Question Paper: Electromagnetic Engineering : Question Paper Dec 2014 - Electronics Engineering (Semester 5) | Mumbai University (MU)
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## 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)