Electronics and Communication Engineering - Electromagnetic Field Theory

Exercise : Electromagnetic Field Theory - Section 1

16.

Consider a 300 Ω, quarter wave long at 1 GHz transmission line as shown in figure. It is connected to a 10 V, 50 Ω source at one end is left open circuited at the other end. The magnitude of the voltage at the open circuit end of the line is

10 V

5 V

60 V

60/7 volt

Answer: Option

Explanation:

γ = a + jβ a = 0 γ = jβ

Propagating wave

v = V_I e^-rz + V_R e^rz

No change in the voltage at the open end it will same,

v_r = 10 volt.

17.

The phase angle corresponding to λ/4 in a standing-wave pattern is

30°

90°

135°

180°

Answer: Option

Explanation:

18.

A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm.

47.33

50.33

Answer: Option

Explanation:

Since, wave is attenuated hence β = 0

and Take, dominant mode m = 1,

n = 0

19.

Calculate the directivity of an antenna for θ_E = 30°, θ_H = 60

100

Answer: Option

Explanation:

20.

Most antenna consisting of a 50 meter long vertical conductor operates over a perfectly conducting ground plane. It is base fed at a frequency of 600 kHz. The radiation resistance of the antenna in ohms is