Deemed University 2009 A.M.I.E.T.E Electronics

(A) Transverse nature of the waves.
(B) Longitudinal nature of the waves.
(C) Reflection from a different medium.
(D) None of the above.

i. The frequencies in ultra high frequency range are propagated by means of

(A) Ground wave. (B) Space wave.
(C) Sky wave. (D) Surface wave.

j. If length of an antenna is increased, the directive gain

(A) Increases. (B) reduces.
(C) Remains the identical. (D) Becomes Infinite.


ans any 5 ques. out of 8 ques..
every ques. carries 16 marks.

Q.2 a. State and discuss Coulombs legal regulations with relevant diagram. (4)

b. A charge of Q1 = three × 10-4 Coulomb at M (1,2,3) and a charge of Q2 = three × 10-4 Coulomb at N (2,0,5) in a vacuum. compute the force exerted on Q2 by Q1. (4)

c. Derive Poissons formula and Laplaces formula using Maxwells formula. Also express the Laplaces formula in Rectangular, Cylindrical and Spherical coordinates. (8)

Q.3 a. describe Biot-Savart legal regulations. Also compute the magnetic field of line current along a thin straight wire of infinite length. (8)

b. discuss the detailed boundary conditions of a magnetic field. (8)

Q.4 a. Write the differential and integral form of Maxwells equations in conducting medium as well as in free space. Mention clearly the notations used in the equations. (8)

b. At the boundary of 2 perfect dielectric materials having permittivity e1 and e2, electric flux density D1 is incident at an angle ?1 with respect to normal to the boundary surface. Prove that (8)
D2 = D1 [cos2 ?1 + (e2/e1)2 sin2 ?1] 1/2

Q.5 a. What do you mean by Polarization? Classify various kinds of Polarizations that occur in wave propagation. (8)

b. A 10 GHz plane wave travelling in free space has an amplitude Ex = one Volt/meter. obtain the following:-
(i) phase velocity, wave length and propagation constant.
(ii) characteristic impedance of the medium.
(iii) amplitude and direction of the magnetic field intensity.
(iv) repeat part (i), if the wave is travelling in a loss less, bounded medium
having permeability the identical as free space but permittivity 4 times that of
free space. (8)

Q.6 a. Derive the transmission-line equations which characterize the wave propagation along the line in terms of line voltage and line current. (8)

b. describe voltage reflection co-efficient and current reflection co-efficient with related equations. (4)

c. discuss how standing wave is generated? compute VSWR, if reflection co-efficient is 0.5. (4)

Q.7 a. discuss the Impedance Transformation property of a quarter wave Transmission Line. (8)

b. What is a dominant mode? An air filled rectangular wave guide of dimensions seven cms × 3.5 cms operates in the dominant TE10 mode. obtain the following:
(i) cut-off frequency.
(ii) phase velocity of the wave at a frequency of 3.5 GHz.
(iii) guided wavelength at the identical frequency. (8)

Q.8 a. discuss Hertzian dipole. compute the directivity of a Hertzian dipole. Also show the variation of current and charge in Hertzian dipole. (10)

b. calculate the directivity of an antenna corresponding to the power density trend function f (?,F) = sin2?.cos2? . (6)


Q.9 Write short notes on:

(i) Critical frequency
(ii) Depth of penetration (or Skin depth)
(iii) Antenna Arrays
(iv) Rectangular cavity Resonator (4 four = 16)

Earning:   Approval pending.