Description : Fortransmission-line loadmatchingover a range offrequencies,itisbesttouse a a. balun b. broadband directional coupler c. double stub d. single stub of adjustable position
Last Answer : c. double stub
Description : To couple a coaxialline toa parallel-wire line,itisbesttouse a a. slotted line b.balun c. directional coupler d. quarter-wave transformer
Last Answer : b.balun
Description : Themaindisadvantage ofthe two-hole directional coupleris a. low directional coupling b. poor directivity c. high SWR d.narrowbandwidth
Last Answer : d.narrowbandwidth
Description : The output from a full wave rectifier is (a) A pulsating uni-directional current (b) A DC voltage (c) Zero (d) An AC voltage
Last Answer : a) A pulsating uni-directional current
Description : _________ utilization is the useof availablebandwidthto achieve specificgoals. A) Frequency B) Bandwidth C) Amplitude D) None of the abov
Last Answer : Bandwidth
Description : What is the meaning of earthing in a ship?
Last Answer : Ask E/O
Description : Zoningis usedwith adielectric antenna inorderto a. reduce the bulk of the lense b. increase the bandwidth of the lens c. increase pin-point focusing d. correct the curvature of the wavefront from a horn that is too short
Last Answer : a. reduce the bulk of the lense
Description : Top loadingissometimesusedwithan antenna in ordertoincrease its a. effective height b. bandwidth c. beamwidth d. input capacitance
Last Answer : a. effective height
Description : The standard reference antenna forthe directive gain isthe a. infinitesimal dipole b. isotropic antenna c. elementary doublet d. half-wave dipole
Last Answer : b. isotropic antenna
Description : Indicatewhich one ofthe followingreasonsforthe use of a groundscreenwith antennasisfalse: a. Impossibility of a good ground connection b. Provision of an earth for the antenna c.Protectionofpersonnelworkingunderneath d. Improvement of the radiation pattern of the antenna
Last Answer : c.Protectionofpersonnelworkingunderneath
Description : Indicate the antenna thatisnotwideband: a. Discone b. Folded Dipole c. Helical d. Marconi
Last Answer : d. Marconi
Description : One ofthe followingis not a reason forthe use of anantenna 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 reradiation of the local oscillator
Last Answer : d. To prevent reradiation of the local oscillator
Description : Indicatewhich ofthe followingreasonsfor usinga counterpoisewith antenna isfalse: a. Impossibility of a good ground connection b.Protectionofpersonnelworkingunderground c. Provision of an earth for the antenna d. Rockiness of the ground
Last Answer : b.Protectionofpersonnelworkingunderground
Description : One ofthe followingconsistsof nonresonant antennas: a.The rhombic antenna b. The folded dipole c. The end-fire array d. The broadside array
Last Answer : a.The rhombic antenna
Description : Anungrounded antennanearthe ground a. acts as a single antenna of twice the height b. is unlikely to need a ground screen c. acts as anantennaarray d. must be horizontally polarized
Last Answer : c. acts as anantennaarray
Description : A disadvantage of using a trap antenna. A. It will radiate harmonics B. It can only be used for single-bad operation C. It is too sharply directional at lower frequencies D. It must be neutralized
Last Answer : A. It will radiate harmonics
Description : The purpose of stacking elements on an antenna. A. Sharper directional pattern B. increased gain C. Improved bandpass D. All of these
Last Answer : D. All of these
Description : ______ is an antenna array which is highly directional at right angles to the plane of the array? A. Broadside array B. End-fire array C. Turnstile array D. Log-periodic array
Last Answer : A. Broadside array
Description : _____ is an antenna with a number of half-wave antenna on it. A. Antenna array B. Tower C. Omni-directional D. Rhombic
Last Answer : A. Antenna array
Description : What is a dummy antenna? A. One which is used as a reference for gain measurements B. And antenna used for hand-held radio C. An non-directional transmitting antenna D. A non-radiating load for a transmitter used for testing
Last Answer : D. A non-radiating load for a transmitter used for testing
Description : Radio wave concentration in the direction of the signal emitted by a directional antenna. A. Back lobe radiation B. Side lobe radiation C. Major lobe radiation D. Transmitted signal
Last Answer : C. Major lobe radiation
Description : The polarization of a discone antenna is _____. A. Horizontal B. Vertical C. Omni D. Directional
Last Answer : B. Vertical
Description : If the current ratios of the two or more elements must be held 5% and the phase angle to 3° the antenna is called a A. end fire array B. critical phased array C. broadband array D. wideband array
Last Answer : B. critical phased array
Description : Space diversity transmission means transmitting and receiving on _______. A. Two or more antennas operating on two different frequencies B. Two or more identical frequencies C. Two or more antennas operating on the same frequency D. Two or more different frequency
Last Answer : C. Two or more antennas operating on the same frequency
Description : Two or more antennas separated by 9 wavelengths are used. A. Hybrid diversity B. Space diversity C. Polarized diversity D. Frequency diversity
Last Answer : B. Space diversity
Description : The best solution to fading is _____. A. space diversity B. frequency diversity C. polarization diversity D. wavelength diversity
Last Answer : A. space diversity
Description : What is the method of diversity reception where the signal is transmitted on 2 different frequencies over the same path? A. Quadruple B. Frequency C. Polarization D. Space
Last Answer : B. Frequency
Description : Mobile Commerce is best described as– (A) The useof Kiosks in marketing (B) Transporting products (C) Buyingand selling goods/services through wirelesshandhelddevices (D) Using notebook PC's in marketing (E) None of the above
Last Answer : Buyingand selling goods/services through wirelesshandhelddevices
Description : A devicethat connects toa network without the useof cables is said to be– (A) distributed (B) free (C) centralized (D) open source (E) None of these
Last Answer : free
Description : White smoke coming out of the chimney of a furnace indicates the useof (A) Low excess air (B) Very high excess air (C) Gaseous fuel in the furnace (D) Liquid fuel in the furnace
Last Answer : (B) Very high excess air
Description : Which is the most suitable power device for high frequency ( more 100 kHz) switching application? a) Power MOSFET b) BJT c) SCR d) UJT
Last Answer : Ans: Power MOSFET
Description : Why is it necessary that incoming alternator frequency is more than bus bar?
Last Answer : Prior to paralleling alternators together, the frequency of the incoming alternator is made slightly higher. This is to ensure that the incoming generator will take some of the bus load. If the incoming ... onto the bus. If this happens it is possible to cause other generators to trip off line.
Description : The absorption ofradiowaves bythe atmosphere depends on a. their frequency b. their distance from the transmitter c. the polarization of the waves d. the polarization of the atmosphere
Last Answer : a. their frequency
Description : Arange ofmicrowave frequenciesmore easilypassed bythe atmospherethan are theothersis called a a.window b. critical frequency c. gyro frequency range d. resonance in the atmosphere
Last Answer : a.window
Description : Distancesnearthe skip distance should beused forthe sky-wave propagation a. to avoid tilting b.topreventsky-wave andupper rayinterference c. to avoid the Faraday effect d. so as nor to exceed the critical frequency
Last Answer : b.topreventsky-wave andupper rayinterference
Description : Even though the main engine runs at varying speeds, how does the alternator maintain constant frequency?
Last Answer : By use of thyristor controlled frequency (rpm) converters.
Description : The minimum frequency required to eject electrons from a metallic surface is called a) Critical frequency b) Peak value of frequency c) Threshold frequency d)Photo frequency
Last Answer : c) Threshold frequency
Description : The minimum energy required to eject an electron from a metal surface is called a) Intensity b) Threshold frequency c) Work function d) Photo energy
Last Answer : c) Work function
Description : Silicon transistors are preferred because: (a) High operating temperature (b) Low leakage current (c) Suited to high frequency circuits (d) All
Last Answer : (d) All
Description : Can you guys explain the advantages of frequency converter against the star delta or soft starter?
Last Answer : ¬Soft starters A soft starter is, as you would expect, a device which ensures a soft starting of a motor. A softstarter has different characteristics to the other starting ... at rated current from zero to full speed. Frequency converters are becoming cheaper all the time.
Description : Substances which have permeability less than the permeability of free space are known as (a) ferromagnetic (b) paramagnetic (c) diamagnetic (d) bipolar
Last Answer : (c) diamagnetic
Description : As electromagneticwavestravelinfree space, onlyone ofthefollowingcan happento them: a. absorption b. attenuation c. refraction d. reflection
Last Answer : b. attenuation
Description : Tick the wrong statement. a) Velocity of light is independent of the motion of the observer. b) Velocity of light in free space is the same in all directions. c) Velocity of light in free space is different in different directions. d) Absolute motion or absolute rest is meaningless to talk about
Last Answer : c) Velocity of light in free space is different in different directions
Description : The space around the charge within which other charges are influenced by it is called: (a) Electric field (b) Magnetic field (c) Electric flux (d) Electric intensity
Last Answer : a) Electric field
Description : The value of permitivity of free space: (a) 8.85 × 10−12 C2/Nm2(b) 8.85 × 10−12 C2m2/N (c) 8.85 × 10−12 Nm2/C (d) 8.85 × 10−11 Nm2/C2
Last Answer : a) 8.85 × 10−12 C2/Nm2
Description : Part of a microwave link can be approximated by free space conditions. The antenna gain are each 40 dB, the frequency is 10 GHz, and the path length is 80 km. Calculate the receive power for a transmitted power of 10 W? A. 0.871 μW B. 871 μW C. 0.871 mW D. 871 nW
Last Answer : A. 0.871 μW
Description : Space diversity transmission means transmitting and receiving on A. two or more antennas operating on two different frequencies B. two or more identical frequencies C. two or more different frequencies D. two or more antennas operating on the same frequencies
Last Answer : D. two or more antennas operating on the same frequencies
Description : A one-hop, full duplex, microwave system in a space diversity arrangement. Determine “how many receivers in all are used?” A. 8 B. 2 C. 4 D. 6
Last Answer : B. 2
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Description : Paramagnetic materials have relative permeability (a) slightly less than unity (b) equal to unity (c) slightly more than unity (d) equal to that ferromagnetic mate rials
Last Answer : (c) slightly more than unity