Deck 1: Antennas and Frequency Multipliers

Question 1

The major drawback of frequency multipliers is that they have:

A)higher attenuation
B)complex construction methods
C)complex design
D)none of the mentioned

Answer 1

complex design

Question 2

Oscillators operating at millimeter wavelength are difficult to realize and are also less efficient.

Answer 2

True

Question 3

A major disadvantage of frequency multipliers is that they multiply the noise factor along with frequency.

Answer 3

True

Question 4

If a frequency multiplier has a multiplication factor of 10, then the increase in noise level due to frequency multiplication is:

A)10 db
B)20 db
C)25 db
D)15 db

Question 5

In a diode frequency multiplier, an input signal of frequency fo applied to the diode is terminated with__________at all frequencies other than required harmonic.

A)real impedances
B)reactive impedance
C)complex impedance
D)none of the mentioned

Question 6

Resistive multipliers are more efficient as compared to reactive multipliers.

Question 7

Reactive multipliers have a disadvantage that they cannot be used at very high frequencies and they become less efficient.

Question 8

For a resistive frequency multiplier of multiplication factor 2, the maximum theoretical conversion efficiency is:

A)50 %
B)25 %
C)75 %
D)12.5 %

Question 9

__________is a device that converts electrons to photons or vice-versa.

A)antenna
B)electron gun
C)photon amplifier
D)microwave tube

Question 10

The basic equation of radiation that is applied to any antenna irrespective of the type of the antenna is:

A)il= qv
B)iq = lv
C)i/l=q/v
D)none of the mentioned

Question 11

The number of patterns radiation pattern required to specify the characteristic are :

A)three
B)four
C)two
D)five

Question 12

The beam width of the antenna pattern measured at half power points is called:

A)half power beam width
B)full null beam width
C)beam width
D)none of the mentioned

Question 13

An antenna has a field pattern E (?) =cos ?. cos 2?. The first null beam width of the antenna is:

A)450
B)900
C)1800
D)1200

Question 14

The solid area through which all the power radiated by the antenna is:

A)beam area
B)effective area
C)aperture area
D)beam efficiency

Question 15

A __________  is a device that converts a guided electromagnetic wave on a transmission line into a plane wave propagating in free space.

A)transmitting antenna
B)receiving antenna
C)radar
D)mixer

Question 16

Dipole antennas are an example for:

A)wire antennas
B)aperture antennas
C)array antennas
D)none of the mentioned

Question 17

__________antennas consist of a regular arrangement of antenna elements with a feed network

A)aperture antennas
B)array antennas
C)printed antennas
D)wire antennas

Question 18

A parabolic reflector used for reception with the direct broadcast system is 18 inches in diameter and operates at 12.4 GHz. The far-field distance for this antenna is:

A)18 m
B)13 m
C)16.4 m
D)17.3 m

Question 19

__________of an antenna is a plot of the magnitude of the far field strength versus position around the antenna.

A)radiation pattern
B)directivity
C)beam width
D)none of the mentioned

Question 20

Antennas having a constant pattern in the azimuthal plane are called __________        

A)high gain antenna
B)omnidirectional antenna
C)unidirectional antenna
D)low gain antenna

Question 21

Beamwidth and directivity are both measures of the focusing ability of an antenna.

Question 22

If the beam width of an antenna in two orthogonal planes are 300 and 600. Then the directivity of the antenna is:

A)24
B)18
C)36
D)12

Question 23

If the power input to an antenna is 100 mW and if the radiated power is measured to be 90 mW, then the efficiency of the antenna is:

A)75 %
B)80 %
C)90 %
D)insufficient data

Question 24

If an antenna has a directivity of 16 and radiation efficiency of 0.9, then the gain of the antenna is:

A)16.2
B)14.8
C)12.5
D)19.3

Question 25

Gain of an antenna is always greater than the directivity of the antenna.