Punjab Engineering College 2005 B.Tech Antenna & Wave Propagation - Question Paper

ECE 305 fifth Sem May 2005

ANTENNA & WAVE PRPAGATION

Note: part A is compulsory. Attempt any 4 ques. from part B and 2 from part C.

part A Marks two every

1.

(a) What do you mean by antenna tuning?
(b) How do you distinguish ranging from “near zone” and “far zone” of an antenna?
(c) How does an antenna radiate electromagnetic energy?
(d) What do you mean by elliptical polarization?
(e) How do you describe an impedance of an antenna?
(f) What is folded dipole?
(g) What do you mean by parasitic elements?
(h) What is maximum usable frequency?
(i) What is optimum traffic frequency?
(j) What is the effect of fading on signal strength?

part B Marks five every

2. obtain out the phase difference ranging from the direct and reflected rays in space wave propagation.
3. Write notes on any 1 of the following:
(a) Duct propagation
(b) Whip Antennas.

4. What is paraboloid antenna? Derive an expression for its gain.

5. calculate the radiation resistance, the power radiated and efficiency of an antenna having total resistance of 50 ohms, an effective height of 60.96 meters and current of 50 A (r.m.s.) at 0.480 MHz.

6. An antenna has radiation resistance and loss resistance of 72 O and eight O respectively. compute its directivity provided that its power gain is 17.

part C Marks 10 every

7. Show that radiation field electric intensity of quarterwave monopole is:

Eq=60Im/r {[cos(p/2 cos q)]/sin q} V/m

8. Derive an expression for radiation trend of broad side, uniform, linear array of four equally spaced (l/2) isotropic antenna. compute the width of its major lobe ranging from 1st null and draw its trend.

9. Radio waves projected towards the atmosphere do not return if the frequency is raised above a particular frequency which also modifications with the angle of projection. discuss.

Earning:   Approval pending.