1.
Coaxial lines are most suitable for............
Correct Answer
B. High frequency
Explanation
Coaxial lines are most suitable for high frequency because they have a central conductor surrounded by an insulating layer, which is further surrounded by a metallic shield. This design allows for efficient transmission of high frequency signals while minimizing interference and signal loss. The coaxial structure also provides good shielding against external electromagnetic interference, making it ideal for high frequency applications where signal integrity is crucial.
2.
Parallel wire lines characteristic impedance is
Correct Answer
A. 100 ohm to 300 ohm
Explanation
Parallel wire lines can have a characteristic impedance ranging from 100 ohms to 300 ohms. The characteristic impedance of a transmission line is the ratio of voltage to current in the line and is determined by the line's physical properties, such as its dimensions and the dielectric material between the wires. The range of 100 ohms to 300 ohms is commonly used for parallel wire lines in various applications.
3.
Transmission line have
Correct Answer
D. All of these
Explanation
The correct answer is "all of these" because a transmission line consists of resistance (R), inductance (L), and capacitance (C). These parameters are inherent to transmission lines and affect the behavior of the line. Resistance causes power losses, inductance affects the transmission line's impedance and can cause voltage drop, while capacitance affects the line's charging and discharging characteristics. Therefore, all three parameters are present in a transmission line.
4.
Quarter wave lines are used to match transmission lines with...........
Correct Answer
A. Antenna
Explanation
Quarter wave lines are used to match transmission lines with the antenna. Quarter wave lines are transmission lines that have a length equal to a quarter of the wavelength of the signal being transmitted. They are used to transform the impedance of the transmission line to match the impedance of the antenna, ensuring maximum power transfer between the two. By matching the impedance, the quarter wave line helps to minimize signal reflections and optimize the performance of the antenna system.
5.
A line without characteristics impedance termination have
Correct Answer
A. Reflected wave
Explanation
A line without characteristic impedance termination will result in a reflected wave. When a transmission line is not terminated properly with its characteristic impedance, the signal traveling through the line encounters an impedance mismatch at the end. This mismatch causes a portion of the signal to be reflected back towards the source, resulting in a reflected wave. This can lead to signal degradation and interference.
6.
Condition for a line to distortion less is
Correct Answer
A. L/C=R/G
Explanation
The condition for a line to be distortionless is when the ratio of inductance (L) to capacitance (C) is equal to the ratio of resistance (R) to conductance (G). This means that the impedance of the line remains constant and there is no distortion in the signal being transmitted.
7.
VSWR of a transmission lines is
Correct Answer
C. Equal to Zo and load impedance
Explanation
The VSWR (Voltage Standing Wave Ratio) of a transmission line is equal to the characteristic impedance (Zo) and the load impedance. This means that the VSWR is determined by the ratio of the characteristic impedance of the transmission line to the impedance of the load connected to it. A VSWR of 1:1 indicates a perfect match between the transmission line and the load, while higher VSWR values indicate a mismatch and can lead to signal reflections and power loss.
8.
VSWR of A TRANSMISSION LINE IS
Correct Answer
D. BETWEEN 1 AND ∞
Explanation
The VSWR (Voltage Standing Wave Ratio) of a transmission line is a measure of the mismatch between the impedance of the transmission line and the impedance of the load. A VSWR value of 1 indicates a perfect match, meaning that all the power is transferred from the source to the load without any reflections. However, in practical scenarios, there are always some reflections and mismatches, resulting in a VSWR greater than 1. A VSWR between 1 and ∞ signifies that there is some degree of mismatch and reflection in the transmission line.
9.
Higher value of SWR shows
Correct Answer
B. Mismatching between line and load is high
Explanation
A higher value of SWR indicates that there is a high level of mismatching between the line and the load. SWR, or Standing Wave Ratio, is a measure of how well the impedance of the transmission line matches the impedance of the load. A high SWR value suggests that there is a significant mismatch, which can result in poor signal transmission, power loss, and potential damage to the equipment.
10.
Condition for a low loss transmission line is
Correct Answer
C. R>> wC
Explanation
A low loss transmission line occurs when the resistance (R) is much greater than the product of the angular frequency (w) and the capacitance (C). This means that the resistance dominates the losses in the transmission line, resulting in minimal power loss during transmission.
11.
From following which is high frequency transmission lines
Correct Answer
D. All of these
Explanation
All of the options mentioned - coaxial cable, open wire, and twin lead - are examples of high frequency transmission lines. Coaxial cable consists of a central conductor surrounded by an insulating layer and an outer conductor, which provides better shielding against interference. Open wire transmission lines have two parallel conductors with insulators holding them apart, allowing for high frequency signals to be transmitted. Twin lead transmission lines also have two parallel conductors, but they are usually closer together and have a different type of insulation. Therefore, all of these options can be used for high frequency transmission.
12.
Equations of phage velocity of a transmission lines is
Correct Answer
A. V=1 ⁄ √LC
Explanation
The equation of phage velocity of a transmission line is v=1/√LC. This equation represents the relationship between the velocity (v) of a phage (a type of virus) and the inductance (L) and capacitance (C) of the transmission line. The inverse square root of the product of L and C is used to calculate the velocity, indicating that the velocity is inversely proportional to the square root of the product of the inductance and capacitance.
13.
Which is a vector quantity
Correct Answer
B. Reflection coefficient
Explanation
The reflection coefficient is a vector quantity because it has both magnitude and direction. It represents the ratio of the amplitude of the reflected wave to the amplitude of the incident wave. The reflection coefficient can be positive or negative, indicating whether the wave is reflected in the same direction or opposite direction as the incident wave. Therefore, it possesses both magnitude and direction, making it a vector quantity.
14.
Secondary constants of a transmission lines are
Correct Answer
A. α,β,Z₀
Explanation
The secondary constants of a transmission line refer to the parameters that characterize the line's behavior. α and β are the attenuation and phase constants, respectively, which determine how the signal is attenuated and phase-shifted as it travels along the line. Z₀ represents the characteristic impedance of the line, which is the ratio of voltage to current in a wave propagating through the line. Therefore, the correct answer is α, β, Z₀ as these constants are essential in understanding and analyzing the transmission line's characteristics.
15.
Condition for a loss less transmission line is
Correct Answer
B. Z₀=√ L/C
Explanation
The condition for a lossless transmission line is given by Z₀=√ L/C. This equation represents the characteristic impedance of the transmission line, where Z₀ is the characteristic impedance, L is the inductance per unit length of the line, and C is the capacitance per unit length of the line. This condition ensures that there is no loss of power during transmission, as the characteristic impedance matches the impedance of the source and load.
16.
Correct equation of VSWR is
Correct Answer
A. VSWR=1+K/1-K
Explanation
The correct equation for VSWR is VSWR=1+K/1-K. This equation represents the Voltage Standing Wave Ratio, which is a measure of how well a transmission line is matched to the impedance of the connected load. The numerator 1+K represents the maximum voltage amplitude on the line, while the denominator 1-K represents the minimum voltage amplitude. The ratio of these two values gives the VSWR, with values greater than 1 indicating a mismatch and values equal to 1 indicating a perfect match.
17.
A simplest standing wave induced when reflection coefficient is
Correct Answer
A. 1
Explanation
When the reflection coefficient is 1, it means that all of the incident wave is reflected back with the same amplitude. This creates a standing wave where the crests and troughs of the incident and reflected waves align perfectly, resulting in a stationary pattern. The amplitude of the standing wave remains constant at all points along the medium, creating a stable and simplest standing wave.
18.
Definition of VSWR is
Correct Answer
A. E max / E min
Explanation
The correct answer is "E max / E min" because VSWR (Voltage Standing Wave Ratio) is a measure of how efficiently a transmission line is transferring power from the source to the load. It is defined as the ratio of the maximum voltage amplitude (E max) to the minimum voltage amplitude (E min) along the transmission line. By calculating this ratio, we can determine the level of mismatch between the impedance of the transmission line and the load impedance.
19.
If Zo=characteristics impedance,Zsc=input impedance when line is terminated in short circuitZoc=input impedance when line is terminated in open circuit then
Correct Answer
B. Zo=√ZscZoc
Explanation
The given equation, Zo=√ZscZoc, is the correct answer. It represents the characteristic impedance (Zo) of a transmission line, which can be calculated by taking the square root of the product of the input impedance (Zsc) and the open circuit impedance (Zoc). This equation is derived from the properties of transmission lines and is used to determine the impedance matching required for optimal signal transfer.
20.
Mismatch between load and transmission lines known as
Correct Answer
C. Reflection coefficient
Explanation
A mismatch between load and transmission lines is known as the reflection coefficient. When there is a mismatch, some of the signal power is reflected back towards the source instead of being transmitted to the load. The reflection coefficient quantifies the magnitude of this reflection, indicating the extent of the mismatch. It is an important parameter in understanding and analyzing the performance of transmission lines and ensuring efficient power transfer.
21.
Q of transmission line is equal to
Correct Answer
C. WL/R
Explanation
The value of Q (quality factor) in a transmission line is determined by the product of the angular frequency (w), the inductance (L), and the resistance (R) of the line. Therefore, the correct answer is wL/R, as it represents the correct formula for calculating the quality factor of a transmission line.
22.
Best method of coupling a coaxial cable with a parallel wire is
Correct Answer
B. Balun
Explanation
A balun is the best method of coupling a coaxial cable with a parallel wire. A balun, short for balanced-unbalanced, is a device that converts between balanced and unbalanced signals. In this case, it would convert the unbalanced coaxial cable signal to a balanced signal that can be used with the parallel wire. This allows for efficient and accurate transmission of signals between the two different types of transmission lines.
23.
For a good conductors ,constants relationship is
Correct Answer
A. α=β=√wμσ/2
Explanation
The correct answer is α=β=√wμσ/2. This relationship represents the constants α and β, which are related to the conductivity of a material. The equation includes the variables w, μ, and σ, which stand for the angular frequency, permeability, and conductivity respectively. By taking the square root of wμσ/2, we find that α and β are both equal to this value. Therefore, this equation accurately describes the relationship between the constants for a good conductor.
24.
For a transmission line Zoc=20 ohm and Zsc=5 OHM then Zo will be
Correct Answer
C. 10 ohm
Explanation
The characteristic impedance (Zo) of a transmission line is given by the square root of the product of the open-circuit impedance (Zoc) and the short-circuit impedance (Zsc). In this case, Zoc = 20 ohm and Zsc = 5 ohm. Therefore, Zo = sqrt(20 ohm * 5 ohm) = sqrt(100 ohm) = 10 ohm.
25.
If VSWR=2 then reflection coefficient will be,,,
Correct Answer
D. 1/2
Explanation
The reflection coefficient is a measure of the amount of power that is reflected back from an impedance mismatch in a transmission line. VSWR (Voltage Standing Wave Ratio) is a related parameter that describes the ratio of the maximum voltage to the minimum voltage in a standing wave pattern on the transmission line. The relationship between VSWR and reflection coefficient is given by the equation VSWR = (1 + |Γ|) / (1 - |Γ|), where Γ is the reflection coefficient. Given that VSWR = 2, we can rearrange the equation to solve for |Γ|, which gives us |Γ| = (VSWR - 1) / (VSWR + 1). Substituting VSWR = 2, we find |Γ| = 1/3. Since the reflection coefficient is the magnitude of Γ, the correct answer is 1/3.