Chendu College of Engineering & Technology (Approved by AICTE, New Delhi and Affiliated to Anna University) Zamin Endathur, Madurantakam, Kancheepuram, District 603311. DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING SUBJECT NAME: ANTENNAS & WAVEPROPAGATION YEAR/SEM: III/VI SUBJECT CODE: EC 2353 QUESTION BANK UNIT I ELECTROMAGNETIC RADIATION AND ANTENNA FUNDAMENTALS 1.Distinguish between power gain and directive gain (Nov/Dec 2014) 2.Define an isotropic radiator? (Nov/Dec 2014) 3.What is the significance of radiation resistance of an antenna? 4.Draw E and H plane radiation pattern of a dipole. 5.What is an elementary dipole and how does it differ from the infinitesimal dipole? 6.what is the effective area of a halfwave dipole operating at 1 Ghz? 7.What are θ & φ patterns in antenna radiation pattern? (Nov/Dec 2013) 8.What are db i and db d? Write their significances? (Nov/Dec 2013) 9.An Antenna has the field pattern given bye(θ)=cos2 θ for 0 θ 90.Find HPBW? 10. Define directivity and effective aperture of an antenna? (May/June2012& Nov/Dec 2011) 11. If an redefine an isotropic radiatordiation resistance of an antenna is 65 ohms and a loss resistance is 10 ohms,find its antenna efficiency? (Nov/Dec 2012) 12. Define half power beamwidth? (Nov/Dec 2012) 13. Define gain and directivity of an antenna? (Apr/May2011) 14. What is significance of radiation resistance of an antenna? (Apr/May2011) 15. What is significance of gain of an antenna? (Nov/Dec 2011) 16. Define array factor? (Dec-2007) 17. What is the relationship between effective aperture and directivity? (Dec-2007) 18. Write the principle of pattern multiplication? (May-2004, Dec-2004, May-2005) 19. Define radiation intensity? (May-2005, May -2010) 20. Define a Hertzian dipole? (NOV-2007,Dec-2010) 21. What are applications loop antennas? (May-2005) 22. List out the applications helical antenna? (APR-2010) 23. What is meant by Polarization? 24. What is meant by uniform linear array? 25. What are the types of array? PART-B 1.a)i) Derive the wave equations using Maxwell s equation and get the solution of wave equations(8) ii) Explain how electric field lines are formed and get detached from short dipole antenna (8) (Nov/Dec 2014) 2. The power radiated by a lossless antenna is 10 watts. The directional characteristics of the antenna are represented by the radiation intensity of U=B 0 cos 3 θ ω/s r for 0< θ π/2 & 0<φ 2π. Find the maximum power density at a distance of 1000 m, assuming far field distance. Specify the angle where this occurs and find the directivity and half power beamwidth of the antenna (16) (Nov/Dec 2014) 3. a)i. Define the following parameters and their dependence on antenna performance. 1) Radiation pattern,2)input impedance,3)polarization.(8) ii. Derive the magnetic field components of a dipole having the dimension l<<l/2 (8) 4. a) i. Explain the terms 1)Beam solid angle,2)antenna temperature,3)reciprocity principle.(8) ii. Derive the current and vector potential of a hertizian dipole (8) 5. a.i.explain the principle of reciprocity as applied to an antenna.(6)
ii.derive the wave equation and obtain it s solution.(10) 6. a.i.what is the effective length of linear antenna?(4) ii.derive the expression for the radiated fields of a center fed λ/2 dipole antenna.sketch the radiation pattern.(12) 7. a i. derive the radiation resistance of an oscillating electric dipole (8) (Nov/Dec 2013) ii. Define and explaine the polarization and its significance in antenna analysis(8) (Nov/Dec 2013) 8. i.state and prove Lorentz Reciprocity theorem for antennas(8) (Nov/Dec 2013) 9. Solve the wave equation for uniform plane waves in an infinitely extending conducting mdium.(16) 10. Write short notes on (i) Radiation Pattern (6) (ii) Polarization (5) (iii) Antenna Temperature (5) 11.Define and explain in detail the terms Radiation resistance, gain, directivity, effective aperture and polarization of an antenna.(16) ((Nov/Dec 2013)Nov/dec 2012, Apr/may 2011, Nov/dec 2011) 12. Derive the electric and magnetic field components of Hertzian dipole.(16) (Nov/dec 2012) 13. What are Hertizian dipoles? Derive the electric and magnetic field quantities of infinitesimal dipole and radiation pattern.(16) (Nov/dec 2011) 14. Obtain the expression for the field and the radiation pattern Produced by a 2 element array of infinitesimal with distance of Separation λ/ 2 and currents of unequal magnitude and phase Shift 180 degree? (16) (Dec-2007) 15. Write short note on i) Vector potential ii) modification potential iii) Retarded Potential iv) capacitance Hat 16. Derive the expression for radiation field and radiation resistance UNIT II WIRE ANTENNAS AND ANTENNA ARRAYS 1.Draw the radiation pattern of a vertical dipole 2.What is Binomial array? 3.Compare short dipole from half wave dipole. 4. What are the advantages of antenna arrays? 5.A uniform linear array contains 50 isotropic radiation with an inter element spacing of λ/2.find the directivity of broadside forms of arrays. 6. What is pattern multiplication and draw the pattern of 2 point sources separated by λ/2 7. How a dipole antenna can be formed from a 2 wire open circuited transmission line? (Nov/Dec2013) 8. Mention the features of radiation pattern multiplication principle (Nov/Dec2013) 9.Calculate the radiation resistance of λ/8 wire dipole in free space. 10. What is Hansen- woodyard array? 11. State the principle of pattern multiplication. (Nov/Dec 2012) 12. What are the conditions to obtain end fire array pattern? (Nov/Dec 2012) 13. What are the applications of loop antenna? (Apr/May2011) 14. Define Pattern multiplication. (Apr/May2011& Nov/Dec 2011) 15. Why is loop antenna called as magnetic dipole? (Nov/Dec 2011) 16. Differentiate broadside array and end fire array? (May-2008) 17. What are applications loop antennas? (May-2005 18. What is radiation resistance of a half wave dipole? (May-2006) 19. What is a Short Dipole? 20. How radiations are created from a short Dipole? 21. Why a short dipole is also called an elemental dipole? 22. What is a Infinitesimal Dipole? 23. Why a short dipole is called a oscillating dipole? 24. What do you understand by retarded current? 25. What are Electrically Small loop antennas?
26. What are electrically large loop antennas? 27. List out the uses of loop antenna. 28. What is capacitance hat? 29. Define top loading 30. What is a loop antenna? 31. Give an expression of radiation resistance of a small loop PART-B 1. Obtain the expressions for power radiated and the radiated resistance of a Half wave dipole (16) 2.i)Describe the method of pattern multiplication (8) ii) A linear broadside array consists of 4 equal isotropic inphase point sources with λ/3 spacing. Find the Directivity and beamwidth (8) 3. Derive the near field and far field electric and magnetic component of a finite length dipole and obtain the radiation pattern for various values of the length. (16) (May/June2014,Nov/Dec 2012) 4. i.derive the expression for the field produced by a linear array and deduce it for an end fire array.(10) ii) Compare end fire and broadside array.(6) 5. a.i.what is binomial array?(2) a.ii.draw the pattern of 10 element binomial array with spacing between the elements of 3λ/4 and λ/2.(14) (May/June13) 6. Derive the expression for field pattern of broad side array of n point sources. 7. i.explain the difference between half wave dipole quarter wave monopole antenna?(6)(nov/dec 2013) ii. derive the directivity of half wave dipole antenna(10) (Nov/Dec 2013) 8.i.Explain about loop antenna and discuss the radiation pattern (8) (Nov/Dec 2013) ii.derive array factor of an Uniform linear array. Explain the significance of array factor (Nov/Dec 2013) 9. A short dipole antenna of length L is positioned at the origin and is aligned along the Z-axis. It carries a current, varying sinusoidal with time and its amplitude. Calculate the total field at a distance point P and opts impedance.(16) 10. Derive the expressions for field pattern of end fire array of n sources of equal amplitude and spacing. (16) 11. For a 2 element linear antenna array separated by a distance d=3λ/4, derive the field quantities and draw its radiation pattern for the phase difference of 45. (Nov/Dec 2012) 12. Deduce the field quantities and draw radiation pattern for a half wavelength dipole.(16) (Apr/May2011, Nov/dec 2011) 13.Two identical vertical radiators are spaced d=λ/4 meters apart and fed with currents of equal magnitude but with a phase difference β.evaluate the resultant radiation for β=0 and thereby identity the direction of maximum and minimum radiation.(16) (Apr/may 2011, Nov/dec 2011) 14.Derive the expression for far field components of a small loop antenna(june-2007, Dec-2004,Apr-2010) 15. i. Explain in detail assumed current distribution for wire antennas (8) ii. Write in brief about the use of capacitance hat and loading coil for short antennas. (8) 16. i. Derive the fields radiated from a quarter wave monopole antenna? (8) ii. Derive the power radiated and radiation resistance of current element?(8) 17. Derive the expression for radiation resistance of loop antenna with circumference equal to wavelength 18. i)what is folded dipole antenna? ii) Explain the term pattern multiplication 19. Obtain the expression for the field and the radiation pattern produced by a 2 element array of infinitesimal dipole with distance of separation λ/2 & currents of equal magnitude and phase shift 180 20. For an array N element feed with signal of equivalent amplitude and phase, determine the maxima and minima directions. Draw the radiation pattern.
UNIT III APERTURE ANTENNAS 1.What is meant by resonant and non-resonant antenna? 2.What is the basic concept of reflector antenna? 3.What is called method of imaging? 4.State field equivalence principle. 5. State Babinet s principle and how it gives rise to the concept of complementary antenna. 6.The aperture dimension s of a pyramidal horn are 12 6 cm and operating at a frequency of 10GHz.Find the beamwidth and directivity. 7. What are the merits & applications of offset feed reflector antenna? 8.State uniqueness theorem. 9.What are the field Zones? 10. State Huygen s principle. (Nov/Dec 3013,Nov/Dec 2012&Apr/May 2011) 11. What are the features of slot antenna? ( Nov/Dec 2012) 12. What are the features of pyramidal horn antenna? (Apr/May2011) 13. What are the limitations of lens antenna? (Nov/Dec2011) 14. State Babinet s principle (Nov/Dec2011) 15. What are traveling Wave antenna? (Dec-2007, Dec-2004, May-2008) 16. Mention the relation between the length l and spacing S of adjacent elements of log periodic dipole array. (May-2010 17. What is the type of radiation pattern produced when a Wave travels in a wire? (June-2007) 18. What are the drawbacks of lens antenna? (Dec-2009) 19. List the applications of parabolic reflector. (Dec-2010) 20. What is the advantage of traveling wave antenna? 21. What is beverage or wave antenna? 22. What is Lunenburg lens? 23. What are the advantages of lens antenna. 24. Mention the uses of lens antenna. 25. Define lens antenna. 26. What are the different types of lens antenna? 27. What is a dielectric lens antenna? 28. What are the drawbacks of lens antenna? PART B 1.i) Explain the effect of earth on radiation patterns above earth(8) ii) Discuss in detail the methods of feeding slot antenna(8) 2. Describe the radiation patterns and fileds on the axis of an E-plane and H-plane sectoral horns (16) 3. a) i) Explain the principle of rectangular horn antenna with neat sketch.(8) ii. Explain the salient features of flat and corner reflector antenna.(8) 4. With neat diagram explain the principle of parabolic reflector antenna and various types of feed used.(16) 5. i.compare flat reflector and corner reflector antennas.(2) ii.explain how a paraboloid antenna gives a highly directional pattern.(6) iii.explain in detail about the feeding structure of parabolic reflector antenna.(8) 6. Write short notes on (i) Slot antenna (8) (May/June2013, May/June2012) (ii)lens antenna (8) 7. i.explain the image theory and its application in detail (8) (Nov/Dec 2013) ii.explain the construction and principle of pyramidal horn antenna. A pyramidal horn antenna having aperture dimensions of a=5.2cm & b=3.8cm is used at a frequency of 10GHz.Calculate its gain and half power beam widths (8) (Nov/Dec 2013) 8. i.discuss the various feed techniques for rectangular patch antenna with neat diagrams (Nov/Dec 2013)
ii. Find the diameter of a dish antenna that will form a beam having 0.5 deg,half power beam width(hpbw) at afrequency of 8.2 GHZ. Assuming an efficiency constant of 0.6, calculate the antenna gain and effective aperture (8) (Nov/Dec 2013) 9. (i).with field equivalence principle explain radiation mechanism.(8) ii) Explain the different types of lens antenna (8) 10. (i)what is reflector antenna? With necessary diagrams, explain parabolic reflector antenna and its different types of feeding system.(12) (ii)how is aperture blockage in reflector antennas avoided?(4) 11. Explain the principle of rectangular horn antenna with a neat sketch. Draw various types of horn structure.(16) ( Nov/Dec 2012) 12. With neat diagram, explain the principle of parabolic reflector antenna and various types of feed used(16) ( Nov/Dec 2012) 13. Explain the radiation pattern of slot antenna with diagram.(16) (Apr/May2011) 14. Explain the special features of reflector antenna and discuss on different types of feed used with neat diagram. (16) Apr/may 2011, Nov/Dec2011 15. Explain the mechanism of microwave horn with neat diagram. Nov/Dec2011 16. Describe the parabolic reflector used at micro frequencies (16) UNIT IV SPECIAL ANTENNAS AND ANTENNA MEASUREMENTS 1.Define pitch angle of a helical antenna 2.Differentiate V antenna from Rhombic antenna 3.Why frequency independent antennas are called so? 4.Mention any two applications of turnstile antenna 5.Mention the types of feeding structures used for microstrip patch antennas. 6.Design a 3 element yagi-uda antenna to operate at a frequency of 200MHz. 7.What is then difference between Yagi-Uda antenna and log periodic dipole array? (Nov/Dec2013) 8.Mention the types of feed method for micro strip antenna. 9.Draw the diagram of rhombic antenna and its radiation characteristics. 10. Mention any two applications of helical antenna. (Nov/Dec 2012) 11. What are the features of Anechoic chamber? (Nov/Dec2013,Nov/Dec 2012) 12. What are the applications of microstrip antenna? (Apr/May 2011) 13. What are near and far field measurements? (Apr/May 2011) 14. What are the features of microstrip antenna? (Nov/Dec2011) 15. Why log periodic antenna is called so? (Nov/Dec2011) 16. What do you meant by pyramidal horn? 17. What is back lobe radiation? 18. What are the various feeds used in reflectors? 19. What are the different types of horn? 20. Define refractive index of lens antenna? 21. What are secondary antennas? Give examples 22. State Huygen s Principle. 23. What is Slot Antenna? 24. Which antenna is complementary to the slot dipole? 25. How will you find the directivity of a large rectangular broadside array? 26. What is the relationship between the terminal impedance of slot and dipole antenna? 27. What do you meant by pyramidal horn? PART B 1.i) Explain the construction and characteristics features of frequency independent antennas(8) ii) Illustrate the reciprocity in antenna measurements (8) 2. Describe construction and radiation characteristics of normal and axial mode helical antenna (16)
3. i) Explain the measurement of antenna gain(8) ii) With necessary illustrations explain the radiation characteristics of Yagi Uda antenna.(8) 4. With suitable diagram explain the construction and principle of Helical antenna in different mode of operation.(16) 5. With neat diagram explain helical antenna and briefly describe it s operation in the axial mode. How does it differ from other antennas? (16) 6. With neat block diagram explain how radiation pattern and gain of an antenna can be measured. (16) 7. i.differentiate V antenna from Rhombic antenna.explain their construction and principles in detail(8) ii. Explain the design details of log periodic antenna (8) (Nov/Dec 2013) 8. i.draw a neat block diagram for antenna radiation pattern measurement. Explain the procedure in detail (10) ii.give an account on Helical antenna (6) (Nov/Dec 2013) 9. a.i.discuss briefly on construction and working principle of turnstile antenna.(8) a.ii.with suitable geometry describe the design of a log periodic dipole array.(8) 10. Explain in detail (i) Directivity measurement (8) (ii)gain measurement (8) 11. With necessary illustrations explain the radiation characteristics of multi element log periodic antenna and mention its possible applications.(16) (Nov/Dec 2012) 12. Draw and explain the function of Helical antenna and various modes of radiation.highlight some of its applications. (16) (Nov/Dec 2012) 13. With a neat sketch, explain the construction and operation of helical antenna. (Apr/May 2011) 14. Explain the principle of operation of Yagi-Uda array with neat schematic diagram.(16) (Apr/May 2011, Nov/dec2011) 15. With necessary illustrations explain the radiation characteristics of microstrip antenna and its possible application. (Nov/Dec2011) UNIT V RADIO WAVE PROPAGATION 1.What are the factors that affect radio wave propagation? (Nov/Dec 2014) 2.What is meant by skip distance? (Nov/Dec 2014, Nov/Dec 2012,Dec-2007, June-2007) 3.Differentiate virtual height from actual height. 4.What are the effects of ground on low frequency wave transmission? 5.Find the maximum distance that can be covered by a space wave, when the antenna heights are 60m and 120m. 6.What is Fading? And how it is compensated. 7.What is free space loss factor? (Nov/Dec 2013) 8.What is Gyro-Frequency? (Nov/Dec 2013) 9.What is the critical frequency for reflection at vertical incidence if the maximum value of the electron density is 1.24 10 6 cm-3? 10. Define skip distance and virtual height. 11. What is the critical frequency for reflection at vertical incidence if the maximum value of the electron density is 1.24 10 6 cm-3? (Nov/Dec 2012) 12. Define MUF. (Apr/May 2011) 13. What is meant by Faraday Rotation? (Apr/May2011&Nov/Dec2011) 14. Define Critical frequency. (Nov/Dec2011) 15. Define duct propagation? (Dec-2007) 16. What is Snell s law? (Dec-2009) 17. Define Sky wave.
18. Define Troposphere wave. 19. Define Ground wave. 20. What are the types of Ground wave? 21. What is meant by Space Wave? 22. What is meant by Surface Wave? 23. What is meant by fading? 24. What is the type of fading? 25. What is inverse and multi path fading? PART B 1.i) Expalin in detail the mechanism of space wave propagation over ideal flat earth with a neat sketch(8) ii) Discuss the factor that give rise to fading in ionosphere radio wave propagation (8) (Nov/Dec 2014) 2.i)Explain the ground wave propagation of radio waves(8)( Nov/Dec 2014,May/June2014,Apr/May 2011,Nov/Dec2011) ii)write notes on faraday rotation.(8) 3. i.describe the space wave propagation and explain the importance of line of sight propagation.(8) ii. Explain the following terms with diagram 1) Duct propagation,2)critical frequency, 3)Skip Zone 4.a.i.Describe the Troposcatter propagation.(8) a.ii.explain the effect of Earth s magnetic field on ground wave propagation.(8) 5. Describe the theory of propagation of Electromagnetic wave through the ionosphere in the presence of external magnetic field and show that the medium acts as doubly refracting crystal. (16) 6. Describe the structure of the atmosphere and specify the factors affecting the radio wave propagation.(16) 7. Explain in detail about effect of earth s magnetic field on radio wave propagation.(16) (Nov/Dec 2013,May/June2012) 8. (i)explain the structure of the ionosphere with neat diagram.(6) (Nov/Dec 2012) (ii)why do we use high frequency waves in sky wave propagation? Explain the mechcanism of propagation.(10) (Nov/Dec 2013,Nov/Dec 2012) 9. (i)describe the troposphere and explain how ducts can be used for microwave propagation.(8) (ii)explain the term (Nov/Dec 2012) Optimum working frequency Skip distance Virtual height 10. a)explain the terms: (Nov/Dec 2013) Optimum working frequency Duct propagation Virtual height b) What are the effects of earth magnetic field? (Apr/May 2011) 11. i.explain the mechanisms of ionosphere propagation.(8) (Apr/May 2011,Nov/Dec2011) ii.how does earth affect ground wave propagation?(8) (Apr/May 2011, Nov/Dec2011) 12. Explain important features of ground wave propagation? (Nov/Dec2011) 13.i. Derive an expression for the refractive index of the ionosphere in terms of the electron number density and frequency (8) ii. Deduce an expression for the critical frequency of an ionized region in terms of its maximum ionization density (8)