Current and voltage relationships

Figure 44.3 below presents us a voltage source VS supplied to the input terminals of an infinite line, or a line terminated in its characteristic impedance, so that a current IS flows into the line.At a point, say, one km down the line let the current be I1. The current I1 will not have the same magnitude as IS because of line attenuation; also I1 willlag IS by some angle β. The ratio IS/I1 is therefore aphasor quantity. Let the current a further onekm down theline be I2, & so on, as demonstrated in Figure 44.3 below. Each unit-length of line can be considered as a section of a repetitive network. The attenuationis in the form of a logarithmic decay &