7e Applied EM by Ulaby and Ravaioli

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

2 Types of Transmission Lines

3 Fields of Transmission Lines

4 Transmission Lines = Roads for Wave
A transmission line connects a generator to a load Transmission lines include: Two parallel wires Coaxial cable Microstrip line Optical fiber Waveguide etc.

5 - Dispersion (분산 = 주파수에 따른 불균일 특성) - 분산이 크면 신호왜곡 증가 - Distortion (신호왜곡)

6 Modes in Transmission Line Mode: 전기장의 분포형태
- TEM (transverse electromagnetic) mode: Ez = 0, Hz = 0, # of conductors > 1 fc = 0 (차단 주파수), Example = coaxial cable TEM mode - Quasi-TEM: TEM with mixed dielectric, fc (cutoff frequency) = 0 Example = microstrip line - TE (transverse electric) mode: Ez = 0, fc > 0, Example = rectangular waveguide - TM (transverse magnetic) mode: Hz = 0, fc > 0, Example = coaxial TM01 mode - Hybrid mode: TE+TM, fc > 0, Example = optical fiber HE11 mode

7 Electric and Magnetic Fields in A Transmission Line
- 전송선에는 전기장 파동, 자기장 파동이 진행 - 회로이론 적용을 위해 전송선의 전압, 전류 개념 적용 Voltage and Current: obtained from E and H

8 Transmission Line Circuit Model

9 Transmission Line Parameters: R, L, G, C
R', G', C' from electrostabics; L' from magnetostatics Expressions will be derived in later chapters

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

11

12 Phase constant complex propagation constant attenuation constant (전파상수) (감쇠정수) (위상정수)

13 (특성임피던스)

14 Example 2-1: Air Line

15 Lossless Transmission Line
Lossless Line: Lossless TEM Line:

16 Material Parameters in Transmission Lines
- Conductor (도체, 금속) - Dielectric (유전체,플라스틱)

17 Low-Loss Transmission Lines

18 Distortionless Transmission Line

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20 Distortionless Transmission Line: Heaviside Condition

21 Reflected Wave 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

22 Microstrip Line - A Quasi-TEM line
Quasi-TEM : Ez & Hz very small Phase velocity in dielectric: Phase velocity for microstrip:

23 Microstrip (cont.) s = w/h

24 Coaxial Transmissioni Line (TEM Line)

25 Skin Depth (AC Resistance)
Table: Copper (Cu) skin depth