1. LOSSY TRANSMISSION LINES
Fields and Waves
Lesson 1.4
LOSSY TRANSMISSION LINES
Darryl Michael/GE CRD

2. Lossless/Lossy Models of TL
Lossless Model of TL:
Lossy Model of TL:
Loss effects due to Resistances:
R - resistance of conductors
G - conductivity of insulators
- both are ideally small

3. Estimation of R On a per meter basis,
, if constant cross-section
On a per meter basis,
Inner
Outer
because inner and outer conductors are in series
At high frequencies, not all the copper is used for conducting (see Lesson 3.1)
Current only flows in outer portion due to skin depth effects

4. Estimation of G
The 1/G component represents radial current flow, due to small s of insulator
the cross-sectional area is not constant I
Estimation of G:
From Electrostatics,
Also,
Do Problem 1a &1b

5. Effects on Zc - Characteristic Impedance
For Lossless system,
Rc represents V I
Replace j.w.l with r + j.w.l
Replace j.w.c with g + j.w.c
Characteristic Impedance

6. Attenuation Factor For lossless systems: For lossy systems:
The phasors have the factor:
Attenuation/loss factor due to resistance