DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
QUESTION BANK
SUBJECT: ANTENNA AND WAVE PROPAGATION
CLASS / SEM / DEPT: III YEAR / VI SEM / ECE
UNIT I-BASIC ANTENNA CONCEPTS
PART -A
1. Define Radiation patterns?
2. What is antenna and its application?
3. Define duality of an antenna?
4. Define radiation intensity?
5. Define directive gain?
6. What is meant by antenna efficiency (η)?
7. What are the types of radiation pattern lobes?
8. Define power gain?
9. Define impedance of an antenna?
10. What is meant by antenna effective area (Ae)?
11. What are the basic antenna elements?
12. Find the effective area of a Hertizian dipole operating at 100 MHz?
13. Write the Friis transmission formula in terms of gain of an antenna (assume non-identical transmitting and receiving antennas)?
14. Define power pattern of an antenna?
15. What are the factors determining the system temperature?
16. What is radian?
17. What is the effective length of an antenna?
18. Write the three field zones with their boundaries of an antenna under test?
19. A power gain test of a reference antenna and a test antenna resulted in the following data. (a) Input power to the reference antenna= 400mW, (b) Input power to the test antenna =100mW. Calculate the power gain?
20. What is steradian?
21. Define Directivity (D)?
22. Define Antenna temperature?
23. Define polarization?
24. Define Effective aperture?
25. Define system temperature?
PART- B
1. Explain (i) Radiation pattern
(ii) Polarization
(iii) Beam solid angle
(iv)Effective aperture?
2. Explain the different types of radiation patterns in detail?
3. Compute Effective area and directivity of half wave dipole antenna?
4. Derive the expressions of the near and far fields due to a short dipole. Find also the distance at near and far fields are equal?
5. Briefly explain
a) Impedance of an antenna
b) Directive gain and directivity
c) E plane and H plane pattern
6. (i) Derive the Friis transmission formula?
(ii) A dipole having a length 3cm is separated at 1GHz. The efficiency factor k=0.6. Calculate the radiation resistance, antenna gain and the effective aperture?
7. Explain in brief :-
a) System temperature
b) Antenna temperature
8 .Derive an expression for
a) Beam solid angle
b) Poynting vector.
9. Write short notes on
a) Cross field
b) Duality of antenna.
10. Write short notes on
a) System temperature
b) Antenna temperature
UNIT II-POINT SOURCES
PART-A
1. Define point sources?
2. What is pattern multiplication concept?
3. What is meant by broadside array?
4. Define end fire array?
5. Define field pattern ?
6. Define half power beam width?
7. What are the factors for choosing the directivity of a broadside array?
8. State the directivity of improved end fire array?
9. What is mean by beam width of major lobes?
10. What is the direction of minor lobes maxima for a broadside array?
11. What are the disadvantages of binomial array?
12. Define isotropic radiators?
13. What is an array factor?
14. Obtain the expression of beam width of a broadside array and end fire array?
15. How can the side lobes of a broadside array be eliminated?
16. How can broadside array be differentiated from end fire array?
17. Define antenna array?
18. Define power pattern?
19. Define uniform linear array?
20. What is meant isotropic antenna?
21. Define binomial array?
22. What is meant by main lobes?
23. What is meant by side lobes?
24. What is meant by back lobes?
25. Define null pattern?
PART B
1. Derive the expression for field radiation pattern of an array of two point sources of same amplitude and phase?
2. Derive an expression for directions of pattern maxima, minima, and beam width of major lobe for a broadside array. Make suitable assumptions?
3. Derive an expression for field strength of a uniform linear array and prove that non directional elements?
4. With a neat sketch and examples explain the principle of pattern multiplication?
5. Explain isotropic antenna and if an array of isotropic radiators is operated at a frequency of 6Ghz and is required to produce a broadside beam ,find Null to Null beam width if the array length is 10m.also find the directivity.
6. Derive the expressions for the directivity of broadside array and an end fire array?
7. Explain the operation of impedance matching techniques with neat diagram?
8. If the array factor of a linear array has zeros at Ø=90,180,270 degree and the elements are spaced λ/4,design the array?
9. Write short notes on a) End fire array? b) Broadside array?
10. Write short notes on a) BWFN ? b)Radiation patterns?
UNIT III-SMALL ANTENNAS
PART A
1. What is half wave dipole antenna?
2. What are the salient features of loop antenna?
3. What is helical antenna?
4. What are the salient features of helical antenna?
5. Calculate the physical height of a half wave dipole having antenna Q of 30 and BW of 10MHz?
6. Define loop antenna and give the applications of loop antenna?
7. What are the advantages and disadvantages of loop antenna?
8. What are the types of loop antenna? List them and give the limitations of loop antenna?
9. Draw the basic structure of a helical antenna with a coaxial line feed?
10. What is the limitation of the micro strip antenna?
11. What is ‘Hertz antenna’?
12. Why a small loop is referred to as a magnetic dipole?
13. What is meant by Loop antenna?
14. Define circular loop?
15. Define square loop?
16. What is meant by folded dipole antenna?
17. Define halfwavedipole?
18. Define large loop antenna?
19. What is Antenna effect?
20. Define axial mode of helical antenna?
21. Define normal mode of helical antenna?
22. Define multifilar helical antenna?
23. State the applications of helical antenna?
24. Compare loop and helical antennas?
25. Compare circular loop and square loop?
PART B
1. (i)Write a technical note on ‘small loop antenna’?
(ii)Derive an expression for radiation resistance of an oscillating electric dipole?
2. Derive the expression for the electric fields and radiation resistance of a dipole antenna?
3. (i) Draw a neat sketch of a helical antenna? Describe its principle of operation?
(ii) Explain the development of half wave dipole radiator from an open circuited transmission line with neat sketches?
4. (i) Derive the expressions for far field due to a loop antenna?
(ii). Explain helical antenna in detail?
5. (i) Explain the radiation resistance of a λ/2 dipole antenna?
(ii) Explain the merits and demerits of helical antenna?
6. Explain the two mode operation of helical antenna and its application?
7. Write short notes on
a) Helical antenna?
b) Loop antenna ?
8. Write short notes on
a) Axial mode operation?
b) Normal mode operation?
9. Write short notes on
a) Antenna effect?
b) Night effect?
10. Explain the operation of monofilar and multifilar of helical antenna?
UNIT IV-SPECIAL ANTENNAS
PART-A
1. What is meant by Yagi Uda antenna?
2. What are the special features of Yagi Uda antenna?
3. Name and draw a frequency independent antenna?
4. What is the limitation of micros trip antenna?
5. What are sectoral horn antennas?
6. What is meant by frequency independent log periodic antenna?
7. What is LPDA? Why is it called so?
8. Name and sketch an antenna which provides circularly polarized waves?
9. What are the disadvantages of rhombic antenna?
10. What is a micro strip antenna?
11. Draw the log periodic antenna structures at UHF and VHF ranges?
12. List the applications of horn antenna?
13. What are the advantages of horn antenna?
14. Define rhombic antenna?
15. Define parasitic arrays?
16. What is phase steered array antenna?
17. Define log periodic antenna?
18. Define turnstile antenna?
19. What is meant by ‘V’ antenna?
20. What is meant by inverted ‘V’ antenna?
21. Define micro strip antennas?
22. What is meant by slot antenna?
23. Define traveling wave antennas?
24. Define horn antenna?
25. What is meant by reflector antenna?
PART- B
1. (i) Differentiate ‘V’ antenna from ‘Rhombic antenna’?
(ii) Explain the principles of reflector antennas and their feed systems?
2. Explain about (i) Yagi Uda antenna?
(ii) What are parasitic arrays? Explain in brief?
3. (i) Write short notes on advantages and potential applications of micro strip antennas?
(ii) Explain the basic principle of operation of a phase steered array antenna?
4. Explain the method of measurement of antenna gain and impedance?
5. Explain the geometry of a log periodic antenna? How wide the operation is possible with this antenna? Give the design equations?
6. Explain the operation and construction of reflector antenna with neat block diagram?
7. Explain the operation of slot antenna with neat block diagram?
8. Write short notes on
a) Traveling wave antennas?
b) Slot antennas?
9. Write short notes on
a) ‘V’ antenna ?
b) Inverted ‘V’ antenna?
10.Write short notes on
a) Rhombic antenna?
b) Log periodic antenna?
UNIT- V-WAVE PROPAGATION
PART- A
1. Define MUF
2. What is meant by multi-hop propagation?
3. What is meant by Diversity reception?
4. What is fading?
5. What are the factors that affect the propagation of radio waves?
6. Define: critical frequency?
7. What is space wave?
8. Define: Gyro Frequency?
9. What is Space Propagation?
10. What are the Applications of corner reflector?
11. What is the critical frequency of Radio wave for reflection at vertical incidence if the maximum value of electron density is 1.26 × 10^6 cm^-3
12. A pulse of a given frequency transmitted upwards is received after a period of 5 milliseconds. Find the Virtual height of the reflecting layer?
13. How are critical frequency and maximum usable frequency related?
14. Define Diversity Reception?
15. Define Ionosphere Propagation?
16. What is meant by Ground wave propagation?
17. Define Space wave propagation?
18. Define Sky wave Propagation?
19. What is OTF?
20. What are the limitations of ground wave propagation?
21. What are the Limitations of ground wave propagation?
22. What are the advantages of troposphere wave propagation?
23. Different between space and ground wave propagation?
24. Different between space and sky wave propagation?
25. Define troposphere wave propagation?
PART- B
1. Discuss the effects of earth’s magnetic field on ionosphere radio wave propagation. Comment on Appleton Hartees magnetic ionic formula.
2. Explain: Space wave propagation & Sky wave Propagation
3. (i) Derive an expression for effective relative dielectric constant of the Ionosphere.
(ii) What are the factors that affect the propagation of radio waves?
4. Explain in detail: Ionospheric Propagation
5. (i) Derive an expression for effective permittivity of ionized gas.
(ii) Explain the advantages of tropospheric wave propagation.
6. (i) Explain the Limitations of ground wave propagation.
(iii) Draw the profile diagram of Ionosphere and Explain.
7. Explain in detail about Ground wave propagation.
8. Write brief notes on Diversity Reception.
9. Explain the characteristics of ionosphere?
10. Explain the operation of ground wave propagation?
