Microwave-Lab-Manual.pdf

8/14/2019 Microwave-Lab-Manual.pdf

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Joginpally BR Engineering College (J2)

JOGINPALLY B.R.ENGINEERING COLLEGE

POST: Yenkapally, Moinabad Mandal! "i#aya$%na&a' po($!, "yd'eabad)*+

DEPARTMENT OF ELECTRONICS & COMMUNICATION

ENGG.

MICROWAVE&

OPTICAL COMMUNICATION LAB(IV B.Tech I Semester)

LAB TEC"NICIAN Man al p'epa'ed by

M. U E!"ER RE""# -"ARA AT RAMES"B.TECH, M.TECH(VLSI SYS DESIGN).,

Associate professor in ECE.

V. SRIRAMRetd. Scientist(DRDO),

B.TECH, M.TECH

M$% &C ' B


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JOGINPALLY B.R.ENGINEERING COLLEGE POST: Yenkapally, Moinabad Mandal! "i#aya$%na&a' po($!, "yd'eabad)*+

DEPARTMENT OF ELECTRONICS & COMMUNICATIONENGG.

MICROWAVE&

OPTICAL COMMUNICATION LAB(IV B.Tech I Semester)

Na#e o/ $%e E0pe'i#en$

Name of the Student : Experiment No :

Roll No. : Date of Experiment :

Class & Section : Date of Submission :

Marks A arded :

M$% &C ' B2


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Signature of the Teacher

M$% &C ' B*


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!. RE"#E$ %# S'R(N C)ARAC'ER*S'*CS

A*M: To study the mode characteristics of the reflex klystron tube and to determine its

Electronic tuning range.

E+,*-MEN' RE+,*RED:1. Klystron power supply {SK S !1" #

$. Klystron tube $k%$& with klystron mount {'(%$&1#

*. )solator {' 1%!$

*. +re,uency meter {'+%-1"#

&. etector mount {' %*&1#

!. /ariable 0ttenuator {'0%&$"#

-. a2e guide stand {'3%&4

+. /S 5 meter {S %$1

6. 7scilloscope

1". 89: :able

8lock iagram;

')E(R : The reflex klystron is a single ca2ity 2ariable fre,uency microwa2e generator of low power and low efficiency. This is most widely used in applications where 2ariable fre,uency is

desired as

. )n radar recei2ers

2.


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-o er (utput Characteristics ; The mode cur2es and fre,uency characteristics. The fre,uency

of resonance of the ca2ity decides the fre,uency of oscillation. 0 2ariation in repeller 2oltages

slightly changes the fre,uency.

E$-ER*MEN'A# -R(CED,RE ;

:055)E5 0/E 7 E50T)79;

1. :onnect the e,uipments and components as shown in the figure.

2. Set the 2ariable attenuator at maximum osition.

*. Set the (7 switch of Klystron ower Supply at : position> beam 2oltage control

knob to fully anti clock wise and repeller 2oltage control knob to fully clock wise and meter

switch to ?7++@ position.*. 5otate the Knob of fre,uency meter at one side fully.

4. :onnect the : microampere meter at detector.

1. Switch A79B the Klystron power supply> :57 and cooling fan for the Klystron tube..

8. ut the meter switch to beam 2oltage position and rotate the beam 2oltage knob clockwise

slowly up to 4"" /olts and obser2e the beam current on the meter by changing meter switch

to beam current position. The beam current should not increase more than 4" m0.

+. :hange the repeller 2oltage slowly and watch the current meter> set the maximum 2oltageon :57.

9. Tune the plunger of klystron mount for the maximum output.

. 5otate the knob of fre,uency meter slowly and stop at that position> where there is

less output current on multimeter. 5ead directly the fre,uency meter between two horiContal

line and 2ertical marker. )f micrometer type fre,uency meter is used read the micrometer

reading and find the fre,uency from its fre,uency calibration chart.

. :hange the repeller 2oltage and read the current and fre,uency for each repeller

2oltage.

8. SD305E 0/E 7 E50T)79;

1. :onnect the e,uipments and components as shown in figure

2. Set (icrometer of 2ariable attenuator around some osition .

4. Set the range switch of /S 5 meter at *" db position> input selector switch to crystal

impedance position> meter switch to narrow position.*. Set (od%selector switch to 0(%(7 position .beam 2oltage control knob to fully anti

clockwise position.

M$% &C ' B4


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&. Switch A79B the klystron power Supply> /S 5 meter> :57 and cooling fan.

!. Switch A79B the beam 2oltage. Switch and rotate the beam 2oltage knob clockwise up to

4""/ in meter.

-. Keep the 0( (7 amplitude knob and 0( +5ED knob at the mid position.

. 5otate the reflector 2oltage knob to get deflection in /S 5 meter or s,uare wa2e on

:57.

6. 5otate the 0( (7 amplitude knob to get the maximum output in /S 5 meter or

:57.

1". (aximiCe the deflection with fre,uency knob to get the maximum output in /S 5 meter

or :57.

11. )f necessary> change the range switch of /S 5 meter 4"d8 to &"d8 if the deflection in

/S 5 meter is out of scale or less than normal scale respecti2ely. +urther the output can be

also reduced by 2ariable attenuator for setting the output for any particular position.

:. M(DE S',D (N (SC*##(SC(-E ;

1. Set up the components and e,uipments as shown in +ig.

$. Keep position of 2ariable attenuator at min attenuation position.

4. Set mode selector switch to +(%(7 position +( amplitude and +( fre,uency knob at mid

position keep beam 2oltage knob to fully anti clock wise and reflector 2oltage knob to fully

clockwise position and beam switch to ?7++@ position.

*. Keep the timeFdi2ision scale of oscilloscope around 1"" GH fre,uency measurement and

2oltFdi2. to lower scale.

&. Switch ?79@ the klystron power supply and oscilloscope.

!. :hange the meter switch of klystron power supply to 8eam 2oltage position and set beam

2oltage to 4""/ by beam 2oltage control knob.

-. Keep amplitude knob of +( modulator to max. osition and rotate the reflector 2oltage anti

clock wise to get the modes as shown in figure on the oscilloscope. The horiContal axis

represents reflector 2oltage axis and 2ertical represents oFp power.

. 8y changing the reflector 2oltage and amplitude of +( modulation in any mode of klystron

tube can be seen on oscilloscope.

M$% &C ' B1


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78SE5/0T)79 'A0#E ;

8eam /oltage ;IIII/ J:onstant

8eam :urrent ;IIII.m0

5epeller

/oltage J/

:urrent

Jm0

ower

Jm

ip

+re,uency

JLGC

E' E:TE L50 G;

5ES3


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1. 2,NN D*(DE C)ARAC'ER*S'*CS

A*M: To study the /%) characteristics of Lunn diode.

E+,*-MEN' RE+,*RED ;

1. Lunn power supply

$. Lunn oscillator

4. )9 (odulator

*. )solator

&. +re,uency (eter !. /ariable attenuator

-. Slotted line

. etector mount and :57.

0#(C% D*A2RAM

M$% &C ' B

:/nnoscillator3: 0

Matche;termination3' 0,


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')E(R : Lunn diode oscillator normally consist of a resonant ca2ity> an arrangement for

coupling diode to the ca2ity a circuit for biasing the diode and a mechanism to couple the 5+

power from ca2ity to external circuit load. 0 co%axial ca2ity or a rectangular wa2e guide ca2ity

is commonly used.

The circuit using co%axial ca2ity has the Lunn diode at one end at one end of ca2ity along

with the central conductor of the co%axial line. The 7F is taken using a inducti2ely or

capaciti2ely coupled probe. The length of the ca2ity determines the fre,uency of oscillation.

The location of the coupling loop or probe within the resonator determines the load impedance

presented to the Lunn diode. Geat sink conducts away the heat due to power dissipation of the

de2ice.

E$-ER*MEN'A# -R(CED,RE ;

olta/e3Current Characteristics:

. Set the components and e,uipments as shown in +igure.

2. )nitially set the 2ariable attenuator for minimum attenuation.

4. Keep the control knobs of Lunn power supply as below

(eter switch A7++B

Lunn bias knob +ully anti clock wise

)9 bias knob +ully anti clock wise

)9 mode fre,uency any position

*. Set the micrometer of Lunn oscillator for re,uired fre,uency of operation.

&. Switch A79B the Lunn power supply.

!. (easure the Lunn diode current to corresponding to the 2arious Lunn bias 2oltage through

the digital panel meter and meter switch. o not exceed the bias 2oltage abo2e 1" 2olts.

8. lot the 2oltage and current readings on the graph.

. (easure the threshold 2oltage which corresponding to max current.

Note: o not keep Lunn bias knob position at threshold position for more than 1"%1& sec.

readings should be obtained as fast as possible. 7therwise due to excessi2e heating Lunn diode

may burn

M$% &C ' B9


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E$-EC'ED 2RA-):

(0SER A'*(N 'A0#E:

Lunn bias 2oltage

J2

Lunn diode current

Jm0

RESULT:

M$% &C ' B

Volts (V)

T%'e(%old 1ol$a&e

I) C"ARACTERISTICS O2 G3NN OSCILLATOR

I(m )


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4. A''EN,A'*(N MEAS,REMEN'

A*M: To study insertion loss and attenuation measurement of attenuator.

E+,*-MEN' RE+,*RED:

. (icrowa2e source Klystron tube J$k$&

$. )solator Jx)%!$1

4. +re,uency meter Jx+%-1"

*. /ariable attenuator J'0%&$"

&. Slotted line J'S%!&1!. Tunable probe J' %!&&

-. etector mount J' %*&1

. (atched termination J'


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')E(R :

The attenuator is a two port bidirectional de2ice which attenuates some power when

inserted into a transmission line.

0ttenuation 0 Jd8 N 1" log J 1F $

here 1 N ower detected by the load without the attenuator in the line

$ N ower detected by the load with the attenuator in the line.

-R(CED,RE:

1. :onnect the e,uipments as shown in the abo2e figure.

2. EnergiCe the microwa2e source for maximum power at any fre,uency of operation

*. :onnect the detector mount to the slotted line and tune the detector mount also for max

deflection on /S 5 or on :57

,. Set any reference le2el on the /S 5 meter or on :57 with the help of 2ariable attenuator.


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/S 5 meter or on :57.


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5. MEAS,REMEN' (" "RE+,ENC AND 6A E#EN2')

A*M: To determine the fre,uency and wa2elength in a rectangular wa2e guide working in TE 1"

mode.

E+,*-MEN' RE+,*RED:

1. Klystron tube

$. Klystron power supply &kps !1"

4. Klystron mount '(%$&1

*. )solator ')%!$1

&. +re,uency meter '+%-1"!. /ariable attenuator '0%&$"

-. Slotted section 'S%!&1

. Tunable probe ' %!&&

6. /S 5 meter S %11&

1". a2e guide stand '3%&4&

11. (o2able Short 'T%* 1

1$. (atched termination '


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')E(R :

The cut%off fre,uency relationship shows that the physical siCe of the wa2e guide will determine

the propagation of the particular modes of specific orders determined by 2alues of m and n. The

minimum cut%off fre,uency is obtained for a rectangular wa2e guide ha2ing dimension aOb> for

2alues of mN1> nN"> i.e. TE 1" mode is the dominant mode since for T( mn modes> nP" or nP" the

lowest%order mode possible is TE 1"> called the dominant mode in a rectangular wa2e guide for

aOb.

+or dominant TE 1" mode rectangular wa2e guide Qo> Qg and Qc are related as below.

1FQoR N 1FQgR 1FQcR

here Qo is free space wa2e length

Qg is guide wa2e length

Qc is cut off wa2e length

+or TE 1" mode Qc $a where ?a@ is broad dimension of wa2e guide.

-R(CED,RE:

. Set up the components and e,uipments as shown in figure.

$. Set up 2ariable attenuator at minimum attenuation position.

4. Keep the control knobs of klystron power supply as below;

8eam 2oltage 7++

(od%switch 0(

8eam 2oltage knob +ully anti clock wise

5epeller 2oltage +ully clock wise

0( 0mplitude knob 0round fully clock wise

0( +re,uency knob 0round mid position

,. Switch ?79@ the klystron power supply> :57 and cooling fan switch.

&. Switch @79@ the beam 2oltage switch and set beam 2oltage at 4""/ with help of beam

2oltage knob.

1. 0d ust the repeller 2oltage to get the maximum amplitude in :57

8. (aximiCe the amplitude with 0( amplitude and fre,uency control knob of power supply.

+. Tune the plunger of klystron mount for maximum 0mplitude.

9. Tune the repeller 2oltage knob for maximum 0mplitude.

. Tune the fre,uency meter knob to get a ?dip@ on the :57 and note down the fre,uency from

fre,uency meter.11. 5eplace the termination with mo2able short> and detune the fre,uency meter.

M$% &C ' B4


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2. (o2e the probe along with slotted line. The amplitude in :57 will 2ary .9ote and record

the probe position > 2elocity of light

1FQoR N 1FQgR 1FQcR

$$"

c g

c g

+=

Qg N $x Ud+or TE 1" mode NO Qc N $a

a wa2e guide inner broad dimension

a N $.$ !cmB Jgi2en in manual

Qc N *.!cm

M$% &C ' B1


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(0SER A'*(N 'A0#E:

8 e a m

2 o l

t a g e

J 2 K

8 e a m

c u r r e n t J m

0 K

5 e p e l

l e r 2 o l

t a g e J 2 K

f o J u s i n g

f r e , m e t e r

K

J L G H K

d1Jcm

d$Jcm

d4Jcm

d*Jcm

Ud1Nd$%d1Jcm

Ud$Nd4%d$Jcm

U d 4 N

d * %

d 4

U d N J U d 1 S U d $ S U d 4 K F 4

Q g N

$ x

U d

Q o J c m

K

f o J G H K

RES,#':

M$% &C ' B8


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7. C)ARAC'ER*S'*CS (" #ED

A*M:

1. To study the relation ship between the


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')E(R :

whether the system transmits digital or analog signals. )n the case of analog transmission> direct

intensity modulation of the optical source is possible> pro2ided the optical output from the source

can be 2aried linearly as a function of the modulating electrical signal amplitude. higher performance is

achie2ed by +( modulation is simple to realiCe> higher performance is achie2ed by +(

modulating the base band signal prior to intensity modulation.

+7 pin has a !!V higher sensiti2ity at &"nm as compared to !!"nm for the same input

optical power .This corresponds to a sensiti2ity higher by $.$ d8. 9ote that to calibrate the

power meter at &"nm>deduct $.$d8 from the measured reading. )n computing losses in cables

and fibers this gets eliminated while sol2ing the e,uations.

E$-ER*MEN'A# -R(CED,RE:

1.:onnect circuit as shown in diagram. :onnect one end of cable 1 J1m to the +7 So that the power meter reads %1&." d8m.

*. :onnect the digital (ulti%meter at / "1 terminal pro2ided at +"


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(0SER A'*(N 'A0#E:

"or 889nm:

S.97 / 71Jm/

)f1N / "1 F1""Jm0

"

Jd8m

"or 79nm:

S.97 / 7$

Jm/

)f$N/ "$F1""

Jm0

"

Jd8m

-RECA,'*(NS:

1. 02oid loose connections.

$. 02oid arallax errors.

RES,#':

M$% &C ' B2


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8. #ASER D*(DE C)ARAC'ER*S'*CS

A*M: 1.(easurement of /%) characteristics of


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lasers are; 1. 0bsorption> $. Spontaneous emission> 4. Stimulated emission. The starting material

is an n%type La 0S doped with silicon in the range of $%*x1" 1 cm %4. 0 p%type is grown on the

wafer by the li,uid%phase epitaxial process. The wafer is lapped to a thickness of -& =m and

surfaces are metalliCed. The wafer is then clea2ed into sli2ers. The next step is to e2aporate a

reflecti2e coating onto one of the cleared facts of the sil2er so that the laser can emit from only

one facet.


"or ard current s for ard ;olta/e:

. :onfirm that the power switch is in 7++ position and then connect it to the kit.

$. (ake the umper settings and connection as shown in the block diagram.

*. )nsert the umper connection in umper W 1> W$> W4 at position shown in the diagram.

*. :onnect the 0mmeter and 2oltmeter as shown in the block diagram.

4. Keep the potentiometer & anti% clock wise rotation is used to control intensity of


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E$-EC'ED 2RA-):

(0SER A'*(N 'A0#E:

S


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-R(CED,RE:

1. :onnect one end of the ((0 +7 cable to o of (TS+7< T' 3nit and the other end to

the 90 Wig> as shown.

$. lug the 0: mains. pro2ided in the kit 2ertically at a distance of 1&mm J the intensity within the spot may not be e2enly

distributed. To ensure e2en distribution of light in the fiber> first

5emo2e twists on the fiber and then wind &turns of the fiber on to the mandrel as shown.

3se an adhesi2e tape to hold the windings in position. 9ow 2iew the spot. The intensity

will be more e2enly distributed within the core.

78SE5/0T)79 T08


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. D*REC'*(NA# C(,-#ER C)ARAC'ER*S'*CS

A*M: To study the function of multi%hole directional coupler by measuring the following

parameters.. The :oupling factor> )nsertion


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')E(R :

0 directional coupler is a de2ice with which it is possible to measure the incident and

reflected wa2e separately. )t consist of two transmission lines the main arm and auxiliary arm>

electromagnetically coupled to each other 5efer to the +ig.1. The power entering> in the main%

arm gets di2ided between port $ and 4> and almost no power comes out in port J* ower

entering at port $ is di2ided between port 1 and *.

The coupling factor is defined as

:oupling Jdb N 1" log 1" X 1F 4Y where port $ is terminated> )solation Jd8 N 1" log 1" X $F 4Y

where 1 is matched.

ith built%in termination and power entering at ort 1> the directi2ity of the coupler is a

measure of separation between incident wa2e and the reflected wa2e. irecti2ity is measured

indirectly as follows;

Gence irecti2ity Jdb N )%: N 1" log 1" X $F 1Y

(ain line /S 5 is S 5 measured> looking into the main%line input terminal when the

matched loads are placed at all other ports.

0uxiliary li2e /S 5 is S 5 measured in the auxiliary line looking into the output terminal

when the matched loads are placed on other terminals.

(ain line insertion loss is the attenuation introduced in the transmission line by insertion of

coupler> it is defined as;

)nsertion detector mount to the auxiliary port 4 and matched termination to port $ without

changing the position of 2ariable attenuator.

1. 9ote down the amplitude using :57>


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9. :onnect the matched termination to the auxiliary port 4 and detector mount to port $ and

measure the amplitude on :57>


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=. SCA''ER*N2 -ARAME'ERS (" MA2*C 'EE

A*M: To Study the operation of (agic Tee and calculate :oupling :o%efficient and )solation.

E+,*-MEN' RE+,*RED:

1. (icrowa2e source ; Klystron tube J$k$&

$. )solator J')%!$1

4. +re,uency meter J'+%-1"

*. /ariable 0ttenuator J'0%&$"

&. Slotted line JS'%!&1

!. Tunable probe J' %!&&-. etector (ount J' %*&1

. (atched Termination J'


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+ig; (agic Tee

')E(R :

The de2ice (agic Tee is a combination of E and G plane Tee. 0rm 4 is the G%arm and arm * is

the E%arm. )f the power is fed> into arm 4 JG%arm the electric field di2ides e,ually between

arm1 and $ with the same phase and no electric field exists in the arm *. )f power is fed in arm *

JE%arm it di2ides e,ually into arm 1 and $ but out of phase with no power to arm 4> further> if

the power is fed in arm 1 and $ simultaneously it is added in arm 4 JG%arm and it is subtracted in

E%arm i.e.> arm *.

0. )solation;

The )solation between E and G arm is defined as the ratio of the power supplied by the

generator connected to the E%arm Jport * to the power detected at G%arm Jport 4 when side arm

1 and $ terminated in matched load.

)solation Jd8 N 1" log 1" X *F 4Y

Similarly> )solation between other ports may be defined.

8. :oupling +actor;

)t is defined as :i N 1" F$"

here ? @ is attenuation F isolation in d8 when ?i\ is input arm and ? @ is output arm.

Thus> N 1" log 1" X *F 4Y

here 4 is the power deli2ered to arm ?i@ and * is power detected at ? @ arm.

M$% &C ' B*


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1. Setup the components and e,uipments as shown in figure.

2. EnergiCe the microwa2e source for particular fre,uency of operation and tune the detector

mount for maximum output.*. ith the help of 2ariable fre,uency of operation and tune the detector mount for maximum

output attenuator> set any reference in the :57 let it be / 4.

,. ithout disturbing the position of the 2ariable attenuator> carefully place the (agic Tee after

the slotted line> keeping G%arm to slotted line> detector mount to E%arm and matched

termination to ort%1 and ort%$.

4. 9ote down the amplitude using :57>


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!9. S:0TTE5)9L 050(ETE5S 7+ :)5:3


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*S(#A'(R:

0n )solator is a two%port de2ice that transfers energy from input to output with little attenuation

and from output to input with 2ery high attenuation.

The isolator> shown in +ig. can be deri2ed from a three%port circulator by simply placing a

matched load Jreflection less termination on one port.

The important circulator and isolator parameters are;

0. )nsertion


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1. :ompute )nsertion loss gi2en as / 1%/$ in db.

Measurement of *solation:

-. +or measurement of isolation> the isolator or circulator has to be connected in re2erse i.e.

output port to slotted line and detector to input port with other port terminated by matched

termination Jfor circulator .

+. 5ecord the output of :57 and let it be / 4.

9. :ompute )solation as / 1%/4 in db.

1". The same experiment can be done for other ports of circulator.

11. 5epeat the abo2e experiment for other fre,uency if needed.

-RECA,'*(NS:

1. 02oid loose connections.

$. 02oid arallax errors.

RES,#':

M$% &C ' B*,


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!! . /S 5 (E0S35E(E9TA*M: To determine the standing%wa2e ratio and reflection coefficient.

E+,*-MEN' RE+,*RED:

1. Klystron tube J$k$&

$. Klystron power supply Jskps % !1"

4. /S 5 meter JS 11&

*. Klystron mount J'( $&1

&. )solator J'+ !$1

!. +re,uency meter J'+ -1"

-. /ariable attenuator J'0 &$"

. Slotted line J' &!&

6. a2e guide stand J'3 &4&

1". (o2able shortFtermination '< *""

. 89: :ableS%S Tuner J'T **1

')E(R : 0ny mismatched load leads to reflected wa2es resulting in standing wa2es along the

length of the line. The ratio of maximum to minimum 2oltage gi2es the /S 5. Gence

minimum 2alue of S is unity. )f S^1" then /S 5 is called low /S 5. )f SO1" then /S 5 is

called high /S 5. The /S 5 2alues more than 1" are 2ery easily measured with this setup. )t

M$% &C ' B*4


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can be read off directly on the /S 5 meter calibrated. The measurement in2ol2es simply

ad usting the attenuator to gi2e an ade,uate reading on the meter which is a .:. mill 2olt meter.

The probe on the slotted wa2e guide is mo2ed t get maximum reading on the meter. The

attenuation is now ad usted to get full scale reading. 9ext the probe on the slotted line is

ad usted to get minimum> reading on the meter. The ratio of first reading to the second gi2es the

/S 5. The meter itself can be calibrated in terms of /S 5. ouble minimum method is used

to measure /S 5 greater than 1". )n this method> the probe is inserted to a depth where the

minimum can be read without difficulty. The probe is then mo2ed to a point where the power is

twice the minimum.

-R(CED,RE:

1. Set up e,uipment as shown in figure.

$. Keep 2ariable attenuator in minimum attenuation position.

4. Keep control knobs of /S 5 meter as below

5ange d8 N *"db F &"db

)nput switch N low impedance

(eter switch N 9ormal

Lain Jcoarse fine N (id position approximately

*. Keep control knobs of klystron power supply as below.

8eam /oltage N 7++

(od%Switch N 0(

8eam /oltage Knob N fully anti clock wise

5eflection 2oltage knob N fully clock wise

0(%0mplitude knob N around fully clock wise

0( fre,uency and amplitude knob N mid position

&. Switch ?79@ the klystron power supply> /S 5 meter and cooling fan.

!. Switch ?79B the beam 2oltage switch position and set Jdown beam 2oltage at 4""/.

-. 5otate the reflector 2oltage knob to get deflection in /S 5 meter.

. Tune the 7F by turning the reflector 2oltage> amplitude and fre,uency of 0( modulation.

6. Tune plunges of klystron mount and probe for maximum deflection in /S 5 meter.

1". )f re,uired> change the range db%switch 2ariable attenuator position and Jgi2en gain control

knob to get deflection in the scale of /S 5 meter.

11. 0s your mo2e probe along the slotted line> the deflection will change.

M$% &C ' B*1


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(0SER A'*(N 'A0#E:


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!1. *M-EDANCE MEAS,REMEN' ,S*N2 RE"#E$ %# S'R(N

A*M: To measure an unknown impedance using the smith chart.

E+,*-MEN' RE+,*RED:1. Klystron tube $k$&

2. Klystron power supply Skps%!1"

4. Klystron mount '(%$&1

*. )solator '+ !$

&. +re,uency meter '+ -1"

!. /ariable attenuator '0 &$"

-. Slotted line 'S &!&. Tunable probe ' !&&

6. /S 5 meter

1". a2e guide stand S3 &4&

11. S%S tuner J'T **1

1$. (o2able shortFtermination

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')E(R :

The impedance at any point on a transmission line can be written in the form 5 x.

+or comparison S 5 can be calculated as

R

R

S

+

=1

1

where reflection coefficient ?5@

Li2en as

"

"

Z Z

Z Z R

+

=

Ho N characteristics impedance of wa2e guide at operating fre,uency.

H is the load impedance

The measurement is performed in the following way.

The unknown de2ice is connected to the slotted line and the position of one minima is

determined. The unknown de2ice is replaced by mo2able short to the slotted line. Two

successi2e minima portions are noted. The twice of the difference between minima position will

be guide wa2e length. 7ne of the minima is used as reference for impedance measurement. +ind

the difference of reference minima and minima position obtained from unknown load. taking ?1@ as centre> draw a circle of radius e,ual to S. (ark a point on

circumference of smith chart towards load side at a distance e,ual to dFQg.Woin the center with this point. +ind the point where it cut the drawn circle. The co%

ordinates of this point will show the normaliCed impedance of load.

-R(CED,RE:

1. :alculate a set of /min 2alues for short or mo2able short as load.

$. :alculate a set of /min 2alues for S%S Tuner (atched termination as a load.

Note: (o2e more steps on S%S Tuner

*. +rom the abo2e $ steps calculate d N d 1`d $

*. ith the same setup as in step $ but with few numbers of turns J$ or 4 . :alculate low

/S 5.

Note: Gigh /S 5 can also be calculated but it results in a complex procedure.

&. raw a /S 5 circle on a smith chart.

1. raw a line from center of circle to impedance 2alue JdFQg from which calculate admittance

and 5eactance JH N 5 x

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!4. #(SSES *N (-'*CA# "*0RES A' 889nm& 79nm

A*M:

1. To study the 2arious types of losses in 7ptical +iber.

$. To measure the bending losses in the 7ptical +iber at wa2e length of !!"nmM &"nm.4. To measure the propagation or attenuation loss in 7ptical +iber at wa2e length of

!!"nm M &"nm.

E+,*-MEN' RE+,*RED:

1. 0nalog +iber optic trainer.

$. +iber optic links of 1m and &m length.

4. )nline S(0 0dopter.

*. $"(GC :57

&. igital (ulti%meter.

')E(R :

+iber optic links can be used for transmission of digital as well as analog signals.

8asically a fiber optic link contains three main elements >a transmitter> an optical fiber and a

recei2er. The transmitter module takes the input signal in electrical and then transforms it into

optical energy containing the same information. The optical fiber is the medium which takes the

energy to the recei2er. 0t the recei2er light is con2erted back into electrical form with same

pattern as originally fed to the transmitter.

0ttenuation in an optical fiber is a result of number of a effects . e will confine our

studies to measurement of attenuation in two fiber cablesJ cable 1m and cable$ &m employing

an S(0%S(0 in line adopter. e will also compute loss per meter of fiber in d8 and the

spectral response of fiber at two wa2e lengths !!"nm and &"nm.

+7 pin has a !!V higher sensiti2ity at &"nm as compared to !!"nm for the same input

optical power .This corresponds to sensiti2ity higher by $.$ d8. 9ote that to calibrate the power

meter at &"nm> deduct $.$d8 from the measured reading. )n computing losses in cables and

fibers this gets eliminated while sol2ing the e,uations.

ue to difference in alignment at different at different connectors> in each of the remo2al

and replacement operation> we experience 2ariations in loss. The obser2ed 2alues will be closer

to the true 2alues> if we take the a2erage of many readings. The attenuation coefficient of approx.

".4db per meter at !!"nm is normally well defined> as per the specifications of the manufacturer.

e2iation i6n any> will be 2alue of loss in the in%line adaptorJ1."d8 may be off the mark in

some cases. The loss per meter of cable at &"nm is not specified by the manufacturer. The range

of loss 4.& F".&d8 is acceptable

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Measurement of 0endin/ #oss:

1. :onnect the circuit as shown in diagram.

$. :onnect one end of cable 1 J1meter to the +7 say%1&."d8m. 9ote

down this as 71 .

4. ind one turn of the fiber cable on the mandrel or on the circular type material and note

down the new reading of the power meter as 7$ .

!. Switch 7++ the power supply.

8. 9ow the loss due to bending and strain on the plastic fiber is 7$ % 71 d8. Typically the

loss due to the strain and bending the fibre is ".4 to ". d8.

. 5epeat the experiment for the


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!5. *N'ENS*' M(D,#A'*(N S S'EM (" A #ASER D*(DE

A*M: The main aim of the experiment is to study the following ac characteristics of an intensity

modulation laser and optics systems.1. /inJac /s /out for fixed carrier o and signal fre,uency >+o

$. /in max /s o for known distortion free /out at fixed +o.

E+,*-MEN'S RE+,*RED:

1.


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$. Set (( to the $"""m/ range and connect it to o.

oN J5eading F1"d8m.

7n the Tx 3nit> connect /in to a function generator J1"GC to &""khC sine wa2e output>

1"m/ to $"""m/ p%p output The black terminal is ground. Li2e the function generator

output to :G1> as shown below.

4. 7n the 5x 3nit> connect /out to :G$ of the dual trace oscilloscope. :onnect the 8lack

terminal to ground.

*. ith the ((0 +7 cable connected to the power meter > ad ust the SET 7 knob to set

the optical carrier power o to a suitable le2el say >%14d8m.9ext disconnect the cable

from the power meter and connect to +7 T.

&. Set signal fre,uency and amplitude to $ kGC and 1""m/ respecti2ely. 7bser2e the

transmitted and recei2ed signals on the oscilloscope. Set 5in suitably to get /outN/in or

a known gain. The most preferred setting is the extreme anticlockwise position where 5in

Jminimum N&1ohms. The system gain is now set. 9ext 2ary /in in suitable steps from

1"m/ to 1"""m/p%p and note the 2alues of /out. Tabulate and plot a graph /out /s

/in.

1. Set signal fre,uency to $ kGC and o to %$&."d8m. isconnect /in before o

measurement. 0d ust / in to its maximum 2alue for distortion free /out. 9ote the 2alues

of / in and / out. 5epeat this for other 2alues of o and record change in gain if any .[ou

may additionally obser2e the wa2eforms in the oscilloscope dc coupled position too.

'A0,#AR "(RM:

/out /s /in

+re,uency N$khC :arrier le2el o N %14."d8m initial gain N minFunity.

Sl.no /inJm/p%p /out Jm/p%p LainN/oF/in

'A0,#AR "(RM:

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/in max /s o

S.97 oJd8m /inJm/p%p /out Jm/p%p LainN/oF/in

RES,#':.

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le2els. )t is important that these ointing techni,ues may be applied with ease in the field

locations where cable connection takes place.

-R(CED,RE:

1. Slightly unscrew the cap of


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Fig.Characteristics of LED

M$% &C ' B4

! '&: 5IBER & TIC TR I!ER


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Fig.Losses in Cable

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QUESTION BANK

SUBJECT : MICROWAVE AND OPTICAL COMM. SEM / YEAR : IV / I

EXP:1. State Faradays rotation law.2. State the properties of S matrix.3. What are the reasons that low frequency parameters cannot be Measured in microwaves?4. State the two parameters that describe a directional coupler? Define them.5. State TEE junction theorems.6. What is S matrix and write the S matrix of N port network?7. What is meant by hybrid coupler?8. Compare z parameters and ABCD parameters with S-parameters.9. What are hybrid rings?

10.List the parameters that determine the performance of a directional coupler.11. Explain the action of a rat-race junction.12.Why are waveguide bends and twists constructed so that the direction of propagated energyisgradually changed?

EXP:

1.Define GUNN effect.2. What is the necessary condition for an IMPATT to produce oscillations?3. List the differences between microwave transistor and TED devices.

4. What are the advantages and disadvantages of parametric amplifier?5. What is meant by avalanche transit time device?6. Discuss the applications of PIN diode.7. What is a parametric amplifier? How is it different from a normal amplifier?8. What is the theory of a negative resistance amplifier?9. Explain how a tunnel diode can be used as a amplifier.10.List the several donation formation modes of a Gunn diode.11.State the performance characteristics of IMPATT and TRAPATT diode.12. An IMPATT diode has a drift length of 2 m. Determine the operating frequency of IMPATTdiode if the drift velocity for Si is 107 cms/secEXP:

1. Draw the electronic admittance diagram of reflex klystron.2. State the differences between TWT and klystron?3. Can a two cavity klystron amplifier be used an oscillator? If yes, how?4. What is the purpose of slow wave structures in TWT?5. What is meant by frequency pushing and frequency pulling?.6. What is velocity modulation?7. What are the limitations of conventional tubes at microwave frequencies?Explain how theselimitations can be overcome.8. What are the performance characteristics of a Klystron amplifier?

9. How is bunching achieved in a cavity magnetron?10. What are cross field deices?11. How is tuning achieved in reflex klystron oscillators?

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12. What is strapping in magnetron? How is the same effect obtained without strapping?

EXP:

1. What are the advantages of microstrip line over strip line?

2. What are the advantages of MMIC over discrete circuit?3. What are the properties of dielectric materials?4. What are the losses in strip lines?5. List the various MMIC fabrication techniques.6. Microstrip line is also called an open strip line.Comment on this.7. Why is it difficult to establish microstrip short circuits?8. What are the design considerations for a microstrip line?9. Why are propagating modes along the strip lines are non-TEM and not pure TEM modes?10.How are waveguides different from normal two wire transmission lines?11.Give the physical interpretation for phase and group velocity in relation to speed of light.

EXP:

1. What is Bolometer? Give two examples?2. A wave guide load is used to absorb power of 2W., reflected power is 3mW.Find magnitude ofVSWR.3. Why reflex klystron is a square wave 1kHz PAM while microwave measurements are doneusingVSWR?4. What are the sources of error in return loss measurement using a waveguide reflectometerandklystron source?

5. What is meant by duty cycle?6. How are microwave measurements different from low frequency measurements?7. List the various techniques of measuring unknown frequency of a microwave generator.8. How can you extend the range of power measurement?9. Describe how an ordinary voltmeter can be calibrated to VSWR directly.What are thedrawbacksof such a VSWR meter?10. List any two methods of measuring impedance of a terminating load in a microwave system.11. Explain the concept of double minimum method of measuring VSWR.

EXP:

1. Among Microwaves and light waves which have high bit rate distance product?Why?2. Mention the three advantages of optical fiber as waveguide over conventionalmetallic waveguide?3. What is meant by mode and index profile?4. Mention the advantages of Graded Index fiber.5. Write the expression for the refractive index in Graded index fiber.6. Define Numerical Aperture of step index fiber.7. Give the expression of the effective number of modes that are guided by a curvedmultimode fiber of radius a.8. State Snells Law.9. Define Critical angle?10. Define TIR?11. What is the need of Cladding?

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12. Define core index difference.13. Define refractive index?14. What are leaky modes in optical fibers?15. Define External reflection of light rays?16. What is meant by modes of waveguide?

17. Define V number?18. What is relation between V number and power flow in cladding?19. What is the fundamental parameter of SM fiber?20. Give the relation between rays and modes?21. What are the advantages and disadvantages of SM fiber?22. What are the advantages and disadvantages of MM fiber?23. Define skew rays and merdional rays?24. Define cutoff conditions?25. What is meant by Degenerate modes?26. What is meant by linearly polarized modes?27. Define MFD?

28. Define Bi refrigence and beat length?29. A point source of light is 12cm below the surface of a large body of water (n=1.33).What is the radius of the largest circle on the water surface through which the lightscan emerge?30. Consider a parabolic index waveguide with n 1=1.75,n 2=1.677 and core radius 52 m.Calculate the numerical aperture at the axis and at a point 20 m from the axis.31. Why do we prefer step index single mode fiber for long distance communication?32. Why do we use LP 01 mode for long distance communications?33. What are three operating windows?34. Alight ray is incident from glass to air. Calculate critical angle?

EXP:

1. An optical signal has lost 55% of its power after traversing 3.5 km of fiber. What isthe loss in dB/km of this fiber?2. Define mode-field diameter.3. What are the causes of absorption?4. Define normalized propagation constant.5. List the basic attenuation mechanisms in an optical fiber.6. What is meant be mode coupling ? What causes it ?7. Mention the two causes of intramodal dispersion.8. Define fiber loss.9. What do you mean be polarization mode dispersion?10. Commonly available single mode fibers have beat lengths in the range 10cm


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1. Define radiance.2. What is meant by population inversion?3. what is meant by heterojunction?4. What is meant by indirect band gap semiconductor material?5. Draw the three key transition processes involved in laser action.

6. Give examples for direct and indirect semiconductor materials.7. Define internal quantum efficiency of an LED.8. Name few splicing methods in fiber optics.9. Compare LED and LASER.10. What so you mean by heterojunction ? Mention its advantages.a. List the different types of mechanical misalignments that can occur betweentwo joined fibers.b. Calculate the ratio of stimulated emission rata to the spontaneous emissionrate for a lamp operating at a temperature of 1000 K. Assume averageoperating wavelength is 0.5 m.11. Define lambertian pattern .

12. Define FWHM.13. Define Modal or speckle noise.14. Define Kinks.15. Define Mode partition noise.16. Define Lensing Schemes.17. Define Splicing ? What are types of Splicing.?18. What are the Characteristics of Light Source .EXP:

1. Define diffusion length.

2. Define avalanche effect .3. Define responsivity.4. Define Quantum efficiency of photo detector.5. Write the noise sources in the receiver section.6.Define Quantum limit.7.What are the desired features of photo detector.8.A photo diode is constructed of GaAs which has a bandgap energy of 1.43Ev at 300k.What is meant by long wavelength cutoff?9.What are the benefits of trans impedance amplifier.10.Define long wave length cutoff related photo diode.11.What is meant by bulk dark current?12.A photo diode has a capacitance of 6pf.Calculate the max load resistance which allowsan 8MHz post defection BW.13. What is meant by impact ionization. In APD?14.What is transit time of photo carriers?15.What is meant by ionization rate?16. Define avalanche multiplication?17.Define S/N ratio of an optical receiver?What are the conditions are requiredto achieve high S/N?18.Define BER?19.Define Extinction ratio?20. Define photo current?21. What is p+ _ pn+ reach through structure?22.Define excess noise factor?23. What is meant by Pre amplifier? What are the advantages of pre amplifier?

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24.Whar are the draw backs of high impedance amplifier?

EXP:

1. List out the requirements that are to be considered in analyzing a link2. Differentiate link power budget and rise time budget.3. What is SONET? How does it differ from SDH?4. What are solitons?5. What is meant by modal noise?

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