attenuation

SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGYDEPT. 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


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 VoltsOUTPUT 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

VARIABLEATTENUATOR

FREQUENCY METER

POWER DETECTOR


ATTENUATION MEASUREMENT

AIM:To measure the attenuation introduced by the given wave guide.


1. Microwave source (klystron power supply)

2. Klystron Mount

3. Isolator


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:

V1

FIGURE – 1 (Without DUT)

V1 V2

FIGURE – 2 (With DUT)

MICRO WAVE SOURCE

ISOLATOR VARIABLEATTENUATOR

FREQUENCYMETER

DETECTOR

MICRO WAVE

SOURCE

ISOLATOR VARIABLEATTENUATOR

DUT(FIXED

ATTENUATOR)

DETECTORFREQUENCYMETER


VSWR MEASUREMENT

AIM:

To measure VSWR introduced by the wave guide in dominant mode of propagation.



2. Klystron Mount

3. Isolator


5. Slotted section

6. Matched Termination

7. VSWR meter (or) CRO

FORMULA:VSWR = V max / V min

PROCEDURE:


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

SOURCEISOLATOR

VARIABLEATTENUATOR

FREQUENCYMETER

VSWR METER

SLOTTEDSECTION

MATCHED TERMINATIO

N


WAVELENGTH & FREQUENCY MEASUREMENT

AIM:To determine the guide wavelength of rectangular wave guide in a

dominant mode propagation.



2. Klystron Mount

3. Isolator


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_ 2

1 - λc a + b

PROCEDURE:


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

SOURCEISOLATOR

VARIABLEATTENUATOR

FREQUENCYMETER

VSWR METER

SLOTTEDSECTION

MATCHED TERMINATIO

N


LED CHARACTERISTICS

AIM:

To find the VI characteristics of given LED.


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:

Jp 16 Jp 17

TABULAR COLUMN:

MODEL GRAPH:

IF in mA

O VF in Volts

. 1

. 2

. 3

. 4

1 .

2 .

3 .

V

A

S.No.FORWARD VOLTAGE

(VF in Volts)FORWARD CURRENT

(IF in mA)


CHARACTERISTICS OF LASER DIODE

AIM: To find the output power (Po) versus forward current (IF) characteristics of LASER diode.


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:

SET UP FOR ACC MODE

TABULAR COLUMN:

S.No. Vi IF = Vi / 50 Vo IP = Vo / 50 Po (dbm) = 10 log IP

MODEL GRAPH:

Output Power (Po)

O Forward Current (IF)

TX UNIT ACC MODE

APC MODE

DMM

RXUNIT

OFCCABL

E

DMM


DIRECTIONAL COUPLER CHARACTERISTICS

AIM:

To find the characteristics of given directional coupler.


1. Micro wave source

2. Klystron Mount

3. Isolator


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:

0 S12 0 S14

S12 0 S23 0

S = 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:

3

4

1 DIRECTIONAL 2 COUPLER

MICRO WAVE

SOURCEISOLATOR VARIABLE

ATTENUATOR

MATCHED TERMINATION

(or) DETECTOR

DETECTOR(or)

MATCHED TERMINATION


WAVE GUIDE PARAMETERS MEASUREMENT

AIM:To measure the Q – factor of the given wave guide.



2. Klystron Mount

3. Isolator


5. Frequency meter

6. DUT

7. Power Detector

PROCEDURE:


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

SOURCEISOLATOR

VARIABLEATTENUATOR

FREQUENCYMETER DUT DETECTOR


FERRITE DEVICES

AIM:

To find the characteristics of ferrite device – circulator.



2. Klystron Mount

3. Isolator


5. Frequency meter

6. Circulator

7. Power Detector


FORMULA:

1. The S – matrix of 3 – port circulator is

0 0 1

S = 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 2

3

MICRO WAVE

SOURCEISOLATOR

VARIABLEATTENUATOR

FREQUENCYMETER

DETECTOR(or)

MATCHED TERMINATION

CIRCULATOR

MATCHED TERMINATION

(or) DETECTOR


MAGIC – TEE CHARACTERISTICS

AIM:

To find the characteristics of given Magic – Tee.


1. Micro wave source(klystron power supply)

2. Klystron Mount

3. Isolator


5. Frequency meter

6. Magic – Tee

7. Power Detector

8. Matched termination ----- 2 No’s

FORMULA:

0 0 1 1

0 0 1 -1

The S – matrix of the magic – tee is S =1/√ 2 1 1 0 0

1 -1 0 0

Where S13 = √ V1/V3

S14 = √ V1/V4

S23 = √ V2/V3

S24 = √ V2/V4

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:

3

1 2

4

MICRO WAVE

SOURCEISOLATOR VARIABLE

ATTENUATOR

MATCHED TERMINATION

(or) DETECTOR

DETECTOR(or)

MATCHED TERMINATION

MATCHED TERMINATION

(or) DETECTOR

FREQUENCYMETER

MAGIC

TEE


INTENSITY MODULATION OF LASER OUTPUT THROUGH OPTICAL FIBRE

AIM: To study the following characteristics of an intensity modulation of LASER output through optical fibre.


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:

SET UP FOR ACC MODE

TABULAR COLUMN:

MODEL GRAPH:

Vo in Volts

TX UNIT ACC MODE

APC MODE

CRO

RXUNIT

OFCCABL

E

FG

S.No.INPUT VOLTAGE

Vi in VoltsOUTPUT VOLTAGE

Vo in Volts

0 Vi in Volts


GUNN DIODE CHARACTERISTICSAIM:

To study the characteristics of Gunn Diode.


1. Gunn Diode Power Supply

2. Gunn Diode

3. Pin Modulator

4. Isolator


6. Frequency meter

7. Power Detector

PROCEDURE:


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:

MODEL GRAPH:

I in mA

S.No.GUNN BIAS VOLTAGE

(V in Volts)OUTPUT CURRENT

(I in mA)

O V in Volts

BENCH SETUP DIAGRAM OF GUNN DIODE CHARACTERISTICS:

GUNN POWER SUPPLY

GUNN DIOD

EISOLATOR

VARIABLEATTENUATOR

FREQUENCY METER

POWER DETECTO

R

PIN MODULATO

R


FIBRE OPTIC DIGITAL LINK

AIM:

To study the fibre optic digital link.


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:

OPTICAL FIBRECABLE

LASER AVALANCHE DIODE PHOTE DIODE

SEP UP DIAGRAM OF FIBRE OPTIC DIGITAL LINK:

Pr 10 Emitter Ground

Terminal of Q2 Amp Base Digital Output of Q1 buffer output

JP 18 JP 20

ENCODERLASER DRIVE

CIRCUIT

DIGITALINFORMATION

SOURCE

AMPLIFIER DECODER

ORIGINALDIGITAL

FORM


MAGIC – TEE AS MIXER

AIM:

To construct a Mixer using Magic - Tee.


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


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

S1 4 E – ARM

1 2 MIXED OUTPUT SIGNAL

H – ARM S2 3

Signal 2

ISOLATORMICRO WAVE

SOURCE – 1

VARIABLEATTENUATOR

MATCHED TERMINATION

MAGIC TEE

VARIABLEATTENUATORISOLATOR

MICRO WAVE

SOURCE – 2


CIRCULATOR AS MIXER

AIM:

To construct a Mixer using Circulator.


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:

Signal 1

1

2

3

Signal 2

ISOLATOR 1

MICRO WAVE

SOURCE – 1

VARIABLEATTENUATOR

2

CIRCULATOR DETECTOR

VARIABLEATTENUATOR

1

ISOLATOR 2

MICRO WAVE

SOURCE – 2

attenuation

Documents

klystron mount

given wave guide

voltsoutput power

power detectorformula

power p2

input power

attenuation measurements

ece attenuation measurementaim