ter-Aided Design of Microwave Circuits, Artech House Inc, Norwood MA 02062 USA, ISBN: 0-89006-105-X. AppCAD is a proprietary software program from the Hewlett Packard Co, Page Mill Road, Palo Alto CA, USA. Transmission lines CHAPTER 2.2 2.2.5.1 Representation of primary line constants In Figure 2.2-8, let: R represent the resistance per metre (ohms/metre) L represent the inductance per metre (henry/metre) G represent the conductance per metre (siemen/ metre) (2.2.16) C represent the capacitance per metre (farad/metre) It follows that for a short length ol, we would obtain Rôl, Substituting for Z and Z1, we get Lol, Gôl, and Col respectively. Hence (2.2.12) In the limit when ol 0, and taking the positive 181= = (2.2.13) square root term Y8l = (G + jwC)8l (2.2.14) (2.2.17) (2.2.15) If you examine the expression for Z a bit more closely, you will see that there are two regions where Z tends to be resistive and constant. The first region occurs at very low frequencies when R > jwL and G >> This results in 2.2.5.2 Derivation of line impedance The input impedance Zin of the short section ol when Zo=VAL (2.2.18) terminated by a matched line is given by8 The second region occurs at very high frequencies when jwL R and jwC >> G. This results in (2.2.19) Since the line is terminated by another line, Zin = Z The second region is also known as the frequency region where a transmission line is said to be 'lossless' because there are 'no' dissipative elements in the line. Equation 2.2.19 is also useful because it explains why inductive loading, putting small lumped element Cross-multiplying, we get inductors in series with lines, is used to produce a more constant impedance for the line. The frequency regions of operation described by Equations (2.2.18) and (2.2.19) are important because under these conditions, line impedance tends to remain frequency independent +201(2101+20) and a state known as 'distortionless transmission' exists. The distortionless condition is very useful for pulse Simplifying waveform/digital transmissi