180+ Radiation and Microwave Techniques Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .

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151.	_________ and __________ contribute to the impedance of a transmission line in the lumped element representation.
A.	resistor, inductor
B.	resistor, capacitor
C.	capacitor, inductor
D.	transistor, capacitor
Answer» A. resistor, inductor

discuss

152.	Characteristic impedance of a transmission line is:
A.	impedance z of a transmission line
B.	impedance which is a constant at any point on the transmission line
C.	reciprocal of admittance of a transmission line
D.	none of the mentioned
Answer» B. impedance which is a constant at any point on the transmission line

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153.	The major advantage of single stub tuning over other impedance matching techniques is:
A.	lumped elements are avoided
B.	it can be fabricated as a part of transmission line media
C.	it involves two adjustable parameters
D.	all of the mentioned
Answer» D. all of the mentioned

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154.	Shunt stubs are preferred for:
A.	strip and microstrip lines
B.	coplanar waveguides
C.	circular waveguide
D.	circulators
Answer» A. strip and microstrip lines

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155.	In shunt stub matching, the key parameter used for matching is:
A.	admittance of the line at a point
B.	admittance of the load
C.	impedance of the stub
D.	impedance of the load
Answer» A. admittance of the line at a point

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156.	For co-axial lines and waveguides, ________ is more preferred.
A.	open circuited stub
B.	short circuited stub
C.	slotted section
D.	co-axial lines cannot be impedance matched
Answer» B. short circuited stub

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157.	Maxwell’s equation for electromagnetic waves in a waveguide is:
A.	∇×e = -jωµ(vector h)
B.	∇×e =-jωμ(vector e)
C.	∇×h=-jωμ(vector h)
D.	∇×h=jωμ(vector h)
Answer» A. ∇×e = -jωµ(vector h)

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158.	The modes of wave propagation that a rectangular waveguide can support are:
A.	tem, te, modes
B.	tem,tm, te modes
C.	tem, tm modes
D.	te,tm modes
Answer» D. te,tm modes

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159.	In TM mode, if the direction of wave propagation is in ‘z’ direction, then:
A.	hz=0
B.	ez=0
C.	ey=0
D.	hy=0
Answer» A. hz=0

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160.	TEₒₒ mode for a rectangular waveguide:
A.	exists
B.	exists but defined only under special cases
C.	does not exist
D.	cannot be determined
Answer» C. does not exist

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161.	S parameters are expressed as a ratio of:
A.	voltage and current
B.	impedance at different ports
C.	indecent and the reflected voltage waves
D.	none of the mentioned
Answer» C. indecent and the reflected voltage waves

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162.	Ferrite isolators are ____ port microwave devices.
A.	two
B.	three
C.	four
D.	none of the mentioned
Answer» A. two

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163.	Directional coupler for waveguide are characterized by
A.	insertion loss
B.	coupling specification
C.	directivity
D.	all of the above
Answer» D. all of the above

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164.	A “circulator” is a device that:
A.	rotates signal polarity in a waveguide
B.	allows a signal to pass in one direction only
C.	separates signals among various ports
D.	prevents microwaves from being “trapped” in a waveguide
Answer» C. separates signals among various ports

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165.	The device commonly used in microwave ovens is the:
A.	twt
B.	klystron
C.	magnetron
D.	yig
Answer» C. magnetron

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166.	Power dividers and couplers are ______ microwave components used for power division or power combining.
A.	passive
B.	active
C.	linear
D.	non linear
Answer» A. passive

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167.	T- junction is an example for:
A.	2 port network
B.	3 port network
C.	4 port network
D.	none of the mentioned
Answer» B. 3 port network

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168.	If a device is passive and contains no anisotropic elements, then the device is_______ network.
A.	reciprocal
B.	non reciprocal
C.	lossless
D.	lossy
Answer» A. reciprocal

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169.	If a microwave network is lossless, then S matrix of the microwave network is:
A.	zero matrix
B.	symmetric
C.	identity matrix
D.	unitary
Answer» D. unitary

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170.	The junction resistance and capacitance of the intrinsic region in a PIN diode are connected______ in the equivalent circuit of PIN diode.
A.	series
B.	parallel
C.	connected across package capacitance
D.	none of the mentioned
Answer» B. parallel

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171.	The width of depletion region of a varactor diode ________with increase in reverse bias voltage.
A.	increases
B.	decreases
C.	remains constant
D.	none of the mentioned
Answer» A. increases

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172.	When a reverse bias voltage exceeding the breakdown voltage is applied to an IMPATT diode, it results in:
A.	break down of depletion region
B.	avalanche multiplication
C.	high reverse saturation current
D.	none of the mentioned
Answer» B. avalanche multiplication

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173.	Micro strip can be fabricated using:
A.	photo lithographic process
B.	electrochemical process
C.	mechanical methods
D.	none of the mentioned
Answer» A. photo lithographic process

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174.	________ is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity.
A.	backward wave oscillator
B.	reflex klystron
C.	travelling wave tube
D.	magnetrons
Answer» B. reflex klystron

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175.	Klystrons operates on the principal of
A.	amplitude modulation
B.	frequency modulation
C.	pulse modulation
D.	velocity modulation
Answer» D. velocity modulation

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176.	Which of the following can be used for amplification of microwave energy?
A.	magnetron
B.	reflex klystron
C.	traveling wave tube
D.	gunn diode
Answer» C. traveling wave tube

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177.	When the electric field applied to GaAs specimen is less than the threshold electric field, the current in the material:
A.	increases linearly
B.	decreases linearly
C.	increases exponentially
D.	decreases exponentially
Answer» A. increases linearly

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178.	The primary purpose of the helix in a traveling-wave tube is to
A.	prevent the electron beam from spreading in the long tube
B.	reduce the axial velocity of the rf field
C.	ensure broadband operation
D.	reduce the noise figure
Answer» B. reduce the axial velocity of the rf field

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179.	A cavity resonator can be represented by
A.	an lc circuit
B.	an lcr circuit
C.	a lossy inductor
D.	a lossy capacitor
Answer» A. an lc circuit

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180.	Ionospheric preparation is not possible for microwaves because
A.	microwaves will be fully absorbed by the ionospheric layers
B.	there will be an abrupt scattering in all directions
C.	microwave will penetrate through the ionospheric layers
D.	there will be dispersion of microwave energy
Answer» C. microwave will penetrate through the ionospheric layers

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181.	Which of the following is not possible in a circular wave guide ?
A.	te10
B.	te01
C.	te11
D.	te12
Answer» A. te10

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182.	The maximum theoretical output circuit efficiency of a double resonator klystron amplifier is
A.	25%
B.	50%
C.	58%
D.	85%
Answer» C. 58%

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183.	The substrate of an MMIC must be a _____________ to accommodate the fabrication of all the type of devices.
A.	semiconductor
B.	insulator
C.	partial conductors
D.	metals operable at high frequencies
Answer» A. semiconductor

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184.	For the capacitors used in MMICs, the insulating dielectric films used are:
A.	air
B.	sio
C.	titanium
D.	gaas
Answer» B. sio

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185.	Processing in MMICs is done by __________
A.	ion implantation
B.	net list generation
C.	floor planning
D.	none of the mentioned
Answer» A. ion implantation

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180+ Radiation and Microwave Techniques Solved MCQs

_________ and __________ contribute to the impedance of a transmission line in the lumped element representation.

Characteristic impedance of a transmission line is:

The major advantage of single stub tuning over other impedance matching techniques is:

Shunt stubs are preferred for:

In shunt stub matching, the key parameter used for matching is:

For co-axial lines and waveguides, ________ is more preferred.

Maxwell’s equation for electromagnetic waves in a waveguide is:

The modes of wave propagation that a rectangular waveguide can support are:

In TM mode, if the direction of wave propagation is in ‘z’ direction, then:

TEₒₒ mode for a rectangular waveguide:

S parameters are expressed as a ratio of:

Ferrite isolators are ____ port microwave devices.

Directional coupler for waveguide are characterized by

A “circulator” is a device that:

The device commonly used in microwave ovens is the:

Power dividers and couplers are ______ microwave components used for power division or power combining.

T- junction is an example for:

If a device is passive and contains no anisotropic elements, then the device is_______ network.

If a microwave network is lossless, then S matrix of the microwave network is:

The junction resistance and capacitance of the intrinsic region in a PIN diode are connected______ in the equivalent circuit of PIN diode.

The width of depletion region of a varactor diode ________with increase in reverse bias voltage.

When a reverse bias voltage exceeding the breakdown voltage is applied to an IMPATT diode, it results in:

Micro strip can be fabricated using:

________ is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity.

Klystrons operates on the principal of

Which of the following can be used for amplification of microwave energy?

When the electric field applied to GaAs specimen is less than the threshold electric field, the current in the material:

The primary purpose of the helix in a traveling-wave tube is to

A cavity resonator can be represented by

Ionospheric preparation is not possible for microwaves because

Which of the following is not possible in a circular wave guide ?

The maximum theoretical output circuit efficiency of a double resonator klystron amplifier is

The substrate of an MMIC must be a _____________ to accommodate the fabrication of all the type of devices.

For the capacitors used in MMICs, the insulating dielectric films used are:

Processing in MMICs is done by __________

_ and __ contribute to the impedance of a transmission line in the lumped element representation.