WorksheetsCOGNITIONIS#5 BATCH-1
Total questions: 20
Worksheet time: 10mins
Parabolic and lens antennas are extensively used for
shortwaves
medium frequency waves
microwaves
all of the above
If the antenna increases 3.5 times, how much does the radiated power increase?
7.0 times
6.6 times
3.5 times
12.25 times
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
End fire array
Critical phased array
broadband array
wideband array
The solid area through which all the power radiated by the antenna is:
Beam area
Effective area
Aperture area
Beam efficiency
Which among the following defines the angular distance between two points on each side of major lobe especially when the radiation drops to zero?
Half power beam width
First null beam width
Side lobe level
Front to back ratio
Among the following which one is a nonresonant antenna?
The folded dipole
The rhombic antenna
The end-fire array
The broadside array
An antenna “efficiency” is computed by using one of the following equations:
Efficiency = (radiation resistance / transmission resistance)
Efficiency = (total resistance / radiation resistance) x 100%
Efficiency = (effective radiated power / transmitter output) x 100%
Efficiency = (radiation resistance / total resistance) x 100%
The antenna efficiency of an HF grounded vertical antenna can be made comparable to that of a half-wave antenna
By installing a good ground radial system
By isolating the coax shield from ground
By shortening the vertical
By lengthening the vertical
For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce the most effective performance?
As low as possible on the vertical radiator
Near the center of the vertical radiator
As close to the transmitter as possible
At a voltage node
A Hertz antenna is operating on a frequency of 2182 kHz and consists of a horizontal wire that is hanged between two towers. What is the frequency of its third harmonic?
727.3 kHz
6546 kHz
6.546 kHz
1091 kHz
Determine the length of an antenna operating at a frequency of 500 kHz? (Velocity factor is 0.95)
600m
570m
595m
800m
How will you increase the gain of an antenna?
By adding several antennas in parallel
By focusing the radiated energy in one desired direction
By making antenna rods thicker
By making the antenna size larger
Lightning rods must be mounted a top structure not less than _ above the highest point.
40 cm
20 cm
30 cm
10 cm
An antenna has a field pattern of E (θ) = cos2θ, θ varies between 0 and 90. Half power beam width of the antenna is:
45
22.5
90
None of the mentioned
Which of the following is not a near field wireless power transfer?
Inductive coupling
Magnectic resonant coupling
RF based wpt
Capacitive coupling
At what frequency does Qi Wireless Charging work?
100-200 kHz
150-400 kHz
90-200 kHz
80 - 300 kHz
The transfer function of an RF oscillator is given by:
A/ (1-AH (ω))
A/ (1+AH (ω))
A/ (-1+AH (ω))
1/ (1-AH (ω))
Which is a non-linear circuit that converts DC power to an AC waveform of desired frequency based on the oscillator design.
Attenuator
Amplifier
Oscillator
None of the mentioned
The criterion on which oscillations are produced in the oscillator circuit is called:
Shannon’s criteria
Barkhausen criteria
Colpitts criteria
None of the mentioned
The voiced speech of a typical adult male will have a fundamental frequency from ___, and that of a typical adult female from ____
165 to 255 Hz, 80Hz to 150Hz
80 to 150 Hz, 155 to 245 Hz
85 to 180 Hz, 165 to 255 Hz
155 to 245 Hz, 85 to 180 Hz
