# Antenna Noise Temperature MCQ’s

This set of Antenna Multiple Choice Questions & Answers (MCQs) focuses on “Antenna Noise Temperature”.

1. If the reflection co-efficient is ½ then emissivity is ___
a) 3/4
b) 1/4
c) 1/2
d) 3/2

2. Overall receiver noise temperature expression if T1, T2… are amplifier 1, 2, and so on noise Temperature and G1, G2, and so on are their gain respectively is_____
a) T = T1+T2G1+T3G1G2+⋯
b) T = T1+T2 (1-G1)+T3(1-G1G2)+⋯
c) T = T1+T2(1−G1)+T3(1−G1G2)+⋯
d) T = T1+T2 (G1)+T3(G1G2)+⋯

3. Relation between brightness temperature TB and physical body temperatureTp is ____
a) TB=(1−∣Γs∣2)Tp
b) TB=Tp/(1−∣Γs∣2)
c) TB=(1−∣Γs∣)Tp
d) TB=(1−∣Γs∣)2Tp

4. Total noise power of the system is P=_____
a) k(TA+TR)B
b) k(TA+TR)/B
c) k(TR)B
d) kB/Tsys

5. Which expression suits best when the solid angle obtained by the noise source is less than antenna solid angle?
a) PA ΩA=PB ΩB and ΔTA=ΩBΩATB
b) PA ΩB=PB ΩA and ΔTA=ΩBΩATB
c) ΔTA=ΩAΩBTB and PA ΩB=PB ΩA
d) ΔTA=ΩAΩBTB and PA ΩA=PB ΩB

6. Effective noise temperature Te in terms of noise figure is ____
a) Te=To (F-1)
b) Te=To/(F-1)
c) Te=To/(F+1)
d) Te=To (F+1)

7. What is the relation between noise temperature introduced by beam TB and the antenna temperature TA when the solid angle obtained by the noise source is greater than antenna solid angle?
a) TA= TB
b) TA > TB
c) TA < TB
d) TA « TB

8. Expression for noise figure F related to the effective noise temperature Te is ____
a) F=1+TeTo
b) F=1+T0Te
c) F=1−TeTo
d) F=1−T0Te

9. Which of the following statement is false?
a) Noise power of antenna depends on the antenna temperature as well as the noise due to the receiver surroundings
b) Noise figure value lies between 0 and 1
c) Any object with physical temperature greater than 0K radiates energy
d) Noise power per unit bandwidth is kTA W/Hz

10. Find the effective noise temperature if noise figure is 3 at room temperature (290K)?
a) 290K
b) 580K
c) 289K
d) 195K

11. What should be the noise figure value at which the effective noise temperature equals to room temperature?
a) 2
b) 1
c) 0
d) 1/T_(o )