1. 7e Applied EM by Ulaby and Ravaioli
2. Transmission Lines
7e Applied EM by Ulaby and Ravaioli

2. Transmission Lines = roads for a wave to travel
A transmission line connects a generator to a load
Transmission lines include:
Two parallel wires
Coaxial cable
Microstrip line
Optical fiber
Waveguide
etc.

3. Types of Transmission Modes

4. Dispersion

5. Example of TEM Mode fc (cutoff frequency): f > fc = travel, f < fc = blocked
TEM (transverse electromagnetic) mode: Ez = 0, Hz = 0, # of conductors > 1
quasi-TEM: TEM with mixed dielectric, fc (cutoff frequency) = 0
TE (transverse electric) mode: Ez = 0, fc > 0
TM (transverse magnetic) mode: Hz = 0, fc > 0
Hybrid mode: TE+TM, fc > 0

6. Electric and Magnetic Fields in A Transmission Line Voltage and Current from E and H
Voltage and Current: obtained from E and H

7. Transmission Line Circuit Model

8. Expressions will be derived in later chapters

9. Transmission-Line Equations
ac signals: use phasors
Telegrapher’s equations

11. Phase constant
complex propagation constant
attenuation constant
(전파상수)
(감쇠정수)
(위상정수)

12. (특성임피던스)

13. Solution of Wave Equations (cont.)
In general:
wave along +z because coefficients of t and z have opposite signs
wave along –z because coefficients of t and z have the same sign

14. Example 2-1: Air Line

15. Microstrip Line Phase velocity in dielectric:
Phase velocity for microstrip:
Quasi-TEM : Ez & Hz very small

16. Microstrip (cont.)
s = w/h

17. Lossless Transmission LineIf
Then: