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SPPU Electronics and Telecom Engineering (Semester 6)
Antenna and Wave Propagation
May 2017
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Solve any one question from Q.1(a,b,c) &Q.2(a,b,c)
1(a) A uniform plane wave of frequency 5MHz has a average poynting vector 1.5W/m2. If the medium is lossless with relative permeability μr = 2 and relative permittivity $$\varepsilon r=3.$$/ Determine velocity of propagation, wavelength, intrinsic impedance of a medium and r.m.s. value of electric field.
8 M
1(b) Explain the following characteristic of wireless channel
i) Coherence band width.
ii) Coherence time and
6 M
1(c) Deriv vector potential A for an magnetic current source J.
6 M

2(a) What is polarization of wave? Explain linear and circular polarization of wave.
6 M
2(b) Write short note on
i) Virtual height.
Multihope Propagation.
6 M
2(c) The power radiated by a lossless antenna is 10 watts. The radiation intensity of this antenna is $$U=Bo\cos ^{3}\theta \left ( W/Sr \right )0\leq \pi /2 \ \ 0\ \ \leq \Phi \leq 2\pi .$$/ Find.
i) The maximum power density in (W/m2) at a distance of 1000 meter (assume for field distance) specify the angle where this occurs. ii) Directivity
iii) Gain of the antenna.
8 M

Solve any one question from Q.3(a,b) &Q.4(a,b)
3(a) Derive the equation for input impedance and directivity of half wave dipole.
8 M
3(b) Show the current distribution on small dipole and derive the equation for its input impedance.
8 M

4(a) Find the radiation efficiency of a single turn and eight-turn small circular loop at f = 100MHz. The radius of the loop is λ/25, the radius of the wire is 10-4λ and the turns are spaced 4×10-4λ apart. Assume the wire is copper with a conductivity of 5.7 × 107 (S/m) and antenna is radiating into free sace. (Where ohmic resistance per unit length/ohmic skin effect resistance per unit length = 0.38)
10 M
4(b) Give the comparison of far fields of small loop and short dipole.
6 M

Solve any one question from Q.5(a,b) &Q.6(a,b)
5(a) For two element array consisting identical radiators carrying equal currents in phase, obtain positions of maxima and minima of the radiation pattern if the distance of seperation d = λ
8 M
5(b) Derive antenna array factor for N-element linear array taking the centre element as reference for N is odd and even.
8 M

6(a) Draw and explain the radiation pattern of an endfire array.
8 M
6(b) Explain in brief Dolph - Tchbyscheff distribution. What is the need for Tchbyscheff distribution?
8 M

Solve any one question from Q.7 & Q.8(a,b)
7 Explain the following antennas with its structural details dimensions, radiation pattern, diagram, specifications, features and applications.
i) Micro strip antenna
ii) Lens antenna.
iv) Biconical antenna
18 M

8(a) Explain the working of Rhombic antenna in detail.
8 M
8(b) With the help of suitable diagram explain the operating principle of
i) Super turnstile
ii) Slot antenna.
10 M

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