ANNA
UNIVERSITY PREVIOUS YEAR QUESTION PAPER
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ANNA
UNIVERSITY PREVIOUS YEAR QUESTION PAPER EC2353 ANTENNA AND WAVE
PROPAGATION , IMPORTANT QUESTIONS, 2 MARKS AND 16 MARKS QUESTIONS FOR EEE
DEPARTMENT
B.E./B.Tech.
DEGREE EXAMINATION, APRIL/MAY 2011
Sixth
Semester
Electronics
and Communication Engineering
EC 2353 —
ANTENNA AND WAVE PROPAGATION
(Regulation
2008)
Time : Three
hours Maximum : 100 marks
Answer ALL
questions
PART A — (10
× 2 = 20 marks)
1. Define gain and directivity of an antenna.
2. What is the significance of radiation resistance of an antenna?
3. What are the applications of loop antenna?
4. Define Pattern Multiplication.
5. State Huygens Principle.
6. What are the features of pyramidal horn antenna?
7. What are the applications of microstrip antenna?
8. What are near and far field measurements?
9. Define maximum usable frequency.
10. What is meant by Faraday rotation?
2. What is the significance of radiation resistance of an antenna?
3. What are the applications of loop antenna?
4. Define Pattern Multiplication.
5. State Huygens Principle.
6. What are the features of pyramidal horn antenna?
7. What are the applications of microstrip antenna?
8. What are near and far field measurements?
9. Define maximum usable frequency.
10. What is meant by Faraday rotation?
PART B — (5
× 16 = 80 marks)
11. (a)
Derive the Electric and magnetic field quantities of Hertzian dipole. (16)
Or
(b) Explain the following terms with respect to antenna:
(i) Polarization (4)
(ii) Effective aperture (3)
(iii) Directivity (3)
(iv) Antenna temperature (3)
(v) Radiation pattern. (3)
12. (a) Deduce the field quantities and draw radiation pattern for a half
wavelength dipole. (16)
Or
(b) Two identical vertical radiators are spaced 4 / λ = d meters apart and fed
with currents of equal magnitude but with a phase difference ‘ β’.
Evaluate the resultant radiation for β= 0° and thereby identify the
direction of maximum and minimum radiation. (16)
13. (a) Explain the radiation mechanism of slot antenna with diagram. (16)
Or
(b) Explain the special features of Reflector antenna and discuss on different
types of feed used with neat diagram. (16)
14. (a) With a neat sketch, explain the construction and operation of Helical
antenna. (16)
Or
(b) Explain the principle of operation of Yagi-Uda array with neat schematic
diagram. (16)
15. (a) (i) Explain the mechanism of ionosphere propagation. (8)
(ii) How does the earth affect ground wave propagation? (8)
Or
(b) (i) Explain the terms :
(1) Optimum working frequency
(2) Duct propagation
(3) Virtual height (10)
(ii) What are the effects of earth magnetic field? (6)
Or
(b) Explain the following terms with respect to antenna:
(i) Polarization (4)
(ii) Effective aperture (3)
(iii) Directivity (3)
(iv) Antenna temperature (3)
(v) Radiation pattern. (3)
12. (a) Deduce the field quantities and draw radiation pattern for a half
wavelength dipole. (16)
Or
(b) Two identical vertical radiators are spaced 4 / λ = d meters apart and fed
with currents of equal magnitude but with a phase difference ‘ β’.
Evaluate the resultant radiation for β= 0° and thereby identify the
direction of maximum and minimum radiation. (16)
13. (a) Explain the radiation mechanism of slot antenna with diagram. (16)
Or
(b) Explain the special features of Reflector antenna and discuss on different
types of feed used with neat diagram. (16)
14. (a) With a neat sketch, explain the construction and operation of Helical
antenna. (16)
Or
(b) Explain the principle of operation of Yagi-Uda array with neat schematic
diagram. (16)
15. (a) (i) Explain the mechanism of ionosphere propagation. (8)
(ii) How does the earth affect ground wave propagation? (8)
Or
(b) (i) Explain the terms :
(1) Optimum working frequency
(2) Duct propagation
(3) Virtual height (10)
(ii) What are the effects of earth magnetic field? (6)
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Older question banks
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III
B.Tech I Semester Regular Examinations, November 2007ANTENNAS AND WAVE PROPAGATION (Common to Electronics &
Communication Engineering and Electronics &Telematics) Time: 3 hours Max
Marks: 80Answer any FIVE QuestionsAll Questions carry equal marks
1. (a) Draw the Dual characteristics of an
antenna.(b) Explain the Radiation from Two wire. [8+8]
2. (a) Derive the expressions for electric field in
case of short current element andhence obtain the conditions for the field to be
in Franhofer region.(b) Find the distance from a radiating element with 60Hz
current such that radi-ation and induction fields are equal. [10+6]
3. (a) A linear broadside array consist of 4
identical equal in phase point source with λ/3 spacing. Calculate and plot the
field pattern. Also find the directivityand beam width.(b) What is optimum
spacing used in parasitic array? Why. [12+4]
4. (a) Write short notes on “Helical Antenna”.(b)
Derive an expression for radiated electric field strength of a traveling
waveradiation of length ‘l’. [8+8]
5. (a) Sketch the current distribution of folded
dipole and find out input impedancewhen two legs have unequal diameters.(b) A
Parabolic dish provides a power gain of 50dB at 10GHz, with 70% efficiency.Find outi.
HPBW.ii. BWFN, diameter. [8+8]
6. (a) Describe the method of measuring the gain and
radiation pattern of an an-tenna.(b) A standard gain horn antenna with a power
gain of 12.5, is used to measure thegain of a large directional antenna by
comparison method. The test antennais connected to the receiver and an
attenuator adjusted to 23dB in order tohave the same receiver output. Find out
the gain of the large antenna. [8+8]
7. (a) Describe the following:i. Space wave
propagation.ii. Duct propagation.
(b) VHF
communication is to be established with a 50watt transmitter at
100MHz.Calculate the LOS distance if the heights of transmitting and receiving
an-tennas are respectively 50m and 10m. Assuming the capture area of
thetransmitting antenna is 25sqmts, calculate the field strength at the
receivingneglecting ground reflected wave. [8+8]
8. (a) Discuss the characteristics of F1 and F2
layers.(b) Discuss the reasons for reduction of field strength in sky wave
propagation.[8+8]
III
B.Tech I Semester Regular Examinations, November 2007ANTENNAS AND WAVE PROPAGATION(
Common to Electronics & Communication Engineering and Electronics
&Telematics)Time: 3 hours Max Marks: 80Answer any FIVE QuestionsAll
Questions carry equal marks
1. (a) Distinguish between Directive Gain and Power
Gain.(b) An antenna has a radiation resistance of 73 ohms and a lossy
resistance of 7ohms. If the power gain is 20, calculate the directivity and the
efficiency of the antenna.
[8+8]
2. (a) Derive an expression for radiance resistance
of current element starting fromthe expression for radiation fields.(b) Prove
that the impedance of an isolated antenna when used for receiving issame as
when used for transmitting. [8+8]
3. (a) In order to scan the beam of a linear array
to 300 off broadside. Calculate
theinner element phase shift required if the elements are spaced at 3 cms and
thefrequency is 64 KHz.(b) What are linear arrays. Compare Broadside array and
End fire array. [8+8]
4. (a) Derive an expression for electric field of a
Non Resonant antenna of length ‘l’carrying current.(b) Sketch and explain the
constructional features of a Helical Antenna. [10+6]
5. (a) What is a Parasitic Element? Describe the use
of different types of
parasitesin TV receiving antennas.(b) Derive an expression for aperture field
distribution of a parabolidal reflector.[8+8]
6. (a) Describe the method of measuring the gain and
radiation pattern of an an-tenna.(b) A standard gain horn antenna with a power
gain of 12.5, is used to measure thegain of a large directional antenna by
comparison method. The test antennais connected to the receiver and an
attenuator adjusted to 23dB in order tohave the same receiver output. Find out
the gain of the large antenna. [8+8]
7. (a) Define MUF and Critical frequency. Derive the
expressions for the same.What is Secant law?(b) Describe the Ground wave
propagation. [8+8]8. (a) Derive the field strength of tropospheric wave. (b)
Give an account of effect
of earths imperfections and roughness. [8+8]
III
B.Tech I Semester Regular Examinations, November 2007ANTENNAS AND WAVE
PROPAGATION( Common to Electronics & Communication Engineering and
Electronics &Telematics)Time: 3 hours Max Marks: 80Answer any FIVE
QuestionsAll Questions carry equal marks
1. (a) Define the terms:i. Beam Widthii. Side Lobe
Leveliii. Polarizationiv. Effective
Aperture Area.(b) What is the effective
length of an antenna. Determine the effective
length of a half wave dipole antenna. [8+8]
2. (a) Show that the radiation resistance of a small
loop is equal to 320π4(A/λ2)ohms where A is loop area.(b) What is Folded Dipole
? Find its Radiation Resistance. [8+8]
3. (a) Explain the procedure for measuring the
radiation pattern of a half wavedipole.(b) What is the requirement for tapering
of arrays.(c) State the applications of arrays. [8+4+4]
4. (a) State the advantages and disadvantages of
Rhombic Antenna.(b) Draw the radiation pattern for traveling wave antenna for
L=λ/2,λ,2λ ,4λ and 8λ. [8+8]
5. (a) What is a Parasitic Element? Describe the use
of different types of
parasitesin TV receiving antennas.(b) Derive an expression for aperture field
distribution of a parabolidal reflector.[8+8]
6. (a) Describe the method of measuring the gain and
radiation pattern of an an-tenna.(b) A standard gain horn antenna with a power
gain of 12.5, is used to measure thegain of a large directional antenna by comparison
method. The test antennais connected to the receiver and an attenuator adjusted
to 23dB in order tohave the same receiver output. Find out the gain of the
large antenna. [8+8]
7. It is defined to establish short wave
communication between two points on earthssurface(assumed flat) separated by
1200km. Calculate MUF and angle of take off
1 of 2 of the transmitted wave from the following: Highest signal frequency
returned to earth after vertically upward propagation=7.2MHz. Virtual height of
the ionized layer=200kms. Deduce the working formula. [16]
8. (a) Distinguish between Radio and Optical
horizons. Give the reasons.(b) Write short notes on M-Curves.
Set No. 4
III
B.Tech I Semester Regular Examinations, November 2007ANTENNAS AND WAVE
PROPAGATION( Common to Electronics & Communication Engineering and
Electronics &Telematics)Time: 3 hours Max Marks: 80Answer any FIVE
QuestionsAll Questions carry equal marks
1. (a) Define antenna beam width and directivity and
obtain the relation between them.(b) Calculate the electric field (Erms) due to
an isotropic radiator radiating 3KWpower at a distance of 2 Km from it. [8+8]
2. (a) State the following antenna theorems and bring
out their importance in antenna measurements :i. Reciprocity theorem. ii.
Maximum power transfer theorem.(b) A half wave transmitting antenna radiates
10KW of power at 100MHz.If the heights of transmitting and receiving antennas
are 100m and 9m, calculate the power received at a distance of 10kms from the
transmitting antenna. [8+8]
3. (a) Calculate i. HPBW ii. Solid Angle if a linear
array having 10 isotropic point source with λ/2spacing and phase difference δ=900.(b) Write
short notes on Hansen-Wood yard end fire array. [8+8]
4. (a) Distinguish between Traveling wave and
Standing wave antennas.(b) Compare Resonant and Non Resonant antennas.(c)
Explain the working of Rhombic antenna. [4+4+8]
5. (a) Compute the gain, principle beam width and
HPBW of a 10m diameter par-abolic dish with a half wave length dipole feed in
focus at 10GHz.(b) Explain the Cassegrain mechanism in transmission mode. List
out the advantages and disadvantages of Cassegrain feed. [8+8]
6. (a) What is an electromagnetic horn antenna? What
are its applications? The length of an E-plane sectoral horn is 15cms. Design
the horn dimensions such that it is optimum at 10GHz.(b) Calculate the minimum
distance required to measure the field pattern of anantenna of diameter 2m at a
frequency of 3GHz. Derive the necessary equa-tion. [8+8]
7. (a) Show that Ionosphere act as a variable
refractive index medium.(b) A radio link has to be established between two
earth station at a distance of 25000kms. If the height of ionosphere is 200kms
and its critical frequency is 5MHz, calculate the MUF for the given path. Also
calculate the electron density in the ionosphere layer. [8+8]
8. (a) Describe the troposphere and explain how
tropospheric ducts can be used formicrowave propagation.(b) Derive the
expression for space wave electric field produced by an antenna ata distance
point, assuming a flat earth. [8+8)
