Abstract: The equivalent resistance of 3 × n-step network is studied again. By means of virtual current method, the 3 × n-network is analyzed and a model of two-variable difference equation is proposed. The matrix transform is constructed by artifice. Based on different marginal conditions, a general formula for the inlet resistance of 3 × n-network as well as an utmost rule for the equivalent resistance of 3 ×n-network are presented. It is proved that the utmost equivalent resistance of infinity resistance network is equal to a constant.

Key words: 3 × n step network, matrix transform, difference equation model, equivalent resistance, general formula