Mumbai University Previous year question papers
VI Sem Electronics Examination June 2007
Antena and Wave Propogation
N.S.: (1) Question No.1 is compulsory.
(2) Attempt any four questions out of remaining six questions.
(3) Assume suitable data wherever required.
(4) Figures to the right indicates full marks.
1. (a) Explain in brief -,
(ii) Pattern multiplication
(iii) Isotropic and omnidirectional antenna
(iv) Friis transmission formula.
(b) Derivethe expressionfor electricand magneticfield for a small loop antenna. Compare them with those of infinitesimal electric pole.
2.(a) State and explain Maxwell’s equation for electromagnetic field sta;-tingfrom Maxwell’s equation deduce the wave equation for a plane wave in free spac-e. Show that it represents propagating wave.
(b) Compare half wave dipole antenna and folded dipole antenna, 10
3.(a) A broadside array consists of 4 isotropic sources with a distance of)..)2between them. Find –
(i) The array factor
(ii) Directions of major lobe and minor lobe maxima
(iii) Direction of minima
(iv) HPBW and FNBW
(v) Plot the pattern.
(b) What is travelling wave antenna. Discuss different travelling wave antennas. 10
4.(a) Explainthe different types of feeds for parabolic reflector antenna.
(b) Explain Log -,periodic antenna in detail.
5.(a) Explain Dolph- Tchebyscheff optimum distribution for linear array with non-uniform amplitude distribution.
(b) Describe various feeding methods for microstrip antenna. Give applications. 10
6. (a) Drawand explainVagiantenna.’Sketch its radiation pattern. Write down the application of Vagiantenna. 10
(b) Explain the mechanism of ionospheric propagation. Define critical frequency, MUF, OW~ 10
7. Write short notes on any two:
(a) Sky wave propagation
(b) Biconical antenna
(c) Sleeve dipole.