The parameters of Transmission line are R = 50 Ω/ km, L= 1mH/km ,C = 0.1µf/km, G = 2µV/km. calculate characteristic impedance.
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 : A load of 200 ohm is used to match 300 ohm transmission line to achieve SWR=1. Find out the required characteristic impedance of a quarter of a quarter wave transformer connected directly to the load.
Last Answer : Solution :
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 : A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation constant
Last Answer : A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation 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 : 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 : 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 : 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 : 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 : What is the characteristic impedance of a single wire with a diameter d= 0.25 mm placed at the center between grounded parallel planes separated by 1 mm apart. The wire is held by a material with a velocity factor of 0.75. A. 85 Ω B. 63 Ω C. 50 Ω D. 75 Ω
Last Answer : D. 75 Ω
Description : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.
Last Answer : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.
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 : 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 : 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 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 : The input impedance of a short circuited loss less transmission line of characteristic impedance 50 Ohm is
Last Answer : Capacitive
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 : For a transmission line open circuit and short circuit impedances are 20 Ω and 5 Ω. Then characteristic impedance is: (1) 100 Ω (2) 50 Ω (3) 25 Ω (4) 10 Ω
Last Answer : For a transmission line open circuit and short circuit impedances are 20 Ω and 5 Ω. Then characteristic impedance is: 10 Ω
Description : What is the impedance of a balance 4-wire with a diameter of 0.25 cm and spaced 2.5 cm apart using an insulator with a dielectric constant of 2.56? A. 100Ω B. 65Ω C. 75 Ω D. 50 Ω
Last Answer : A. 100Ω
Description : Determine the conductance of a two-wire open line with the following parameters: D = 4 in., d = 0.1 in. and ρ = 2.6x108 Ω-m. A. 2.76x10-9 S/m B. 2.76x10-6 S/m C. 2.76x10-12 S/m D. 2.76x10-3 S/m
Last Answer : A. 2.76x10-9 S/m
Description : A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is: (1) 4000 Ω (2) 400 Ω (3) 40 Ω (4) 4 Ω
Last Answer : A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is: 400 Ω
Description : Define critical frequency w.r. to wave propagation.
Last Answer : Define critical frequency w.r. to wave propagation.
Description : A transmission line of 200 km has a certain A, B, C and D parameters. If the length is reduced to 60 km
Last Answer : A transmission line of 200 km has a certain A, B, C and D parameters. If the length is reduced to 60 km A increases, B decreases
Description : The charging reactance of 50 Km length of line is 1500Ω. The charging reactance for 100Km length of line will be (A) 1500 Ω (B) 3000 Ω (C) 750 Ω (D) 600 Ω
Last Answer : Ans: B Characteristic reactance per km = 1500/50 = 30 ohms ∴ Characteristic reactance per 100km = 30 x 100 = 3000 ohms
Description : The input terminal impedance at the center of a folded dipole antenna is A. 72 Ω B. 300 Ω C. 50 Ω D. 73 Ω
Last Answer : B. 300 Ω
Description : Most mobile satellite array uses ___________ in transforming 50 to 150 Ω impedance. A. stub B. balun C. quarter-wavelength transformer D. microstrip tapers.
Last Answer : C. quarter-wavelength transformer
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 : Why is the physical length of a coaxial cable transmission line shorter than its electrical length? A. Skin effect is less pronounced in the coaxial cable B. RF energy moves slower along the ... higher in the parallel feed line D. The characteristic impedance is higher in the parallel feed line
Last Answer : B. RF energy moves slower along the coaxial cable
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 : Referred to the dielectric constant of a transmission line material. A. Inductance and capacitance B. Velocity factor C. Characteristic impedance D. Propagation velocity
Last Answer : B. Velocity factor
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 : If the terminating impedance is exactly equal to the characteristic impedance of the transmission line the return loss is ___________. A. zero B. one C. infinite D. None of these
Last Answer : C. infinite
Description : In swept-frequency testing the impedance of a transmission line, what electrical characteristic is actually being measured?
Last Answer : Swr on the transmission line.
Description : Short-circuited stubs are preferred to open-circuited stubs because thelatter are a. more difficult to make an connect b. made of a transmission line with a different characteristic impedance c. liable to radiate
Last Answer : c. liable to radiate
Description : A transmission line is terminated at its characteristic impedance. The reflection coefficient is (a) 1 (b) –1 (c) 0 (d) ∞
Last Answer : A transmission line is terminated at its characteristic impedance. The reflection coefficient is 0
Description : Describe line of sight propagation in brief.
Last Answer : Line of sight propagation or Space wave propagation:- Explanation:- Space wave propagation of electromagnetic energy includes radiated energy that travels in the lower few miles of Earth's ... waves reflected by Earth's surface as they propagate between the transmit and receive antennas.
Description : Grid cables are 15 km long with a resistance of 0.20 Ω km-1, powers wasted as heat in these cables are A. 50 kW B. 60 kW C. 20 kW D. 30 kW
Last Answer : 30 kW
Description : The driving point impedance with poles at ω = 0(zero) and ω = ∞ (infinity) must have the (a) s term in the denominator and an excess term in the numerator (b) s term in the ... the numerator and denominator (d) s term in the denominator and equal number of terms in the numerator and denominator
Last Answer : The driving point impedance with poles at ω = 0(zero) and ω = ∞ (infinity) must have the s term in the denominator and an excess term in the numerator
Description : A receiver connected to an antenna whose resistance is 50 Ω has an equivalent noise resistance of 30Ω. Calculate its equivalent noise temperature if the noise figure is equal to 1.6. A. 17.4 K B. 174K C. 1.74K D. 17K
Last Answer : B. 174K
Description : Which of the following is not common transmission line impedance? A. 50 ohms B. 120 ohms C. 75 ohms D. 650 ohms
Last Answer : B. 120 ohms
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 : Define the following terms related to antennas; (i) Antenna resistance (ii) Directivity (iii) Antenna gain (iv) Power density
Last Answer : Antenna Resistance - The resistance of an antenna has two components: 1. Its radiation resistance due to conversion of power into electromagnetic waves 2. The resistance due to actual losses in the ... the transmitter power divided by the surface area of a sphere (4πR2) at that distance.
Description : Draw practical set-up and explain the procedure to measure selectivity of radio receiver.
Last Answer : Procedure to measure selectivity of radio receiver: Throughout the measurement the receiver is kept tuned to desired frequency 950 Khz. Now the generator output frequency is deviated below ... the generator output voltage is adjusted to get a standard 50 miliwatt receiver output power.
Description : Draw and label the circuit diagram of ratio detector
Last Answer : Draw and label the circuit diagram of ratio detector
Description : Draw the structure and state applications of: i) Ferrite loop (rod) antenna ii) Horn antenna
Last Answer : Horn antenna: Application:- i) Used at microwave frequency. ii) Used in satellite tracking. Ferrite loop antenna: Application:- In Am radio receiver to receive MW and SW band signals. In FM radio receiver
Description : State the need of stub. Explain single stub and double stub matching.
Last Answer : Stub:- Stub is the piece of short circuited transmission line which is used to tune out the reactance of the load when connected across the transmission line as close as possible. ... but lengths are independently adjustable. The double stub matching provides wide range of impedance matching.