Antennas and Microwave Engineering solved MCQs

The major drawback of frequency multipliers is that they have:

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

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

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

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.

Resistive multipliers are more efficient as compared to reactive multipliers.

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

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

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

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

When the separation between two lines that carry the TEM wave approaches λ the wave tends to be radiated.

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

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

An antenna has a field pattern of E (θ) = cos2 θ, θ varies between 0 and 900. Half power beam width of the antenna is:

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

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

Power radiated from an antenna per unit solid angle is called radiation intensity.

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

Antennas are bidirectional devices.

Dipole antennas are an example for: