Punjab Technical University 2009-5th Sem B.Tech Electronics and Communications Engineering AWP- ( ) - Question Paper

ANTENNA AND WAVE PROPAGATION(DEC 2009)

part A

Q1.
(A) How does antenna radiate electromagnetic radiation ?
(B) What is retarded potential?
(C) Explain directivity and resolution.
(D) What is meant by effective height?
(E) What is duality of antenna?
(F) Define aperture efficiency.
(G) What is point source?
(H) Give the expression of beam width for broadside array and end fire array.
(I) What is continuous aperture distribution?
(J) elaborate the factors that affect the propagationof radio waves?

part B

Q2. For an antenna having effective temperature of 20 kelvin, compute available noise power per unit bandwidth.
Q3. Derive an expression for the power radiated by a monopole using sinusoidal current distribution. What is its radiation resistance?
Q4. Compare the basic principle of radiation through wire antennas and aperture antennas.
Q5. describe a uniform linear array. discuss the principle of operation of linear array antenna. elaborate its advantages?
Q6. define the troposphere and discuss how ducts can be used for microwave propagation.

part C

Q7. describe reciprocity theorem. Use this theorem to prove the equality of impedances and effective lengths of an antenna used in transmission and reception.
Q8. A linear broadside array consists of 4 equal in phase point sources with lambda/3 spacing. compute and plot field trend. Also obtain directivity and beam width.
Q9. discuss the terms(a)Virtual height (b) Multihop transmission (c) Sporadic E layer with reference to sky wave propagation.

Earning:   Approval pending.