Acelii Manual

H. J. Thim Trust’s

THEEM COLLEGE OF ENGINEERING

ADVANCED COMMUNICATION

ENGINEERING LABORATORY-II MANUAL

PREPARED BY

Prof. Anup Kori

Department of Electronics and Telecommunication Engineering

THEEM COLLEGE OF ENGINEERING

(Affiliated to Mumbai University)

LIST OF EXPERIMENTS PAGE NO

1. To study characteristics of reflex klystron……………..………………….3

2. Measurement of VSWR using microwave bench…………………………5

3. Measurement of unknown impedance using microwave bench ………….7

4. Determination of characteristics of directional coupler…………………...9

5. Study of Microwave Tees i.e. E Plane, H Plane & Magic Tee……...……11

6. To establish and Study a 650nm fiber optic analog link…………….…....13

7. To establish and Study a 650nm fiber optic digital link………………….16

8. Measurement of propagation or attenuation loss in optical fiber………...19

9. To measure propagation loss in optical fiber using optical power meter...22

10. Measurement of numerical aperture of the optical fiber..………………..24

EXPERIMENT 1

CHARACTERISTICS OF REFLEX KLYSTRON

AIM: To study the Reflex Klystron oscillator characteristics.

APPARATUS: 1.Klystron Power supply

2. Klystron tube with mount

3. Isolator

4. Variable Attenuator

5. Frequency Meter

6. Slotted section

7. Detector Mount

8. CRO & CRO probes

9. Cooling Fan

BLOCK DIAGRAM:

V-I CHARACTERISTICS OF REFLEX KLYSTRON OSCILLATOR:

PROCEDURE:

1. Set the various components and instruments as per the block diagram.

2. Switch on the Klystron Power Supply Unit (PSU) and CRO

3. Set the beam voltage to 300Vand repeller voltage for maximum output.

4. Decrease the repeller voltage to -30V.

5. Note down the output by increasing the repeller voltage in step of 10V.

6. Plot the graph between repeller voltage and output.

7. Verify the characteristics.

PRECAUTIONS:

Beam voltage should be minimum and repeller voltage should be normal before switch ON/OFF the Klystron PSU.

RESULT:

The characteristics of Reflex Klystron are verified.

EXPERIMENT 2

MEASUREMENT OF VSWR USING MICROWAVE BENCH

AIM: To measure the VSWR of given load.



3. Isolator


5. Frequency Meter

6. Slotted section

7. Detector Mount

8. CRO & CRO probes

9. Cooling Fan

10. Loads

BLOCK DIAGRAM:

PROCEDURE:




4. Note down the maximum output (Vmax).

5. By varying the slotted section note down the minimum o/p(Vmin) .

6. Find out the VSWR of the load by the formula VSWR= Vmax/ Vmin.

7. Repeat the same procedure for other loads.

8. Compare the practical values with manufacturer’s specifications.

PRECAUTIONS:


RESULT:

The VSWR of given load is measured.

EXPERIMENT 3

MEASUREMENT OF UNKNOWN IMPEDANCE USING MICROWAVE BENCH

AIM: To measure the unknown impedance of load.



3. Isolator


5. Frequency Meter

6. Slotted section

7. Detector Mount

8. CRO & CRO probes

9. Cooling Fan

10. Loads

11. Short

BLOCK DIAGRAM:

PROCEDURE:




4. Connect load for which impedance to be measured.

5. Find the position of minimum o/p at slotted section.

6. Remove the unknown load and place a short in place of load and move the probe towards the shorting plane and locate first minimum.

7. The difference between these two adjacent positions of probe will be the distance of first minimum from the load.

8. Measure the distance between the adjacent minimum and find the guide wavelength λg.

9. Take a Smith Chart taking ‘l’ as center and draw a circle of radius equal to VSWR reading. Mark a point on circumference towards load side at a distance equal to the ratio of the distance of first minimum from load to the λg .Join center with this point found the point will give the normalized impedance of the load. By multiplying the normalized impedance with characteristic impedance, find the true impedance of the load.

PRECAUTIONS:


RESULT:

The unknown impedance of given load is measured.

EXPERIMENT 4

DETERMINATION OF CHARACTERISTICS OF DIRECTIONAL COUPLER

AIM: To measure the coupling factor and directivity of given directional coupler.



3. Isolator


5. Frequency Meter

6. Slotted section

7. Detector Mount

8. CRO & CRO probes

9. Cooling Fan

10. Directional coupler (DC)

11. Matched termination

BLOCK DIAGRAM:

PROCEDURE:




4. It is noted as power at port 1.

5. Remove the detector mount and connect the directional coupler in place of detector mount.

6. Measure the power at port 3.

7. Now remove the DC and reverse it.

8. Measure the power at port 2.

9. Calculate the coupling factor by the formula.

Coupling factor = power at port 3 / power at port1.

10. Calculate the directivity by the formula

Directivity = power at port1 / power at port2.

11. Compare the practical values with manufacturer specifications.

PRECAUTIONS:


RESULT:

The coupling factor and directivity of given directional coupler are measured.

EXPERIMENT 5

STUDY OF MICROWAVE TEEs I.E. E PLANE, H PLANE & MAGIC TEE

AIM: To measure power distribution of various magic Tees (E plane, H plane & Magic Tee)



3. Isolator


5. Frequency Meter

6. VSWR Meter

7. Detector Mount

8. BNC cables & CRO probes

9. Matched load

10. E plane

11. H plane

12. Magic Tee.

BLOCK DIAGRAM:

THEORY: Waveguide Tee’s are used for connecting a branch section of waveguide in series or parallel with the main waveguide. Tees are also be used as power divider field.

1) Input VSWR: Value of SWR corresponding to each port as a load to the line while other ports are terminated in matched load.

2) Isolation: The isolation between E and H arm is defined as the ration of the power supplied by the generator connected to the E port 4 to the power detected at H arm port 3

Isolation=10 log10 P4/P3

3) Coupling coefficient It is defined as Cij=10 –_/20 Where _ is attenuation /isolation in dB when it is input arm and j is output arm

Thus _= 10 log Pi/Pj Where Pi is power delivered to arm i and Pj is power detected at j arm

E plane Tee Model 6031 E plane Tee is a type T junction & consist of 3 section wave guide joint together in order to divide & compare power levels .The signals entering first part of the P junction will be equally divided at 2nd 3rd port of magnitude but opposite in direction.

H plane Tee Model 3065 H plane TEE are shunt type Tjunction that is used in conjunction with VSWR meter, Frequency meter &other detector devices.

Magic Tee – Model 3045 EH consist of section of waveguide with both series & shunt wave-guide are mounted at exact mid point of the main arm. This becomes four terminal devices where one terminal is isolated from the i/p. VSWR of 1.40 over + 15% freq range. This is achieved by inserting & connecting piece with stub.

PROCEDURE :

H plane Tee :

a) Give i/p at port 1b) Observe o/p on VSWR meter at port 2&3.

E plane Tee :

a) Give i/p at port 1. b) Observe output at port

Magic Tee :

a) Give i/p at port 1. b) Observe the output at port 2,3&4 c) Give i/p at port 4. d) Observe the o/p at port 1,2&3.

RESULT:

Thus we have studied the power distribution in each Tee.

EXPERIMENT 6

STUDY OF A 650nm FIBER OPTIC ANALOG LINK

AIM: To establish and study a 650nm fiber optic analog link.

APPARATUS: 1. ST2502 trainer with power supply cords

2. Optical Fiber cable.

3. Cathode ray oscilloscope with necessary connecting probe.

THEORY:

Fiber optic links can be used for transmission of digital as well as analog signals. Basically a fiber optic link contains three main elements : a transmitter, an optical fiber and a receiver. The transmitter module takes the input signal in electrical form and then transforms it into optical energy containing the same information.The optical fiber is the medium which takes the energy to the receiver. At the receiver, light is converted back into electrical form with the same pattern as fed to the transmitter.

Transmitter: Fiber optic transmitters are composed of a buffer, driver and optical source.The buffer provides both an electrical connection and isolation between the transmitter and the electrical system the data. The driver provides electrical power to the optical source. Finally, the optical source converts the electrical current to the light energy with the same pattern. The optical source used is LED. Simple LED circuit for analog transmission is shown below.

Transconductance drive circuit for analog transmission-common emitter configuration

The transmitter section comprises of Function Generator which generates input signals that are going to be used as information to transmit through optical fiber.

The Fiber Optic Link: Emitter and Detector circuit on board form the fiber optic link. This section provides the light source for the optic fiber and the light detector at the far end of the fiber optic links. The optic fiber plugs into the connectors provided in this part of the board. Two separate links are provided.

The Receiver: The AC amplifier circuit forms receiver on the board.

BLOCK DIAGRAM:

Analog Fiber Optic Link

PROCEDURE:

1. Connect the power supply to the board.

2. Ensure that all switched faults are off.

3. Make the following connections.

Connect the Function generator 1KHz sine wave output to emitter‟s input.

Connect the Fiber optic cable between emitter output and detectors input.

Detector‟s output to AC amplifier input.

4. On the board, switch emitter‟s driver to analog mode.

5. Switch ON the power.

6. Observe the input to emitter with the output from AC amplifier and note that the two signals are same.

CONNECTION DIAGRAM:

Connections on Trainer Kit

OBSERVATIONS:

Input voltage = 1.2V

Detector output = 0 .1V

Amplifier output = 1.4V

RESULT:

The 650nm fiber optic Analog link has been established.

EXPERIMENT 7

STUDY OF A 650nm FIBER OPTIC DIGITAL LINK

AIM: To establish and study a 650nm fiber optic digital link.

APPARATUS: 1. ST2502 trainer with power supply cords


3. Cathode ray oscilloscope with necessary connecting probe.

THEORY:

Fiber optic links can be used for transmission of digital as well as analog signals. Basically a fiber optic link contains three main elements : a transmitter, an optical fiber and a receiver. The transmitter module takes the input signal in electrical form and then transforms it into optical energy containing the same information.The optical fiber is the medium which takes the energy to the receiver. At the receiver, light is converted back into electrical form with the same pattern as fed to the transmitter.

Transmitter: Fiber optic transmitters are composed of a buffer, driver and optical source. The buffer provides both an electrical connection and isolation between the transmitter and the electrical system the data. The driver provides electrical power to the optical source. Finally, the optical source converts the electrical current to the light energy with the same pattern. The optical source used is LED. The simple driver circuit is shown below.

Simple drive circuit for binary digital transmission using a common emitter saturating switch

The transmitter section comprises of Function Generator which generates input signals that are going to be used as information to transmit through optical fiber.

The Fiber Optic Link: Emitter and Detector circuit on board form the fiber optic link. This section provides the light source for the optic fiber and the light detector at the far end of the fiber optic links. The optic fiber plugs into the connectors provided in this part of the board. Two separate links are provided.

The Receiver: The comparator circuit and AC amplifier circuit form receiver on the board.

BLOCK DIAGRAM:

Digital Fiber Optic Link

PROCEDURE:

1. Connect the power supply to the board.

2.Ensure that all switched faults are off.

3. Make the following connections.

Connect the Function generator 1KHz square wave output to emitter’s input.

Connect the Fiber optic cable between emitter output and detector’s input.

Detector’s output to comparator’s input.

Comparator’s output to AC amplifier’s input.

4. On the board, switch emitter’s driver to digital mode.

5. Switch ON the power.

6. Monitor both the inputs to comparator . Slowly adjust the comparator’s bias preset, until DC level on the input lies midway between the high and low level of the signal on the positive input.

7. Observe the input to emitter with the output from AC amplifier and note that the two signals are same.

CONNECTION DIAGRAM:


OBSERVATIONS:

Input Voltage = 0.16V

Comparator output = 0.05V

Amplifier output = 1V

RESULT:

The 650nm fiber optic Digital link has been established.

EXPERIMENT 8

MEASUREMENT OF PROPAGATION / ATTENUATION LOSS IN OPTICAL FIBER

AIM: To measure propagation or attenuation loss in optical fiber.

APPARATUS: 1. ST2502 trainer with power supply cord.

2. Optical Fiber cable

3. Cathode ray oscilloscope with necessary connecting probe

CONNECTION DIAGRAM:


PROCEDURE:

1. Connect power supply cord to the main power plug & to trainer ST2502.

2. Make the following connections as shown in figure.

a. Function generator’s 1 KHz sine wave output to Input 1 socket of emitter 1 circuit via 4 mm lead.

b. Connect 0.5 m optic fiber between emitter 1 output and detector l's input.

c. Connect detector 1 output to amplifier 1 input socket via 4mm lead.

3. Switch ON the Power Supply of the trainer and oscilloscope.

4. Set the Oscilloscope channel 1 to 0.5 V / Div and adjust 4 - 6 div amplitude by using X 1 probe with the help of variable pot in function generator block at input 1 of Emitter 1.

5. Observe the output signal from detector TP10 on CRO.

6. Adjust the amplitude of the received signal same as that of transmitted one with the help of gain adjust potentiometer in AC amplifier block. Note this amplitude and name it V1.

7. Now replace previous FG cable with 1 m cable without disturbing any previous setting.

8. Measure the amplitude at the receiver side again at output of amplifier 1 socket TP 28. Note this value end name it V2.

PRECAUTIONS:

a. The optical fiber must not be bent, so as to avoid bending losses.

b. The circuit must be neat and secure.

OBSERVATIONS:

1. Using output of cables of different diameters:

O/P of .5m cable-.56V; O/P of 1m cable-.52V

Attenuation=20log56/52=.64dB

2. Using formula α= -1/(L1+L2)ln(V1/V2)=.429dB/m

3. Using OPM, Pn=-31.3dBm, Pf=-31.4dBm

α = .1dB

CALCULATIONS:

Calculate the propagation (attenuation) loss with the help of following formula.

V1 / V2 = e- α (L1 + L2)

Where α is loss in nepers / meter & 1 neper = 8. 686 dB

L 1 = length of shorter cable (0.5 m)

L 2 = Length of longer cable (1 m)

RESULT:

Thus the practical & theoretical values of attenuation loss are verified.

EXPERIMENT 9

MEASUREMENT OF PROPAGATION LOSS IN OPTICAL FIBER USING OPTICAL POWER METER

AIM: To measure propagation loss in optical fiber using optical power meter.

APPARATUS: 1. ST2502 trainer with power supply cord

2. Optical fiber cable

3. Cathode ray oscilloscope with necessary connecting probe

4. Power Meter ST2551 with power supply cord

CONNECTION DIAGRAM:

PROCEDURE:

1. Connect the Power supply cord to mains supply and to the trainer ST2501.

2. Keep the mode switch in emitter 1 circuit in analog mode

3. Connect the 0.5m fiber cable in between the emitter LED & I/P of power meter.

4. Switch on the instrument fiber optic trainer & power meter (Keep the wavelength switch in 660 nm, position). Note the reading in power meter.

5. Replace the 0.5m fiber cable with the 1m cables without disturbing any setting.

6. Again note the reading in power. This reading will be lesser then the previous one, indicating that the propagation loss increases with increase in length.

7. Perform the same experiment with emitter 2.

PRECAUTIONS:

a. The optical fiber must not be bent, so as to avoid bending losses.

b. The circuit must be neat and secure.

RESULT:

Using OPM, Pn=-31.3dBm, Pf=-31.4dBm. Hence, α = .1dB was measured.

EXPERIMENT 10

MEASUREMENT OF NUMERICAL APERTURE OF THE OPTICAL FIBER

AIM: To measure the Numerical Aperture (NA) of the optical fiber.

APPARATUS: 1. ST2502 trainer with power supply cord


3. Numerical Aperture measurement Jig/Paper & Scale.

CONNECTION DIAGRAM:

THEORY:

The numerical aperture refers to maximum angle at which the light incident on fiber end is totally internally reflected and is transmitted along the fiber. The cone formed by rotation of this angle along the axis of the fiber is the cone of acceptance of fiber. if light ray should strike the fiber end withinthis cone of acceptance it will be transmitted properly else it is refracted out of fiber.

PROCEDURE:

1. Connect the Power supply cord to mains supply and to the trainer ST2502.

2. Connect the frequency generator's 1 KHz sine wave output to input of emitter 1 circuit. Adjust its amplitude at 5Vpp.

3. Connect one end of fiber cable to the output socket of emitter 1 circuit and the other end to the numerical aperture measurement jig. Hold the white screen facing the fiber such that its cut face is perpendicular to the axis of the fiber.

4. Hold fiber vertically at a suitable distance to make the red spot .

5. Record the distance of screen from the fiber end L and note the diameter W of the spot. Compute the numerical aperture from the formula given belowNA= (W/2) / √(W/2)^2+L^2

RESULT:

The N.A. of fiber measured is 0.34 using trigonometric formula.

Acelii Manual

Documents

klystron psu

klystron tube

beam voltage

vand repeller voltage

klystron power supply

cro cro probes

measurement of vswr

optical power meter