1. Set transmission line
or device is a means by which information is propagated or transmitted (electromagnetic waves) at high frequencies.
2. Describe a transverse electromagnetic wave:
is spread mainly in the dielectric, for a transverse wave propagation direction is perpendicular to the direction of propagation.
3. Define wave velocity:
speed signal transmission line is slower than the speed of a signal in free space.
4. frequency and wavelength for a transverse wave
The transverse wave oscillations are periodic and repetitive so it s length is removed by dividing the speed of light between the frequency and the frequency is the reciprocal of the period.
5. Describe what transmission lines are balanced and unbalanced. Balanced
: Two current-carrying wires two wires, one carrying the signal and the other is the return. The signal propagates along the wire is measured as the difference potential between the two drivers.
Unbalanced: A wire is at ground potential while the other has the potential
signal transmission lines
6 naked conductors
is a host of two parallel wires a short distance and separated by spacers that keep putting air the same distance between them.
7. Describe a transmission line conductors twins: twins
cables are another form of transmission line for a two-conductor parallel cables.
8 lines twisted pair transmission
each is formed by twisting two insulated conductors, which are twisted in units carried in nuclei with different linings depending on the application.
9. What is a transmission line shielded cable?
To reduce radiation losses and interference, often contain transmission lines of two parallel wires in a conductive metal mesh.
The shield is connected to ground and acts as a protection. The shield also prevents the signals are spread beyond its borders and prevent electromagnetic interference reaches the signal conductors.
10
concentric transmission line for high frequencies are used to reduce losses and isolate the transmission paths.
11. Describe the electrical and physical properties of a transmission line
The characteristics of a transmission line are determined by their electrical properties such as conductivity of the wires and insulation dielectric constant and its physical properties such as diameter wire and distance between conductors.
12
four primary constant capacitance, conductance, inductance, resistance
13. Define the characteristic impedance of a transmission line
The characteristic impedance (Z0 a transmission line is a complex quantity that is expressed in ohms, which ideally is independent of the length of the line, and can not be measured.
14 which properties of the transmission line determine its characteristic impedance
The four primary constants and the angular frequency multiplied by an imaginary number.
15. Define the propagation constant of a transmission line.
is used to determine the reduction in voltage or current in the distance as a TEM wave propagates along the transmission line.
16
speed factor constant speeds also called the speed ratio actual propagation through certain medium between the speed of propagation through the gap.
17. What properties of a transmission line determines the speed factor?
The speed at which an electromagnetic wave propagates along a transmission line varies with the inductance and capacitance of the cable.
18 properties that determine transmission line
dielectric constant is the permittivity of the material in relation to the permittivity in a vacuum.
19. Define what is the electrical length of transmission line
At low frequencies (wavelengths large), the voltage along the line remains relatively constant. 20
five kinds of losses in transmission lines
Lost in the driver, dielectric heating, by radiation coupling and corona.
21. Describe what is an incident wave and reflected:
The voltage that propagates from the source to the load, called the incident voltage and the voltage that propagates from the load to the source is called reflected voltage.
22 transmission line resonant and nonresonant
The non-resonant is that no reflected power, voltage and current are constant toa length. The is resonant incident and reflected wave energy is transmitted as an alternative.
23. Define the reflection coefficient:
is a vector quantity representing the ratio of reflected voltage to incident voltage 0 current reflected to the incident current.
24 waves and SWR
nodes have minimum separated by a half wavelength of traveling waves and has maxima antinodes. Their relationship is defined between the minimum and maximum voltage or current minimum and maximum.
25. Describe the standing waves that exist in an open transmission line.
When waves voltage and current incidents reach an open termination, no power is absorbed, the whole is reflected back to the source.
26 waves in a transmission line shorted
In this case the voltage and current incidents are reflected and return in the opposite way.
27. Define what input impedance in a transmission line
For a lossless line, the impedance varies from infinity to zero. However, in a more practical case where energy leaks, the amplitude of the reflected wave is always less than that of the incident wave, except in the end. Therefore, the impedance varies from a maximum to some minimum value, or vice versa, depending on whether the line ends in a short or open circuit.
28 describes the behavior of a transmission line terminating in short and is longer than a quarter wavelength. Do the same with a line shorter than quarter wavelength.
when a quarter wave phase becomes 180 degrees so you have to add the reflected voltage and the incident to obtain the total voltage. If less than quarter-wave phase takes 45 degrees.
29. Describe the behavior of a transmission line open circuit end is longer than a quarter wavelength. Do the same with a line shorter than quarter wavelength.
longer than quarter wavelength, the incident current I and voltage E incident are in phase. Reflected voltage wave is delayed 45 ° in going from the source to the load and 45 º to the load back to the source. Therefore, when the reflected wave reaches the end of the source, this delayed 90 ° with the incident wave.
shorter than quarter wavelength, the reflected voltage is delayed three-quarter wavelength, or 270 º. Therefore, in fact the voltage by 90 º to the incident voltage. The reflected wave power is late and suffered a 270 ° phase inversion 180 in the open end.
30 describes the behavior of a transmission line open circuit element
can behave as a resistor or capacitor inductor depending on its wavelength.
31. Describe the behavior of a transmission line short circuit element:
It can behave like a resistor, inductor or capacitor, depending on its electrical length. Standing waves are repeated every half wavelength, and therefore also repeated the input impedance.
32 describe the characteristics of input impedance of a transmission line a quarter wavelength
incident and reflected voltages are in phase so the total voltage for the two previous ones are added but the incident and reflected currents are offset 180 degrees so that the above and must be subtracted to obtain the total current.
33. Describe the characteristics of input impedance of a transmission line shorter than a quarter wavelength; do the same with a transmission line a quarter wavelength.
shorter than quarter wavelength: The input impedance has a phase angle of -90 ° and is therefore qualified.
A quarter wavelength, has a phase angle 0 ° and is resistive and therefore is minimal. 34
describe the adaptation transformer quarter wavelength
are used to compensate for transmission lines with purely resistive load whose resistance is not equal to the characteristic impedance of the line.
35. Describe how the adjustment is made to line coupling:
When a load is a complex impedance, and this is usually the case, it is necessary to eliminate the reactive component to adapt the transmission line to the load. For this purpose the coupling lines are used. Line coupling to a transmission line is but a further length of transmission line that connects between the threads of the primary line as close as possible to the load. For the adaptation line coupling lines are placed in open court. However, the lines are preferred short lines, because open lines tend to radiate, especially at higher frequencies. 36
describe domain reflectometry
time with it you can locate faults in transmission lines using the well-established theory of the effects of short lines and openings as the TDR works similar to a radar sends a signal of short duration.
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