This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “Noise Characteristics of Receivers”.

1. Equivalent noise temperature of a transmission line connecting the antenna to the receiver is:

a) T_{P} (L_{P}-1)

b) T_{P} (L_{P} + 1)

c) T_{P}/ (L_{P}-1)

d) T_{P} / (L_{P} + 1)

2. In a receiver, if the noise figure of the mixer stage in the receiver is 7 dB, then the equivalent noise temperature is given that the receiver is operating at 290 K:

a) 1163 K

b) 1789 K

c) 1000 K

d) 1234 K

3. The noise power will determine the maximum detectable signal level for a receiver.

a) True

b) False

4. If a transmission line connecting the antennas to the receiver has a loss of 1.5 dB, given the physical temperature is 27^{0}C, noise equivalent temperature is:

a) 123 K

b) 145 K

c) 345 K

d) 234 K

5. If a receiver is operating at a bandwidth of 1 MHz and has antenna noise temperature of 210 K, then the input noise power is:

a) -90 dBm

b) -115 dBm

c) -56 dBm

d) -120 dBm

6. If the received power at antenna terminals is -80dBm, and if the input noise power is -115 dBm, then the input SNR is:

a) 45 dB

b) -195 dB

c) -35 dB

d) 35 dB

7. Given that the antenna efficiency is 0.9, equivalent brightness temperature is 200 K; physical temperature is 300 K, noise temperature of an antenna is:

a) 220 K

b) 210 K

c) 240 K

d) None of the mentioned

8. Antenna noise temperature of a system is 210 K, noise temperature of transmission line is 123 K, loss of a transmission line connecting the antenna to receiver is 1.41 and noise temperature of the receiver cascade is 304 K. then the total system noise temperature is:

a) 840 K

b) 762 K

c) 678 K

d) 1236 K

9. A receiver system is operating at a bandwidth of 1 MHz and has a total system noise temperature of 762 K. then the output noise power is:

a) -110 dBm

b) -234 dBm

c) -145 dBm

d) -124 dBm

10. If the received power at the antenna terminals is Si=-80 dBm and the output noise power is -110 dBm then the output signal to noise ratio is given by:

a) 30 dB

b) -30 dB

c) 35 dB

d) -35 dB