klystron magnitron

7/30/2019 Klystron Magnitron

1/12

Microwaves

Which of the following can be used for amplification of microwave energy.a) TWT

b) Magnetron

c) Reflex Klystron

d) Gunn Diode

The transit time for the electrons in the repeller space of a reflex klystron oscillator for

sustained oscillations (n is any integer including zero)a) 2(n-1)

b) 2n-1

c) n+2

1

d) n +4

3

A 2 cavity klystron is basically ___________ tubea) Amplitude modulated

b) Velocity modulated

c) Frequency modulated

d) None

In reflex klystron maximum power output is obtained when n = _________ mode

a) 0b) 1

c) 2

d) None

Maximum fundamental current component in 2 cavity klystron will get at X =

a) 0.52

b) 1.25c) 2.408

d) 1.841

Efficiency of Reflex klystron amplifier is given bya) 22.7%

b) 58%

c) 75%

d) None

For maximum energy transfer x = __________ in Reflex klystron amplifiera) 0.58

b) 1.84

c) 1.21

d) 2.408

Reflex klystrons produce ________________ oscillators

a) Low Powerb) Medium Power

c) High Powerd) None

The maximum theoretical output circuit efficiency of a double resonator klystron amplifier isa) 25%

b) 50%c) 58%

d) 85%

Which one of the following can be used for amplification of microwave signalsa) Gunn diode

b) strapped magnetronc) Reflex klystron


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Microwaves

d) Double cavity Klystron

In Microwave circuits, gain bandwidth product limitation can be overcome by use ofa) Re entrant cavities

b) Slow wave tubes

c) Bothd) None

Applegate diagram is aa) DistanceVelocity Plot

b) VelocityAcceleration Plot

c) DistanceTime Plotd) None

For perfect coupling is

a) 0

b) 1c) 2d) 3

The bunching parameter x of a Klystron amplifier is defined as

a) x = 01

0

2

V

Vi

b) x =0

0

1

2

V

Vi

c) x =10

01

2

VVi

d) None

In reflex Klystron, earlier the modea) Larger the O/P Power

b) Smaller the O/P Power

c) Either a or b

d) None

Generally range of wave length of microwaves in the order of

a) 1cm30 cm

b) 1cm30 mmc) 30cm1mm

d) None

Range of frequency for Xband in GHz is

a) 12

b) 48c) 812

d) 1827

To avoid the inter electrode capacitance effect

i) Smaller size electrodes can be usedii) Increasing distance between electrodes

a) Either i or iib) Only i

c) Only ii

d) Both i & ii

Basically amplifier circuit is aa) Inverterb) AND gate

c) NOT gate

d) a & c


3/12

Microwaves

In a linear beam or Otype tube the magnetic field and electric field area) Perpendicular to each other

b) Co inside with each other

c) Both a & b

d) None

Electronic admittance is function of

a) DC beam admittanceb) DC transit angle

c) Both a & b

d) None

In the TWT

i) Distributed intraction between electron beam & traveling wave is requiredii) And they are both traveling in same direction with nearly same velocity

a) i is correctb) ii is correct

c) i & ii are correctd) Both are wrong

The most widely used slow wave structure is

a) Folded backb) Zig zag

c) Helical line

d) corrugated wave line

The pitch angle of helical coil is given as

a)

c

VP1sin:

b)C

Vp:

c)

PV

cec 1cos:

d) a & c

The period of the helical structure is given as

a) 22 )( dP

b)c

VP

c) P

d)22

)( dP

P

Calculate the pitch angle if phase velocity is half of the free space velocitya) 00

b) 30

0

c) 600

d) 900

The axial electricfield in TWT is available at

a) Focusing magnetic platesb) At the centre of helical structure

c) At RF out

d) None

The electron beam is focused by a constant magnetic field along the electron beam is termed as

a) Klystronb) Reflex klystron


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Microwaves

c) TWT

d) Magnetron

The electric field propagates with the velocity of

a)

P

rVVP

2.

0

b)d

PVVP

2.

0

c)r

PVVP

2.

0

d)P

dVVP

2.0

The o / p power gain of TWT is given as

a) AP = 9.5447.3 NC dB

b) AP = 9.54 + 47.3 NC dBc) AP = -9.54 + 47.3 NC dB

d) None

The length of the interaction can be calculate by using

a) N =e

l

b) N =e

2

c) N =

2

el

d) a & c

The wave length e is calculator by using

a)e

e

2

b)w

Vee

2

c)f

wee

d) All the above

The gain parameter calculated by using

a) c =

3/1

0

00

4

V

ZI

b) c =

3/1

0

00

4

Z

VI

c) c =

3/1

0

00

4

I

ZV

d) None

Consider the following data given

V0 = 10 KV, I0 = 500 m amp, Z0 = 25 , L = 20 cm, f = 4 GHz

Calculate N valuea) 14.825

b) 13.49c) 14.825 X 10-3

d) 13.49 X 10 -3


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Microwaves

Calculate e value

a) 14.825b) 13.49

c) 14.825 X 10-3

d) 13.49 X 10-3

Power gain AP is given by value of

a) 14.82 dB

b) 13.49 dBc) 33.85 dB

d) 68dB

Gain parameter C is given by value ofa) 0.01482

b) 0.01349c) 0.03385

d) 0.0678

The propagation of Cout of TWT is given as

a) r = j

b) jw

c)

PV

wj

d) a & c

Wave guide acts as a

a) Low pass filterb) High pass filter

c) All pass filter

d) None

The dominant mode in a wave guide is characterized by

a) Longest cutoff wave length

b) Shortest cut off wave lengthc) Infinite attenuation

d) Zero attenuation

Which one of the following modes of transmission will not be supported by a rectangular waveguide

a) TE10

b) TE11c) TM11

d) TM10

Guide wave length ( g), cut off wave length ( c) and free space wave length ( o) of a wave

guide are related as

a)cog 222

111

b)cgo 222

111

c)goc 222

111

d)cog

111

Which of the following mode cannot exist in a wave guide

a) TE

b) TM

c) TEM


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Microwaves

d) none

Which of the following relation holds good for a rectangular wave guide

a) 0c

c) o>g


7/12

Microwaves

c)2

m

d) None

In the magnetron if magnetic field strength is increased (Electric field is constant) the

path of electron will take a circular path with radius of

a)m

eB

b)eB

m

c)eB

mv

d)mv

eB

The Hull cutoff magnetic field Bc is given as (If b >> a)

a)e

mV

b

081

b)0

8

1

mV

e

b

c) 22

08

bBm

e

d) 22

0

8bB

e

m

The Hull cutoff magnetic voltage VC is given as (If b >> a)

a)e

mV

b

081

b)08

1

mV

e

b

c) 22

08

bBm

e

d) 22

0

8bB

e

m

The cutoff frequency at TE10 mode in rectangular wave guide is

a) fc = c / 2ab) fc = c / 2b

c) fc = 2a / c

d) fc = 2b/c

The cutoff wave length at TE10 mode in the rectangular wave guide is

a) C = 2a

b) C = 2b

c) C = 2ab

d) C = ab

An air filled rectangular wave guide of inside dimension 7 / 3.5 cm operates in the dominant

TE mode. Find the cutoff wave length

a) 7 cm

b) 2. 14 cmc) 14 cm

d) 3.5 cm

Phase velocity p, group velocity g are related as

a) p. g=c2


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Microwaves

b) 2cg

p

c) 2cp

g

d) None

The degenerate modes in a wave guide are characterized bya) Same cutoff frequencies

b) Same cut off wave lengths

c) Both

d) None

Which one of the following statement is true , for electromagnetic wave propagation through a

rectangular wave guide of cross section 2axa?

a) c for TE10 is same as that for TE01 mode

b) c for TE10 mode is half that for TE01 modec) c for TE10 is same as that for TM10 mode

d) c for TE20 is same as that for TE01 mode

Reflection and standing waves are produced ,if a transmission line is terminated in aa) Short circuit

b) Open circuit

c) Bothd) None

In a cavity resonator, the distance between two shorting plates (d) should be

a) d2

g

c) Equal to integer multiple of2

g

d) None

The condition for the resonator to resonate is

a) =d

p

b) =d

p 2

c) =p

d

d) None

wher P=1,2,3 D : length of the resonator.

Resonator frequency (fo) in a rectangular cavity resonator is given as

a) fo =

2

c

2/1222

d

p

b

n

a

m

b) fo=2

c2/1

222

d

p

b

n

a

m

c) fo =2

c

2/122

b

n

a

m

d) None

To minimize power losses in a wave guide, the inner surface of the wave guide is usually coated

witha) Gold


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Microwaves

b) Silver

c) Bothd) None

In a rectangular cavity resonator, the dominant mode is

a) TE101 for a>bbb>d

d) None

Which of the following method is used for low power measurement

a) Bolometer Techniqueb) Calorimetric Technique

c) Calorimetric Meter

d) None

Bolometer is aa) Temperature sensitive device

b) Square law devicec) Pressure sensitive device

d) All of the above

The magnitude of reflection coefficient of a transmission line interms of the load and

characteristic impedance is given by

a)Lo

oL

ZZ

ZZ

b)Lo

Lo

ZZ

ZZ

c)OL

oL

ZZ

ZZ

d) None

Barretters have

a) Positive temperature coefficient

b) Negative temperature coefficient

c) Bothd) None

Double minimum method is relevant to the measurement ofa) Low attenuation coefficient

b) High attenuation coefficient

c) High VSWRd) Low VSWR

In an ideal transmission line with matched load, the VSWR and reflection coefficient are

respectively

a) 1 & 1b) and 1c) and 0d) 1 & 0

The function of a short circuit device used in microwave system isa) To obtain desired value of output impedance

b) To match the impedance of the wave guide

c) To vary the impedance of the wave guided) None

In the measurement of impedance using slotted line method, if the Vmin is shifted to the leftside, then the impedance is ____________


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Microwaves

a) Resistive

b) Inductivec) Capacitive

d) None

Which of the following method uses variable precision attenuation, to give attenuation of thenetwork directlya) Power ratio method

b) RF Substitution methodc) Both

d) None

Calorimetric technique measures power in terms ofa) Rise in pressure

b) Rise in humidityc) Rise in temperature

d) None

Scattering matrix is aa) Square matrix

B) Symmetric matrix

c) Unitary matrix

d) All of the above.

Two linearly polarized plane waves A and B traveling in free space in the positive X direction

meet at a point. The wave A is polarized in the Y direction and the wave B is polarized on the

Z direction. The resulting wave is linearly polarized. Therefore A and Ba) Must have equal amplitudes and must also be in time phase with each other.

b) Must have equal amplitudes but need not be in time phasec) May have different amplitudes but must be in phase with each other in time

d) May have different amplitudes and may also different in time phase

A microwave junction is supposed to be matched at all ports if in the S-matrixa) All the diagonal elements are zero

b) All the diagonal elements are equal but not zero

c) All the diagonal elements are complex.d) Is hermitian

A duplexer is used to

a) Couple two antennas to a transmitter with out interference.

b) Isolate the antenna from the local oscillator

c) Prevent interference between 2 antennas connected it a receiver

d) Use an antenna for reception or transmission with out interference.

The magnitude of the reflection coefficient of a transmission line is

a) P=0

0

zz

zz

L

L

b) P=L

L

zz

zz

0

0.

c)0

0

zz

zz

L

L

d) None

Magic T is a ___________Hybrid functiona) 00

b) 1800

c) Both a & b

d) None .


11/12

Microwaves

A 20dB coupler has a directivity of 30dB the value of isolation isa) 60dB

b) 50dB

c) 10dB

d) None

Gyrator is a 2 port device which provides a phase difference of __________for transmission

from port (1) to port (2) and ________phase shift for transmission prom port (2) to (1)a) 900 ,1800

b) 1800

, 00

c) 900

, 00

d) None

All the 3 arms of H-plane tee lie in the plane ofa) Electric field

b) Magnetic fieldc) Both

d) None

H plane T is also called as

a) Current junction

b) 3- dB splitterc) Both

d) None

In a H- plane tee when TE 10 mode is allowed to propagate into port (3) the waves that come

out of ports (1) and (2) are

a) Equal in magnitude and out of phaseb) Equal in magnitude and phase

c) Both

d) None

In an E-plane T, I/P at port 3 cause outputs at port (2) and (1) to be ofa) Equal in magnitude and differing in phase by 180

0

b) Equal in magnitude and 00

phase changec) Both

d) None

In a magic Ta) Only 2ports are matched

b) All the 4 ports are matched

c) Only input port is matchedd) None

2 matched hybrid Ts are connected through two H-plane arms to form a 6port device as

shown in figure below. If 4mw of power is fed into port 1, the output power in the other 5 ports

namely 11, 2

1, 4, 4

1will be respectively

a) 0,4,0,0,0

b) 1,0,1,0,2c) 1,0,1,2,0

d) 0,2,1,1,0

Tuning screw exhibits __________ susceptance when h

klystron magnitron

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