Trackside Loss Analysis: An Application in a Radio-Frequency Chain of a Communication-Based Train Control System

A key assumption in the process of optimized design of radio-frequency (RF) networks 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 composed of multiple cascaded or forked segments connects one to the other. An example of such a transmission network is the RF transmission chain of the communication-based train control (CBTC) trackside antenna system. The data communication subsystem (DCS) design requirements and validation processes necessitate development of means for realistic evaluation and analysis of the reflection/return loss (RL) and insertion loss (IL) 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 RL and IL values in a general multistage RF transmission network. To provide a more realistic and credible assessment, the comparison has been further substantiated with measurement data.