The document discusses transmission lines and their characteristics. It notes that there are four main types of transmission lines: two-wire parallel lines, coaxial lines, strip lines, and waveguides. Transmission lines transmit energy from one point to another effectively without power loss by considering important parameters. The transmission of signals on a line can be modeled as either a lumped element or distributed element system depending on the frequency.

1. WavePropagationandAntenna
TransmissionLines(1/2)
March, 2019
Department of Electrical Engineering
Balochistan UET Khuzdar

2. Wave Propagation and Antenna
 Transmission Lines
 Transmission line
 A transmission line is a connector which transmits energy from one
point to another.
 The study of transmission line theory is helpful in the effective usage
of power and equipment.
 There are basically four types of transmission lines
 Two-wire parallel transmission lines
 Coaxial lines
 Strip type substrate transmission lines
 Waveguides
 While transmitting or while receiving, the energy transfer has to be
done effectively, without the wastage of power.
 To achieve this, there are certain important parameters
which has to be considered.
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3. Wave Propagation and Antenna
 Transmission Lines
 Transmission line
 There are basically four types of transmission lines
 Two-wire parallel transmission lines
 Coaxial lines
 Strip type substrate transmission lines
 Waveguides
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4. Wave Propagation and Antenna
 Transmission Lines
 Transmission line
 There are basically four types of transmission lines
 Two-wire parallel transmission lines
 Coaxial lines
 Strip type substrate transmission lines
 Waveguides
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5. Wave Propagation and Antenna
 Transmission Lines
 Circuit concepts
• Electric I current is a measure of the charge flow/ movement.
• Voltage V is the difference of electrical potential between two points
of an electrical or electronic circuit.
• Impedance Z = R + jX is a measure of opposition to an electric
current.
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6. Wave Propagation and Antenna
 Transmission Lines
 Lumped and Distributed Element Systems
• Lumped element system
• The current and voltage along a transmission line may be considered
unchanged (which normally means the frequency is very low). The
system is called a lumped element system.
• Distributed element system
• The current and voltage along a transmission line are functions of the
distance from the source (which normally means the frequency is
high), thus the system is called a distributed element system.
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7. Wave Propagation and Antenna
 Transmission Lines
 Transmission Line Model
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 If we divide the transmission line into many (almost infinite) short
segments of length ∆𝑧, which is much smaller than the wavelength of int
erest, each segment can then be represented using a set of lumped ele
ments.

8. Wave Propagation and Antenna
 Transmission Lines
 Transmission Line Model
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 To make the analysis easier, the equivalent circuit of the segment of the tra
nsmission line is simplified in the below figure, where
R = R1 + R2 and L = L1 + L2.