Impedance mismatch that degrades signal power transfer and affects communication reliability is a major obstacle for power line communications (PLC). Impedance matching techniques can be designed to effectively compensate for the impedance mismatch between PLC modems and power line networks at a specific frequency or for a given frequency band. In this paper, we discuss the tradeoffs that need to be made when designing an effective impedance matching network. We also make a comprehensive review of previous state-of-the-art PLC impedance matching techniques and provide a useful classification of each technique. Finally, we discuss important issues (concerns) and provide suggestions for research directions deserving more attention. This review provides a useful guideline for researchers and manufacturers to quickly understand impedance matching principles and facilitate the design of an effective impedance matching coupler for PLC applications.

The quality of the communication links in VPLC (vehicular power line communication) suffer from an impedance mismatch resulting from fluctuating VPLN (Vehicular Power Line Network) access impedance, which renders the fixed impedance matching circuit inefficient. In this paper, we designed a T-shaped adaptive impedance matching system on the basis of the resonance-and absorption-based T-shaped network complex impedance matching approach. We identified the load-Q (quality factor) for different matching situations to facilitate designing T-shaped networks with broad bandwidths. The designed T-shaped adaptive impedance matching system adjusts the component values of the T-shaped network to implement adaptive impedance matching between the VPLC modem and VPLN. A set of simulations are conducted for 1 MHz-100 MHz, which demonstrates that the designed adaptive matching system with a simple circuit structure and control logic is capable of significantly improving signal power transfer.

In the above article [1] , we used the wrong command when plotting the graphs in Figs. 13 and 14 . This only affected the levels of the frequency responses ( $V_{out} /V_{in}$ (dB)) of the designed T-shaped networks and had no influence on the analysis and conclusions. The corrected graphs of Figs. 13 and 14 are provided here.