[Nov-12]

[EUREC-306/EIREC-306]
B.Tech. & Integrated Dual Degree (B.Tech.+M.Tech.)
Examination
ECE & Int. ECE
III SEMESTER
ELECTROMAGNETIC WAVES & TRANSMISSION LINES
(Effective ECE from the admitted batch 200708)
(Effective Int. ECE from the admitted batch 201011)
Time: 3 Hours Max.Marks: 60
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Instructions: Each Unit carries 12 marks.
Answer all units choosing one question from each unit.
All parts of the unit must be answered in one place only.
Figures in the right hand margin indicate marks allotted.
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UNIT-I
1. a) Convert a point P(1,3,5) from cartesian to cylindrical and
spherical coordinates 2
b) Establish Poissons and Laplace equation from Gauss law 4
c) A very long cylindrical conductor of radius a has a charge q
coulombs/meter distributed along its length. Find the electric
field strength E in air normal to the surface of the cylinder 6
OR
2. a) Find the magnitude of the electrostatic force between a 100c
change at (-1,1,-3) m and a 20c change at (3,1,0) m 2
b) Find the energy stored in a parallel plate capacitor 4
c) State and prove the uniqueness theorem 6
UNIT-II
3. a) State Biot-Savarts law 2
b) Using the vector potential, determine the magnetic field strength
about a long straight wire carrying a current I 4
c) A circular loop of radius a carries a current I, obtain an
expression for the magnetic field from the loop 6
 OR
4. a) Define self and mutual inductances 2
b) Obtain the boundary conditions at the boundary of two
dielectric materials 6
c) Obtain the expression for the energy density and energy stored
in a static magnetic field 4
UNIT-III
5. a) Define depth of penetration 2
b) State and prove poynting theorem 6
c) Express Maxwells equations in phasor form 4
OR
6. a) Explain the terms conduction current and displacement
current. Deduce the equation of continuous of current
0
J + = 0 6
t
b) Prove for parallel polarization that
Er tan (1 2 )
= . The symbols have their usual meanings 6
Ei tan (1 + 2 )
UNIT-IV
7. a) Define reflection coefficient and Transmission coefficient and
find the expression interms of intrinsic impedance of medium 6
b) Determine the reflection coefficient for an electromagnetic
wave incident normally on a sheet of iron the corresponding
parameters are frequency f = 1MHz , ( iron ) = 1 106 mnos / m,
= 10000 and =
0 4 107 Henry / m 6
OR

E
8. a) Prove that = 120 for free space 6
H
b) If a wave of 6GHz is propagating between two parallel
conducting plates separated by 30mm. Find the cutoff
frequency, guide wavelength and also the impedance of the
dominant mode 6
 UNIT-V
9. a) Derive the relation between the reflection coefficient and
V.S.W.R. 3
b) Define primary and secondary constants of a Transmission line 3
c) Determine the reflection coefficients when
i) Z L = Z 0 ii) Z L = short circuit iii) Z L = open circuit
iv) when Z L is purely resistive 6
OR
10. a) A high frequency line has the following primary constants,
L = 2mH/km, C = 0.06 F/km, R = G = negligible. Determine
the characteristic impedance and propagation constant of the
line 6
b) Discuss about single and double stub matching 6

[4/III S/112]
[4/III S/312]