Electromagnetic Engineering - Dec 2014
Electronics Engineering (Semester 5)
TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
Answer the following any four:
1 (a) What do you understand by conservative field.(5 marks)
1 (b) Derive wave equations for time harmonic fields.(5 marks)
1 (c) The radiation resistance of antenna is 72Ω and the loss resistance is 8Ω. Calculate its directivity in dB if the power gain is 16.(5 marks)
1 (d) Explain the important advantages and drawback of FDM.(5 marks)
1 (e) Define critical frequency, MUF and OWF.(5 marks)
2 (a) State and Explain Maxwell's equations in differential and internal form for static field.(8 marks)
2 (b) A 10 GHz plane wave traveling in free space has an amplitude of Ex=10V/m. Find
i) The phase constant
ii) Intrinsic impedance and
iii) The amplitude and the direction of H.(8 marks) 2 (c) Explain the operating modes of helical antennas.(4 marks) 3 (a) Explain the mechanism of ionospheric propagation. A high frequency radio link has to be established between two points at a distance of 2000 km. On the earth's surface. Considering the height of 200km and critical frequency of 5MHz. Calculate MUF for given path.(8 marks) 3 (b) Derive an expression for radiation resistance of an infinitesimal dipole antenna and explain its significance.(8 marks) 3 (c) Derive Laplace's and Poisson's equations.(4 marks) 4 (a) Find the transmission and reflection coefficients at the boundary for normal incidence. Given that for region 1:?r1=1, &insin;r1=9 and for region 2 is a free space. Consider the perpendicular polarization.(8 marks) 4 (b) Derive an expression for vector magnetic potential wave equation.(8 marks) 4 (c) Explain the physical significance of the terms α, β and γ related to wave propagation in lossy dielectrics.(4 marks) 5 (a) Give the comparison of FDM, FEM and MOM.(8 marks) 5 (b) Determine the poynting vector and explain the power flow terms due to the time varying fields.(8 marks) 5 (c) The height of monopole antenna is ?/100 what is the radiation resistance.(4 marks)
Write a short notes on:-
6 (a) Boundary conditions for static E and M fields.(5 marks) 6 (b) Polarization of waves.(5 marks) 6 (c) Antenna parameters.(5 marks) 6 (d) Space wave propagation.(5 marks)