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1)What are the various reasons pertaining to the wide use of microwaves 2)What are the two types of terminations. Give the differences between Isolator and Circulator 3)Define s-matrix 5) What are the .Properties of s-matrix? 6) Why is s-matrix used in MW analysis? 7) What is ABCD matrix? 8) Give the applications of directional coupler 9) Define VSWR 10) What is Tee junction?Give two examples 11.What is the other name for magic TEE? 12.What is hybrid ring? 13.What is the other name for Hybrid ring? . 14) What are nonreciprocal devices? Give two examples 15) What is the condition for oscillation in Reflex klystron ? 16) Give the drawbacks of klystron amplifiers. What are the applications of reflex klystron ? What is the purpose of slow wave structures used in TWT amplifiers? How the klystron amplifier can act as klystron oscillator? What are the applications of klystron amplifier? Applications: Define Transit time in Reflex klystron. What is CFA? State the applications of CFA. Applications: What are the elements that exhibit Gunn effect? What are the applications of Gunn Diode? What is negative resistance? Define GUNN EFFECT. Define insertion loss? Define dielectric constant? What is radiation pattern? What is radiation efficiency? . Why can’t conventional tubes be used at microwave frequencies? what is the operating principle of reflex klystron? What is velocity and current modulation in a reflex klystron? . How does bunching occur in a reflex klystron? What are the materials used in the construction of Gunn diode? What are the other names of Gunn diode and Gunn oscillator? Define guide wavelength.

Define cutoff wavelength for a waveguide. Write the relation between guide wavelength, cutoff wavelength and free space wavelength. What are the various power losses in a waveguide? Define wave impedance and characteristic impedance. What is reflection coefficient? Write the relation between VSWR and reflection coefficient. Write the values of VSWR for open circuit, short circuit & matched load. What is a matched load? Define insertion loss. What is magic tee? What are the properties of magic tee? What are the devices used for microwave powermeasurements/ What is cavity resonator? It is a metallic enclosure that confines the EM energy

1) What are the various reasons pertaining to the wide use of microwaves Bandwidth,Improved directivity with an Aerial array ,Reliability, Power Requirement. 1) What are the two types of terminations. Matched load Variable short circuit 2) Give the differences between Isolator and Circulator

3) Define s-matrix

In a microwave junction there is intersection of three or more components.There will be an output port ,in addition there may be reflection from the junction of other ports.Totally there may be many combinations,these are represented easily using a matrix called S matrix. 5) What are the .Properties of s-matrix? 1.It possess symmetric property sij =sji 2.It possess unitary property [s][s]*=[i] 6) Why is s-matrix used in MW analysis?

S matrix is used in MW analysis to overcome the problems which occurs when H,Y,&Z parameters are used in high frequencies. 1.Equipment is not readily available to measure total voltage &total current at the ports of the network. 2.Short and open circuits are difficult to achieve over a broad band of frequencies. 3.Active devices,such as power transistor &tunnel diodes,frequently won’t have stability for a short or open circuit. 7) What is ABCD matrix? ABCD matrix is a transmission matrix.these parameters express voltage and current at output in terms of those at input port. V1=AV2-BI2 I1=CV2-DI2 8) Give the applications of directional coupler

1.Unidirectional power measurement 2.SWR measurement 3.Unidirectional wave launching 4.Reflectometer 5.Balanced duplexer 9) Define VSWR Voltage standing wave ratio is defined as the ratio of maximum voltage to the minimum vottage VSWR=Vmax/Vmin 10) What is Tee junction?Give two examples In MW circuits a wave guide or coaxial junction with three independent ports is referred to as tee junction. Eg: E- Plane Tee,H-plane Tee 11.What is the other name for magic TEE? Hybrid Tee 12.What is hybrid ring? Hybrid ring consists of an annular line of proper electrical length to sustain standing waves,to which four arms are connected at proper intervals by means of series or parallel junctions. 13.What is the other name for Hybrid ring? Rat-race circuit. 14) What are nonreciprocal devices? Give two examples The devices which are having the property that the forward characteristics are not equal to the reverse characteristics are called non reciprocal devices. 15) What is the condition for oscillation in Reflex klystron ? The necessary condition for oscillation is that the magnitude of the negative real part of the electronic admittance should not be less than the total conductance of the cavity circuit i.e. |-Ge|>=G. Where G=Gc + Gb +G1 = -----Rsh Rsh _ effective shunt resistance Gc _ copper losses of cavity Gb _ beam loading conductance G1 _ load conductance 16) Give the drawbacks of klystron amplifiers. . As the oscillator frequency changes then resonator frequency also changes and the feedback path phase shift must be readjusted for a positive feedback. The multicavity klystron amplifiers suffer from the noise caused because bunching is never complete and electrons arrive at random at catcher cavity. Hence it is not used in receivers. What are the applications of reflex klystron ? 1) Signal source in MW generator 2) Local oscillators in receivers 3) It is used in FM oscillator in low power MW links.

4) In parametric amplifier as pump source. What is the purpose of slow wave structures used in TWT amplifiers? Slow wave structures are special circuits that are used in microwave tubes to reduce wave velocity in a certain direction so that the electron beam and the signal wave can interact. In TWT, since the beam can be accelerated only to velocities that are about a fraction of the velocity of light, slow wave structures are used. How the klystron amplifier can act as klystron oscillator? What are the applications of klystron amplifier? When the klystron amplifier is given a positive feedback such that the overall phase shift becomes zero 360° and |Avβ |= 1 then klystron amplifier acts as an oscillator. Applications: (1) UHF TV Transmitters (2) Long ranger radar (3) Linear particle accelerator Define Transit time in Reflex klystron. The time taken by the electron to travel into the repeller space and back to the gap. T =n + ¾ What is CFA? State the applications of CFA. CFA _Cross Field Amplifier CFA is a microwave power amplifier. It is a cross between TWT and magnetron in its operation. i.e., it has a magnetron structure to provide an interaction between crossed dc electric and magnetic fields on one hand and an RF field on the other hand. It also uses a slow wave structure as in TWT to provide a continuous interaction between the electron beam and a moving RF field. Applications: (1) Radar system (2) Electronic counter measure. What are the elements that exhibit Gunn effect? The elements are a)Gallium arsenide b)Indium phosphide c)Cadmium telluride d)Indium arsenide What are the applications of Gunn Diode? The applications are a) Low and medium power oscillators b) Used in high pump frequencies c) Burglar alarms and aircraft rate-of-climb indicators. What is negative resistance? Negative resistance is defined as that property of a device which causes the current through it to be 180 degree out of phase with the voltage across it.

Define GUNN EFFECT. Guneffect was first observed by GUNN in n_type GaAs bulk diode.according to GUNN,above some critical voltage corresponding to an electric field of 2000-4000v/cm,the current in every specimen became a fluctuating fuction of time.The frequency of oscillation was determined mainly by the specimen and not by the external circuit Define insertion loss? It is defined as difference in power arriving at the terminating load .with or witout The network in circuit Insertion loss(db)=10 log(po/pi) Define dielectric constant? It is defined by the ratio of permittivity of medium to permittivity of Freespace. What is radiation pattern? Radiation pattern is a representation of radiation characteristics of an antenna which is a function of elevation angle azimuth angle for a constant radial distance and frequency. What is radiation efficiency? Radiation efficiency is defined as the ratio of total power radiated to total power accepted at its input. Why can’t conventional tubes be used at microwave frequencies? Conventional tubes can’t be used at microwave frequencies because of transit time effect. Lead inductance and inter electrode capacitance of the devices will finally limit the output which may even be zero. What is the operating principle of reflex klystron? It works on the principle of velocity modulation and current modulation What is velocity and current modulation in a reflex klystron? Variation in velocities of the electrons in the electron beam is called velocity modulation; variation in the current density of the electron beam is referred to as current modulation. How does bunching occur in a reflex klystron? A reference electron passing the gap when the gap voltage is zero travels with no change in velocity. An electron leaving the gap earlier during slightly positive voltage would travel further into repeller space and hence would take longer time then the reference electron to return to the gap. An electron leaving the gap later will face slightly negative voltage and gets retarded. So it returns back after a shorter travel in the repeller space.Thus all the electrons would arrive back to the gap in bunches. Bunching around reference electron takes place once per cycle of RF oscillations. What are the materials used in the construction of Gunn diode? GaAs (Gallium Arsenide), InP (Indium Phosphate) doped in Si. What are the other names of Gunn diode and Gunn oscillator? Transferred electron device and transferred electron oscillator. Define guide wavelength. It is the distance between two identical points on standing waves in a waveguide.

Define cutoff wavelength for a waveguide. It is the longest wavelength beyond which there is no propagation of EM waves within the waveguide Write the relation between guide wavelength, cutoff wavelength and free space wavelength.

What are the various power losses in a waveguide? 1) Losses in guide walls 2) losses in dielectric (if any other than air) Define wave impedance and characteristic impedance. Wave impedance Zz looking in the z direction is the ratio of the transverse electric field strength to the total magnetic field strength. Characteristic impedance Zo of a line is the impedance offered by the line of infinite length. What is reflection coefficient? It is the ratio of reflected voltage to incident voltage on standing waves. Write the relation between VSWR and reflection coefficient. S = (1 + K)/ (1 – K) Where S – standing wave ratio; K – Reflection coefficient. Write the values of VSWR for open circuit, short circuit & matched load. Open/closed circuit: VSWR = ∞ Matched load: VSWR = 1 What is a matched load? A load that offers the characteristic impedance to a transmission line is called a matched load. Define insertion loss. Insertion loss is the attenuation introduced due to addition of any component in any circuit. If p1 is the output power without the component and p2 is the output power with the component, then the insertion loss in dB is given by 10log10 (p1/p2) dB. What is magic tee? It is a combination of E plane and H plane tee. It is a 4 port device

What are the properties of magic tee? Power fed to arm 3 (H arm) divides equally between arms 1 and 2. The electric field in the 2 arms will be in phase. No coupling to arm 4. Similarly power fed to arm 4 is not coupled to arm 3. It is divided equally between arms 1 & 2 but the electric fields in these differ in phase by 1800. Powers fed in arms 1 & 2 are added in arm 3 (H arm) and subtracted in arm 4 ( E arm). What are the devices used for microwave powermeasurements/ 1)Bolometer 2)Calorimeter

What is cavity resonator? It is a metallic enclosure that confines the EM energy

Define cutoff wavelength for a waveguide. Write the relation between guide wavelength, cutoff wavelength and free space wavelength. What are the various power losses in a waveguide? Define wave impedance and characteristic impedance. What is reflection coefficient? Write the relation between VSWR and reflection coefficient. Write the values of VSWR for open circuit, short circuit & matched load. What is a matched load? Define insertion loss. What is magic tee? What are the properties of magic tee? What are the devices used for microwave powermeasurements/ What is cavity resonator? It is a metallic enclosure that confines the EM energy

1) What are the various reasons pertaining to the wide use of microwaves Bandwidth,Improved directivity with an Aerial array ,Reliability, Power Requirement. 1) What are the two types of terminations. Matched load Variable short circuit 2) Give the differences between Isolator and Circulator

3) Define s-matrix

In a microwave junction there is intersection of three or more components.There will be an output port ,in addition there may be reflection from the junction of other ports.Totally there may be many combinations,these are represented easily using a matrix called S matrix. 5) What are the .Properties of s-matrix? 1.It possess symmetric property sij =sji 2.It possess unitary property [s][s]*=[i] 6) Why is s-matrix used in MW analysis?

S matrix is used in MW analysis to overcome the problems which occurs when H,Y,&Z parameters are used in high frequencies. 1.Equipment is not readily available to measure total voltage &total current at the ports of the network. 2.Short and open circuits are difficult to achieve over a broad band of frequencies. 3.Active devices,such as power transistor &tunnel diodes,frequently won’t have stability for a short or open circuit. 7) What is ABCD matrix? ABCD matrix is a transmission matrix.these parameters express voltage and current at output in terms of those at input port. V1=AV2-BI2 I1=CV2-DI2 8) Give the applications of directional coupler

1.Unidirectional power measurement 2.SWR measurement 3.Unidirectional wave launching 4.Reflectometer 5.Balanced duplexer 9) Define VSWR Voltage standing wave ratio is defined as the ratio of maximum voltage to the minimum vottage VSWR=Vmax/Vmin 10) What is Tee junction?Give two examples In MW circuits a wave guide or coaxial junction with three independent ports is referred to as tee junction. Eg: E- Plane Tee,H-plane Tee 11.What is the other name for magic TEE? Hybrid Tee 12.What is hybrid ring? Hybrid ring consists of an annular line of proper electrical length to sustain standing waves,to which four arms are connected at proper intervals by means of series or parallel junctions. 13.What is the other name for Hybrid ring? Rat-race circuit. 14) What are nonreciprocal devices? Give two examples The devices which are having the property that the forward characteristics are not equal to the reverse characteristics are called non reciprocal devices. 15) What is the condition for oscillation in Reflex klystron ? The necessary condition for oscillation is that the magnitude of the negative real part of the electronic admittance should not be less than the total conductance of the cavity circuit i.e. |-Ge|>=G. Where G=Gc + Gb +G1 = -----Rsh Rsh _ effective shunt resistance Gc _ copper losses of cavity Gb _ beam loading conductance G1 _ load conductance 16) Give the drawbacks of klystron amplifiers. . As the oscillator frequency changes then resonator frequency also changes and the feedback path phase shift must be readjusted for a positive feedback. The multicavity klystron amplifiers suffer from the noise caused because bunching is never complete and electrons arrive at random at catcher cavity. Hence it is not used in receivers. What are the applications of reflex klystron ? 1) Signal source in MW generator 2) Local oscillators in receivers 3) It is used in FM oscillator in low power MW links.

4) In parametric amplifier as pump source. What is the purpose of slow wave structures used in TWT amplifiers? Slow wave structures are special circuits that are used in microwave tubes to reduce wave velocity in a certain direction so that the electron beam and the signal wave can interact. In TWT, since the beam can be accelerated only to velocities that are about a fraction of the velocity of light, slow wave structures are used. How the klystron amplifier can act as klystron oscillator? What are the applications of klystron amplifier? When the klystron amplifier is given a positive feedback such that the overall phase shift becomes zero 360° and |Avβ |= 1 then klystron amplifier acts as an oscillator. Applications: (1) UHF TV Transmitters (2) Long ranger radar (3) Linear particle accelerator Define Transit time in Reflex klystron. The time taken by the electron to travel into the repeller space and back to the gap. T =n + ¾ What is CFA? State the applications of CFA. CFA _Cross Field Amplifier CFA is a microwave power amplifier. It is a cross between TWT and magnetron in its operation. i.e., it has a magnetron structure to provide an interaction between crossed dc electric and magnetic fields on one hand and an RF field on the other hand. It also uses a slow wave structure as in TWT to provide a continuous interaction between the electron beam and a moving RF field. Applications: (1) Radar system (2) Electronic counter measure. What are the elements that exhibit Gunn effect? The elements are a)Gallium arsenide b)Indium phosphide c)Cadmium telluride d)Indium arsenide What are the applications of Gunn Diode? The applications are a) Low and medium power oscillators b) Used in high pump frequencies c) Burglar alarms and aircraft rate-of-climb indicators. What is negative resistance? Negative resistance is defined as that property of a device which causes the current through it to be 180 degree out of phase with the voltage across it.

Define GUNN EFFECT. Guneffect was first observed by GUNN in n_type GaAs bulk diode.according to GUNN,above some critical voltage corresponding to an electric field of 2000-4000v/cm,the current in every specimen became a fluctuating fuction of time.The frequency of oscillation was determined mainly by the specimen and not by the external circuit Define insertion loss? It is defined as difference in power arriving at the terminating load .with or witout The network in circuit Insertion loss(db)=10 log(po/pi) Define dielectric constant? It is defined by the ratio of permittivity of medium to permittivity of Freespace. What is radiation pattern? Radiation pattern is a representation of radiation characteristics of an antenna which is a function of elevation angle azimuth angle for a constant radial distance and frequency. What is radiation efficiency? Radiation efficiency is defined as the ratio of total power radiated to total power accepted at its input. Why can’t conventional tubes be used at microwave frequencies? Conventional tubes can’t be used at microwave frequencies because of transit time effect. Lead inductance and inter electrode capacitance of the devices will finally limit the output which may even be zero. What is the operating principle of reflex klystron? It works on the principle of velocity modulation and current modulation What is velocity and current modulation in a reflex klystron? Variation in velocities of the electrons in the electron beam is called velocity modulation; variation in the current density of the electron beam is referred to as current modulation. How does bunching occur in a reflex klystron? A reference electron passing the gap when the gap voltage is zero travels with no change in velocity. An electron leaving the gap earlier during slightly positive voltage would travel further into repeller space and hence would take longer time then the reference electron to return to the gap. An electron leaving the gap later will face slightly negative voltage and gets retarded. So it returns back after a shorter travel in the repeller space.Thus all the electrons would arrive back to the gap in bunches. Bunching around reference electron takes place once per cycle of RF oscillations. What are the materials used in the construction of Gunn diode? GaAs (Gallium Arsenide), InP (Indium Phosphate) doped in Si. What are the other names of Gunn diode and Gunn oscillator? Transferred electron device and transferred electron oscillator. Define guide wavelength. It is the distance between two identical points on standing waves in a waveguide.

Define cutoff wavelength for a waveguide. It is the longest wavelength beyond which there is no propagation of EM waves within the waveguide Write the relation between guide wavelength, cutoff wavelength and free space wavelength.

What are the various power losses in a waveguide? 1) Losses in guide walls 2) losses in dielectric (if any other than air) Define wave impedance and characteristic impedance. Wave impedance Zz looking in the z direction is the ratio of the transverse electric field strength to the total magnetic field strength. Characteristic impedance Zo of a line is the impedance offered by the line of infinite length. What is reflection coefficient? It is the ratio of reflected voltage to incident voltage on standing waves. Write the relation between VSWR and reflection coefficient. S = (1 + K)/ (1 – K) Where S – standing wave ratio; K – Reflection coefficient. Write the values of VSWR for open circuit, short circuit & matched load. Open/closed circuit: VSWR = ∞ Matched load: VSWR = 1 What is a matched load? A load that offers the characteristic impedance to a transmission line is called a matched load. Define insertion loss. Insertion loss is the attenuation introduced due to addition of any component in any circuit. If p1 is the output power without the component and p2 is the output power with the component, then the insertion loss in dB is given by 10log10 (p1/p2) dB. What is magic tee? It is a combination of E plane and H plane tee. It is a 4 port device

What are the properties of magic tee? Power fed to arm 3 (H arm) divides equally between arms 1 and 2. The electric field in the 2 arms will be in phase. No coupling to arm 4. Similarly power fed to arm 4 is not coupled to arm 3. It is divided equally between arms 1 & 2 but the electric fields in these differ in phase by 1800. Powers fed in arms 1 & 2 are added in arm 3 (H arm) and subtracted in arm 4 ( E arm). What are the devices used for microwave powermeasurements/ 1)Bolometer 2)Calorimeter

What is cavity resonator? It is a metallic enclosure that confines the EM energy