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Code: 9A04406

B.Tech II Year II Semester (R09) Supplementary Examinations January/February 2014

ELECTROMAGNETIC THEORY TRANSMISSION LINES (Electronics and Communication Engineering)

Time: 3 hours Max Marks: 70 Answer any FIVE questions

All questions carry equal marks *****

*****

1 (a) State and prove Gauss law and explain its application through example. (b) Three co-axial cylindrical sheets of charge are present in space, of charge densities

; and 4 find the displacement density .

2 (a) Define relaxation time. (b) An anisotropic dielectric material is characterized by matrices of D-to-E as:

For E , find the value of ‘ ’ for which D is parallel to E, hence also find effective permittivity.

3 (a) Calculate the field at any point due to two infinitely long solenoids having surface current densities located at z = 0 and z = h respectively.

(b) A flux density of in a material having magnetic susceptibility 2.5, find magnetic field, current density and magnetization.

4 (a) Discuss about the inconsistency of Ampere’s law and hence concept of displacement current

density. (b) Explain the importance of displacement current.

5 (a) What is skin effect? Explain. Define skin depth. (b) A lossy dielectric has an intrinsic impedance of 200 030∠ at a particular radian frequency ω.

If at that frequency the plane wave propagating through the dielectric has the magnetic field component. H = 10e-αxcos (ωt-0.5x)ay A/m. Find E and α. Determine the skin depth and wave polarization.

6 The electric and magnetic field in free space in a spherical coordinate system are given by:

E = θπωθ art

r)

34cos(sin10

− V/m, H = φπωθ

πart

r)

34cos(sin

12010

− A/m

Determine the poynting vector. What is the direction of power flow? Determine the total time average power leaving the spherical closed regions of radius 100 m and 10,000 m.

7 (a) Discuss about different types of transmission lines. (b) Define and differentiate phase and group velocity as applied to a uniform transmission line.

8 (a) Obtain standing wave ratios in terms of reflection coefficient. (b) Discuss about normalized impedance.

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