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AME_Question bank

AME_Question bank

UDHAYAKUMAR1
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AME_Question bank

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  1. DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGIENNRING EC8701 – ANTENNAS AND MICROWAVE ENGINEERING Unit – I - INTRODUCTION TO MICROWAVE SYSTEMS AND ANTENNAS Part – A 1.What is retarded potential? (Dec – 09, Nov-16) 2.Define isotropic radiator. Write expression for average power density of it. (Dec – 14) 3.Define directive gain of an antenna. (May – 11) 4.What is meant by directivity? (Dec – 09, May-11,12) 5.Define half power beam width. (May-10, Dec-12) 6.Define self-impedance and mutual impedance of an antenna. (Dec-09) 7.What is the significance of radiation resistance of antenna? (May-11,14,15) 8.What is the significance of aperture? (May-15) OR Define effective aperture of an antenna. (Dec-11, May-12) 9.What are the field zones? (May-12) 10.What is the significance of gain of an antenna? (Dec-11) 11.What are θ and ϕ patterns in antenna radiation pattern? (Dec-13) 12.What are dBi and dBd? Write their significances. ( Dec-13) 13.How a dipole antenna can be formed from a two wire open circuited transmission line? (Dec- 13) 14.Compare short dipole from half wave dipole. (May-14) 15.What is radiation resistance? (May-16) 16.The voltage induced by the application of an electric field of strength 2 volts/meter is 0.7. Calculate the effective length of the element. (Nov-16) 17.Determine the electric field intensity at a distance of 10 km from a dipole antenna of directive gain of 6 dB and radiating power of 20 kW. (May-17) 18.Define gain of an antenna. (May-17) 19.An antenna has a field pattern given by E(θ) = Cos2(θ) for 0o<=θ<=90o. Find HPBW. (Dec- 17) 20.Differentiate Radian and Steradian. (Dec-17) 21.List the microwave frequency bands. 22.Write the Friss equation. 23.What is meant by link power budget? 24.What are the noise characteristics of microwave receiver?

  2. 25.Define antenna. 26.What is meant by radiation? 27.What is radiation pattern? 28.Define aperture efficiency. 29.Define antenna bandwidth. 30.Define antenna beam width and its types. 31.What is antenna temperature? 32.Define half wave dipole antenna. Part – B&C 1.Explain following the term with respect to antenna I. Radiation pattern (May-11,14, Dec-11, May-12) II. Beam solid angle (Dex-11,May-14) III. Radiation intensity IV. Directivity (May-11, Dec-11, Dec-13, May-15) V. Gain ( Dec-12, 13) VI. Bandwidth (Dec-11) VII. Antenna impedance (May-14,Dec-13) VIII.Effective aperture (May-11,15, Dec-12) IX. Antenna temperature (May-11, Dec-13, May-12,14) X. Polarization (May-11,12,14,15, Dec-11) XI. Power gain XII. Antenna efficiency XIII.Beam width XIV.Beam efficiency XV. Effective length 2.Define and explain radiation resistance of antenna. (Dec-12) 3.Define and explain polarization and its significance in antenna analysis. (Dec-13) 4.Derive the relationship between directive gain, effective length and radiation resistance. 5.Write a note on different types of antenna apertures. 6.What are Hertzian dipoles? Derive the electric field and magnetic field quantities of infinitesimal dipole and radiation pattern. (Dec-11) 7.Derive the electric and magnetic field components of a Hertzian dipole. (May-15) 8.Derive an expression for power radiated by a small current element. (Dec-09,10) 9.Show that the radiation resistance of adipole is 80. (May-10) 10.Derive radiation resistance of an oscillating electric dipole. (Dec-13) 11.Derive the current and vector potential of a Hertzian dipole. (May-14) 12.Derive the expression for power radiated and the radiation resistance of a half wave dipole. (Dec-14, May-15) 13.Explain difference between half wave dipole antenna and quarter wave monopole antenna. (Dec-13)

  3. 14.Deduce the field quantities and draw radiation pattern for a half wave dipole. (May-11) 15.What is an induction field? (May-10) 16.Derive the expressions for the far field of a half wave dipole antenna. (May-10) 17.Derive the field quantities and radiation resistance of a half wavelength dipole. (Dec-11) 18.Derive the electric and magnetic field components of a finite length dipole antenna and show its current distribution with respect to its length in terms of wavelength. (May-14) 19.Explain in detail about the link power budget and link margin. 20.Describe the noise characteristics of microwave receiver. Unit – II - RADIATION MECHANISMS AND DESIGN ASPECTS Part - A 1.State field equivalence principle. (May-14) 2.State Huygen's principle. (May-11,15, Dec-12,13) 3.What are the features of pyramidal horn antenna? (May-11,15) 4.What are the merits and applications of offset feed reflector antenna? (Dec-13) 5.What is the significance of reflector antenna? (Dec-14) 6.What are the features of microstrip antenna? (Dec-11) 7.Brief out about feed methods of microchip antennas. (May-13) OR Mention the types of feed methods for microstrip antenna. (May-12) 8.Mention applications of microstrip antennas. (May-15) 9.Draw the different types of horn antennas. (Nov-16) 10.Name some numerical tools that can be used to analyze an antenna. (Nov-16) 11.What are the different types of horn antenna? (May-17) 12.Mention any four advantages of microstrip antenna? (May-17) 13.What is meant by antenna tapering? 14.What is an aperture antenna? 15.What is pyramidal horn? 16.Define reflector antenna. 17.List the different types of reflector antenna. 18.State Image theory. 19.Write the function of the plane reflector. 20.State the design equation of a parabolic reflector. 21.Define spill over. 22.Give the comparison between parabolic reflector and corner reflector. 23.Define paraboloid. 24.What are the various feeds used in reflector? 25.Give the advantages of cassegrain feed system. 26.Define aperture blockage. 27.What is slot antenna?

  4. 28.Define loop antenna. 29.What is meant by wire antenna? 30.Why log periodic antenna called so? (DEC-11) 31.Why frequency independent antennas are called so? (May-14) 32.State Rumsey principle on frequency independence. (May-16, Nov-16, May-17) 33.Write the design parameters of a log periodic antenna. 34.Give the relationship between spacing factor and acute angle of a log periodic antenna? 35.Mention the ideal characteristics of dielectric material used in MMIC. Part – B&C 1.Give the applications of horn antenna. (Dec-09) 2.Derive the design equations of horn antenna. (Dec-10) 3.Explain the radiation mechanism of microwave horn antenna with diagram. (Dec-11, May- 15) 4.Explain the principle of rectangular horn antenna with a neat sketch. (May-14) 5.Explain the construction and principle of pyramidal horn antenna. (Dec-13) 6.Explain the radiation pattern and fields on the axis of E-plane and H-plane sectoral horn. (Dec-14) 7.Draw different types of horn antenna structures. (May-15) 8.Explain dish antenna. (Dec-09) 9.Explain the geometry of cassegrain feed. Mention it’s advantages. (Dec-10) 10.Explain special features of reflector antenna and discuss on different types of feed used, with neat diagram. (May-11) 11.Explain salient features of flat and curved reflector. (May-14) 12.With the help of neat sketch explain principle of parabolic reflector antenna and explain various types of feed used. (May-14) 13.Explain the special features of parabolic reflector antenna and discuss on different types of feed used with neat diagram. (Dec-11) 14.What is reflector antenna? With necessary diagrams, explain parabolic reflector antenna and it’s different types of feeding system. (May-12,15) 15.How is aperture blockage in reflector in reflector antennas avoided? (May-12) 16.With necessary illustrations explain the radiation characteristics of microstrip antenna and mention it’s possible application. (Dec-11) 17.Discuss various feed techniques for rectangular patch antenna with neat diagrams. (Dec-13) 18.Derive thefield equations of loop antenna with necessary equations. 19.Explain construction and characteristics features of frequency independent antennas. (Dec- 14) 20.Explain conical spiral antenna. 21.Explain with examples, equiangular spiral antenna. 22.Explain the working of log-periodic dipole array with diagram. (May-10) 23.With suitable geometry describe the design of a log periodic array. (May-12)

  5. 24.In a log periodic dipole array, describe the relationship between apex angle, scale constant and spacing. (Dec-10) 25.Explain design details of light periodic dipole antenna. (Dec-13) 26.Explain principle of operation of log periodic antenna with neat schematic diagram. (May- 15) 27.What are the materials used for MMIC fabrication? Explain the neat diagram the fabrication process of MMIC.(May/Jun 2014) UNIT – III - ANTENNA ARRAYS AND APPLICATIONS Part – A 1.What are the advantages of antenna array? OR What is the significance of antenna array? (May-14) 2.What is binomial array? (Dec-14) 3.Define pattern multiplication. (Dec-11, May-15, Dec-17) 4.Mention the features of radiation pattern multiplication principle. (Dec-13) 5.How we can eliminate minor lobes?(Nov-16) 6.What is the basic principle of antenna synthesis? (Nov-16) 7.Using pattern multiplication find the radiation pattern for the broadside array of 4 elements, spacing between each element is λ/2. (May-17) 8.Draw the radiation pattern of an isotropic point sources of same amplitude and same phase that are λ/2 apart along X axis symmetric with respect to origin. (May-17) 9.What is tapering of arrays? (Dec-17) 10.What is meant by an antenna array? 11.What is meant by uniform linear array? 12.Define array factor. 13.Define broad side array. 14.Define end fire array. 15.Give the difference between broad side array and end fire array. 16.Define phased array. 17.Write the objectives of the phased array. 18.What is an adaptive array? 19.Define smart antenna. 20.What is DBF antenna? 21.Define the term antenna synthesis. Part – B&C 1.Compare end fire array and broad side array. 2.Derive Maxima, minima and half power point directions with two point sources are fed with currents equal in magnitude and phase. 3.Derive an expression for resultant radiation pattern of two element array. (Dec-09)

  6. 4.Derive Maxima, minima and half power point directions with two point sources are fed with currents equal in magnitude but opposite in phase. 5.Derive conditions for two point sources with currents unequal in magnitude and with any phase. 6.Derive array factor of a uniform linear array. Explain significance of array factor. (Dec-13) 7.Write a note on n-element uniform linear array. 8.Obtain null directions for array of n isotropic point sources of equal magnitude and spacing. (Dec-10) 9. What is broad side array? Derive expressions for the radiation pattern of a broad side array of a n elements. 10.Derive the expressions for field pattern of end-fire array of n sources of equal amplitude and spacing. (May-12) 11.Obtain null directions for array of n isotropic point sources of equal magnitude and spacing. (Dec-10) 12.Derive depression for field produced by a array and deduce it for an end fire array. (May- 14) 13.Describe the method of pattern multiplication method. (Dec-14) 14.Write short note on Binomial array. 15.What is Tchebyscheff polynomial? Derive Tchebyscheff polynomials upto 6th order. 16.What is meant by adaptive array? 17.Explain in detail about phased arrays and scanning arrays. UNIT – IV - PASSIVE AND ACTIVE MICROWAVE DEVICES Part – A 1.A directional coupler is having coupling factor of 20db and directivity of 40db. If the incident power is 100mw. What is the coupled power?(Nov/Dec 2012) 2.Draw the diagram of H-plane Tee junction. (Nov/Dec 2012) 3.Give the significance of Rat-race junctions. (May/Jun 2013) 4.Power at the input is 900mw. If this power is incident on 20dB coupler with directivity 40dB, what is the coupled power and transmitted power. (May/Jun 2013) 5.What are factors that reduce the efficiency of IMPATT diode? (May/Jun 2014) 6.What is negative resistance in Gunn diode? (May/Jun 2014) 7.Compare PIN diode and PN junction diode. 8.How will you define magnetron? 9.Write short notes on Tetrodes and Pentodes? 10.State the limitations of conventional tubes at microwave frequency. 11.A helix travelling wave tube operates at 4 GHz, under a beam voltage of 10 kV and beam current of 500mA. If the helix is 25 Ώ and interaction length is 20cm, find the gain parameter. 12.Mention the major differences between the TWT & Klystron. 13.Compare O-type and M-type device.

  7. 14.What is meant by Hull cut-off voltage? 15.State transferred electron effect.(Nov/Dec 2012) Part – B&C 1.Explain the properties of H-plane Tee and give reasons why it is called shunt Tee.(Nov/Dec 2012) 2.With neat diagram explain the operation of the following devices (i)Gyrator (ii)Two hole directional coupler. (Nov/Dec 2012) & (Apr/May 2015) 3.Explain the properties of Magic Tee and derive the scattering matrix for it.(May/Jun 2013)&(May/Jun 2014) 4.Discuss the properties scattering matrix. Determine the scattering matrix representations of E plane Tee junctions. (Nov/Dec 2014) 5.Demonstrate the working principle of two-hole directional coupler and derive its S – matrix. (8) 6.Draw and explain the operation of an Isolator. (8) 7.Explain the characteristics of Magic tee and derive its S matrix. (8) 8.Give the types of attenuator and discuss the working principle of precision type attenuator. (8) 9.Discuss the working principle of Gunn diode as a transferred electron device with two valley model, Also draw the structure, equivalent circuit and V-I characteristics of Gunn diode. (16) (Nov/Dec 2013), (May/Jun 2014) & (Apr/May 2015) 10.Draw the physical structure and doping profile of IMPATT diode and explain in detail.(Nov/Dec 2013)&(Apr/May 2015). 11.Explain the reflex klystron with neat diagram. (Nov/Dec 2012) 12.A two cavity klystron amplifier has the following parameters: Beam voltageV0=1000v, Beam current I0=25mA, frequency f=3GHz, R0=40kΩ, gap spacing in either cavity d=1mm, spacing between the two cavities L=4cm, effective shunt impedance R s h=30kΩ. Calculate the input gap voltage, voltage gain and efficiency.(Nov/Dec 2012) 13.Explain the bunching process of a two cavity klystron and derive expression for the optimum distance L o p t.(May/Jun 2013) 14.A pulsed cylindrical magnetron is operated with following parameters: anode voltage=25Kv, Beam current=25A,magnetic density=.35Wb/m2,radius of cathode cylinder =4cm,radius of anode cylinder=8cm. Calculate a)angular frequency b)The cutoff voltage c)The cut off magnetic flux density.(May/Jun 2013) 15.Briefly explain the working principle of Travelling Wave Tube Amplifier. 16.Derive the equation of velocity modulated wave and discuss the concept of bunching effect in two cavity klystron with neat diagram. 17.Explain the operation cylindrical cavity magnetron oscillator and derive the Hull cut off equations. 18.Explain the working principle of reflex klystron oscillator and derive the expression for power output and efficiency.

  8. Unit – V - MICROWAVE DESIGN PRINCIPLES Part – A 1.What is the need for matching network? 2.Give the importance of matching network. 3.Name the factors used for selecting a matching network. 4.What is the need of Smith chart in the design of matching network? 5.List the drawbacks of matching networks using discrete networks. 6.What is stub matching? 7.List the different types of stub matching. 8.What is single stub matching? 9.What is the need for double-stub matching networks? 10.Why quarter-wave transformers are needed? 11.Define microwave filter. 12.What is image parameter method in microwave filter design? 13.State the principles used in the insertion loss method. 14.Define power loss ratio. 15.What is elliptic function filter? 16.Define amplifier efficiency. 17.What do you mean by power added efficiency? 18.Define compressed gain. 19.Why dielectric resonator oscillators are needed? 20.What is the function of mixer? 21.Define conversion loss. Part – B&C 1.Define matching network and also explain its necessity. 2.Illustrate the design of L-type networks with neat diagrams. 3.Demonstrate the working principle of single-stub matching. 4.Describe about the working principle double-stub matching with neat sketches. 5.With the help of neat diagrams, illustrate how quarter-wave transformers are working of impedance matching? 6.Explain in detail about the filter design by an image parameter method with neat sketches. 7.Discuss in detail about the filter design by an insertion loss method with neat sketches. 8.Explain in detail about the low-noise amplifier design with neat sketches. 9.Write a note on low-noise MOSFET amplifier. 10.Discuss in detail about the microwave power amplifier design with neat sketches. 11.Explain in detail about microwave oscillators with neat diagrams. 12.Discuss in detail about the mixer characteristics with neat sketches. 13.Explain the operations of balanced mixer with neat sketches. 14.Explain in detail about double balanced and antiparallel diode mixers with neat sketches.

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