Download AKTU B-Tech 5th Sem 2018-2019 REC 051 Antenna And Wave Propagation Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 5th Semester (Fifth Semester) 2018-2019 REC 051 Antenna And Wave Propagation Question Paper

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ETECH.
' (SEM V) THEORY EXAMINATION 2018-19
ANTENNA AND WAVE PROPAGATION
nine: 3 Haurs . Total Marks: 70
Note: 1. Attempt all Sections. If require any missing data; then choose suitably.
SECTION A
1. 4 Attempt all questions in brief. 2 x 7 = 14
3) Give reason why does retardation petentinl take place?
h) A thin dipole antenna is 1/15 long if its loss resistance is 1.5 W. F ind radiation resistance and
ef?ciency?
e) What is end-?re array and broud-side array?
d) Define the gain of antenna?
e) De?ne virtual height and skip distance? .
f) Estimate the distance & effective aperture of a paraboloid re?ectot antenna required to
produce Null beam width of 10? at 3GHz.
3) Find the radiation emciency of a In diameter loop of diameter coppet wire at lOMHz. \,
SECTION?
2. Attempt any three of the following: ?$?I?Q 7 x 3" 3%
a) Calculate the effective aperture for : antenna of length 2cm at a 1.2 G
will be the power received for nt power density of 2mW/m2.
b) Sketch the horizontal and verti lane radiation pattern of Centre fed $531 dipole
for the following length- (i ipole (ii) 31/2 dipole (iii) 27. dipoley\
c) What is folded dipole ? Describe Yagi-Uda antenna and exlhem its operation?
d) Explain the principle 0 ration of parabolic dish? Why IS th Whom: shape 13
used? Q
e) Explain the phenomenon of Duct Propagation What are figmospheric conditions
under which duct propagation can take place?
SECTION c {3
3. Attempt any one part of the following: {2?} 7 x 1 = 7
a) Discuss about antenna impedance and ant ?\temperamre?
b) How the directivity of any antenna is lg? and what is the relationship between
directivity and gain of the antenna? 5;),
4. Attempt any one part of the f g: 7 x 1 = 7
3) Explain the principle of w multiplication. Obtain the radiation pattern of 4
element fed in-phase, sp e 2?apart using pattern multiplication.
b) De?ne the isotropic sour ? N-isotnopic sources are arranged in a uniform linear
array Derive an expression for the array factor?
5. Attempt any one part of the following: 7 x 1 = 7
a) A linear broad-side array consists of four equal isotropic in-phase point source width
1/2 spacing. Find the directivity, BWFN and HPBW of the array?
b) An end fire array consisting of several half wavelength isbtropic radiators him a
directive gain of 30. Find the array length and width of the major lobe. What will be
the value for broadside array?
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Attempt any one part of the following: 7 x 1 = 7
2) Explain with suitable diagram log periodic antenna? What are practical application of
these antenna? .
b) A loop antenna consists of 10 turns, each having an area of 1 m2. A radio wave having
a frequency of 1 MHz induces a sinusoidal emf of 100 mV(mis) in this antenna when
it is oriented for maximum response. Calculate the peak value of the magnetic ?eld
intensity of the RF wave. (uo=4ux10'7h/m)
Attempt any one part of the following: , 7 x l = 7
3) Assume that re?ection take place at a height of 350m & that the maximum density in
the ionosphere corresponds to a 0.8 refractive index at 15. MHz what will be range for
which the MUF is 20MHz. Assume ?at Earth.
8 IN
f 2 I
b) Derive expression for refractive index of ionosphere p = [?
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