# EMLAB 1 Transmission line. EMLAB 2 An apparatus to convey energy or signal from one place to another place. Transmitter to an antenna connections between.

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EMLAB 1 Transmission line

EMLAB 2 An apparatus to convey energy or signal from one place to another place. Transmitter to an antenna connections between computers in a network hydroelectric generating plant and a substation several miles away interconnect between components of a stereo system CATV service provider and your TV set Connections between devices on a circuit board Transmission line

EMLAB 3 Example – Cable TV

EMLAB 4 Example – Computer network

EMLAB 5 Example – Electric power transmission line

EMLAB 6 Example – Printed circuit board

EMLAB 7 Example – Printed circuit board

EMLAB 8 Types of transmission lines Microstrip line Coaxial cable Two-wire transmission line

EMLAB 9 Distribution of electric field strengths of typical TEM lines E/H distributions vary as the structures of transmission lines change. For electromagnetic compatibility, E/H should be confined to small area. Microstrip Two-wire Parallel plate

EMLAB 10 Field representation in waveguides

EMLAB 11 Wave Solution TEM mode (Transverse electromagnetic mode)

EMLAB 12 Parallel plate waveguide With a wide enough line trace, variation along y-axis can be ignored.

EMLAB 13 i (z, t) v (z, t) + - zz L  z C  z i (z+  z, t) v (z+  z,t) + - i (z, t) zz v (z, t) + - Transmission line 등가 회로

EMLAB 14 Transmission line eq. solution

EMLAB 15 Transmission line 의 특징 H E Direction of propagation H 1.For a magnetic field and an electric field propagating in the same direction, the ratio of E and H (E + /H + ) is kept constant. 2.For a voltage and a current current propagating in the same direction, V + /I + ratio is equal to Z 0. 3.When the ratio is disturbed, reflected waves are generated.

EMLAB 16 +V-+V- Reflection coefficient

EMLAB 17 +V-+V- +V-+V- +V-+V- +V-+V- +V-+V- Z s = 20  Z 0 = 50  Z L = 1k  0.5m Influence of line length on load voltage Impedance mismatched VinVout R R2 R=1k Ohm MLIN R R1 R=20 Ohm VtPulse SRC1 t Z 0 = 50 

EMLAB 18

EMLAB 19 Ringing : Time domain

EMLAB 21 Impedance matching – Digital logic ~ ~ Source matching Load matching

EMLAB 22 Impedance matching topologies

EMLAB 23 Frequency domain solution β : propagation constant, v p : speed of light

EMLAB 24 Phasor representation +V-+V-

EMLAB 25 Transmission line terminated with short, open Zs = Zo V refl V inc For reflection, a transmission line terminated in a short or open reflects all power back to source In phase (0 ) for open o Out of phase (180 ) for short V refl o

EMLAB 26 Transmission Line Terminated with 25 Ω Zs = Zo Z L = 25 W V refl V inc Standing wave pattern does not go to zero as with short or open

EMLAB 27 Equivalent input impedance

EMLAB 28 Input impedance of short

EMLAB 29 Input impedance of open

EMLAB 30 Some transmission line examples case 1) matched load

EMLAB 31 case 2) unmatched load

EMLAB 32 Ringing : Time/frequency domain

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