models developed to quantitatively assess reflection and insertion losses in a general multi-stage RF transmission network. To provide a more realistic and credible assessment, the comparison has been further substantiated with measurement data.