Download AKTU B-Tech 5th Sem 2015-2016 Antenna Wave Propagation Nec 504 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) 2015-2016 Antenna Wave Propagation Nec 504 Question Paper

Printe? Pages: 4 231 NEC-504 ,
(Following P'aper ID and Roll No. to be filled in your
' Answer Book)
Roll No.
B.Tech.
(SEM.V)THEORY EXAMINATION,2015-16
ANTENNA AND WAVE PROPAGATION
[Time:3 hours] , I [TotalMarksz1001
Section-A
Q.1 Attempt all parts. All parts carry equal marks. Write
, answer of each part in short. ' (2X10=20)
(a) Classify various types of antenna arrays.
? (b) Define effective height of an antenna.
(0) Relate MUF with skip distance for ?at earth. '
(d) At what frequency a wave must propagate for the
D region to have an refractive index of 0.7? Given
N = 400 electrons/ cm}
11000 (1) P.T.O.

(e)
(0
(g)_?
(h)
(i)
(1')
11000
A 12-tum axial helix antenna of circumference ,1
has turn spacing of 1 /4. Determine I-[PBW, BWFN,
directivity and also examine polarization
characteristic of the antenna.
. A pyramidal horn antenna of mouth length 10 1
cm is fed by a rectangular waveguide?in TE 10
mode. Determine the design parameters of the
antenna atoperating frequency 2.5 Hz.
What do you mean by frequency independent
antenna?
Write dovyn the expression for the electric ?eld
eomponents of a short dipole.
A lOMHz satillite communication is taking place
through ionosphere layer with refractive index
0.975 and height 500Km. Calculate the ground
' range of this propagation assuming, 1 OGHz as MUF
and 2.24GHz as critical frequency.
A thin dipole antenna is 21/10 long. If loss
resistance is 1.5 - Q , Find radiation resistance and
ef?ciency. ?
(2) ' NEC-504
Section-B
Attempt any ?ve questions from this section.
(10x5=50)
(a) Write a short note on Antenna Temperature,
Directivity and Antenna Impedance.
(b) A TV transmitter.is designed to establish
communication at a distanCe of 50 Km from it.
The height of TX antenna is 100m and transmits a
power of 45 W at 90 MHz. Find the height of
receiver and ?eld intensity at the RX antenna. ,
Derive the relation between the Effective height and
Effective apertUre area. An antenna has a radiation
resistance of .1000hm, a loss resistance of 15 ohm and a
power gain of 10dB. Calculate Antenna ef?ciency and
its directiVity.
Explain operation of Log Periodic Antenna in detail.
Discuss applications of loop antenna as direction ?nder.
What are disadvantage of loop direction ?nders. Also
explain 180 degree ambiguity and how is it resolved.
Explain how ground-wave and space-wave propagates the
signal via troposphere. Distinguish clearly between
surface wave, space wave and sky wave.
11000 (3) P.T.O.

Explain Yagi Uda Antenna and Design a 5-dipolvkl Yagi-
Uda array for operation at 500MHz.
Explain how earths magnetic ?eld affects the propagation
of radio waves in ionosphere.
Explain in detail Induction ?eld (near ?eld) and
Radiation field (far ?eld) (magnetic ?eld only)
applicable to alternating current element.
Section-C
Attempt any tWo questions from this section.
10.
ll.
12."
(.15x2=30)
Why we use the term modi?ed refractive index in
propagation of radio waves? Explain Duct Propagation.
Explain Parabolic re?ector and comer re?ector antenna.
Derive the relation between MUF and skip distance. Al so
explain critical frequency, MUF, Virtual Height, skip
distance
11000 (4) ' -' NEC-504/11000