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SPPU Electronics and Telecom Engineering (Semester 6)
Antenna and Wave Propagation
December 2015
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 Q1 and Q2
1 (a) What is Poynting vector? What is its significance? Derive an expression for Poynting vector?
6 M
1 (b) Derive the fundamental equation for free space propagation and explain its parameter
6 M
1 (c) A lossless resonant λ/2 dipole antenna with input impedance of 73 Ω is to be connected to a transmission line whose characteristics impedance is 50Ω. Assuming that the pattern of the antenna is given approximately by U=Bosin 3θ. Find the overall maximum gain of this antenna.
8 M

2 (a) State Maxwell's field equation with their significane and derive the wave equation foe lossless dielectric medium.
6 M
2 (b) Derive vector potential A for an magnetic current source J.
6 M
Explain the following wireless channel characteristics
2 (c) (i) Coherence bandwidth
4 M
2 (c) (ii) Coherence time
4 M

Solve any one question from Q3 and Q4
3 Find the following terms for half wave Dipole:
a) Specify the current
b) Vector magnetic potential
c) Far field components of Electric & Magnetic fields
f) Directivity
18 M

4 (a) Calculate the radiation resistance of a double turn and an eight turn small circular loop when radius of loop is λ/10 and the medium is free space. Calculate its efficiency if loss resistance is 25Ω.
6 M
4 (b) Derive the expression for radiation resistance of Infinitesimaldipole.
6 M
4 (c) Derive the expression for input impedance of small dipole.
6 M

Write short notes on:
5 (a) (i) Pattern Multiplication
4 M
5 (a) (ii) Binomial Array
4 M
5 (b) An Endfire array with element spaced at λ/2 and with axes of elements at right angles to the line of array is required to have directivity of 36. Determine - the array length and the width of major lobe.
8 M

6 (a) Design a broad side Dolph-Tschebhysheff array of five elements with half wavelength spacing between elements and with major to minor lobe ratio to be 19dB. Find the excitation coefficients & array factor.
6 M
6 (b) Give the comparison of broadside and End fire antenna array.
5 M
6 (c) Explain planar array. State its advantages and applications.
5 M

Solve any one question from Q7 and Q8
7 (a) What is Microstrip patch antenna? Give structure details, radiation pattern, specification and application of such antenna.
5 M
7 (b) What is meant by Rhombic Antenna? How it is constructed? Explain how unidirectional pattern is obtained in properly terminated Rhombic Antenna.
5 M
7 (c) Write a short notes on following antennas with respect to structural details, radiation pattern, features and applications.
i) Hertz antenna
ii) Whip antenna
6 M

Write a short note on the following antennas
8 (a) (i) Lens Antenna
4 M
8 (a) (ii) Resonant Antenna
4 M
8 (a) (iii) Super - turnstile Antenna
4 M
8 (b) A paraboloidal reflector antenna with diameter 20m is designed to operate at frequency of 6 GHz and illumination efficiency of 0.54. Calculate the antenna gain in decibels.
4 M

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