RCN has attracted special attention in the field of WPT since it was put forward. A lot of research work has been done in rectifier basing on RCN for the purpose of increasing conversion efficiency. It is reported that many kinds of rectifier incorporating RCN which operate at various of circuit forms and physical forms are proposed. RCN and all kinds of modified versions are studied deeply in these paper, the rectifiers related to which are analyzed also. The results show that RCN only play the role of BPF in the rectifying circuit, which are not reaching the original idea of the first proposer.