Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January EEE 7th Sem 71962 Antenna And Wave Propagation Previous Question Paper
Roll No.
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech.(Electronics & Electrical Engg.) (2012 to 2017) (Sem.?7)
B.Tech.(Electrical & Electronics Engg.) (2013 & Onwards)
ANTENNA & WAVE PROPAGATION
Subject Code : BTEEE-801
M.Code : 71962
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Answer briefly :
1.
Define slot antenna.
2.
Define directivity for an antenna and write down the various expressions for directivity.
3.
Describe the fundamental propagation modes of radio waves.
4.
Define radiation resistance for an antenna. What is the radiation resistance for half wave
dipole?
5.
Write down the range of frequencies for different modes of radio wave propagation.
6.
What do you mean by antenna arrays?
7.
What do you mean by effective aperture?
8.
Differentiate between actual and virtual height.
9.
A plane wave is characterized by
E = (0.5x + yej/2) ej(wt-kz). Find out the wave polarization with orientation.
10. Consider a lossless antenna with a directive gain of +6 dB. If 1 mW of power is fed to it
then what will be the total power radiated by the antenna.
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SECTION-B
11. A plane wave is incident on a short dipole with same polarization and current on the dipole
is assumed constant and in phase over its entire length and the terminating resistance RT is
assumed equai to the dipole radiation resistance Rr. the antenna loss resistance is assumed
equal to zero. What is a) the dipole's maximum effective aperture and b) its directivity?
12. Calculate the exact directivity of a unidirectional antenna if the normalized power pattern is
given by a) Pn = cos b) Pn = sin2 . in all cases these patterns are unidirectional ( in + Z
direction) with having Pn having a value only for Zenith angle 0 90 and with Pn = 0
for 90 180. The patterns are independent of the azimuth angle .
13. Derive an expression for E() for an array of two identical (non-isotropic) out of phase
point sources separated by a distance of d = /2, each source having normalized field
pattern in the plane is given by sin . Also plot, approximately, normalized filed pattern.
14. Calculate the gain, FNBW and HPBW of parabolic reflector antenna which is operating at
10 GHz and diameter of its circular aperture is 6 .
15. The refractive index of an ionospheric layer is 0.8 and MUF is 9 MHz. If the height of the
ionospheric layer is 400 km above the earth's surface, then find out the maximum electron
density, critical frequency and distance between transmitter and receiver assuming that
earth's surface is flat.
SECTION-C
16. Derive the expressions for maxima, minima, FNBW and directivity of N-elements Uniform
linear end fire array.
17. Derive the fields radiated from a short electric dipole with linear current distribution over
its length.
18. Write short notes on following :
a. Maximum usable frequency
b. Tropospheric propagation
.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 26 June 2021