Master of Science I (Electronics Science) Examination:
Oct Nov 2016 Semester II (New CBCS)
SLR No. Day
Date Time Subject Name Paper
No. Seat No.
SLR SJ
341
Thursday
17/11/2016
10:30 AM
to
01:00 PM
Modern Antenna Design
C
V
Instructions: Q.No.1 and 2 are compulsory.
Answer any three questions from Q.No.3 to Q.No.7.
All questions carry equal marks.
Total Marks: 70
Q.1 Objective Questions. 14
Select correct alternatives: 06
Radiation intensity is dependent of
Distance r Both
Direction None
Dipole antenna has maximum radiation in a plane
Normal to the axis Both
Perpendicular to the
axis
None
The radiation resistance of the dipole of the length λ /10 is
80Ω 804Ω
720 Ω None
is the meansurement of a unilateral antenna properties of
directivity.
Phase Angle Antenna gain
Beamwidth Bandwidth
For linear uniform two elements array for d λ 2 and α 0 the
radiation pattern is
Vertical figure of eight Cardioids
Horizontal figure of
eight
Combination of A B
is the horizontal pointing angle of an antenna.
Azimuth Right angle
Angle of elevation Beam width
State True or false: 08
Lenses widely used in combination with horn antenna.
Electromagnetic radiator converts time varying voltage into wave in free
space.
Resolution of antenna is equal to its twice power beam width.
Resonant antenna carries current of standing wave.
The vertical plane pattern of short dipoles and half wave dipole is
dumbbell.
For the absence of the side lobes, the spacing of the elements of the
binomial array must be greater than equal to λ 2.
The antenna that can give pencil beam pattern is Yagi Uda.
Lens antennas are used at the frequencies above 3GHz.
Page 2 of 2
Q.2 Answer the following: 14
Define the radiation resistance and explain its significance. 05
What is effective length? What is its significance in description the
performance of linear antenna?
05
Define corner reflector antenna. 04
0
Q.3 Answer the following: 14
Derive expression for the retarded potentials. 08
What is meant by directivity? What is meant by antenna beam width? 06
Q.4 Answer the following: 14
Explain radiation mechanism of two wires. Discuss the types of lobes. 10
A short vertical grounded antenna is designed to radiate at 10 MHz. Calculate
the radiation resistance if the effective height of the antenna is 50 m.
04
Q.5 Answer the following: 14
Write short notes on:
Broadside arrays
ii) EFA
08
Define the antenna efficiency. What are different losses associated with the
antenna system?
06
Q.6 Answer the following: 14
Describe the parabolic reflector used at micro frequencies? 10
List the applications of helical antenna? 04
Q.7 Answer the following: 14
Explain the different types of lens antenna and list their important features. 08
Define reciprocity theorem as application to antenna. 06