Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EST > Chapter - 3 Transmission Lines > Flashcards

Chapter - 3 Transmission Lines Flashcards

1
Q

It is a metallic conductor system used to transfer electrical energy from one point to another using electrical current flow and it is designed to deliver RF power from the transmitter to the antenna and maximum signal from the antenna to the receiver

A

Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Two Main Categories of Transmission Lines

A
  • Guided

- Unguided

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

those with some form of conductor that provides a conduit which electromagnetic energy are contained

A

Guided Media (wired)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

signals are emitted then radiated through air or vacuum those signals propagating down the unguided transmission media are available to anyone who has a device capable of receiving them

A

Unguided (Wireless)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Types of Transmission Lines

A
  • Balanced

- Unbalanced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

also known as “differential transmission line”, which is made up of two parallel conductors spaced from one another by a distance of 1/2 inch up to several inches and both conductors carry signal currents , which are equal in magnitude with respect to electrical ground but travel in opposite direction

A

Balanced Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

it has an advantage that most noise interference is induce equally in both wires, producing longitudinal currents that cancel in the load

A

Balanced Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Example of Balanced Transmission Lines are

A

Parallel Conductor Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

it is also known as “single ended transmission lines” or “concentric transmission lines”, which consists of a solid conductor surrounded by an insulator, wherein one wire is at ground potential and the other wire is at signal potential. its disadvantages is its reduced immunity to common mode signals

A

Unbalanced Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Example of Unbalanced Transmission Lines are

A

Coaxial Cable Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

current flows in opposite directions are known as

A

metallic circuit currents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

current flows in same directions are known as

A

longitudinal circuit currents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

balun stands for

A

balanced and unbalanced

- use to connect balanced and unbalanced transmission lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

most common type of balun is

A

Narrowband Balun which is also known as choke , sleeve or bazooka

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

balun has turns ratio of

A

4 : 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

it is comprised of two or more metallic conductors , separarted by non conductive insulating material known as dielectric (air , rubber , polyethylene , paper ,mica , glass and teflon ).

A

Parallel Conductor Transmission Lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

it is also known as ladder cable , which consist of two parallel wires , closely spaced and separated by air. it has non conductive spacers which are placed at periodic intervals for support and to keep distance between conductors is generally between 2 to 6 inches. but because no shielding radiation losses are high

A

Open Wire Line

primary use : voice-grade telephone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

it is also known as ribbon cable. and it is the same with open wire transmission lines except that the spacers between the two conductors are replaced with a continuous solid dielectric that ensures uniform spacing along the entire cable , the distance between two conductors is 5/16 inches for Television Transmission Cable. the most common dielectric is TEFLON (polytetrafluoroethylene)

A

Twin Lead

primary use : television to rooftop antenna

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

it is formed by twisting together two insulated conductors around each other; the purpose of twisting is to reduce the effects of EMI (Electromagnetic Interference) and RFI (Radio Frequency Interference)

A

Twisted Pair : UTP and STP

primary use : Local Area Network because it is easy to install and inexpensive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

it consist of two copper wires where each wire is separately encapsulated in PVC ( polyvinyl chloride ) insulation

it is inexpensive , flexible and easy to install but it is also the most susceptible to external electromagnetic interference

A

UTP - Unshielded Twisted Pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the minimum number of twist for UTP is

A

Two Twist per Foot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

7 types of UTP according to EIA/TIA 568 Standard:

A

Level 1 , 2 , Category 3 ,4 ,5 Enhanced Category 5 and Category 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

it consists of two copper conductors separated by a solid dielectric material, and its wires and dielectric are enclosed in a conductive metal sleeve known as FOIL
if sleeve is woven into a mesh it is known as BRAID

more expensive than UTP but greater security and greater immunity to interference

A

STP - Shielded Twisted Pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

7 typer of STP according to EIA/TIA 568 Standard:

A

Category 3,4,5 Enhanced Category 5 , Category 7 , Foil Twisted Pair , and Shielded Foil Twisted Pair.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

is an electromagnetic interference between two conductors that occurs when current flows through one conductor, it produces a magnetic field that can interfere with the adjacent conductor.

A

Crosstalk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

for twisted pair as category number increases

A

the number of twist also increases and also the information capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

UTP Connectors are:

A

RJ:(registerred jack)

  • 45
  • 11
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

it consist of center conductor surrounded by a dielectric material, then a concentric shielding, and finally a rubber environmental protection outer jacket

it provide excellent shielding against external interference, it is commonly used in high frequency applications to reduce losses and to isolate transmission paths

A

Coaxial Cable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

types of coaxial cable:

A
  • Rigid Air-Filled Coaxial Cable

- Solid Flexible Coaxial Cable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

it has a center conductor surrounded coaxially by a tubular outer conductor and the insulating material is air some are pressurized with an inert gas to prevent moisture from entering.

A

Rigid Air-Filled Coaxial Cable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

it consists of a flexible inner conductor and a concentric outer conductor of metal braid, the two are separated by a continuous insulating material (commonly teflon which is white color).

A

Solid Flexible Coaxial Cable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

are military standards and specifications for coaxial cables by the US Department of Defense

A

RG ( Radio Government )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Coaxial Cable Connectors:

A
  • BNC ( Bayonet Neil Concealman ) Connector

- N-Type Connector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

it is also known as bayonet mount as they can easily twisted on or off

A

BNC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

it is threaded and must be screwed on and off

A

N-Type Connector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

refers to the woven stranded mesh that surrounds some types of coaxial cables

A

Shielding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

coax with one layer of foil and one layer of braided shielding is known

A

Dual Shielding

there is also Quad Shielding which is two foil and two braided shielding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

the characteristics of a transmission lines are determined by its ______, such as wire conductivity and insulator dielectric constant, and its ______, such as wire diameter and conductor spacing

A

electrical properties and physical properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

these are uniformly distributed throughout the length of the line and are commonly known as distributed parameters ( the combined parameters are known as lumped parameters )

A

Primary Constants

RL // RC - lumped parameters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

primary constants:

A

–series resistance and series inductance
ohm/length and henry/length

–shunt conductance and shunt capacitance
siemen / length and farad / length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

parallel conductor transmission line

Series Inductance :

A

L=(u/pi) ln(2S/d)
where :
S= Separation or Distance between two Conductors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

parallel conductor transmission line

Series Capacitance :

A

C=(pi x e/ ln(2S/d)
where:
e=permittivity of medium
d=diameter of inner diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Coaxial Cable Transmission Line

Series Inductance :

A

L= (u/2pi) ln (D/d)
where:
D=inside diameter of the outer conductor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

parallel conductor transmission line

Series Capacitance :

A

C=2 pi e / ln (D/d)
where:
e=permittivity of medium
d=diameter of inner diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

these are the transmission characteristics of a transmission lines:

A

Secondary Constant:

  • Characteristic Impedance
  • Propagation Constant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

it is also known as “surge impedance” and it is defined as the impedance seen looking into an infinite long line or the impedance seen looking into a finite length of a line that is terminated in a purely resistive load with resistance equal to the characteristic impedance of the line

A

Characteristic Impedance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Characteristic Impedance Formula:

A

Zo = sqrt ( R + JwL / G + JwC )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Characteristic Impedance Formula for RF / High Frequencies , R = G = 0

A

Zo = sqrt ( L/C ) … Lucy Torres

49
Q

Characteristic Impedance Formula for Audio Frequencies / Low Frequencies , wL = wC = 0

A

Zo = sqrt (R/G) … Richard Gomez

50
Q

Characteristic Impedance Formula for Parallel Conductor Transmission Lines :

A

Zo = ( 276 / sqrt(er) ) log (2S/d)
er = relative permittivity
d=diamter of inner conductor

51
Q

Characteristic Impedance Formula for Coaxial Cable Transmission Lines

A

Zo = ( 138 / Sqrt(er) ) log (D/d)
er = relative permittivity
D= inside diameter of the outer conductor
d=diamter of inner conductor

52
Q

it is also known as propagatoin coefficient that is used to express the attenuation ( signal loss ) and the phase shift per unit length of the transmission lines.

A

Propagation Constant:
y = sqrt ( (R+JwL) (G+JwC) )
y = a + jB

53
Q

Attenuation Coefficient :

A 
a = R / Zo
a(np/m) = R / (2 x Zo)
a(db/100ft) = 4.343 (R / Zo)
54
Q

Phase Shift Coefficient :

A 
B = 360 / lambda = 2 pi / lambda
B = w sqrt(LC) .... for High Frequency
55
Q

it is also known as velocity constant, and it is defined as the ratio of the actual velocity of propagation of an electromagnetic wave through a given medium to its velocity of propagation in free space vacuum.

A

Velocity Factor

56
Q

Velocity Factor Formula:

A 
vf = vp / c
vf = 1/sqrt (er)
vf = 1/n
57
Q

it is simply the relative permittivity of a material, and it depends on the type of insulating material used.

A

Dielectric Constantc

58
Q

these are transmission lines designed to intentionally introduce a time delay in the path of the electromagnetic wave.

the amount of time delay is a function of the transmission line’s inductance and capacitance

A

Delay Lines

59
Q

Time Delay :

A

td = Distance / Velocity

60
Q

Time Delay For 1 Meter :

A

td = sqrt (LC)

61
Q

Time Delay For 1 Foot

A

td = 1.016 sqrt(er)

62
Q

the length of a transmission line relative to the length of the wave propagating down it is an important consideration when analyzing

A

” transmission line behavior “ :

  • physical length = 10km
  • length in terms of wavelength =0.25lambda
  • electrical length = 120degrees
63
Q

Transmission Line Losses

A
  • Conductor Loss
  • Dielectric Heating Loss
  • Radiation Loss
  • Coupling Loss
  • Corona
64
Q

it is also known as “conductor heating loss” or “I^2R los”, and it is directly proportional to the square of the length of the line and inversely proportional to the characteristic impedance.

it is the inherent and unavoidable power loss because of the finite resistance of the transmission lines, and depends somewhat on frequency because of a phenomenon known as “skin effect”

A

Conductor Loss

65
Q

it is caused by a difference of potential between conductors in a metallic transmission line (ie., it is caused by the heating of the dielectric material between conductors, taking power from the source).

it increases for solid dielectric lines because of gradually worsening properties with “increasing frequency”

A

Dielectric Heating Loss

66
Q

if the separation between the conductors in a transmission line is an appreciable fraction of wavelength, the electrostatic and electromagnetic that surrounds the conductor caused the line to act as an antenna ( radiation of signal occurs ).

it depends on dielectric material , conductor spacing and length of the transmission line, and it can be reduced by “properly shielding the cable”

A

Radiation Loss

67
Q

it occurs whenever a connection is made to or from a transmission line or when two section of transmission lines are connected together.

A

Coupling Loss

68
Q

it is a luminous discharge that occurs between the two conductors of a transmission line when the difference of potential between them exceeds the breakdown voltage of the dielectric insulator, and when this occurs , usually the transmission line is destroyed

A

Corona

69
Q

is a phenomenon wherein the signals tend to propagate at the outer edge of the cable if the frequency of the operation is too high. this happens when frequency increases , the region of high current density becomes thinner, reducing the cross-sectional area and increasing the resistance of the conductor

A

Skin Effect

70
Q

it is also known as Flat Line or a Matched Line, wherein there is no reflected power in the transmission line

a transmission line is a resonant line if it is a infinite length or if it is terminated with a resistive load equal to the ohmic value of the characteristic impedance of the transmission line

A

Non-Resonant Transmission Line:

Zo=Zl

71
Q

it is also known as a mismatched line, in which if the load impedance is not equal to characteristic impedance of the line some of the incident power is reflected back to the load.

in a resonant line, the energy is alternately transferred between the magnetic and electric fields of the distributed inductance and capacitance of the line

A 
Resonant Transmission Line:
Zo not equal to Zl
ZL is Shorted
ZL is Open
ZL = R + jX
72
Q

it is also known as coefficient of reflection, wherein it is a vector quantity that represents the ratio of the reflected voltage to the incident voltage or reflected current to the incident current

A 
Reflection Coefficient :
r= Vref/Vinc
r=Iref/Iinc
r=sqrt(Pref/Pinc)
r=ZL-Zo/Zl+Zo
r= SWR-1/SWR+1
r= Vmax - Vmin / Vmax + Vmin
r= Imax - Imin / Imax + Imin
73
Q

it is defined as the ratio of the maximum voltage or current to the minimum voltage or current of a standing wave in a transmission line

it is a measure of mismatch between the load impedance and characteristic impedance

A 
Standing Wave Ratio :
VSWR = Vmax / Vmin
ISWR = Imax / Imin
SWR = ZL/Zo
SWR = Zo/ZL
SWR = Vinc + Vref / Vinc - Vref
SWR = Iinc + Iref / Iinc - Iref
SWR = 1 + r / 1 - r
74
Q

Typical Value:

A

r < 1

SWR > 1

75
Q

Ideal Value:

A 
r = 0
SWR = 1
76
Q

Worst Case Value:

A 
r = +1 or -1
SWR = Infinite
77
Q

it is an “interference pattern” setup by two travelling waves. it is the formation of which due to the interaction between the incident and reflected waves that causes what appears to the stationary pattern of waves on the line.

A

Standing Wave

78
Q

standing wave on an open circuited line

A

the “voltage incident wave” is “reflected back” just as if it were to continue down the line

the “current incident wave” is “reflected 180” degrees from how it would have continued

the sum of incident and reflected current waveform is “minimum at open”

the sum of incident and reflected voltage waveform is “maximum at open”

79
Q

standing wave on a short circuited line

A

the “voltage incident wave” is “reflected 180” degrees from how it woulds have continued

the “current incident wave” is “reflected back” just as if it were to continue down the line

the sum of incident and reflected current waveform is “maximum at short”

the sum of incident and reflected voltage waveform is “minimum at short”

80
Q

Absorbed Power by the Load :

A 
Pabs = Pinc - Pref
Pabs = Pinc ( 1 - r^2 )
Pabs = Pinc ( 4SWR / ( 1 + SWR )^2 )
81
Q

Return Loss And Mismatch Loss:

A 
RL = 1 / r^2
RL(db) = -20log(r)
82
Q

Mismatch Loss :

A 
ML = 1 / 1-r
ML(db) = -10log(1-r)
83
Q

Transmission Line Input Impedance:

A

Zin = Zo ( Zl + j Zo Tan(Bl ) / Zo + jZl Tan(Bl) )

84
Q

Matched Load : ZL=Zo

A

V ref = 0 , I ref = 0 , RL=0 , r = 0 , SWR = 0
VL = IL x ZL
IL = VL / ZL
Zin = Zo = ZL

85
Q

Short Circuited Load: ZL=Zo

A 
VL = 0 
V ref = -V inc
Iref = I inc = IL /2 
IL = I inc + I ref
IL = 2 Iinc
SWR = infinite
Zin = jZo Tan (Bl)
86
Q

Open Circuited Load : Zl = infinite

A 
V ref = V inc = Vl/2
I ref = -I inc
VL = V inc + V ref
VL = 2 V inc
IL = 0
r = 1
87
Q

Traveling waves that are coming from the transmitter.

A

Incident Waves

88
Q

Traveling waves that are brought back to the transmitter due to unmatched line

A

Reflected Waves

89
Q

For A Maximum Power Transfer from source to load

A

a transmission line must be terminated in a purely resistive load equal to the characteristic impedance of the transmission line.

90
Q

vector quantity

A

reflection coefficient

91
Q

scalar quantity

A

standing wave ratio

92
Q

the behavior of transmission line depends on its:

A

Length And Termination

93
Q

when a transmission line is terminated in either short or open circuit, there is an :

A

impedance inversion in every quarter-wavelength

94
Q

transmission lines that are terminated by either a short or an open circuit can be used as:

A

REACTANCES or as either SERIES or PARALLEL RESONANTS CIRCUITS depending on their length

95
Q

at UHF and Microwave Frequencies where one-half wavelenght is less than 1 foot :

A

transmission lines are commonly used to replace conventional LC Tuned Circuits

96
Q

it is a section of a transmission line, electrically a quarter-wavelenght in the length that is used to match a transmission line to a purely resistive load whose resistance is not equal to the characteristic of the line

A

Quarter Wave Transformer

97
Q

Impedance Of Quarter Wavelength Transformer:

A

Zo(lambda/4) = sqrt ( Zo x ZL )

98
Q

the quarter wave transformer act as a transformer with :

A

1:1 turns ratio
Zo = ZL
a = 1

99
Q

the quarter wave transformer acts as a step-down transformer when :

A

ZL > Zo

a > 1

100
Q

the quarter wave transformer acts as a step-up transformer when :

A

ZL < Zo

a < 1

101
Q

it is a short section of line, usually short-circuited at one end that is used for impedance matching, and it is placed across the primary line as close to the load as possible

it is used to remove (cancel) the reactive component of the complex impedance of the load and to match it to the transmission line

A

Stub

102
Q

Types of Stub matching :

A
  • Series Open Stub
  • Series Short Stub
  • Shunt Open Stub
  • Shunt Short Stub
103
Q

Shorted Stubs are preffered because Open Stubs ?

A

Have tendency to radiate , especially at higher frequencies

104
Q

if the load is inductive

A

the capacitive stub is used

105
Q

if the load is capacitive

A

the inductive stub is used

106
Q

is used to match a resistive load while stub is used to match a complex or reactive load

A

the quarter wave transformer

107
Q

is used to match a complex or reactive load

A

stub

108
Q

it is used to measure the power being delivered to a load or an antenna through a transmission line, moreover , it allows the measurement of power moving along the line in each direction thus it is possible to measure incident and reflected power separately

A

Directional Coupler

109
Q

it is used to measure standing waves ; TDR ( Time Domain Reflectometry) it is a technique that can be used to locate an impairement in a metallic cable

A

Reflectometer

110
Q

in TDR,

A

a step input or pulse is applied to the input of a transmission line ; by examining the reflected signal , much information can be gained about such things as the length of the line , the way in which it is terminated, and the type and location of any impedance discontinuities on the line.

111
Q

it is a short section of air-dielectric coaxial line, with a slot in the outer conductor through which a probe is inserted; the probe does not actually touch the inner conductor , it is CAPACITIVELY COUPLED , so as to disturb the signal on the line as little as possible

it permits convenient and accurate measurement of standing waves

A

SLOTTED LINE

112
Q

it is the graphical calculator, created and developed by Phillip Smith , used for transmission line matching

it is a polar impedance diagram which consist of two sets of circles or arc of circles, which are so arranged that various important quantities connected with mismatched transmission line may be plotted and evaluated fairly easily

A

Smith Chart

113
Q

at low frequencies

A

Standard Transmission Lines would be too long fro practical use as reactive components or tuned circuits

114
Q

for high frequency applications,

A

special transmission lines consctructed with copper patterns on a PCB have been developed to interconnect components on PC boards.

115
Q

these are two printed circuit board implementations of transmisison lines known as _____ and ______are widely used to Create Resonant Circuits and Filters

A

STRIPLINES , MICROSTRIP

116
Q

it is a flat conductor separated from a ground plane by insulating dielectric material.
its characteristic impedance is dependent on its physical characteristics

it has advantage over stripline in being simpler construction and easier integration with semiconductor devices, tending itself well to printed circuit and thin film techniques

A

Microstrip

117
Q

Microstrip Characteristic Impedance :

A

Zo = ( 87 / sqrt(er + 1.41 ) ) ln (5.98h / 0.8w + t )

118
Q

it is a flat conductor sandwiched between two ground planes.

it is more difficult to manufacture than microstrip, but it is less likely to radiate; thus losses in stripline are lower than microstrip

A

Stripline

119
Q

Stripline Characteristic Impedance :

A

Zo = ( 60 / sqrt(er) ) ln ( 4d / ( 0.67pi x w ) ( 0.8 + t/h ) )

EST (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions