Jawaharlal Nehru Technological University Kakinada 2009-1st Sem B.Tech Electronics and Communications Engineering Code No: V3118/R07 I II Regular s, ANTENNAS & WAVE PROPAGATION (Electron

Code No: V3118/R07
I II B.Tech I Semester Regular Examinations, November 2009
ANTENNAS & WAVE PROPAGATION
(Electronics & Communication Engineering)
Time: three hours
Max Marks: 80
ans any 5 ques.
All ques. carry equal marks

1. (a) Establish the relations ranging from directivity and effective area, directivity and
effective length.
(b) An antenna has a radiation resistance of 63 ohms and a lossy resistance of 6
ohms. If the power gain is 30, compute the directivity and the efficiency of
the antenna.
[8+8]

2. (a) Show that the radiation resistance of a small loop is equal to 320p 4(A/ two )
ohms where A is loop area.
(b) What is Folded Dipole ? obtain its Radiation Resistance. [8+8]

3. (a) Enumerate the advantages and disadvantages of linear arrays.
(b) obtain the phasing needed to steer a beam zenith to -400 for a five element array
with 0.4 inter element spacing.
[8+8]

4. (a) Design a Rhombic Antenna to operate at 20MHz when the angle of elevation
= 100 .
(b) define the Non Resonant V-antenna.
[8+8]

5. (a) Write short notes on 'Yagi Aerial'.
(b) What is Corner Reflector Antenna? Derive the expression for the group pat-
tern of system of images due to a 600corner reflector. [8+8]

6. (a) describe Zoning. explain the merits and demerits of zoned antennas.
(b) With reference to aperture blocking, define the performance of paraboloids
and center.
[8+8]

7. (a) What is Angle of Tilt? How does it affect the field strength at a distance from
the transmitter?
(b) A 150m antenna transmitting at 1.2MHz by ground wave has an antenna
current of 8A. What voltage is received by a receiving antenna 40kms away,
with a height of 2meters?
[8+8]
8. (a) Establish the mathematical relation for
i. Radio Horizon
ii. Radius of curvature of array path for LOS waves.
(b) Show that the field strength due to space wave provided by
[8+8]
E = (2E0 /d)sin(2phthr/ d).

Earning:   Approval pending.