Microwave Lab Peri

8/10/2019 Microwave Lab Peri

1/37

LIST OF EXPERIMENTS

Microwave Experiments

1. Reflex Klystron Mode characteristics2. Gunn Diode Characteristics

3. VSWR, Frequency and Wave Length Measurement

4. Directional Coupler Directivity and Coupling Coefficient S

parameter measurement

5. Isolator and Circulator S - parameter measurement

6. Attenuation and Power measurement

7. S - matrix Characterization of E-Plane T, H-Plane T and Magic T.

8. Radiation Pattern of Antennas.

9. Antenna Gain Measurement

STUDY OF MICROWAVE COMPONENTS

AIM:

To study the microwave components.

RECTANGULAR WAVEGUIDE:

Waveguides are manufactured to the highest mechanical and electrical standards and

mechanical tolerance to meet internal specifications, L and S band waveguides are

fabricated by precision brazing of brast plate and all other waveguides are in

extrusion quality. Waveguide sections of specified length can be supplied withflinges, painted outside and silver or gold plated inside.

VARIABLE ATTENUATOR:

Model 5020 is a simple and conveniently variable type set level attenuators to

provide at least 20db of continuously variable attenuation. These consist of a

movable lossy vane inside the section of a waveguide by means of a micrometer. The

configuration of lossy vane is so designed to obtain the low VSWR characteristics

over the entire frequency band. These are meant for adjusting power levels and

isolating a source and load.

FREQUENCY METER MICROMETER TYPE:

Model 4055 are absorption type cavity wavemeter called frequency meter. These are

made of tunable resonant cavity of particular size. The cavity is connected to the

source of energy through a section of waveguide. The cavity absorbs some power at

resonance, which is indicated as a sip in the output power. The tuning of the cavity is

achieved by means of a plunger connected to a Microcontroller. The readings of the

micrometer at resonance gives frequency from the calibration chart, provided

calibration is normally provided at 200 Mhz internals.

TUNABLE PROBE


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Model 6055 tunable probes are designed for use with model 6051 slotted sections.

These are meant for exploring the energy of the electric field in a suitable fabricated

section of the waveguide. The depth of penetration into a waveguide section isadjustable by knob of the probe. The tip picks up the RF power from the line and this

power is rectified by crystal detector, which is then fed to the VSWR meter or

indicating instrument.

WAVEGUIDE DETECTOR MOUNT:

Model 4051 tunable detector mounts are simple and easy to use instruments for

detecting microwave power through a suitable detector. It consists of a detector

crystal mounted in a section of waveguide and a shorting plunging for matching

purpose. The output of the crystal may be fed to and indicating instrument. In K and

R band detector mounts, the plunger is driven by a micrometer.

THREE PORT FERRITE CIRCULATOR:

Model 6021 and 6022 are T and Y type of the three port ferrite circulators

respectively. These are precisely machined and matched three port devices and these

are meant for allowing microwave energy to flow in clockwise direction with

negligible loss but almost no transmission in anticlockwise direction. Purpose and

for measuring reflections and impedance. These consist of a section of waveguide

thus making it a four-part network. However, the fourth port is terminated with a

matched load. These two parallel sections are coupled to each other through many

holes almost to give uniform coupling minimum frequency sensitivity and high

directivity. These are available in 3,6,10,20 and 40 db couplings.

E-PLANE BEND:

Model 7071 E-plane bends are fabricated from a section of waveguide to provide one

90 1 bend in E-plane. The cross section of bent waveguide is kept throughout

uniform to give VSWR less than 1.05 or 1.08 or 1.02 over the entire frequency band.

Bends other than 90 can also be fabricated.

KLYSTRON POWER SUPPLY:

Model KP-1010 power supply has been designed to operate low power klystrons

such as 2K25, 756A, RK5976 etc. Beam voltage may be continuously varied and is

indicated on the front panel meter which can be read the beam supply current and

repeller supply volts also by changing the switch. Internal modulation square waves

with continuous variable frequency and amplitude are provided. An external

modulation may be used through the UHF(F) connector provided on front panel.

GUNN POWER SUPPLY:

Model X-110 Gunn power supply comprises of a regulated DC power supply and a

square wave generator, designed to operate Gunn oscillator model 2151 or 2152 andpin modulate model 451 respectively. The DC voltage is variable from 0 to 10v. The

front panel meter monitors the gunn voltage and the current drawn by the Gunn


3/37


4/37

REFLEX KLYSTRON OSCILLATOR

AIM:To study the characteristics of reflex klystron oscillator.

COMPONENTS REQUIRED:

1.

Klystron Power Supply

2.

Klystron Mount3. 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.


5/37

TABULAR COLUMN:

MODEL GRAPH:

S.No.REPELLER VOLTAGE

in Volts

OUTPUT POWER

in m Watts


6/37


7/37

BENCH SETUP DIAGRAM OF REFLEX KLYSTRON OSCILLATOR:

KLYSTRON

POWER

SUPPLY

KLYSTRON

MOUNT ISOLATOR

VARIABLE

ATTENUATORFRE

M


8/37

ATTENUATION MEASUREMENT

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


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.


9/37

BENCH SETUP DIAGRAM OF ATTENUATION MEASUREMENT:

FIGURE 1 (Without DUT)

V1

FIGURE 2 (With DUT)

MICRO WAVE

SOURCE

ISOLATOR VARIABLE

ATTENUATOR

FREQU

MET

MICRO

WAVE

SOURCE

ISOLATOR VARIABLE

ATTENUATORD

(F

ATTEN

FREQUENCY

METER


10/37

VSWR MEASUREMENT

AIM:

To measure VSWR introduced by the wave guide in dominant mode

of propagation.


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.


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.


11/37

BENCH SETUP DIAGRAM OF VSWR MEASUREMENT:

MICRO

WAVE

SOURCE

ISOLATOR

VARIABLE

ATTENUATORFREQUENCY

METER

V

M

SLO

SEC


12/37

WAVELENGTH & FREQUENCY MEASUREMENT

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

dominant mode propagation.


1.Microwave source (klystron power supply)

2. Klystron Mount3. Isolator

4. Variable Attenuator

5. Frequency meter

6. Slotted section

6. Matched Termination

7. VSWR meter (or) CRO

FORMULA:

1.

Guide wavelength g = 2(d2 d1)

Where (d2 d1) is the difference between two successive minimums(or) maximum.

_1_ _1_

2. The operating frequency of the wave is f = c g2 + c

2

Where c =2a,a = 22 .86mm for X band.

3. The guide wavelength (g) is related to free space wavelength (o) by

1/ o2= 1/ g

2+1/ c

2


13/37

PROCEDURE:

1.


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:

Thusthe wavelength & frequency of the wave is determined.


14/37

BENCH SETUP DIAGRAM OF WAVELENGTH & FREQUENCY MEASUR

MICRO

WAVE

SOURCE

ISOLATOR

VARIABLE

ATTENUATORFREQUENCY

METER

V

M

SLO

SEC


15/37

GUNN DIODE CHARACTERISTICS

AIM:

To study the characteristics of Gunn Diode.


1.

Gunn Diode Power Supply

2. Gunn Diode

3.

Pin Modulator

4.

Isolator

5.

Variable Attenuator

6. Frequency meter

7.

Power Detector

PROCEDURE:

1.


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.


16/37

TABULAR COLUMN:

MODEL GRAPH:

I in mA

S.No.GUNN BIAS VOLTAGE

(V in Volts)

OUTPUT CURRENT

(I in mA)


17/37

O V in Volts


18/37

BENCH SETUP DIAGRAM OF GUNN DIODE CHARACTERISTICS:

GUNN

POWERSUPPLY

GUNN

DIODE ISOLATOR

VARIABLE

ATTENUATOR

FPIN

MODULATOR


19/37

DIRECTIONAL COUPLER-DIRECTIVITY AND COUPLING

COEFFICIENT-SPARAMETER MEASUREMENT

AIM:

To determine the Directional coupler Directivity and coupling coefficient

S - Parameter measurement.

EQUIPMENTS REQUIRED:

Klystron power supply

Klystron Tube

Klystron Mount Isolator

Frequency Meter

Variable Attenuator

Slotted section

Detector Mount

Wave guide Stands

VSWR Meter

BNC Cable

CRO

Directional Coupler

PROCEDURE:

1.

Connect the components and equipment as shown in fig. 2

2.

Keep the control knob of klystron power supply as below:Modulation selection : AM


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Beam voltage knob : Fully anti-clockwise

Reflector voltage knob : Fully clockwise

Selector switch : Beam voltage

3.

Keep the AM modulation control knob of amplitude &frequency at mid position.

4. Switch on the klystron power supply.

5.

Now vary the Beam voltage knob to 295V. Next change the selector knob to Beam

Current. Observe the BEAM CURRENT. [The beam current should not be more

than 30 m amps].

6.

Now change the selector switch to Reflector voltage position.

7.

Now decrease the Reflector voltage to minimum position.

8.

Now observe the square wave form in CRO by varying either reflector voltage or

adjusting the amplitude knob of AM.

9. Connect the slotted section output to detector mount, now measure the input Power

(P1).

10.

Disconnect to setup as shown in fig 2.

11.Now connect the slotted section output to directional coupler input (port1),

connect the detector mount at port2, Terminate the port4 with matched termination.

12. Now measure the Power (P2) at port 2.

13. Then remove detector mount from port2 and connect to port 4

terminate port 2 with matched termination

14. Now measure the power (P3) at port 3.

15. Now remove the directional coupler from slotted section. And connect the slottedsection output to directional coupler port2, connect the detector mount at Port1,

terminate the port4, with matched termination

16. Now measure the power (P4) at port 1 and tabulate readings.


21/37

TABULATION:

Beam Voltage = -- VBeam current = -- ma

Replier Voltage =

S.NoPower of

(P1)

Power of

(P2)

Power of

(P3)

Power of

(P4)

Coupling

Loss

Transmission

LossDirectivity

S -PARAMETER MEASUREMENT:

S P P

SP

P

SP

P

11 1 1

12

2

1

13

3

1

=

=

=

S

S S S S

S S S S

S S S S

S S S S

=

11 12 13 14

21 22 23 24

31 32 33 34

41 42 43 44

.

FORMULA:

Coupling loss (dB) =

= 10 20

1

4

41log logP

PS

Directivity =

=10 20

4

3

41

31

log logP

P

S

S

Transmission loss = =10 2012

21log logP

PS


22/37

RESULT:


23/37

ISOLATOR AND CIRCULATOR S - PARAMETER MEASUREMENT

AIM:

To analyse the isolator and circulator using s parameter measurement.

APPARATUS REQUIRED:


Klystron Tube

Klystron Mount

Isolator

Frequency Meter

Variable Attenuator

Slotted section

Detector Mount

EXPERIMENTAL SET UP FOR ISOLATOR:

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

ISOLATOR VARIABLE

ATTENUATORFREQUENCY

METER

SLOTTED

SECTION

DETECTOR

MOUNT

CRO

PROCEDURE:

1.

Connect the components and equipment as shown in fig. 2

2. Keep the control knob of klystron power supply as below:

Modulation selection : AM




3. Keep the AM modulation control knob of amplitude &frequency at mid position.


24/37


5.

Now vary the Beam voltage knob to 295V. Next change the selector knob to BeamCurrent. Observe the BEAM CURRENT. [The beam current should not be more

than 30 m amps].

6.

Now change the selector switch to Reflector voltage position.

7. Now decrease the Reflector voltage to minimum position.

8. Now observe the square wave form in CRO by varying either reflector voltage or

adjusting the amplitude knob of AM.

9. Connect the slotted section output to detector mount measure the power (or)

voltage (A1) using CRO (or) power meter.

10.Now remove the detector mount from slotted section and connect the Isolator

Port1n to slotted section output , connect the detector mount in Port 2, now

measure the power (or) voltage (A12) using CRO (or) power meter.

11.Now remove the isolator from slotted section and connect the isolator Port 2 to the

slotted section output, connect the detector power (or) voltage (A21) using CRO(or) power meter.

TABULATION:

PORT 1 PORT 2 PORT 3

Insertion Loss (dB) = A1-A12 dB

Isolation dB = A1-A21dB


25/37

EXPERIMENTAL SETUP FOR CIRCULATOR:

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

CRO

ISOLATOR VARIABLE

ATTENUATOR

FREQUENCY

METER

ISOLATOR

CIRCULATOR

SLOTTED

SECTION

DETECTOR

MOUNT

PROCEDURE:

* Connect the slotted section to detector mount and measure the power (or)

voltage (A1) using CRO (or) power.

* Now remove the detector mount from the slotted section, and connect the

slotted section output to circulator port 1, and connect the detector mount to

port 1, terminate to port 3 with matched termination.

* Now measure the power (or) voltage (A2) using CRO (or) power meter.

* Now remove the detector mount from port 2, and connect to port 3,

terminate to port 2 with matched termination.

* Now measure the power (or) voltage (A3) using CRO (or) power meter.

TABULATION:

PORT 1 PORT 2 PORT 3

CIRCULATOR:

Insertion Loss (dB) =A1-A2 dB


26/37

RESULT:

S - MATRIX CHARACTERIZATION OF E-PLANE T,H-PLANE T

AIM:TO Measure the power division in the E-Plane Tee, H-Plane Tee and Magic Tee.



Klystron Tube

Klystron Mount

Isolator

Frequency Meter

Variable Attenuator

Slotted section

Detector Mount

Wave guide Stands

VSWR Meter

BNC Cable CRO

H-Plane Tee

E-Plane Tee

GENERAL EXPERIMENTAL SETUP:

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

ISOLATOR VARIABLE

ATTENUATORFREQUENCY

METER

SLOTTED

SECTIONDETECTOR

MOUNT

CRO


27/37

H-PLANE TEE:

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

CRO

ISOLATOR VARIABLE

ATTENUATORFREQUENCY

METER

SLOTTED

SECTION

DETECTOR

MOUNT

H-PLANE

TEE

PROCEDURE:

1. Connect the components and equipment as shown in fig. 2



Beam voltage knob : Fully anti-clockwiseReflector voltage knob : Fully clockwise


3. Keep the AM modulation control knob of amplitude &frequency at

mid position.


5. Now vary the Beam voltage knob to 295V. Next change the selector knob to

Beam Current. Observe the BEAM CURRENT. [The beam current should not be

more than 30 m amps].

6. Now change the selector switch to Reflector voltage position.7. Now decrease the Reflector voltage to minimum position.

8. Now observe the square wave form in CRO by varying either reflector voltage

or adjusting the amplitude knob of AM.

9. Connect the slotted section output to detector mount , now measure the power (or)

voltage using CRO (or) power meter .

10. Now measure the detector mount from slotted section connect the H-Plane Tee

Port1 to slotted section. Terminate the Port 3, with matched termination.

11. Now measure the power or voltage at Port 2 (P2) using CRO (or) power meter.12. Then remove the detector mount from Port 2, and connect to port 3, terminate the

port 2, with matched termination.


28/37

13. Now measure the power or voltage at Port 3(P3) using CRO (or) power meter

TABULATION:

PORT1 PORT2 PORT 3

E-PLANE TEE:

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

CRO

ISOLATOR VARIABLE

ATTENUATORFREQUENCY

METER

SLOTTED

SECTIONDETECTOR

MOUNTE-PLANE

TEE

PROCEDURE:








mid position.4. Switch on the klystron power supply.


29/37



more than 30 m amps].6. Now change the selector switch to Reflector voltage position.




9. Connect the slotted section output to detector mount , now measure the power (or)

voltage using CRO (or) power meter .

10. Now measure the detector mount from slotted section connect the H Plane Tee

Port1 to slotted section. Terminate the Port 3, with matched termination.

11. Now measure the power or voltage at Port 2 (P2) using CRO (or) power meter.

12. Then remove the detector mount from Port 2, and connect to port 3, terminate the

port 2, with matched termination.

13. Now measure the power or voltage at Port 3(P3) using CRO (or) power meter.

TABULATION:

P1 dB P2 dB P3 dB

RESULT:


30/37

S MATRIX CHARACTERIZATION OF MAGIC T

AIM:

To Measure Isolation between E and Harms of the magic tee & Demonstrate 3dB Power

Division in side arm the magic tee.



Klystron Tube

Klystron Mount

Isolator

Frequency Meter

Variable Attenuator

Slotted section

Detector Mount

Wave guide Stands

VSWR Meter

BNC Cable

CRO

Magic Tee

EXPERIMENTAL SETUP:

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

ISOLATOR VARIABLE

ATTENUATORFREQUENCY

METER

SLOTTED

SECTIONDETECTOR

MOUNT

CRO

Fig 1: For Input Power Measurement


31/37

KLYSTRON

MOUNT

KLYSTRON

POWER

SUPPLY

CRO

ISOLATOR VARIABLE

ATTENUATORFREQUENCY

METERMAGIC

TEE

SLOTTED

SECTIONDETECTOR

MOUNT

Fig 2: For Coupled /Isolated Power Measurement

PROCEDURE:


2. Keep the control knob of klystron power supply as below:Modulation selection : AM





mid position.




more than 30 m amps].

6. Now change the selector switch to Reflector voltage position.





32/37

9. Connect the slotted section output to detector mount now measure the power from

the detector mount P1 (or) voltage using CRO or power meter.

10. Remove the detector mount from the slotted section then connect the magic teecollinear arm 1 to slotted section output connect the detector mount to

collinear arm 2. Terminate the port 4 and port 3 with matched termination.

11. Now measure the power or voltage at port 2 using CRO or power meter.

12. Now remove the detector mount from the collinear arm 2 connect the detector

mount to port 3 terminate the collinear arm 2 and port 4 with matched

termination.

13. Now measure the power or voltage at port 3(P3) using CRO or power meter.

14. Now remove the detector mount from the port3, and connect to port 4 then

terminate the collinear arm and port 3, with matched termination.

15. Now measure the power (or) voltage port (P4) using CRO or power meter.

FORMULA:

RESULT:

Coupling dBP

P

P

P

Isolation dB PP

( ) log log

( ) log

= =

=

10 10

10

1

3

2

3

3

4


33/37

RADIATION PATERN OF HORN ANTENNA

AIM:

To measure the antenna radiation pattern and the gain of a wave guide horn

antenna.

APPARATUS REQUIRED:

1. Klystron power supply with mount.

2.

Isolator.

3. Variable attenuator.

4.

Frequency meter.

5.

Horn antenna.6.

Detector mounts.

7.

CRO

THEORY:The radiation pattern of an antenna is a plot of field strength of the power intensity

as a function of the aspect angle at a constant distance from the radiating antenna. An

antenna radiation pattern is of course three dimensional but for practical reasons it is

normally presented as two dimensional pattern in one or several lobes, the main

lobe, side lobe and back lobe . The major power in connected in the main lobe

and it is required to keep the low power in the side lobes and back lobe as possible.

In this experiment, the aim is to measure the radiation pattern of microwave horn

antenna. Horn Structures can obtained by an open end of the waveguide is elevated with

an angle. Wave guides are meant for guiding electromagnetic waves up to the open end

and that elevated structure of the wave guide, that is Horn, will convert that guided wave

in to free space waves. Incase of open ended rectangular wave guide this antenna

presents a mismatch of about and it radiates in many directions. The match will

improve the open wave guide is a horn shape.


34/37

TABULATION:

S.NOAngle

(Degree)

Output Voltage

(Volts)

GAIN = 20 log

(Vo/Vin) dB


35/37

Vin= Volts


36/37

PROCEDURE:

ANTENNA RADIATION PATTERN

1.

Set up the equipments as shown in figure keep the axis of both the antenna in

same line of sight.

2. Energize the Klystron Mount for maximum output at desired frequency with the

square wave modulation.

3.

Tune the receiving horn to the left in 2 or 5 steps up to 0-5 and note

corresponding output voltage.

4.

Repeat the above step but this time turn the receiving horn to the light

and note down the readings.

5.

Plot the relative power pattern its output vs angle.

6. From diagram determine 3 db width of the horn antenna.

BLOCK DIAGRAM:

RECEIVING HORN

TRANSMITTING

HORN

KLYSTRON

POWERKLYSTRON

TUBE WITH

ISOLATOR VARIABLE

ATTENUATOR

FREQUENCYMETER

SLOTEDSECTION DETECTOR

MOUNT

CRO


37/37

RESULT:

Thus the radiation pattern of a antenna was drawn and its 3 db beam width is

-------

Microwave Lab Peri

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