# Mumbai University Previous year question papers

## Communication System and Application

N.B. : (1) Question No.1 is compulsory.

(2) Attempt any four questions out of remaining six questions.

(3) Assume suitable data if required.

(4) Figures to the right indicate full marks.

1. Attempt any four questions :- 20 ‘

(a) Find the length of a half wave dipole at 30 MHz, 300 MHz and 3000 MHz.

(b) Define directivity, antenna gain, polarisation of antenna.

(c) What is doppler effect? (explain with relevant mathematical equation and example).

(d) In color TV system, explain the significance of color difference signals.

(e) Justify selection of 4.43 MHz as color subcarrier frequency.

2. (a) Derive an expression for maximum possible range of radar. 8

(b) What is pulsed radar system? Explain basic pulse radar system with the neat sketch.

(b) Explain what is meant by term blind speed in MTI Radar. 4

3. (a) Define the terms :- 8

(i) Apogee (iii) Ascending Node i

(ii) Perigee (iv) Descending Node. ;

(b) With the help of neat btock diagram explain satellite earth stations, discl,lss the functions of various blocks in it. Also derive the expression to show that a satellite launched into a circular orbit at a height (H) meters from the surface of the earth moving with a velocity (V).

4. (a) Explain in detail the various mechanisms for fiber attenuation and dispersion. 12

(b) Explain with block diagram the various sub-parts of a fibre optic link. 4

(c) An optical fibre has NA = 0.20 and a cladding refractive index of 1.59. 4

Determine –

(i) The acceptance angle for the fiber in water having refractive index of 1.33.

(ii) The critical angle at the core-cladding interface.

5. (a) Explain Yagi-Uda antenna and log periodic antenna with respect to their radiation pattern dipole spacing, dipole lengths and applications along with the sketch.

(b) Explain the de-gaussing circuit. 4

(c) Discuss the broad side array and its radiation pattern. . 4

6.(a) Explain what is equatorial, polar and inclined orbits.. 5

(b) Distinguish between the resonant and non-resonant antennas. 5

(c) Why green signal is not transmitted? 5

(d) Draw and explain composite video signal. 5

7; Write short notes on the following (any four) :- 20

(a) Effect of ground on antennas