RF & Microwave
Engineering
2 mark questions
Unit-1
1.
Limitations
in measuring Z, Y and ABCD parameters at Microwave frequencies
2.
A
5dB attenuator is specified as having VSWR of 1.2. Assuming that the device is reciprocal, find
the S parameters
3.
Write
down S22 of a two port device in terms of its equivalent Z
parameters
4.
Insertion
loss and express it in terms of S parameters
5.
Write
down the ABCD parameters of an ideal transformer of turns ratio n:1
6.
How
to improve the quality factor in the inductor
7.
Property
of lossless networks
8.
Self
inductance
9.
Advantages
of S parameters (over Z or Y parameters)
10.
Which
component is represented by the scattering matrix 
11.
ABCD
matrix
12.
Relationship
between Z and S matrices
13.
Write
down the transmission parameters of an ideal transformer of turns ratio n:1
14.
Express
S11 of a two port microwave component in terms of its equivalent
ABCD parameters
15.
Write
down the S matrix for an ideal transformer of turns ratio 1:10
16.
Write
down the expression for S11 in terms of transmission parameters of a
two port component
17.
Properties
of S-parameters
18.
How
do you compare S-matrix to Z-matrix
19.
Relationship
between ABCD parameters and S parameters
Unit-2
1.
Parameters
affect the performance of the amplifier
2.
Why
micro-strip line matching networks preferred than discrete components
3.
Distinguish
between conditional and unconditional stabilities of amplifier
4.
Expression
for noise figure of a two port amplifier
5.
Need
for impedance matching networks
6.
Strip
lines
7.
Drawbacks
of microstrip lines
8.
Losses
in a planar transmission line
9.
List
the losses in microstrip lines
10.
Q
of microstrip lines
11.
Expressions
for impedance of microstrip lines based on w/h ratios
12.
How
can you eliminate the radiation loss of microstrip lines
Unit-3
1.
Functions
of matched terminations
2.
Examples
of a two port microwave devices
3.
How
can a isolator be designed using 3 port circulator
4.
Define
directivity and coupling factor of a directional coupler
5.
Hybrid
ring
6.
S-matrix
for a isolator
7.
Faraday
rotation principle
8.
Value
of directivity of an ideal directional coupler?
Why?
9.
Range
of X-band frequencies
10.
Unity
property of S-matrix
11.
Differences
between gyrator and phase changer
12.
Draw
a structure of two hole directional coupler
13.
Find
the resonant frequency of the TE101 mode of an airfilled rectangular
cavity of dimensions 5 cm x 4 cm x 2.5 cm
14.
Frequency
range of microwaves
15.
Hybrid
couplers
16.
Applications
of hybrid ring and hybrid coupler
17.
S-matrix
of microwave circulator
18.
Primary
functions of a microwave isolator
19.
A
cavity resonator having dimensions a=2cm, b=1cm excited by TE 101 mode at 20
GHz. Calculate length of cavity
20.
Principle
advantage of microwave frequencies over lower frequency
21.
Basic
parameters to measure the performance of a directional coupler
22.
Faraday
rotation isolator
23.
Waveguide
corners, bends and twists
24.
S
matrix of a four port microwave circulator
25.
Advantages
of coaxial connectors
26.
Distinguish
between loaded and unloaded Q at microwave frequencies
27.
Properties
of directional coupler
28.
S-matrix
of a phase shifter (ideal phase shifter)
29.
If
the VSWR=1 at the input port of a microwave component, what is S11
30.
Difference
in S matrix representation of E plane tee and H plane tee
31.
Reason
for using S parameters (advantages and applications) for analyzing microwave
circuits
32.
Insertion
loss and express it in terms of A parameters
33.
Functions
of matched terminations
34.
What
is an isolation and write down its S parameters
35.
Advantages
and limitations of microwave communication system
Unit-4
1.
Advantages
of MIC
2.
Draw
the characteristics of tunnel diode
3.
Gunn
effect
4.
Avalanche
transit time devices
5.
Basic
materials required for MIC
6.
Transconductance
and output resistance of a MESFET
7.
Can
inductive elements be fabricated in MMICs?
Justify your answer
8.
Compare
tunnel diode and normal p-n diode
9.
Advantages
of parametric amplifier
10.
Semiconductor
used in Gunn diode
11.
Advantages
of parametric up converter over negative resistance parametric amplifier
12.
Any
two characteristics of ideal substrate materials
13.
Drawbacks
of TRAPATT diode
14.
Expression
for Avalanche multiplication factor
15.
Write
down the Manley Rowe Power relation
16.
Various
stages in epitaxial layer growth
17.
Various
methods of operation of Gunn diode
18.
Features
of transfer electron devices
19.
Why
is it difficult to manufacture large value of inductors in MIC
20.
Transit
time
21.
Any
two applications of parametric amplifier
22.
MMIC
23.
Expand
IMPATT, TRAPATT and BARITT
24.
Transferred
electron effect
25.
Disadvantages
of IMPATT diodes
26.
Advantages
of MMIC
27.
HEMT
28.
MESFET
29.
Various
types of striplines used in MMIC
30.
Applications
of varactor diode
31.
Draw
the equivalent circuit of PIN diode for both forward and reverse bias
conditions
32.
Draw
the equivalent circuit of an IMPATT diode
33.
Characteristic
features of Gunn diode
34.
Difference
between ordinary pn junction and tunnel diode
35.
High
frequency limitations of bipolar transistors
36.
Important
parameters of a microwave transistor
37.
Limitations
of parametric amplifier
38.
Principle
of parametric amplifier
39.
Applications
of IMPATT diode
40.
Draw
the equivalent circuit of a tunnel diode and mention the function of the
individual components in it
Unit-5
1.
Applications
of TWT
2.
Strapping
3.
Significance
of slow wave structures in TWTs
4.
Any
four high frequency limitations
5.
A
helix travelling wave tube operates at 4GHz, under a beam voltage of 10kv and
beam current of 500mA. If the helix is
25 ohm and interaction length is 20cm, find the gain parameter
6.
Draw
the admittance spiral for a reflex klystron
7.
Hull
cut off condition
8.
What
are LOW VSWR and HIGH VSWR and name the methods followed to measure HIGH VSWR?
9.
Any
two methods to measure attenuation
10.
Velocity
modulation
11.
Compare
TWT and klystron amplifier (two, multi cavity)
12.
Differentiate
network and spectrum analyzers
13.
Relationship
between return loss and VSWR
14.
Why
is magnetron called a crossed field devices
15.
Insertion
loss
16.
Two
methods to measure impedance
17.
Need
for helix structure in TWT
18.
Calculate
the SWR of a transmission system operating at 8GHz. The distance between two minimum power points
is 0.9mm on a slotted line whose velocity factor is unity
19.
Two
methods to measure attenuation
20.
Ricke
diagram
21.
List
any two advantages of TWT amplifier over other microwave amplifiers
22.
Why
do we require to measure VSWR in a microwave circuit
23.
Draw
the setup to measure the frequency
24.
Mention
the methods to measure microwave power
25.
Why
the conventional tubes like triode, tetrode cannot generate microwave power
26.
Some
types of slow wave structures (draw)
27.
Beam
loading
28.
Demerits
of single bridge power meter
29.
What
does the accuracy of phase measurement depend on while measuring the impedance
using reflectometer method
30.
Other
names for O-type tubes
31.
Difference
between spectrum analyzer and CRO
32.
Bunching
effect in 2 cavity klystron amplifier
33.
Differentiate
klystron amplifier from reflex klystron oscillator
34.
Draw
the mode characteristics of reflex klystron
35.
List
the performance characteristics of reflex klystron
36.
Applications
of a reflex klystron
37.
What
is meant by Mode characteristics of reflex klystron oscillator
38.
Practical
applications of magnetron
39.
Classification
of bolometer
40.
Difference
between a thermister and a barrater
41.
List
a few sensors used for microwave power measurement
42.
Demerits
of single bridge power meter
43.
How
frequency of source is measured using slotted line
44.
Three
scales on the VSWR meter
45.
VSWR
46.
Return
loss and write its expression
47.
Special
features of spectrum analyser
48.
Draw
the measurement set up to measure impedance
