Description : In transmission line, which of the following is the first step in the procedure of using stub matching? A. Calculate stub susceptance. B. Calculate load admittance C. Connect stub to load D. Transform conductance to resistance
Last Answer : B. Calculate load admittance
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 : Which of the following is and impedance matching ration of coax balun? A. 2:8 B. 1:2 C. 4:1 D. 2:1
Last Answer : C. 4:1
Description : Known as the technique for adding a series inductor at or near the center of an antenna element in order to cancel the capacitive reactance of an antenna. A. Dipole B. Center loading C. Reflector D. loading coil
Last Answer : D. loading coil
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.
Description : What is stub? What do you mean by single stub matching.
Last Answer : Stub is a 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. Single Stub Matching : ... The single stub match is perhaps the most widely used matching circuit and can match any load.
Description : Not a reason for the use of an antenna coupler. A. To make the antenna look resistive B. To provide the output amplifier with the correct load impedance C. To discriminate against harmonics D. To prevent re-radiation of the local oscillator
Last Answer : D. To prevent re-radiation of the local oscillator
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 : A shunt-fed quarter-wavelength Marconi antenna A. has maximum RF impedance to ground at its feedpoint B. has a current null at its feedpoint C. has a zero DC resistance to ground D. has zero RF resistance to ground
Last Answer : C. has a zero DC resistance to ground
Description : A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, ... at the feed-point? A. 4.0 A B. 2.2 A C. 1.25 A D. 2.0 A
Last Answer : D. 2.0 A
Description : Calculate the noise figure of the receiver whose RF amplifier has an input resistance of 1000Ω and an equivalent shot-noise resistance of 2000Ω, a gain of 25 and load resistance of 125 kΩ. Given that the bandwidth is 1. ... to an antenna with an impedance of 75Ω. A. 30.3 B. 3.03 C. 303 D. .303
Last Answer : A. 30.3
Description : What is the input terminal impedance at the center if a folded dipole antenna? A. 300 ohms B. 72 ohms C. 50 ohms D. 450 ohms
Last Answer : A. 300 ohms
Description : What is included in the total resistance of an antenna system? A. Radiation resistance plus space impedance B. Radiation resistance plus transmission resistance C. Transmission line resistance plus radiation resistance D. Radiation resistance plus ohmic resistance
Last Answer : D. Radiation resistance plus ohmic resistance
Description : What is meant by the term radiation resistance for an antenna? A. The resistance in the trap coils to received signal B. An equivalent resistance that would dissipate the same amount of power as ... antenna C. The specific impedance of the antenna D. Losses in the antenna elements and feed line
Last Answer : B. An equivalent resistance that would dissipate the same amount of power as that radiated from an antenna
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 : 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 : What is meant by referring to electromagnetic waves as having circular polarization? A. The electric field is bent into a circular shape. B. The electric field rotates C. The electromagnetic wave continues to circle the earth D. The electromagnetic wave has been generated by a quad antenna
Last Answer : B. The electric field rotates
Description : Best description of a collinear and broadside antenna radiation pattern. A. Bidirectional B. Perfect circle C. Unidirectional D. Omnidirectional
Last Answer : A. Bidirectional
Description : The method of determining the bandwidth of any processing system is ______. A. Bandwidth analysis B. Frequency spectrum C. Spectral analysis D. Frequency analysis
Last Answer : C. Spectral analysis
Description : Which frequency reuse method is less effective because of Faraday’s effect? A. Dual polarization B. Reducing antenna beamwidth C. Zonal rotation D. Spin stabilization
Last Answer : A. Dual polarization
Description : Decreasing the frequency in a capacitive circuit while maintaining a constant circuit voltage, will result in a/an _____________. A. increase in apparent power B. decrease in circuit current C. decrease in capacitive reactance D. decrease in total impedance
Last Answer : Answer: B
Description : The combined effect of inductive reactance, capacitive reactance, and resistance in an AC series circuit is known as _____________. A. reactance B. total reactance C. impedance D. resonance
Last Answer : Answer: C
Description : The ratio of the effective value of the counter EMF in volts, to the effective value of the current in amperes is called _____________. A. impedance factor B. capacitive reactance C. inductive reactance D. root mean square
Description : Give equivalent resistance, reactance and impedance referred to secondary circuit.
Last Answer : Req = R2 +R1' = R2+ R1'/a² Xeq = X2 +X1' = X2+ X1'/a² Zeq = Z2 + Z1' = Z2+ Z1'/a² where a=T1/T2
Description : Give equivalent resistance, reactance and impedance referred to primary circuit.
Last Answer : Req = R1 +R2' = R1+a² R2' Xeq = X1 +X2' = X1+a² X2' Zeq = Z1 +Z2' = Z1+a² Z2' where a=T1/T2
Description : What is impedance and reactance diagram?
Last Answer : The impedance diagram is the equivalent circuit of power system in which the various components of power system are represented by their approximate equivalent circuits. The impedance diagram is ... ddiagram can be obtained from impedance diagram if all the resistive components are neglected.
Description : Distance relays are generally (a) split-phase relays (b) reactance relays (c) impedance relays (d) none of the above
Last Answer : (d) none of the above
Description : relay is preferred for phase fault on short transmission line. (a) Induction type (b) Reactance (c) Impedance (d) None of the above
Last Answer : (b) Reactance
Description : relays are used for phase faults on long line. (a) Impedance (b) Reactance (c) Either of the above (d) None of the above
Last Answer : (a) Impedance
Description : Relays can be designed to respond to changes in (a) resistance, reactance or impedance (b) voltage and current (c) light intensity (d) temperature (e) all above
Last Answer : (e) all above
Description : In a series-RLC circuit, what is the condition of the circuit if there is high impedance, low current, and low reactance voltages
Last Answer : Nonresonant (circuit is either above or below resonance)
Description : Which of the following relays is used on long transmission lines ? (a) Impedance relay (b) Mho's relay (c) Reactance relay (d) None of the above
Last Answer : (b) Mho's relay
Description : Two transformers operating in parallel will share the load depending upon their (A) Rating. (B) Leakage reactance. (C) Efficiency. (D) Per-unit impedance.
Last Answer : Ans: A Transformers having higher kVA rating will share more load.
Description : Define: (i) Inductive reactance (ii) Impedance.
Last Answer : i) Inductive reactance: Inductive reactance is the opposition offered by an inductor to alternating current . It is denoted by XL and given by XL = 2πf LΩ = ωL Ω ii)Impedance: It is the total opposition offered to flow of AC current in an AC circuit. It is denoted by Z and the unit is ohm.
Description : In AC Circuit Theory, the term that replaces the resistance is: w) inductance x) capacitance y) impedance z) reactance
Last Answer : ANSWER: Y -- IMPEDANCE
Description : Define impedance diagram and reactance diagram.
Last Answer : Impedance diagram: Impedance diagram is the simplified equivalent circuits of single line or one line diagrams of power system in which all components are represented by their equivalent circuit. ... machines are neglected and is used only for fault current calculation is called reactance diagram.
Description : A loss less line of characteristic impedance Z0 is terminated in pure reactance of –jZ0 value. VSWR is (1) 10 (2) 2 (3) 1 (4) Infinity
Last Answer : A loss less line of characteristic impedance Z0 is terminated in pure reactance of –jZ0 value. VSWR is Infinity.
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 : Emitter follower is used for (a) reducing the gain (b) increasing the distortion (c) impedance matching (d) none of these
Last Answer : (c) impedance matching
Description : Explain impedance matching of PA system.
Last Answer : Impedance Matching of PA system:- (i) It is necessary to match the total loudspeaker impedance with the output impedance of the power amplifier. It will ensure maximum power transfer to the ... total impedance of speaker unit, then it can cause excessive power dissipation, distortion and noise.
Description : Identify type of BJT configuration having following features : (i) BJT configuration having the least current gain. (ii) KIT configuration called as voltage follower. (iii) BJT ... configuration suitable for voltage amplification. (vi) BJT configuration having the least output impedance.
Last Answer : (i) BJT configuration having the least current gain : Common Base Configuration (ii) KIT configuration called as voltage follower: Common Collector Configuration (iii) BJT ... Emitter Configuration (vi) BJT configuration having the least output impedance: Common Collector Configuration
Description : What is the reactance property at the input of a shorted quarter wavelength line? A. A parallel LC circuit B. A pure inductive reactance C. A series LC circuit D. A pure capacitive reactance
Last Answer : A. A parallel LC circuit
Description : What is the formula for determining total reactance in a series circuit where the values of XC and XL are known?
Last Answer : X = XL – XC or X = XC - XL
Description : Besides a method of trial and error, which of the following methods is employed for solution of network problems in interconnected system ? (a) Circulating current method (b) Thevenin's theorem (c) Superposition of currents (d) Direct application of Kirehhoffs laws (e) All of the above
Last Answer : (e) All of the above
Description : The trial and error method of learning according to Thorndike could be classified as under Options: A) The principle of multiple responses B) The law of exercise C) The principle of partial activity D) The principle of Associative learning
Last Answer : B) The law of exercise
Description : The perimeter of Smith chart is (A) Quarter wavelength (B) Half wavelength (C) Wavelength (D) Three quarter wavelength
Last Answer : The perimeter of Smith chart is Half wavelength
Description : Mark incorrect correct option a) Trial card used for the purpose of determining the relative advantage of alternative mail routes or the cause of detention to articles b) Trial cards are red colour c) Trial card should not be included in any station bundle d) All of these
Last Answer : d) All of these
Description : Transcription centre is a cell established in a) All administrative offices b) All HOs c) All ROs d) A sorting mail office situated at HQ of the circle or at any convenient sorting office in the circle.
Last Answer : d) A sorting mail office situated at HQ of the circle or at any convenient sorting office in the circle.
Description : Pick up the correct statement from the following: (A) To locate a gross error in bearing that may exist in controlled theodolite traverse, we may plot the traverse from each end. The traverse station having ... the same as that of the leg in which the gross error consists (D) All the above
Last Answer : (D) All the above