Electronics and Communication Engineering - Electromagnetic Field Theory

46.
Find the noise factor for an antenna at 27°C with equivalent noise temperature 30°K
20
100
300
1.1
Answer: Option
Explanation:

Te = T0(F - 1)

.


47.
The displacement flux density at a point on the surface of a perfect conductor is = 2(ax - 3 az)c/m2 pointing away from the surface. The charge density at that point c/m2 will be
2
- 2
4
- 4
Answer: Option
Explanation:

∇ . D = r.


48.
Characteristic impedance of a transmission line is 50 Ω. Input impedance of the open circuited line.
Zoc = 100 + J150 Ω. When transmission line is short circuited, then value of the input impedance will be
50 Ω
100 + J150 Ω
7.69 + J11.54Ω
7.69 - J11.54 Ω
Answer: Option
Explanation:

ZC = ZOC - ZSC 50 = (100 + j150)(ZSC) .