Solution :
Description : How quarter wave transformer is used for impedance matching.
Last Answer : In all applications of transmission line, it is required that the load be matched to line, Which requires tuning out the unwanted load reactance and the transformation of resulting impedance to the required value ... Step down transformer If ZL <Zo then it acts as a Step up transformer
Description : a) For a transmission line, Find SWR and reflection coefficient R if, i. There is no reflected voltage. ii. Reflected voltage and incident voltage is equal. iii. If reflected voltage=20V and incident voltage=10V. iv. If reflected voltage=10V and incident voltage =20V.
Last Answer : reflection coefficient R=Vr/Vi i. There is no reflected voltage. i.e,Vr=0 R=0 SWR= 1+R/1-R=1 ii. Reflected voltage and incident voltage is equal. Vr=Vi; R=1 SWR= 1+R/1-R=1+1/1-1=infinity iii. If reflected ... and incident voltage =20V. Vr=10 and Vi=20 R=10/20=0.5 SWR= 1+R/1-R=1+.5/1-.5=3
Description : For a transmission line, the incident voltage. Ei = 6V and Er =2V ,Calculate: (i) Reflection Coefficient (ii) SWR
Last Answer : Reflection Coefficient(K) = Er / Ei = 2V / 6V K = 0.333 SWR = 1+K / 1- K = 1+0.333 / 1-0.333 = 1.333 / 0.667 SWR= 1.998
Description : The parameters of Transmission line are R = 50 Ω/ km, L= 1mH/km ,C = 0.1µf/km, G = 2µV/km. calculate characteristic impedance.
Last Answer : The parameters of Transmission line are R = 50 Ω/ km, L= 1mH/km ,C = 0.1µf/km, G = 2µV/km. calculate characteristic impedance.
Description : What is the input impedance of a transmission line if its characteristic impedance is 300 Ω and the load is 600 Ω? Assume a quarter wavelength section only. A. 150 kΩ B. 150 mΩ C. 150 Ω D. 2 Ω
Last Answer : C. 150 Ω
Description : The minimum impedance of a 75 ohm transmission line with a SWR of 2.5 is a) 100 b) 50 c) 25 d) 30
Last Answer : d) 30
Description : The maximum impedance of a 50 ohm transmission line with SWR of 3 is a) 50/3 b) 3/50 c) 150 d) 450
Last Answer : c) 150
Description : Draw waveform for standing waves on an open and shorted line. Prove that impedance is inverted at every quarter wavelength interval.
Last Answer : Waveform- Explanation When the transmission line is short circuited voltage is zero and current is maximum.The variation is according to the wavelength. When the ... The pattern repeats for every half wavelength. Thus impedance is inverted at every quarter wavelength interval.
Description : List and explain the properties of quarter wave transformer.
Last Answer : Properties of quarter wave transformer: 1. Impedance transfomation: it provides impedance transformation upto the highest frequencies and is compatible with transmission line. 2. Impedance inversion: if ZL is ... or step up transformer,depending on whether ZL IS greater than or less than ZO.
Description : A transmission line of unknown impedance is terminated with two different resistances, and an SWR is measured each time. With a 75 Ω termination, the SWR measures 1.5. With a 300 Ω termination, it measures 2.67. What is the impedance of the line? A. 100 Ω B. 212 Ω C. 300 Ω D. 112 Ω
Last Answer : D. 112 Ω
Description : Calculate the characteristics impedance for a transmission line having L=0.5 mH/Km, C=0.08 µF and negligible R and G.
Last Answer : L=0.5 mH/Km C=0.08 µF
Description : Find the standing wave ratio, when a load impedance of 250 ohm is connected to a 75 ohm line. a) 0.3 b) 75 c) 250 d) 3.33
Last Answer : d) 3.33
Description : Calculate characteristic impedance (Zo) for parallel and co-axial cables.
Last Answer : characteristic impedance for parallel cable characteristic impedance for co-axial cable Zo =Characteristic impedance D=Diameter of outer conductor d= Diameter of inner conductor E=Dielectric constant
Description : For transmission line, the incident voltage Ei = 6V, and Er = 3V. Calculate: (1) Reflection coefficient (2) Standing wave ratio
Last Answer : (1)Reflection coefficient (2) Standing wave ratio (1)Reflection coefficient Reflection coefficient R=Er/Ei =3/6 R=0.5 (2) Standing wave ratio SWR=Ei+Er/Ei-Er =6+3/6-3 SWR =3
Description : The lossless line of characteristics impedance 300 Ohm is terminated in a pure resistance of 200 Ohm. The value of the standing wave ratio is (a) 1.5 (b) 0.67 (c) 1.0 (d) 1.25
Last Answer : The lossless line of characteristics impedance 300 Ohm is terminated in a pure resistance of 200 Ohm. The value of the standing wave ratio is 1.5
Description : The input impedance of a short circuited loss less transmission line of characteristic impedance 50 Ohm is
Last Answer : Capacitive
Description : Transmission lines when connected to antenna have A. capacitive load B. resistive load whose resistance is less than characteristics impedance C. resistive load at the resonant frequency D. resistive load whose resistance is greater than the characteristic impedance of the line
Last Answer : C. resistive load at the resonant frequency
Description : What will be the reflection coefficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ? (a) Zero (b) Unity (c) Infinity (d) None of the above
Last Answer : (a) Zero
Description : Explain the use of baluns for impedance matching.
Last Answer : Balun stands for Balance to unbalance. It can also be used to connect the unbalanced transmission line to a balance load such as antenna. It consist of special type of transformer with an unbalanced primary ... matching. Its input is 300-75ohm. It consist of two quarter wave length.
Description : What is the meaning of the term velocity factor of a transmission line? A. The ratio of the characteristic impedance of the line to the terminating impedance B. The index of shielding for coaxial ... The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.
Last Answer : D. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.
Description : What is the meaning of the term velocity factor of a transmission line? A. The index of shielding for coaxial cable B. The velocity of the wave on the transmission line multiplied by the velocity of ... The velocity of the wave on the transmission line divided by the velocity of light in a vacuum
Last Answer : D. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum
Description : Define the transmission line? Draw it‟s general equivalent circuit.
Last Answer : Transmission line: A conductor or conductors designed to carry electricity or an electrical signal over large distances with minimum losses and distortion. Equivalent circuit:
Description : Draw general equivalent circuit of transmission line.
Last Answer : Fig. General Equivalent circuit of transmission line
Description : State and explain the losses in transmission line.
Last Answer : Losses in Transmission Line:- There are three ways in which energy, applied to a transmission may desperate before reaching the load. They are 1) Radiation Losses:- Its occurs when a ... down voltage of the dielectric insulator. Generally when corona occurs, the transmission line is destroyed.
Description : A 400/200 volts transformer has pu impedance of 0.05. The HV side voltage required to circulate full load current during short circuit test is
Last Answer : A 400/200 volts transformer has pu impedance of 0.05. The HV side voltage required to circulate full load current during short circuit test is 20 V
Description : When a transmission line has a load impedance same as that of the characteristic impedance, the line is said to be a) Parallel b) Perpendicular c) Polarized d) Matched
Last Answer : Ans: D
Description : The magnitude of the open-circuit and short circuit input impedance of a transmission line are 100 ohm and 25 ohm respectively. The characteristic impedance of line is: (1) 25 ohm (2) 50 ohm (3) 75 ohm (4) 100 ohm
Last Answer : The magnitude of the open-circuit and short circuit input impedance of a transmission line are 100 ohm and 25 ohm respectively. The characteristic impedance of line is 25 ohm.
Description : A single-phase transmission line of impedance j 0.8 ohm supplies a resistive load of 500 A at 300 V. The sending end power factor is?
Last Answer : A single-phase transmission line of impedance j 0.8 ohm supplies a resistive load of 500 A at 300 V. The sending end power factor is 0.6 lagging.
Description : Which of the following characterizes a properly terminated transmission line? A. The line loss is minimum. B. The standing wave ratio is minimum. C. The input impedance is twice the load impedance. D. The standing wave ratio is one.
Last Answer : D. The standing wave ratio is one.
Description : Termination means A. result of disconnecting a line from a transmitter B. result of cutting both ends of a conductor C. looking back impedance of a line with no load D. load connected to the output end of a transmission line
Last Answer : D. load connected to the output end of a transmission line
Description : Impedance inversionmaybe obtainedwith a. a short-circuited stub b. an open-circuited stub c. a quarter-wave line d. a half-wave line
Last Answer : c. a quarter-wave line
Description : State and explain the concept of transmission bandwidth.
Last Answer : Bandwidth is defined as the portion of the electromagnetic spectrum occupied by a signal We may also define the bandwidth as the frequency range over which as information signal is transmitted. Bandwidth is the ... to 15 KHZ. Therefore the bandwidth is(f2-f1) BW= f2 - f1= 15000-20=14980Hz
Description : Define critical frequency w.r. to wave propagation.
Last Answer : Define critical frequency w.r. to wave propagation.
Description : Explain virtual height with respect to wave propagation with neat sketch.
Last Answer : In ionization layer the incident wave refracts and bends down gradually than sharply. The incident and refracted rays follow paths that are exactly the same as they would have been if reflection had taken place from a surface located at a greater height called virtual height of this layer.
Description : Explain ground wave propogation with neat sketch.
Last Answer : Sketch- Explanationi) It consists of direct wave which travels near the ground from Transmitter to Receiver. ii) The electromagnetic wave leaves the transmitting antenna & remains close to earth surface ... . The ground wave is the path chosen when frequency in between 30 KHz & 3 MHz
Description : Compare ground wave propagation. Sky wave propagation and space wave propagation.
Last Answer : Sr. N o Parameter Ground Wave Propagation Sky Wave Propagation Space wave Propagation 1 Frequency Range 30 kHz to 3 MHz 3 MHz to 30 MHz frequencies above 30 MHz 2 ... These waves have line of sight propagation, ... 6 Fading Problem less Severe Less
Description : Why electromagnetic waves are said to be transverse wave ? Explain.
Last Answer : The electromagnetic waves are oscillations which propagate through free space. In electromagnetic waves the direction of electric field, magnetic field & propagation are mutually perpendicular. Hence electromagnetic waves are called as transverse wave.
Description : Define electromagnetic wave and polarization.
Last Answer : Electromagnetic wave:-An electromagnetic wave such as light consists of a coupled oscillating electric field and magnetic field which are always perpendicular; by convention Polarization:-polarization" of electromagnetic waves refers to the direction of the electric field.
Description : Describe the term virtual height with the help of diagram showing ionized layer and the path of wave.
Last Answer : Virtual height: -The incident wave returns back to the earth due to refraction. In this process it bends down gradually and not sharply, but the incident and reflected rays follow exactly ... . It is also defined as the maximum height that the hypothetical reflected wave would have reached.
Description : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.
Last Answer : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.
Description : Describe the effect of ionosphere on sky wave propagation.
Last Answer : The Ionosphere is the upper portion of the atmosphere. The ultra violet radiation from the sun will ionize the upper layer of the atmosphere. In this layer free electrons and positive and negative ions are ... layer. Its Frequency Range is from 3 MHz to 30 MHz Polarization: Vertical.
Description : Explain the transverse electromagnetic waves in wave propagation.
Last Answer : 1. The electromagnetic waves are oscillations, which propagate through free space. 2. Em wave travel in free space at the speed of light. 3. Figure shows the simple EM wave, in which the direction of ... electromagnetic waves (TEM). Diagram:- Transverse electromagnetic wave(TEM) OR
Description : Draw the radiation pattern for Dipole antenna: (i) Half wave dipole (ii) Folded dipole.
Last Answer : The radiation pattern for Half wave dipole antenna The radiation pattern for Folded dipole antenna.
Description : Explain the following in wave propagation: 1) Actual height 2) Virtual height
Last Answer : 1) Actual height:- The height attained by the wave during propagation through the ionosphere is known as Actual height. 2)Virtual height: -The incident wave returns back to the earth due to ... It is also defined as the maximum height that the hypothetical reflected wave would have reached.
Description : Define standing wave ratio.
Last Answer : Standing wave ratio is defined as the ratio of maximum voltage (Vmax) to minimum voltage (Vmin). Standing wave ratio is also defined as the ratio of maximum current (Imax) to minimum current (Imin).
Description : at the terminal of a three-phase 6.6Kv alternator a load R=200 ohm is connected between two-phase and the third phase is opened. Z1=z2=5 ohm Zo=2 find out the fault current .
Last Answer : 32A
Description : Explain standing waves with load terminal open circuited and short circuited.
Last Answer : Standing waves with load terminal open circuited Standing waves: The forward and reflected waves on the incorrectly terminated transmission line produce an interference pattern known as Standing ... , the load impedance will not be equal to the transmission line (characteristic)impedence.
Description : The standing wave ratio of a 75 Ω transmission line used to feed a 300 Ω resistive load will be _____.
Last Answer : The standing wave ratio of a 75 Ω transmission line used to feed a 300 Ω resistive load will be 4.
Description : A load with an impedance of 440 ohms is connected across the secondary of the transformer illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given
Last Answer : Answer: B
Description : The outer conductor of a coaxial transmission line is always grounded at the A. Input only B. Input and output C. Output only D. Point of high SWR
Last Answer : B. Input and output