COGNITIONIS#5 BATCH-1

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