Electronics and Communication Engineering - Electromagnetic Field Theory

Exercise : Electromagnetic Field Theory - Section 1

11.

A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls Calculate group velocity for dominant mode.

1.8 x 10⁸ m/sec

5 x 10⁸ m/sec

3 x 10⁸ m/sec

1.5 x 10⁸ m/sec

Answer: Option

Explanation:

V_g . V_p = C²

where

12.

For F₁ layer the maximum ionic density is 2.3 x 10⁴ electrons per cc. The critical frequency for this layer will be

1.36 MHz

13.6 MHz

136 MHz

1360 MHz

Answer: Option

Explanation:

f_c = 9N_max .

13.

Which one of the following does represents the electric field lines for the TE₀₂ mode in the cross section of a hollow rectangular metallic waveguide?

Answer: Option

Explanation:

TE₀₂ m = 0, n = 2

in x direction no propagation, only in y, and normal to the waveguide, tangential component is continuous.

14.

The velocity of electromagnetic wave in a good conductor is

3 x 10⁸ m/s

more than 3 x 10⁸ m/s

very low

high

Answer: Option

Explanation:

, for good conductor ε_r >> 1.

15.

Radiation intensity of a dipole depends strongly on frequency. If at a frequency f, the intensity of radiation is 'I'. Then at a frequency of f/2, the intensity will be