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SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
IV B.Tech ECE I Sem – Microwave & Optical Communication Lab
List of Experiments Cycle Wise
Cycle – 1
1. Characteristics of Reflex Klystron Oscillator.
2. Attenuation Measurements.
3. VSWR Measurements.
4. Frequency& wavelenth Measurements.
5. Characteristics of LED.
6. Characteristics of LASER diode.
Cycle – 2
7. Directional Coupler Characteristics.
8. Wave guide Parameters & Measurements.
9. Scattering Parameters of Circulators.
10.Scattering Parameters of Magic -Tee.
11.Design of Fibre Optic Digital Link.
12.Gunn diode Characteristics.
Design Based Experiments:
1. Intensity Modulation of LASER output through an Optical Fibre.
2. Magic – Tee as a Mixer.
3. Circulator as a Duplexer.
Lab – Incharge
HOD, ECE
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
REFLEX KLYSTRON OSCILLATOR
AIM:
To study the characteristics of reflex klystron oscillator.
COMPONENTS REQUIRED:
1. Klystron Power Supply
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Frequency meter
6. Power Detector
PROCEDURE:
1. Arrange the bench setup as shown in figure.
2. Keep the beam voltage around the value of 300 volts.
3. Vary the repeller voltage in steps of 5 volts and measure
the corresponding beam current by switching into current mode
using in built ammeter.
4. For various values of repeller voltage find the repeller current.
5. To measure the frequency adjust the frequency meter (rolling in either
up or down direction) until minimum dip is obtained in the detector.
6. At this value of dip measure the frequency of incoming signal.
RESULT:
Thus the characteristics of reflex klystron was found and verified
and the graph is plotted for Repeller Voltage versus Output Power.
TABULAR COLUMN:
S.No.
REPELLER VOLTAGE
in Volts
OUTPUT POWER
in m Watts
MODEL GRAPH:
Output
Power
in mWatts
O
Repeller Voltage in Volts
BENCH SETUP DIAGRAM OF REFLEX KLYSTRON OSCILLATOR:
KLYSTRON
POWER
SUPPLY
KLYSTRON
MOUNT
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
POWER
DETECTOR
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
ATTENUATION MEASUREMENT
AIM:
To measure the attenuation introduced by the given wave guide.
COMPONENTS REQUIRED:
1. Microwave source (klystron power supply)
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Frequency meter
6. DUT (Fixed Attenuator)
7. Power Detector
FORMULA:
Attenuation = 20 log (V1 / V2) db
PROCEDURE:
1. Arrange the bench setup as shown in figure 1 and measure the input
power entering into the wave guide (P1).
2. Reconnect the circuit as shown in the figure 2 and find the power
(P2) at the output of the given wave guide.
3. Using formula find the attenuation introduced by the wave guide.
RESULT:
Thus the attenuation introduced by the given wave guide was found
and verified.
BENCH SETUP DIAGRAM OF ATTENUATION MEASUREMENT:
MICRO WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
V1
DETECTOR
FIGURE – 1 (Without DUT)
MICRO
WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY V1
METER
FIGURE – 2 (With DUT)
DUT
(FIXED
ATTENUATOR)
V2 DETECTOR
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
VSWR MEASUREMENT
AIM:
To measure VSWR introduced by the wave guide in dominant mode
of propagation.
COMPONENTS REQUIRED:
1. Microwave source (klystron power supply)
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Slotted section
6. Matched Termination
7. VSWR meter (or) CRO
FORMULA:
VSWR = V max / V min
PROCEDURE:
1. Arrange the bench setup as shown in figure.
2. Adjust the probe carriage to measure V max and note the readings.
3. Adjust the probe carriage to measure V min and note the readings.
4. Use the formula to find VSWR.
RESULT:
Thus the VSWR introduced by the wave guide in dominant mode of
propagation was determined and verified.
BENCH SETUP DIAGRAM OF VSWR MEASUREMENT:
MICRO
WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
SLOTTED
SECTION
VSWR
METER
MATCHED
TERMINATION
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
WAVELENGTH & FREQUENCY MEASUREMENT
AIM:
To determine the guide wavelength of rectangular wave guide in a
dominant mode propagation.
COMPONENTS REQUIRED:
1. Microwave source (klystron power supply)
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Frequency meter
6. Slotted section
6. Matched Termination
7. VSWR meter (or) CRO
FORMULA:
1. Guide wavelength λg = 2(d2 – d1)
Where (d2 – d1) is the difference between two successive minimums
(or) maximum.
_1_ 2
_1_ 2
2. The operating frequency of the wave is f = c
λg
+ 2a
Where a = 2 . 3 cms for X band.
3. The guide wavelength (λg) is related to free space wavelength (λo) by
λo
2
λg =
Where λc =
_λo_ 2
_m 2
_n_
1λc
a
+
b
2
PROCEDURE:
1. Arrange the bench setup as shown in figure.
2. Switch on the microwave source and adjust the attenuator, frequency
meter, etc to get maximum power.
3. Move the carriage probe in the slotted section in particular direction
until there is a minimum deflection in the indicating meter is obtained
note this distance as d1.
4. Once again move the carriage probe from its position d1 in particular
direction in order to get minimum deflection on the indication meter.
Note this distance as d2.
5. Calculate the guide wave length using formula 1, also find frequency
of the wave using formula 2 and verify it with frequency meter.
RESULT:
Thus the wavelength & frequency of the wave is determined.
BENCH SETUP DIAGRAM OF WAVELENGTH & FREQUENCY MEASUREMENT:
MICRO
WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
SLOTTED
SECTION
VSWR
METER
MATCHED
TERMINATION
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
LED CHARACTERISTICS
AIM:
To find the VI characteristics of given LED.
COMPONENTS REQUIRED:
1. Optical trainer kit
2. Ammeter
3. Voltmeter
PROCEDURE:
1. Make the jumper settings as shown in figure.
2. Insert the sockets to connect the jumpers JP17 & JP16 as
shown in figure.
3. Keep the potentiometer Pr 10 to its minimum position.
4. By varying slowly Pr 10 to clock wise direction note down the
readings between voltage and current.
5. Plot the graph VF Vs IF.
RESULT:
Thus the VI characteristics of LED were found and graph was plotted.
SEP UP DIAGRAM OF LED CHARACTERISTICS:
.1
1.
2.
.2
V
3.
.3
A
.4
Jp 16
Jp 17
TABULAR COLUMN:
FORWARD VOLTAGE
(VF in Volts)
S.No.
FORWARD CURRENT
(IF in mA)
MODEL GRAPH:
IF in mA
O
VF in Volts
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
CHARACTERISTICS OF LASER DIODE
AIM:
To find the output power (Po) versus forward current (IF) characteristics of
LASER diode.
COMPONENTS REQUIRED:
1. Laser diode set
2. Fibre optic cable
3. PIN photo detector
4. Power supply for laser diode set
5. Digital multi meter (DMM) ----- 2Nos.
PROCEDURE:
1. Connect the fibre optic cable to TX unit and couple the laser light to the
power meter on the RX unit. Select ACC mode of operation in the TX unit.
2. Set DMM to the 20V DC range and connect the DMM probes to the Vout
and ground points on the RX unit. Now power meter is ready for
use Po = (reading)/10dBm.
3. Set DMM to the 20V DC range and connect the DMM probes to the Vin
and ground points on the TX unit. On the Tx unit. IF = Vo/(50).
4. Adjust the SET 1 of the TX knob to the extreme anti-clock wise position to
reduce IF to zero.
5. Slowly turn the SET 1 knob clockwise to increase IF and Po readings. Take
closer readings prior to and above the laser Threshold.
6. Plot the graph Po Vs IF on a semi log graph
RESULT:
Thus the characteristics of LASER diode was found and graph was plotted.
SEP UP DIAGRAM LASER DIODE CHARACTERISTICS:
DMM
DMM
TX UNIT
ACC MODE
RX
UNIT
OFC
CABLE
APC MODE
SET UP FOR ACC MODE
TABULAR COLUMN:
S.No.
Vi
IF = Vi / 50
Vo
IP = Vo / 50
MODEL GRAPH:
Output
Power (Po)
O
Forward Current (IF)
Po (dbm) =
10 log IP
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
DIRECTIONAL COUPLER CHARACTERISTICS
AIM:
To find the characteristics of given directional coupler.
COMPONENTS REQUIRED:
1. Micro wave source
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Directional coupler
6. Power Detector
7. Matched termination ----- 1 No
FORMULA:
1. Coupling factor of directional coupler C = 10 log (V1 / V3)
2. Directivity of directional coupler
D = 10 log (V3 / V4)
3. Isolation of directional coupler
I = 10 log (V1 / V4)
PROCEDURE:
1. Arrange the bench setup with out connecting directional
coupler and measure the input power.
2. Now connect the directional coupler and note down the output
power at port 2, port 3 & port 4.
3. Using the measured value find the characteristics of given
directional coupler.
SCATTERING MATRIX:
S=
0
S12
0
S14
S12
0
S23
0
0
S23
0
S34
S14
0
S34
0
RESULT:
Thus the characteristics of given directional coupler was found and verified.
BENCH SETUP DIAGRAM OF DIRECTIONAL COUPLER CHARACTERISTICS:
MATCHED
TERMINATION
(or)
DETECTOR
3
4
MICRO
WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
1
DIRECTIONAL
COUPLER
2
DETECTOR
(or)
MATCHED
TERMINATION
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
WAVE GUIDE PARAMETERS MEASUREMENT
AIM:
To measure the Q – factor of the given wave guide.
COMPONENTS REQUIRED:
1. Microwave source (klystron power supply)
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Frequency meter
6. DUT
7. Power Detector
PROCEDURE:
1. Arrange the bench setup as shown in figure.
2. Vary the signal frequency in such a way that the maximum output is
obtained in the detector.
3. This is due to the fact that DUT is having resonant frequency fo.
4. Now vary the frequency to obtain to obtain the half power frequency
by varying the frequency of the signal.
5. In the similar way find other frequency end.
6. Using lower and upper cut – off frequencies calculate the bandwidth
and Q – factor using the below equation.
Q = fo / bandwidth
RESULT:
Thus the Q – factor of the given cavity was determined and verified.
BENCH SETUP DIAGRAM OF WAVE GUIDE PARAMETERS MEASUREMENT:
MICRO
WAVE
SOURCE
VARIABLE
ISOLATOR
ATTENUATOR
FREQUENCY
METER
DUT
DETECTOR
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
FERRITE DEVICES
AIM:
To find the characteristics of ferrite device – circulator.
COMPONENTS REQUIRED:
1. Microwave source (klystron power supply)
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Frequency meter
6. Circulator
7. Power Detector
8. Matched termination ----- 1 No
FORMULA:
1. The S – matrix of 3 – port circulator is
S=
0
0
1
1
0
0
0
1
0
Where
S11 = s22 = s33 = 0
S12 = s23 = s31 = 0
S21 = 20log (V2 / V1)
S13 = 20log (V1 / V3)
2. Insertion loss = 10 log (p1/p2)
3. Isolation
= 10 log (p1/p3)
PROCEDURE:
1. Arrange the bench setup with out connecting circulator
and measure the input power.
2. Now connect the circulator and note down the output
power at port 2 & port 3.
3. Substitute the values to estimate the S – matrix of
circulator.
RESULT:
Thus the characteristics of given 3 – port circulator was obtained and
verified.
BENCH SETUP DIAGRAM OF FERRITE DEVICES:
1
MICRO
WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
2
CIRCULATOR
DETECTOR
(or)
MATCHED
TERMINATION
3
MATCHED
TERMINATION
(or)
DETECTOR
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
MAGIC – TEE CHARACTERISTICS
AIM:
To find the characteristics of given Magic – Tee.
COMPONENTS REQUIRED:
1. Micro wave source(klystron power supply)
2. Klystron Mount
3. Isolator
4. Variable Attenuator
5. Frequency meter
6. Magic – Tee
7. Power Detector
8. Matched termination ----- 2 No’s
FORMULA:
The S – matrix of the magic – tee is
Where
S =1/√ 2
S13 =
√ V1/V3
S14 =
√ V1/V4
S23 =
√ V2/V3
S24 =
√ V2/V4
0
0
1
1
0
0
1 -1
1
1
0
0
1
-1
0
0
PROCEDURE:
1. Arrange the bench setup with out connecting magic – tee and
measure the input power.
2. Now connect the magic – tee and note down the output power
at port 2, port 3 & port 4.
3. Substitute the value of the port currents to obtain the scattering
parameters of given magic – tee.
4. For various values of input power find the scattering matrix.
RESULT:
Thus the characteristics of given Magic – Tee was found and verified.
BENCH SETUP DIAGRAM OF MAGIC – TEE CHARACTERISTICS:
MATCHED
TERMINATION
(or)
DETECTOR
3
MICRO
WAVE
SOURCE
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
1
MAGIC
TEE
2
DETECTOR
(or)
MATCHED
TERMINATION
4
MATCHED
TERMINATION
(or)
DETECTOR
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
INTENSITY MODULATION OF LASER OUTPUT THROUGH
OPTICAL FIBRE
AIM:
To study the following characteristics of an intensity modulation of
LASER output through optical fibre.
COMPONENTS REQUIRED:
1. Laser diode set
2. Fibre optic cable
3. Power supply for laser diode set
4. Function Generator
5. C R O
PROCEDURE:
1. Connect the fibre optic cable to TX unit and couple the laser light to the power
meter on the RX unit. Select ACC mode of operation.
2. Take output from Function Generator (FG) and connect to the input of TX unit
as well as to CH 2 of CRO.
3. Connect the output from RX unit to CH 1 of CRO.
4. Both the TX & RX knobs are kept in maximum position and vary the frequency
from FG .
5. Take outputs from both CH’S of Amplitudes i.e. Vi & Vo.
6. Plot the graph between Vi & Vo.
RESULT:
Thus the characteristics of an intensity modulation of LASER output
through optical fibre was found and graph was plotted.
SEP UP DIAGRAM OF INTENSITY MODULATION OF LASER
OUTPUT THROUGH OPTICAL FIBER:
CRO
FG
TX UNIT
ACC MODE
RX
UNIT
OFC
CABLE
APC MODE
SET UP FOR ACC MODE
TABULAR COLUMN:
INPUT VOLTAGE
Vi in Volts
S.No.
MODEL GRAPH:
Vo in
Volts
0
Vi in Volts
OUTPUT VOLTAGE
Vo in Volts
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
GUNN DIODE CHARACTERISTICS
AIM:
To study the characteristics of Gunn Diode.
COMPONENTS REQUIRED:
1. Gunn Diode Power Supply
2. Gunn Diode
3. Pin Modulator
4. Isolator
5. Variable Attenuator
6. Frequency meter
7. Power Detector
PROCEDURE:
1. Arrange the bench setup as shown in figure.
2. Switch on the gunn power supply.
3. Initially give some gunn bias voltage, fix the attenuation and adjust the
frequency meter to give maximum output.
4. Now keep the gunn bias in minimum position around 0.5V and increase it
slowly.
5. For difference values of voltage measure the gunn diode current.
6. From the tabulation observed, plot the V-I characteristics.
RESULT:
Thus the characteristics of Gunn diode was found and verified and graph
was plotted.
TABULAR COLUMN:
S.No.
GUNN BIAS VOLTAGE
(V in Volts)
OUTPUT CURRENT
(I in mA)
MODEL GRAPH:
I in mA
O
V in Volts
BENCH SETUP DIAGRAM OF GUNN DIODE CHARACTERISTICS:
GUNN
POWER
SUPPLY
GUNN
DIODE
PIN
MODULATOR
ISOLATOR
VARIABLE
ATTENUATOR
FREQUENCY
METER
POWER
DETECTOR
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
FIBRE OPTIC DIGITAL LINK
AIM:
To study the fibre optic digital link.
COMPONENTS REQUIRED:
1. Digital trainer kit
2. Fibre cable
3. Dual trace CRO
4. Function Generator
PROCEDURE:
1. Make the jumper settings as shown in figure.
2. Insert the fibre into IR LED SRH 450v loop.
3. Now short the jumpers JP15, JP16, JP17 & JP20.
4. Connect the power cord to the kit and switch on the power supply.
5. Feed the power end to function generator to connector labeled as
Ext – TTL using connecting cables provided with kit.
6. Connect the circuit and observe the received signal.
7. Vary the frequency of the signal and observe the output.
RESULT:
Thus the fibre optic digital link was studied.
BLOCK DIAGRAM FOR DIGITAL FIBRE CABLE:
ENCODER
DIGITAL
INFORMATION
SOURCE
LASER
DRIVE
CIRCUIT
OPTICAL FIBRE
CABLE
AMPLIFIER
LASER
DIODE
AVALANCHE
PHOTE DIODE
DECODER
ORIGINAL
DIGITAL
FORM
SEP UP DIAGRAM OF FIBRE OPTIC DIGITAL LINK:
Pr 10
Terminal
Emitter
of Q2
JP 18
Ground
Amp
Output
Base
of Q1
JP 20
Digital
buffer output
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
MAGIC – TEE AS MIXER
AIM:
To construct a Mixer using Magic - Tee.
COMPONENTS REQUIRED:
1. Micro wave source ------ 2 No’s
2. Klystron Mount ---------- 2 No’s
3. Isolator -------------------- 2 No’s
4. Variable Attenuator ----- 2 No’s
5. Magic – Tee -------------- 1 No
6. Matched termination ----- 1 No
PROCEDURE:
1. Arrange the bench setup as shown in fig.
2. Apply the signal 1 at port 4, signal 2 at port 3 of the
Magic – Tee.
3. Measure the output signal at port 2.
4. From the output verify the Mixer operation.
RESULT:
Thus Mixer using Magic – Tee was constructed and verified.
BENCH SETUP DIAGRAM OF MIXER:
Signal 1
MICRO
WAVE
SOURCE – 1
VARIABLE
ISOLATOR
ATTENUATOR
S1
4
E – ARM
MATCHED
TERMINATION
1
2
MAGIC
TEE
H – ARM
S2
MICRO
WAVE
SOURCE – 2
VARIABLE
ISOLATOR
Signal 2
ATTENUATOR
3
MIXED
OUTPUT
SIGNAL
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPT. OF ECE
CIRCULATOR AS MIXER
AIM:
To construct a Mixer using Circulator.
COMPONENTS REQUIRED:
1. Micro wave source ------ 2 No’s
2. Klystron Mount ---------- 2 No’s
3. Isolator -------------------- 2 No’s
4. Variable Attenuator ----- 2 No’s
5. Circulator ----------------- 1 No
6. Power Detector ---------- 1 No’s
PROCEDURE:
1. Arrange the bench setup as shown in fig.
2. Apply the signal 1 at port 1 and signal 2 at port 3 of the
circulator.
3. Measure the output signal at port 2.
4. From the output verify the Mixer operation.
RESULT:
Thus Mixer using Circulator was constructed and verified.
BENCH SETUP DIAGRAM OF CIRCULATOR AS DUPLEXER:
MICRO
WAVE
SOURCE – 1
ISOLATOR
1
VARIABLE
ATTENUATOR
1
Signal 1
1
2
CIRCULATOR
3
MICRO
WAVE
SOURCE – 2
ISOLATOR
2
VARIABLE
ATTENUATOR
2
Signal 2
DETECTOR