sietkece.comsietkece.com/.../uploads/2018/08/AWP-Question-bank.docx · Web view6. The radiation...

QUESTION BANK 2018

SIDDHARTH GROUP OF INSTITUTIONS :: PUTTUR(AUTONOMOUS)

Siddharth Nagar, Narayanavanam Road – 517583

MODEL QUESTION BANK

Subject with Code: AWP(16EC418) Course & Branch:B.Tech– ECE

Year &Sem: III-I B.Tech&V-Sem Regulation: R16

UNIT –I

ANTENNAS BASICS AND DIPOLE ANTENNA

Module 1:

Syllabus Topics:

Introduction, Basic antenna parameters- patterns, BeamArea, Radiation Intensity, Beam Efficiency,

Directivity-Gain-Resolution, Antenna Apertures, Effective height, Fields from oscillating dipole,

Field Zones, Shape-Impedance considerations, Polarization – Linear, Elliptical, & Circular

polarizations, Antenna temperature, Antenna impedance, Front–to-back ratio, Antenna theorems,

Radiation – Basic Maxwell‘s equations, Retarded potential-Helmholtz Theorem,

Important Questions:

1.Explain the following.i) Antenna gain ii) Antenna temperature iii) Retarded potential.2.Explain the following i) Antenna field zones ii) Antenna radiation pattern iii) Radiation intensity iv) Beam efficiency3. Define isotropic radiator, gain & beam width of an antenna4. Discuss the shape impedance considerations. 5.Explain basic Maxwell’s equations. 6. The radiation resistance of an antenna is 72Ω and loss resistance is 8Ω. What is the directivity if the power gain is 16. 7.Explain radiation and Beam efficiency.8. An antenna has a field pattern given by E(Ө)=cosӨcos2Ө for 0≤Ө≤.Find i) The half power beam width (HPBW) , ii) Beam width between first nulls (FNBW). 9. Derive the expression for radiation resistance Rr=80π2(dl/λ)2.10.Write about Effective area and Beam width. 11.Show that radiation resistance of half wave dipole is 73Ω. 12. Explain the terms.i)Effective aperture area ii) Directivity iii) Polarization iv) Effective height.

Assignment Questions:

Antenna and wave propagation Page 1

QUESTION BANK 2018

1. Explain the following.i) Antenna gain ii) Antenna temperature iii) Retarded potential.2. Explain the following i) Antenna field zones ii) Antenna radiation pattern iii) Radiation intensity iv) Beam efficiency3. Explain basic Maxwell’s equations.

Objective Questions:

1. Effective length of receiving antenna is____________2. For s Hertz dipole antenna, the half power beam width (HPBW) in the E- plane is_________3. What is the polarization of a discone antenna_______________4. The radiation fields are nothing but far fields_______________5. The impedance of an isolated antenna when used for receiving is__________.when use for

transmitting.6. If antenna diameter is increased four times, the maximum range is increased by a factor of__________7. Sometimes antennas are terminated to make them ______________8. The polarization of a wave with electric field vector 𝐸 = (𝑎𝑥 + 𝑎𝑦)___________9. Power radiated per unit area in any direction is given by the pointing vector_______________10. Maximum effective aperture is given by the relation________________11. Relation between maximum aperture and directive is________________12. The reciprocity theorem can be used to drive the following____________13. _________defined as 2π*.14. Beam efficiency εM=_______________15. Directivity _ Beam area relation___________16. Relation betweenGp&Gd in VHF and UHF range______________17. Scattering ratio β=_____18. Equivalent noise temperature is given by the relation______________19. Beam area in terms of half power points is ΩA=_____________20. solid angle dΩ is_________

Module 2:

Syllabus Topics:

Radiation from Small Electric Dipole, Quarter wave Monopole and Half wave Dipole – Current Distributions, Field Components, Radiated power, Radiation Resistance, Beam width, Natural current distributions, far fields and patterns of Thin Linear Center-fed Antennas of different lengths, Illustrative problems


1.Derive the expression of Half-wave Dipole antenna. 2.Derive the expression of Monopole- Dipole antenna. 3.Derive the expression for small electric dipole antenna. 4.Derive the Field expression for an oscillating current element.

Assignment Questions:Antenna and wave propagation Page 2

QUESTION BANK 2018

1.Derive the expression of Half-wave Dipole antenna. 2.Derive the expression of Monopole- Dipole antenna. 3.Derive the expression for small electric dipole antenna.


1. A straight dipole radiator fed in the centre will cause max. radiation_____________(GATE 2014)2. The radiation resistance of half wave dipole is___ Ω.3. The radiation resistance of quarter wave monopole is____ Ω.4. The current distribution in a half wave dipole is___5. The current distribution in an alternating current element is__________6. Current distribution in very short dipole is_________7. Radiation resistance of current element is_________8. Radiation pattern of a short dipole in horizontal plane is a __________9. Directional pattern of horizontal half wave dipole is___________10. The radiation pattern for a one half wavelength dipole is__________11. The measure of solid angle is a ____________12. The measure of plane angle is____________13. Steradian=__________________ degrees14. The resolution of an antenna=_______________15. The resolution of an antenna=_______________16. An antenna or aerial is a means of ____________ or receiving radio waves17. An antenna can be defined as ________ of EM waves.18. The radiation pattern of an antenna is ________ pattern.19. The field radiation pattern is f(θ,φ)=sinθ, then the power radiation pattern is __________20. The bandwidth of the antenna is inversely proportional to _________ of antenna.

UNIT –II

VHF, UHF AND MICROWAVE ANTENNAS-I


QUESTION BANK 2018

Module 1:

Syllabus Topics:

Loop Antennas - Introduction, Small Loop,Comparison of far fields of small loop and short dipole,

Radiation Resistances and Directives of small and large loops (Qualitative Treatment), Arrays with

Parasitic Elements - Yagi - Uda Arrays, Folded Dipoles & their characteristics.


1. Discuss directivity of small and large loop.2. Compare fields of small loop and short dipole. 3. Explain about construction and operation of Yagi-Uda antenna.4. What are parasitic elements &where they are used? 5. Derive the expression for radiation resistance of small loop antenna.6. Write short notes on

i) Folded dipole antenna ii) Yagi-Uda array iii) Horn antenna7. Design Yagi-Uda antenna of six elements to provide a gain of 12db if the operating frequency

is 200 MHz.8. What are Electrically small loop antenna? 9. List out the uses of loop antenna. 10. Explain and derive the expression of a folded dipole antenna with neat sketch.


1.Derive the expression for radiation resistance of small loop antenna.2.Explain about construction and operation of Yagi-Uda antenna.3.Discuss directivity of small and large loop.4.Explain and derive the expression of a folded dipole antenna with neat sketch.


1.One of the following is very useful as a multiband HF receiving antenna. This is the……….2.Loops are extensively used in_____3.The far field components of loop antennas isEφ=____4.Radiation resistance of small loop Rr is______5.Radiation resistance of large loop Rr is______6.Directivity of small loop is_____7.Directivity of large loop is_____8.The magnetic component of loop antenna in θ direction Hθis ________9.VHF band is______________ 10.SHF band is ____________11.Antennas operating over 3000 MHz are called _________________antennas12.Typical antennas used in SHF band are _______________ 13.An antenna that is circularly polarized is________ (GATE 2011)14.The parasitic element whose length is less than the driven element then it is called_........15.Which antenna has high input impedance & greater bandwidth_____________ 16.Which antenna is used for space communactionsystems_____________17.Lens antennas used for microwaves are usually made of18.Yagi antenna produces _________ pattern Antenna and wave propagation Page 4

QUESTION BANK 2018

19.Disadvantage of Yagi antenna is _______________ 20.The radiation resistance of tripole is __________________

Module 2:

Syllabus Topics:

Helical Antennas-Helical Geometry, Helix modes, Practical Design considerations for Monofilar Helical Antenna in Axial and Normal Modes. Horn Antennas- Types, Fermat‘s Principle, Optimum Horns, Design considerations of Pyramidal Horns, Illustrative Problems.


1. Discuss about the helical antenna geometry, axial mode of radiation and its applications.2. Discuss about the horn antenna types & its characteristics.

3. What are the practical design considerations for Monofilar helical antenna in normal mode?

4. Explain about the construction and characteristics of helical antenna.

5. Discuss the design considerations of pyramidal horn antenna.

6. Discuss the types of horn antennas.

7. Give the applications of helical antennas.

8. Discuss the types of horn antennas.

9. Design 10 turns helix to operate in axial mode for optimum design, a) Determine the circumference (λ0¿, pitch angle ( in degrees)

separation between turns (λ0¿b) Determine the Relative wave velocity (free space) Along the wire

of helix for ordinary endfire design, Hansen-woodyard end –fire designc) Find Half power beam width of the main lobe (in decrease) Find the axial ratio (in decibels)


1.Explain about the construction and characteristics of helical antenna.2. Discuss about the horn antenna types & its characteristics. 3.What are the practical design considerations for Monofilar helical antenna in normal mode?Objective Questions:

1.When an antenna has a gain of 44db then assuming that the main beam of the antenna is circular in cross section the beam width will be_____________(GATE 2008)2.The horn antenna is used with __________ & is used as a radiator.3.A short parabolic right cylinder enclosed by parallel plates is called______ antenna.4.HF band is____ _________5.UHF band is ____________6.Microwave band is __________7.Tower antenna is a ____antenna.8.One application of VLF is__________9.Radiation resistance of two wire folded dipole is___________10.Folded dipole has _____________input impedance.11.Yagi-Uda array consists _________________


QUESTION BANK 2018

12.Parasitic elements are__.__________13.The parasitic element whose length is greater than the driven element then it is called__________14.The parasitic element whose length is less than driven element then it behaves like __________in nature.15.A simple broad band VHF & UHF antenna is ____________16. Helical antenna provides _______polarization characteristics.17.Pitch angle α=________________18.____ antenna may be regarded as a flared out or opened out wave guide.19.The principle of equality of path length is known as____________20.Directivity of pyramidal horn antenna D=_____________

UNIT –III

VHF, UHF AND MICROWAVE ANTENNAS-II

Module 1:

Syllabus Topics:

Micro strip Antennas- Introduction, features,advantages and limitations, Rectangular patch antennas-

Geometry and parameters, characteristics of Micro strip antennas, Impact of different parameters on

characteristics


QUESTION BANK 2018


1.Give the advantages and limitations of micro strip antennas.2. Explain about micro strip antennas with neat diagrams.3. Discuss the construction of rectangular patch antenna.4. What are the different parameters effects the characteristics of micro strip antenna explain?5. What is a patch antenna? 6. What are the applications of MSA?Assignment Questions:

1. Explain about micro strip antennas with neat diagrams.2. Discuss the construction of rectangular patch antenna.3. Give the advantages and limitations of micro strip antennas.


1. Microstrip antenna is a------------------- antenna2. Patch antennas used at frequency’s above_________3. The frequency of operation of patch antenna is_____4. Microstrip antenna is also known as___________5. The f/d ratio of parabolic reflector is lies between_________6. Patch antennas has_______ bandwidth7. The characteristic impedance of patch antenna is_________8. The directivity of patch antenna is____________9. The size of the patch antenna is_____________10. The limitations of patch antennas are____________11. A rectangular patch antenna produce_______pattern12. The important application of patch antenna is__________13. One of the practical antennas in µw frequency ranges are_______14. The equivalent circuit of earth is__________15. Ground wave field strength depends on_________16. The equation of paraboloid will be given as___________17. Advantage of cassegrain feed is__________18. In parabolic reflector, some of the desired rays are not captured by the reflector__________19. The power gain of paraboloid reflector is given by____________20. Typical bandwidth of stepped lens antenna is______ (GATE 2010)21. Earth is considered to be smooth if the roughness is____________22. Wavelength in free space & wavelength in a waveguide are the same_________23. Field strength pattern is the variation of ___________24. Power pattern is the variation of_________25. For far-field antenna measurement, R must be____________26. At X-band , the size of patch antenna is of order of________27. A rectangular patch antenna produces ________pattern28. The important application of patch antenna is_________29. One of the practical antennas in µw frequency ranges are_________30. The equivalent circuit of earth is__________


QUESTION BANK 2018

Module 2:

Syllabus Topics:

Reflector antennas - Introduction, Flat sheet and corner reflectors, parabola reflectors- geometry, pattern characteristics, Feed Methods, Reflector Types - Related Features, Lens Antennas - Geometry of Non-metallic Dielectric Lenses, Zoning , Tolerances, Applications, Illustrative Problems.


1. Write short notes on flare sheet & corner reflector.2. What is reflector? What are the types of reflectors? Explain the features of parabolic reflectors.3. Explain about flare sheet, corner & paraboloidal reflectors. 4. Explain the features of corner reflectors. 5. Explain the basic principle of operation in lens antenna & distinguish between different types

of lens antenna used in practice.6. With a neat sketch explain the constructional features of parabolic reflector and obtain

expression for its curved profile.7. Mention different methods of feeds of parabolic reflector antennas. 8. Explain about zoned lens antenna.9. Explain the basic principle of operation of dielectric lens antenna


1. What is reflector? What are the types of reflectors? Explain the features of parabolic reflectors.2. Explain the basic principle of operation in lens antenna & distinguish between different types

of lens antenna used in practice. 3. Explain about flare sheet, corner & paraboloidal reflectors.


1. VSWR is given by_____________2. Absolute gain measurement method is also known as________3. The gain of antenna over an isotropic lossless antenna is given by_________4. The disadvantage of lens antenna at low frequency’s is_________5. When frequency <10,000MHz, lens antenna as have exvessive thickness which is undesirable this is

overcome by_________6. The thickness of zoned dielectric lens is given by_________7. Lens antenna uses the geometric optics principle known as_______8. Lens antenna are used at frequency of above______ (GATE 2008)9. Typical bandwidth of unstopped lens antenna is_______10. Dielectric lens is also known as ________11. The thickness of un zoned dielectric lens is given by__________12. When comparing the gain & beam-width of lens antenna with reflectors the cost of lens

antenna is__________


QUESTION BANK 2018

UNIT –IV

ANTENNA ARRAYS & MEASUREMENTS

Module 1:

Syllabus Topics:

Point sources - Definition, Patterns, arrays of 2 Isotropicsources- Different cases, Principle of Pattern Multiplication, Uniform Linear Arrays – Broadside Arrays, Endfire Arrays, EFA with Increased Directivity, Derivation of their characteristics and comparison, Broadside Array with Non-uniform Amplitude Distributions - General considerations and Binomial Arrays, Illustrative problems.


1. What is antenna array? Define point sources and uniform linear array.2. Write short notes on broad side and end fire arrays.3. Derive the expression for far field pattern of an array of two isotropic point sources at equalamplitude

& opposite phase.4. Write short notes on


QUESTION BANK 2018

i)Array of two point sources ii) uniform linear array.5. Write short notes on broad side and end fire arrays. 6. A broad side array operating at 10cm wavelength consists of 4 half wave dipole spaced

50 cm each element carries radio frequency current in the same phase and of magnitude 0.5 amps. Calculate the radiated power, half width of major lobe.

7. Write short notes on i) Linear array ii) binomial Array iii) EFA with increased directivity

8. Explain pattern multiplication with appropriate examples.


1. What is antenna array? Define point sources and uniform linear array.2. Write short notes on broad side and end fire arrays.3. Write short notes on

i)Array of two point sources ii) uniform linear array.Objective Questions:

1. Directivity of Broad side array D_______ 2. Directivity of EFA with increased directivity is D_______-3. The technique used in reduction of side lobe level is called_____4. The advantage of binomial array is___5. The beam width of binomial array is_________6. Array factor or secondary pattern=_________7. In broad side case θmax=__________8. HPBW of broad side array is HPBW=______________9. HPBW of End fire array is HPBW=_________10. Directivity of BSA is D=___________11. Phase angle ψ=________12. Antenna arrays are used to increase______13. Side lobe ratio (SLR)=__________14. SLR is ______for a binomial array15. The simplest type of broad side array is also known as__________16. ___________is a system of similar antennas oriented similarly to get greater directivity in a desired

direction.17. If the individual antennas of the array are equally spaced along a straight line then it is said to

be______18. A Broadside array consisting of 200 cm wavelength with 10 half- wave dipole spacing _____ 10 cm.

And if each array element feeding with I amp. current and operating at same frequency then find the half power beam with________.

19. An arrangement in which the principle direction radiation is perpendicular to the array axis & also to the plane containing the array element is called _____________

20. The arrangement in which the principal directive of radiation consider with the direction of array axis called_______

21. Rhombic antenna is _____antenna.22. Resonant antenna has a length in exact multiples of______ (GATE 2013)23. A broadside array operating at 100 cm wavelength consist of 4 half-wave dipoles spaced 50 cm apart.


QUESTION BANK 2018

Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be_________

24. In general , the element of the antenna array is a___________ dipole25. Unidirectional cosine power pattern has directivity of ___________ 26. In BSA ,all the elements are placed parallel to each other & the direction of max.radiation is always

______ to the axis of array.27. In EFA, with the elements are placed equally along a line & the direction off a radization is_______

with the direction of the axis of array.28. Path difference=_______________29. path difference interms of wavelength =________________ 30. All the antennas are arranged co-axially i.e arranged end to end along a single line is called

______array.31. The common example of parasitic elements array with linear half wave dipole as elements of array

is___32. If the elements in the array are fed with currents of equal magnitude & phase along the line is Called

______________ array.33. In end fire case θmax=__________34. Directivity of EFA is D=___________35. The condition for EFA with increased directivity is based on _____ conditions 36. Directivity of EFA with increased directivity is D=___________

Module 2:

Syllabus Topics:

Introduction, Concepts- Reciprocity, Near and Far Fields, Coordinationsystem, sources of errors, Patterns to be Measured, Pattern Measurement Arrangement, Directivity Measurement , Gain Measurements (by comparison, Absolute and 3-Antenna Methods).


1. Explain near & far fields with respect to antenna measurements.2. Define directivity. Give the procedure for the measurement of directivity.3. Explain the gain measurement using absolute & comparison methods.4. What is principle of pattern multiplication? List the advantages and disadvantages.

5. Explain the following antenna measurement techniques.

i) Directivity ii) Pattern multiplication


1. Explain near & far fields with respect to antenna measurements.


QUESTION BANK 2018

2. Explain the gain measurement using absolute & comparison methods.Objective Questions:

1. An Antenna under measurement, the distance between primary &secondary antenna should be _________________

2. Measurement of gain is done by ___________ methods.3. In the absolute method of gain Measurement, G0= ___________________ 4. Measurement of antenna radiation efficiency ηR= _________________

UNIT V

WAVE PROPAGATION

Module 1:

Syllabus Topics:

Introduction, Definitions, Characterizations and general classifications,different modes of wave

propagation, Ray/Mode concepts, Ground wave propagation (Qualitative treatment) - Introduction,

Plane earth reflections, Space and surface waves, wave tilt, curved earth reflections, Space wave

propagation - Introduction, field strength variation with distance and height, effect of earth‘s

curvature, absorption, Super refraction, M-curves and duct propagation, scattering phenomena,

tropospheric propagation, fading and path loss calculations.


1. Discuss the field strength variation with distance & height.2. Discuss the atmospheric effects in space wave propagation.3. Explain ground wave propagation.4. Explain about the troposphere propagation. 5. Explain about scattering phenomenon & Super refraction.6. Explain about plane earth reflections in ground wave propagation. 7. Explain the different modes of wave propagation.


QUESTION BANK 2018

8. What is fading & list different types of fading and explain.


1. Explain ground wave propagation.2. Explain about the troposphere propagation.Objective Questions:

1. Troposcatter propagation is related to__________2. Short waves for long distance communication depends on____________3. Attenuation in atmosphere is inversely proportional to the square of the frequency_______4. When an EM wave whose MUF is 25MHz is incident at 40o , then fc is_______ (GATE 2012)5. The Optimun frequency is ___________ of MUF.6. For Satellite tracking at VHF, helical antenna is often used because of________7. Fading is nothing but__________8. The factor A depends on d as_____________9. Roughness of earth depends upon___________10. Impedance measurement by slotted line method is better suited at_______11. Which of the wave remains unaffected whether it is a day or night________12. D-layer extends approximately from13. Microwave signals follow the curvature of the earth & phenomenon is known as______14. During day which layer doesn’t exist_________15. Wave unaffected by day or night is_________16. When EM wave propagates from air into ionosphere, its velocity_______17. Los distance is affected by atmospheric refraction_________18. Ground wave is affective when the transmitting & receiving antennas are19. Duct propagation takes place when =_________20. Television broadcast generally uses_________Module 2:

Syllabus Topics:

Sky wave propagation - Introduction, structure of Ionosphere, refraction and reflection of sky waves by Ionosphere, Ray path, Critical frequency, MUF, LUF, OF, Virtual height and Skip distance, Relation between MUF and Skip distance, Multi-HOP propagation, Energy loss in Ionosphere, Summary of Wave Characteristics in different frequency ranges, Illustrative problems.


1. Explain the refraction and reflection mechanisms in sky wave propagation. 2. Explain the structure of Ionosphere.3. Explain the terms i) Critical frequency ii) MUF. 4. Explain the following

i) Virtual height ii)Skip distance iii)Multi-hop propagation5. Discuss the effects of earth’s curvature.6. (a) Define Sky wave and Ground Wave.

(b) What are inverse and multi path fading?(c) What are the factors that affect the propagation of radio waves?(d) What is meant by Faraday’s rotation?


QUESTION BANK 2018

7. Explain the termsi) Critical frequency ii) Ray path iii) draw the structure of ionosphere; how it varies with weather


1. Explain the structure of Ionosphere2. Discuss the effects of earth’s curvature.3. Explain the terms

i) Critical frequency ii) Ray path iii) draw the structure of ionosphere; how it varies with weather


1. Long distance short wave radio broadcasting uses________2. The relative permittivity of the Ionosphere at RF is_______3. Critical frequency of a layer is given by__________4. During day time ionosphere consists of________5. The absorption of EM waves by the atmosphere depends on_______6. Skip distance________7. VLF waves are used for some type of service because___________8. Broadcasting antennas are generally__________9. In order to receive vertically polarized wave, the conductor of the dipole should be mounted______10. Scatter transmission is used at frequencies_________11. The velocity of the wave when it passes from air into ionosphere________12. The formula for refractive index for ionized layers is_________ 13. MUF is given by__________14. If a wave of critical frequency 30MHz is departing at an 60o, then MUF is_________ 15. Troposcatter propagation is related to_______________16. Short waves for long distance communication depends on_________17. Attenuation in atmosphere is inversely proportional to the square of the frequency_________18. When an EM wave whose MUF is 25MHz is incident at 40o , then fc is_________19. The Optimun frequency is ___________ of MUF.20. Atmosphere is said to be standard atmosphere when =_______


Date post:	26-Dec-2019
Category:	Documents
Upload:	others
View:	6 times
Download:	0 times

sietkece.comsietkece.com/.../uploads/2018/08/AWP-Question-bank.docx · Web view6. The radiation...

Documents