This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “System Aspects of Antenas”.

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

a) True

b) False

2. A rectangular horn antenna has an aperture area of 3λ × 2λ. Then the maximum directivity that can be achieved by this rectangular horn antenna is:

a) 24 dB

b) 4 dB

c) 19 dB

d) Insufficient data

3. 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

4. A rectangular horn antenna has an aperture area of 3λ × 2λ. If the aperture efficiency of an antenna is 90%, then the directivity of the antenna is:

a) 19 dB

b) 17.1 dB

c) 13 dB

d) 21.1 dB

5. A resistor is operated at a temperature of 300 K, with a system bandwidth of 1 MHz then the noise power produced by the resistor is:

a) 3.13×10^{-23} watts

b) 4.14×10^{-15} watts

c) 6.14×10^{-15} watts

d) None of the mentioned

6. The noise temperature of an antenna is given by the expression:

a) radTb + (1-rad) Tp

b) (1-rad) TP

c) radTb

d) None of the mentioned

7. If an antenna has a directivity of 16 and is operating at a wavelength of λ, then the maximum effective aperture efficiency is:

a) 1.27λ^{2}

b) 2.56λ^{2}

c) 0.87λ^{2}

d) None of the mentioned

8. With an increase in operating frequency, the background noise temperature:

a) Increases

b) Decreases

c) Remains constant

d) Remains unaffected

9. Low is the G/T ratio of an antenna, higher is its efficiency.

a) True

b) False

10._________ has a constant power spectral density.

a) White noise

b) Gaussian noise

c) Thermal noise

d) Shot noise