RMT e Manual

8/11/2019 RMT e Manual

1/27

Experiment No.:-1

Experiment Name: - Characteristics of ReflexKlystron


2/27

KCES`S COLLEGE OF ENGINEERING & IT, JALGAON

ELECTRONICS TELECOMMUNICATION DEPTT.

ACADEMIC YEAR: 2008- 2009 SEMISTER: I / II

Name of student : __________________________________________________________ GradeClass: _________________ Roll No .:_____________Subject: _______________ Date of

CompletionExperiment No .:____ Date of Performance:__________

Title :____________________________________________________________________ Signature

Aim:To study the characteristics of the Reflex Klystron Tube and to determine its electronic tuningrange.

Apparatus:Klystron Power Supply, Klystron Tube with Klystron Mount, Frequency Meter, Variable Attenuator,

Mount, Wave Guide Stand, VSWR Meter and Oscilloscope BNC Cable

Theory:The reflex Klystron makes the use of velocity modulation to transform a continuous electron beam

in to microwave power. Electrons emitted from the cathode are accelerated & passed through the positiveresonator towards negative reflector, which retards and finally, reflects the electrons and the electrons turn

back through the resonator. Suppose an rf-field exists between the resonators the electron travelingforward will be accelerated or retarded, as the voltage at the resonator change in amplitude. Theaccelerated electrons leave the resonator at an increased velocity and the retarded electrons leave at thereduced velocities. The electrons leaving the resonator will need different time to return, due to change invelocities. As a result returning electron group together in bunches, as the electron bunches pass throughresonator, they interact with voltage at resonator grids. If the bunches pass the grid at such a time that theelectrons are slowed down by the voltage then energy will be deliver to the resonator; and Klystron willoscillate. Fig.2 shows the relationship between out put power, frequency and reflector voltages.The frequency primarily determined by the dimensions of resonant cavity .hence, by changing the volumeof resonator, mechanical tuning of Klystron is possible. Also, a small frequency change can be obtained

by adjusting the reflector voltage. This is called electronic tuning.The same result can be obtained, if the modulation voltage is applied on the reflector voltage as shown inFig.


3/27

Procedure

A. Carrier Wave Operation1. Connect the components and equipment as shown in Fig.22. Set the variable attenuator at the maximum position (A zero micrometer reading).3. Set the mode switch of Klystron power supply to CW position, beam voltage control knob to full

anti-clockwise and reflector voltage control, knob to fully clock wise and the meter switch to OFF position.

4. Rotate the knob of frequency meter at one side fully.5. Put the Multimeter in DC microampere range of 250 microampere.6. Switch ON the Klystron power supply, VSWR Meter and Cooling Fan of Klystron tube.7. Put the meter switch to beam voltage position and rotate beam voltage knob clockwise slowly up

to 300V reading. Observe beam current on the meter by changing the meter switch to beamcurrent position. The beam current should not increase more than 30mA.

8. Change the reflector voltage slowly and watch on the VSWR meter. Set the voltage for maximumdeflection in the meter. If no deflection is obtained, change the switch position to 50 microampere.

9. Tune the plunger of Klystron Mount for the maximum output.10. Rotate the knob of frequency meter slowly and stop at the position, when there is less output

current on Multimeter. Read directly frequency meter between two horizontal line and verticalmarker. If micrometer type frequency meter is used, read micrometer frequency and find thefrequency from its calibration chart.

11. Change the reflector voltage and read the current and frequency for each reflector voltage and plotthe graph as shown in Fig.

B. Square Wave Operation1. Connect the equipments and components as shown in the fig. 22. Set micrometer of variable attenuator around zero Position.3. Set the range switch of VSWR meter at 40dB position, input selector switch to crystal

impedance position, meter switch to normal position.

4. Set Mod-selector switch to AM- MOD position. Beam voltage control knob to fullyanticlockwise position and meter switch to OFF position.5. Switch ON the Klystron power supply, VSWR meter and cooling fan.6. Change the meter switch of Klystron power supply to beam voltage knob clockwise up to

300V.7. Keep the AM-MOD amplitude knob and AM-FREQUNCY knob at the mid position.8. Rotate the reflector voltage knob to gate deflection in VSWR meter.9. Rotate the AM-MOD amplitude knob to get the maximum output in VSWR meter.10. Maximize the deflection with frequency control knob of AM-MOD.11. If necessary, change the range switch of VSWR meter 30 db to 50 db if the deflection in

VSWR meter is out of scale or less than normal scale respectively. Further the output can

be also reducing by Variable Attenuator for setting the output for any particular position.12. Find the oscillation frequency by frequency meter as described in the earlier setup.

Result & Conclusion:-The result from graph shows the characteristics of Reflex Klystron.


4/27

Experiment No.:-2

Experiment Name:- V-I Characteristics of GUNNDiode


5/27

KCES`S COLLEGE OF ENGINEERING & IT, JALGAON

ELECTRONICS TELECOMMUNICATION DEPTT.


Name of student : __________________________________________________________ GradeClass: _________________ Roll No .:_____________Subject: _______________ Date of


Title :____________________________________________________________________ Signature

Aim:To study V-I characteristics of Gunn Diode.

Apparatus:Gunn Oscillator, Gun power supply, PIN Modulator, Isolator, Frequency Meter, Variable Attenuator,

Detector Mount, Wave guide Stands, SWR Meter, Cables and accessories

Theory:The Gunn Oscillator is based on negative differential conductivity effect in bulk semiconductors, whichhas two conduction bands minima separated by an energy gap (greater than thermal agitation energies).Adisturbance at the cathode gives rise to high field region, which travels towards the anode. When this highfield domain reaches the anode, it disappears and another domain is formed at the cathode and startsmoving towards anode and so on. The time required for domain to travel from cathode to anode (transittime) gives oscillation frequency.

In gun oscillator. The gun diode is placed in a resonant cavity .In this case the oscillation frequency isdetermined by cavity dimension than by diode itself.

Although Gunn Oscillator can be amplitude modulated with the bias voltage. We have used separate PINmodulator through PIN diode for square wave modulation.

A measure of square wave modulation capability is the modulation depth i.e. the output ratio between,ON and OFF state.

Procedure:1. Set the components and equipments as shown in the fig. 1.2. Initially set the variable attenuator for maximum attenuation.3. Keep the control knob to Gunn power supply as below.

Meter Switch - OFFGunn Bias Knob - Fully anticlockwise

4. Keep the control knob to VSWR Meter as below:


6/27

Meter switch NormalInput switch Low impedanceRange dB Switch 40DbGain control knob fully clockwise

5. Set the micrometer of Gunn oscillator for required frequency of operation.6. Switch on the Gunn power supply VSWR meter and Cooling fan.7. Turn the meter switch of the Gunn power supply to voltage position.8. Measure the Gunn diode current corresponding to the various voltage control by Gunn bias knob

through the panel meter and meter switch. Do not exceed the bias voltage above 10 volts.9. Plot the voltage and current reading on the graph as shown in fig.210. Measure the threshold voltage which, corresponds to maximum current.

Result & Conclusion :-The Characteristics of Gunn diode shows the negative characteristics.


7/27

Experiment No.:-3

Experiment Name: - Polar pattern Horn antenna


8/27

KCES`S COLLEGE OF ENGINEERING & IT, JALGAONELECTRONICS TELECOMMUNICATION DEPTT.


Name of student : __________________________________________________________ Grade

Class: _________________ Roll No .:_____________Subject: _______________ Date of


Title :____________________________________________________________________ Signature

Aim:To measure the polar pattern and a gain of a wave guide horn antenna

Apparatus:Gunn Oscillator, Gun power supply, PIN Modulator or Klystron mount with Klystron tube, Isolator,

Frequency Meter, Variable Attenuator, Detector Mount, VSWR Meter, two-horn antenna, turn table, andaccessories

Theory

If transmission line propagating energy is left open at one end , there will be radiation from this end. Incase of rectangular wave-guide this antenna presents a mismatch of about 2:1 and it radiates in manydirections. The match will improve if the open wave-guide is horn shape.

The Radiation pattern of an antenna is a diagram of field strength or more often the power intensity as afunction of the aspect angle at the constant distance from the radiating antenna pattern is of course three-dimensional but for practical reason it is normally presented as a two dimensional pattern in one orseveral planes. An antenna pattern consists of several lobs, the main lobe, side lobe and the back lobe. Themajor power is concentrated in a main loab.and it is required to keep the power in the side lobe as low as

possible. The power intensity at the maximum of the main lobe compared to the power intensity achievedfrom an imaginary omni directional antenna (reading equally in all directions) with the same power fedto the antenna is defined as the gain of the antenna.

3dB BEAM WIDTH

This angle between the two points on the main lobe where the power intensity is half the maximum powerintensity.When measuring an antenna pattern, it is normally most interesting to plot the pattern far from theantenna.


9/27

Far field patterned is achieved at a minimum distance of2D2

Where D is the size of the board wall of horn aperture and is free space wavelength.

It is also very important to avoid disturbing reflection. Antenna measurement are normally made atoutdoor ranges or in so called anechoic chamber made of absorbing material.Antenna measurement is mostly made with unknown antenna as receiver. There are several methods tomeasure the gain of antenna .One method is to compare the unknown antenna with known gain. Anothermethod is to use two identical antennas, as transmitter and other as receiver. From following formula thegain can be calculated.

Pr=

Where Pt is transmitted power Pr received power, G1.G2 is gain of transmitting and receiving antenna Sis the radial distance between two antennas and is free space wave length.

If both transmitting and receiving antenna are identical having gain G then above equation becomes.

In the above equation, Pt, Pr, S and can be measured and gain can be computed .As is evident from theabove equation, it is not necessary to know the absolute value of Pt,& Pr ,only ratio is required which can

be measured by VSWR meter.

Procedure :Antenna Radiation Pattern Plotting

1. Set up the equipments as shown in figure 1 keeping the axis of both antennas in same axis line.2. Energize the Microwave source of maximum output at desired frequency with square wave

modulation by tuning square wave amplitude and frequency of modulating signal of Gunn powersupply and by tuning the detector.

3. Also tune the S.S. Tuner in the line of maximum output (if S.S. Tuner is in the step up).4. Obtain full scale deflection (0db) on normal dB scale (0-10dB) at any convenient range switch

position of the VSWR meter by gain control knob of VSWR meter or by variable attenuator.5. Turn the receiving horn to the left in 2 or 5 steps up to 40-50 and note the corresponding VSWR

Db reading in normal dB range .When necessary change the range switches to next higher rangeand add 10dB to the observed value

6. Repeat the above step but this time turns the receiving horn to the right and note down the reading.7. Draw a relative pattern i.e. output V/S angle.8. From diagram determine 3dB width-(beam width) of the horn antenna can be measured.

Result & Conclusion :-Horn antenna Beam Width is=_____


10/27

Observation Table for polar pattern of Horn antenna:

Sr.No. Angle Power in DB123456789

1011121314


11/27

Experiment No.:-4

Experiment Name: - Polar pattern ofParabolic antenna


12/27


13/27


14/27

Observation Table for polar pattern of Parabolic Antenna

Sr.No. Angle Power in DB123456789

1011121314


15/27

Experiment No.:-5

Experiment Name: - ATTENUATOR


16/27






Title :____________________________________________________________________ Signature

Aim:To study Attenuator(Variable)

Apparatus:Gunn Oscillator, Gun power supply, PIN Modulator or Klystron mount with Klystron tube, Isolator,

Frequency Meter, Variable Attenuator, Detector Mount, VSWR Meter, two-horn antenna, turn table, andaccessories

Theory:The Attenuator is two port bidirectional devices which attenuate the power when inserted into thetransmission line. The attenuator consists of a rectangular wave guide with resistive vane inside it toabsorb microwave power according their position with respect to side wall of waveguide. As electric fieldis maximum at a centre of waveguide. Moving from centre toward the side wall, attenuation positionIs fixed attenator, the vane position is fixed where as in a variable attenuator; its position can be changed

by the help of micrometer.Following characteristic can be studied:Input VSWRInsertion lossAmount of Attenuation..Frequency sensitivity i.e. variation of attenuation at any fixed position of vane and frequency is changed.

Procedure:1. Connect the equipment as shown in fig.12. Energize the microwave source for maximum power at any frequency of operation.3. Note the Repeller voltage, frequency, Power in Decibels.4. Note down the reading for micrometer 5 cm and reading for power from VSWR meter.5. Move the micrometer of attenuator for the 4 Cm &repeat the procedure mentioned in step No.46 Plot the graph for different attenuation.

Result:As we move deep inside the micrometer the power goes on reducing for variable attenuator.


17/27

Observation table

Sr.No. Reading in mm Output in volts1

2

3

4

5


18/27

Experiment No.:-6

Experiment Name: - INSERTION LOSS&

ISOLATION ISOLATOR/CIRCULATOR


19/27






Title :____________________________________________________________________ Signature

Aim: To study Isolation, Insertion loss of Isolator /circulator

Apparatus:

Gunn Oscillator, Gun power supply, PIN Modulator or Klystron mount with Klystron tube, Isolator, Frequency Meter, Variable Attenuator, Detector Mount, VSWR Meter, Slotted line ,tunable probe testisolation , and accessories.

Theory:Isolator: An Isolator is a two port device that transfer energy from input to output with little attenuation

And from output to input with high attenuation.Circulator: The circulator is defined as a device with ports arranged such that energy entering a portcoupled to an adjacent port but not coupled to other ports. A wave incident on port 1 is coupled to port 2is coupled to port 2 only, a wave incident at port 2 coupled to port 3 only and so on.

Following parameters of Isolator and circulatorA: Insertion Loss : The ratio of power supplied by a source to the input port to the input port to powerdetected by detector in coupling arm i.e. output arm with other port terminated in the matched load isdefined as insertion loss or forward loss.B : ISOLATION : It is a ratio of power fed to the input arm to the power detected at not coupled portother with other port terminated in the matched load.

Procedure:

1. Connect the set up as shown in the figure.2. Energize the microwave source for maximum output particular frequency of operation .Tune the

detector mounts for maximum output in the VSWR meter.3. Set up any reference level of power in VSWR meter with the help of variable attenuator and gain

control knob of VSWR meter .Let it be P1.4. carefully remove the detector mount from slotted line without disturbing the position of set up.

Insert the Isolator /Circulator between slotted line and detector mount. Keeping input port to


20/27


21/27

Experiment No.:-7

Experiment Name: - POWER SPLITTINGTECHNIQUES BY H PLANE TEE


22/27






Title :____________________________________________________________________ Signature

Aim: To study power splitting techniques of H plane Tee.

Apparatus:

Gunn Oscillator, Gun power supply, PIN Modulator or Klystron mount with Klystron tube, Isolator, Frequency Meter, Variable Attenuator, Detector Mount, VSWR Meter, Slotted line, tunable probe testisolation , H plane Tee and accessories.

Theory:At a certain position in a waveguide systems many a time s it becomes necessary to split all or part ofmicrowave energy into particular directions. This is achieved by waveguide or in general microwave

junctions. These ate combined to form coupler units that direct the energy as required.

A T Junction is a intersection of three waveguide in the form of English alphabet T. A H plane Tee junction is formed by cutting a rectangular a rectangular slot along the width of a main

waveguide are called collinear arm called H arm as shown in fig.2.The port 1 and port 2 of mainwaveguide are collinear ports 2 and main waveguide are called collinear ports and port 3 is the H arm orside arm.


23/27

H Plane Tee is so called because the axis of the side arm is parallel to the plane of transmission line. Asall three arms of H plane Tee lie in the plane of magnetic field ,the magnetic field divides itself into thearms. Therefore this is called a current junction.

Procedure:1 Connect the set up as shown in the figure.2 Keep the control knobs of Klystron power supply as below:

Meter switch : OFF

Mod-switch : AMBeam voltage Knob: Fully anticlockwiseReflector voltage : fully clockwiseAM Amplitude Knob: Around fully clockwiseAM Frequency &Amplitude Knob: Around Mid position

3. Switch on Reflex Klystron power supply, VSWR Meter, cooling Fan.

4. Turn the meter switch of power supply to beam voltage position and set beam voltage at 280 voltsWith the help of beam voltage knob.

5. Measure the power at the output of slotted line.

6. Connect the H plane Tee to the slotted line and diode detector. Measure the output power at port 2of H plane Tee on the oscilloscope. The remaining port 3 is connected by the short termination.

7. Connect the H plane Tee to the slotted line. Measure the output power at port 3 of H plane Tee onthe oscilloscope. The remaining port 2 is connected by the short termination.

Result and Conclusion:The Power output at diode detector:________

The Power output at port 2:_______

The Power output at port 3:_________

The power = The Power output at port 2+ The Power output at port 3

Hence power available at H plane is sum of power at port 2 &power at 3.


24/27

Experiment No.:-8

Experiment Name: - MEASURREMENT VSWR


25/27






Title :____________________________________________________________________ Signature

Aim: Measurement of VSWR.

Apparatus: Microwave source, isolator, variable attenuator, frequency meter, slotted line, tunable probe, test Isolator, matched terminator wave guide stand, detector mount, VSWR meter and accessories.

TheoryThe electromagnetic field at any point of transmission line may be considered as the sum of two travelingwaves The Incident wave propagates from generator and reflected wave propagates towards the generator.The reflected wave is set up by the reflection of incident wave from the discontinuity in the line or fromthe load impedance. The magnitude and phase of reflected wave depends amplitude and phase reflecting

impedance .The superposition of two traveling waves is in opposite phase. The distance between twosuccessive minimum where the two waves in opposite phase. The distance between two successiveminimum is half wavelength on the guide. The ratio of electrical field strength of reflected and incidentwave is called reflection coefficient.

Procedure:


26/27

Measurement of Voltage standing wave Ratio:

1.Connect the setup as shown in the fig.1

2 Keep the control knobs of Klystron power supply as below:Meter switch : OFFMod-switch : AMBeam voltage Knob: Fully anticlockwise

Reflector voltage : fully clockwiseAM Amplitude Knob: Around fully clockwiseAM Frequency &Amplitude Knob: Around Mid position

Keep the control knobs of VSWR Meter as follows:

Range - 40/50 dBInput switch - Impedance Low

Meter switch - NormalGain( Coarse-fine) - Mid position approx.

3. Switch on Reflex Klystron power supply, VSWR Meter, cooling Fan.

4 Energize the microwave source for particular frequency and tune for maximum output.5 Move the probe along the slotted line to maximum deflection in VSWR Meter.6 Adjust the VSWR meter gain control knob until meter indicates 1.0 on normal scale (1-infinity)7 Keep all control knobs as it is, move the probe to the next minimum position .Read the VSWR

Scale & record it.8 Repeat the procedure for another frequency

Result and conclusion: The VSWR of the Isolator is ______ for the frequency ______


27/27

OBSERVATION TABLE:

Beam voltage: ____________

Sr.No. Repeller voltage Frequency VSWR1

2

3

RMT e Manual

Documents

Transcript of RMT e Manual