M S Engineering College - · PDF fileAdvanced Communication lab 2010 Department of Electronics...

Advanced Communication lab 2010

Department of Electronics and Communication ,MSEC Page 1

M S Engineering College (ISO 9001-2002 , Affiliated to VTU , Belgaum)

International Airport Road ,NavarathaAgrahara, Sadahlli P.O, Bangalore-

562110

ADVANCED COMMUNICATION MANUAL

(10ECL67)

Department of

Electronics and communication

Engineering

Prepared By

Azra Jeelani Pavithra.S.G MTech , (PhD),Associate Professor MTech, Assistant Professor

M S Engineering College, M S Engineering College,

Bangalore Bangalore

Natya.S Jagadish.B.S MTech, Assistant Professor ME,Assistant Professor, M S Engineering College, M S Engineering College,

Bangalore Bangalore



VTU PRESCRIBED SYLLABUS

Sub Code:10ECL67 IA Marks :25 Hrs/ Week :03 ExamHours: 03

Total Hrs. :42 ExamMarks :50

1. Amplitude Shift Keying

2. Frequency Shift Keying

3. BPSK Generation and Detection

4. DPSK Generation and detection. 5. QPSK Generation and detection 6. TDM of 2 Bandlimited Signals

7. Analog and Digital Communication Link Using Optical Fiber

8. Measurement of frequency ,guided wavelength,power,vswr and attenuationin a

microwave test bench

9. Directivity and gain of an antenna

10. Determination of coupling and isolation characteristics of a stripline directional

coupler.

11. Measurement of resonance characteristics and dielectric constant.

12.Power Division and Isolation characteristics of a microstrip 3dB power divider



Exp 1.: AMPLITUDE SHIFT KEYING

Circuit Diagram:

Modulation Circuit:

Demodulation Circuit



Expected Waveforms



Design :

1. Modulation:

VRE(max) = 2.5v

RE = 𝑉𝑅𝐸

𝐼𝐸=≜𝐼𝐶 =

2.5

2.5𝑚 = 1kΩ

RE = 1kΩ

Assume IB sat = 1.2IB = 0.03mA

RB = 𝑉𝐵

𝐼𝐵𝑠𝑎𝑡 =

0.3

0.03𝑚 = 10kΩ

RB = 10kΩ



2. Demodulation

fm = 1

2п𝑅𝐶 ; fm = 300Hz , C = 0.1 µF

R = 5.6 kΩ

3. Calculation :

a. Modulation: Frequency:

Amplitude:

b. Dernodulation: Frequency:

Amplitude

Aim : To design a circuit for detection and generation of an Amplitude Shift Keying

Components Required: Op-amp(μA-741 ), Diode(OA 79), SL- I 00 transistor, Resistor,

Capacitor, function generator.

Theory : Amplitude-shift keying (ASK) is a form of modulation that represents digital data

as

variations in the amplitude of a carrier wave. The amplitude of an analog carrier signal varies

in accordance with the bit stream (modulating signal), keeping frequency and phase constant.

The level of amplitude can be used to represent binary. Logic 0s and ls. We can think of a

carrier signal as an ON or OFF switch. In the modulated signal. Logic 0 is represented by the

absence of a carrier, thus giving OFF/ON keying operation and hence the name given.

Procedure:

1. Before connection check all the components.

2. Make connections as shown in circuit diagram

3. Observe the waveform pattern on the CRO.

4. Modulated ASK signal is obtained, which will be carrier signal for positive half cycle.

5. Construct the circuit for demodulation and obtain the output which is same as the message

signal.

Result :



Exp2: FREQUENCY SHIFT KEYING

Circuit Diagram:

Modulation Circuit:

DeModulation Circuit:



FSK Modulation And Demodulation Circuit



Design :

a. Modulation:

VRE(max) = 2.5v

RE = VRE(max)

IE =

2.5

2.5𝑚 = 1kΩ

RE = 1kΩ

Assume IBsat = 0.03IB

RB = VB

IBsat =

0.3

0.03 = 10kΩ

RB = 10kΩ

b. Demodulation

fm = 1

2п𝑅𝐶 ; fm = 300Hz , C = 0.1 µF

R = 5.6 kΩ



c. Calculation :

tmin = 0.6∗0.2ms

fmax = 1

tmin =

1

0.6∗0.2 = 8.333 KHz

tmax = 1.4 ∗ 0.5ms

fmin = 1

tmax =

1

1.4∗0.5ms = 1.428 KHz

DeModulation : f = 1

3.7∗1∗10−3 = 270.270 KHz

Aim : To conduct an experiment to generate FSK signal and also design a circuit to

demodulate the same.

Components Required: Op-amp(~1A-74 l ), Diode(OA 79), SL-100 transistor, Resistor,

Capacitor,

function generator.

Theory: Frequency-shift keying (FSK) is a frequency modulation scheme in which digital

information is transmitted through discrete frequency changes of a carrier wave. The simplest

FSK is binary FSK (BFSK). As suggested by the name, BFSK uses two discrete frequencies

to

transmit binary (O's and J's) information. In this scheme, binary 1 represents the frequency of

one carrier and 0 represents the frequency of the other carrier.

Procedure:

1. Before connection check all the components.

2. Make connections as shown in circuit diagram

3. Observe the waveform pattern on the CRO.

4. Modulated FSK signal is obtained then give FSK signal as input to the demodulation circuit..



5. Construct the circuit for demodulation and obtain the output which is same as the

message signal.

Result :

Exp3:BPSK Generation and Detection

Circuit Diagram : Generation



Circuit Diagram : Degeneration

BPSK Modulator :



Demodulator Circuit :



Design :

a. Modulation :

RC = VCC−VCE

IE = 1kΩ

Rb = Vin−Vbe

Ib = 10 KΩ

Ib = If

hfe = 0.025 mA

Rb = Vbe

Isat = 10 KΩ

b. Demodulation :

𝟏

𝒇𝒎>>Rc>>

𝟏

𝒇𝒄

C = 0.1µF , fm = 200Hz, fc = 10kHz

R = 10kΩ

Aim: Design & Demonstrate a BPSK system to transmit digital data using a suitable carrier.

Demodulate the above signal with suitable circuit

Components Required: Resistors, Capacitors, opamps, diodes, signal generators, CRO,

power

Supply

Theorv: Phase shift keying is also one of the simplest digital modulation technique. In this

system of modulation symbol 'l' is represented by phase 'Ǿ1' and symbol 'O' is represented by

phase' Ǿ2' DPSK is one of the digital modulation schemes like PSK. Alternative to P.SK,

instead of using the patterns to set the phase of the wave, it can instead be used to change it

by a specified amount. The demodulator then determines the changes in the phase of the

received signal rather than the Phase itself. Since this scheme depends on the difference

between successive phases, it.i termed Differential phase-shift keying (DPSK).

Procedure:

1. Connections are made as shown in circuit diagram

2. Provide message signal m(t) and carrier signal c(t) using signal generator

3 Observe the BPSK signal at the pin 3 of IC CD405 l and note down the readings

(Voltage and time period)

4. Connect the detection circuit as shown and supply the BPSK signal and c(t)

5. Verify carefully, observe the intermediate ASK signal and finally observe



detected signal, note down its voltage level and time period.

Result :

Expected Waveforms



Exp 4: TDM OF 2 BAND LIIVIITED SIGNALS



Calculations :



Modulation :

Triangular wave , f= 1

1∗1∗10−3 = 1KHz, 1 Vp-p

Sine wave , , f= 1

3.8∗0.5∗10−3 = 526Hz, 4Vp-p

DeModulation :

Triangular wave , f= 1

1∗1∗10−3 = 1KHz

Sine wave , f= 1

1.2∗1∗10−3 = 833.3 Hz

Aim: To design and demonstrated the working of TDM using PAM signals.

Components Required: IC[7493, 4051), Resistor, Capacitors, Function generators CRO.

Theory: A sampled waveform [PAM] is Off most of the t 1me, leaving the channel 2rmilable

for

others purpose during the interval between the samples. In particular, sample values from

several

different signals can be interleaved into a single waveform. This is the concept of Time

Division Multiplexing.

Several input message signals are prefiltered by low pass filter to make them strictly

band-limited to remove high frequency components that are not needed to represent a signal

adequately. The low pass filter output are sampled sequentially.

Procedure:

1. Check the components.

2. Make connections as shown in the circuit diagram.

3. Apply the input signal [square wave] of 10 kHz at pm 14 of 7493 and sine wave of

600Hz,

5Vp-p at pin 13 of IC 4051.

4. Tune the input voltage till we get a sine wave at the output 3 of pin 4051.

5. Now apply triangular wave of 5Vp-p and frequency l kHz at pin 12 of IC 4051

6. Vary the input voltage till we get a TDM wave at the output. Observe in the CRO.

7. Now connect the demodulation circuit to get the demodulated sine wave and triangular

wave.

8. Observe the waveform pattern in the CRO and plot.



Result:

Exp : 5 Communication Link Using Optical Fiber

Block diagram :

Aim : To Study digital communication link in 650nm fiber optic digital cable

Components Required: Fiber optic trainer, CRO, connecting probe, fiber optic wire

Theorv: Fiber optic link can be used for transmission of digital as well as analog signals.

Basically a fiber optic link contains three main elements, a transmitter, an optic fiber and a

receiver. The transmitter module takes the input signal in the electrical form and then

transforms

it into optical energy containing the same information.

Transmitter:

Fiber optic transmitters are typically composed of a buffer, driven and optical source.

The buffer provides both an electrical connection and Isolation between the transmitter and

the electrical system supplying the data.

Fiber optic link:

Emitter and detector circuit on board from the fiber optic link this section provide· the

light source for the optic fiber and the light detector at the far end of the fiber optics links.

The optic fiber plugs into the connectors provided in this part of the board.

Receiver:

The comparator circuit PLL, LPF AC amplifier circuit from receiver on the board. It is

able to do the modulation process in order to recover the original information signal.

Procedure :

1. Connect the power supply to the board.

2. Ensure all the switched faults are off.

Function

Generator

Emitter

Circuit

Detector

Circuit

Comparator AC Amplifier

CRO



3. Make the following connections

Connect 1kHz Square wave output of emitter 1 's input

Connect the fiber optic cable between emitter output and detectors input

Detector 1 's output to comparator 1 's input

Comparator 1 's output to AC amplifier 1‘s input

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

5. Switch ON the power

6. Monitor both the inputs to comparator 1 . Slowly adjust the comparators bias preset, until

DC

level on the input lies mid way between the high and low level of the signal on the positive

input.

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

signals are same.

Result :



Exp 6: Analog Communication Link Using Optical Fiber

Aim : To Study digital communication link in 650nm fiber optic digital cable

Components Required: Fiber optic trainer, CRO, connecting probe, fiber optic wire

Theorv: Fiber optic link can be used for transmission of digital as well as analog signals.

Basically a fiber optic link contains three main elements, a transmitter, an optic fiber and a


transforms it into optical energy containing the same information.

Transmitter:

Fiber optic transmitters are typically composed of a buffer, driven and optical source.

The buffer provides both an electrical connection and Isolation between the transmitter and

the electrical system supplying the data.

Fiber optic link:

Emitter and detector circuit on board from the fiber optic link this section provide· the

light source for the optic fiber and the light detector at the far end of the fiber optics links.

The optic fiber plugs into the connectors provided in this part of the board.

Receiver:

The comparator circuit PLL, LPF AC amplifier circuit from receiver on the board. It is able

to do the modulation process in order to recover the original information signal.

Procedure :




Connect 1kHz Square wave output of emitter 1 's input

Connect the fiber optic cable between emitter output and detectors input


Function

Generator

CRO Emitter

Circuit

AC Amplifier Detector

Circuit



Comparator 1 's output to AC amplifier 1‘s input



6. Monitor both the inputs to comparator 1 . Slowly adjust the comparators bias preset, until

DC level on the input lies mid way between the high and low level of the signal on the

positive input.

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

signals are same.

Result :

Exp 7: Measurement of Numerical Aperture

Block Diagram

Aim : To measure the numerical aperture of the optical fiber

Components Required: Fiber optics trainer kit,CRO, optical fiber wire and scale

Theory : Numerical aperture refers to the wave angle of which the light incident on the fiber

end

is totally internally reflected and is transmitted properly along the fiber. It s formed by the

relation of this angle of the fiber optic in the cone of acceptance of the fiber.

Procedure :

1. Connect power supply to the board.

2. Connect the frequency generator of 1 kHz sine wave output to input of the emitter 1

circuit. Adjust its amplitude to 5Vp-p

3. Connect one end of fiber optic cable to the output socket of emitter l circuit either to

other end of Numerical aperture measurement.



4. Hold the white screen having facing the fiber such that it cut face is perpendicular to

the

axis of fiber.

5. Hold the white screen with four concentric circles (10, 15, 20, 25)mrn diameter,

vertically at the suitable distance to red spot of the fiber coincide with 10rnm circle.

6. Record the distance of screen from the fiber end and note the diameter of the spot.

7. Compute the numerical aperture from the formula given below:

sin 𝜃𝑚𝑎𝑥 = 𝑾

√𝑳𝟐+𝑾𝟐

8. Vary the distance between the screen and optic cable and make it coincide with one of

the concentric circles. Note the distance.

9. Tabulate the various distance and diameter of the circles made on the white screen

and compute the numerical aperture from formula given above.

Tabular Column

Sl No Length(cm) Width(cm) 𝐬𝐢𝐧 𝜽𝒎𝒂𝒙 = 𝑾

√𝑳𝟐+𝑾𝟐

𝜽𝒎𝒂𝒙 =𝐬𝐢𝐧−𝟏 𝑾

√𝑳𝟐+𝑾𝟐

Formula :

W = (𝑀𝑅+𝑃𝑁)

4

𝜽𝒎𝒂𝒙 =𝐬𝐢𝐧−𝟏 𝑾

√𝑳𝟐+𝑾𝟐



4. DPSK GENERATION AND DETECTION

Aim: To conduct an experiment to generate DPSK signal and also design a circuit to

demodulate

it.

Components required: Power supply, kit ADCL-0 I, Connecting wires.

Circuit:

Theorv:

Differentially phase shift keying (DPSK) is differentially coherent modulation. DPSK does

not need a synchronous (coherent) carrier at the demodulator. The input sequence of binary



bits are modified such that the next bit depents upon the previous bit. Therefore in the

receiver the prn ious received bits are used to detect the present bit.The input sequence is d(t).

Ouput sequence is b(t) and b(t-Tb) is the previous output delayed by onJ bit period.

Depending upon valures of d(t) and b(t-Tb) exclusive OR gates generates the output sequence

b(t).DPSK does not need ca~rier at its receiver. Hence the complicated circuitry for

generation of local carrier is avoided.

Procedure:

1.Refer the block diagram and carry out the following connections and switch settings.

2.Connect the power supply in proper polarity to the bit ADCL-0 I and switch to UN.

3 Select data pattern of simulated data using switch 1.

4. Connect SDAT A generator to DATA JN of c\"fferei>'ial er,c:oder.

5. Connect NRZ-L data output to DATA JN of differe;r,tial encoder.

6. Connect the north generator to S-CLK to CLK IN of the differential encoder.

7. Connect differentially encoded data to control input C 1 at carrier modulator.

8. Connect carrier compunents SIN 1 to IN 1 of carrier modulator. i,,i

9. Connect carrier compunents SIN2 to IN2 of carrier modulator.

I 0. Connect DPSK modulated signal MO DO UT to MODIN of BPSK demodulator.

11. Connect ouput of BPSK demodulator b(t) out to input of delay section b(t) and input

b(t)IN of decision device.

12. Connect output of delay section. B(t-Tb) out of the inpur b(t-Tb) In of decision device.

13. Compare the DPSK decoded data at data out with respect to Input SDA TA.

14. Input NRZ-L data in differential encoder.

Result:



5.QUADRATURE PHASE SHIFT KEYING

Aim: To study carrier modulation techniques by Quadrature Phase shifting method.

Components Required: ADCL-02&03 Kits, Connecting chords, Power supply, CRO

Theorv: In this modulation, called Quadraiure PSK(QPSK) or 4 PSK the sine carrier takes 4

phases values, separated of 90deg and determined by the combinations of bit pair (Di bit) of

the

binary data signal. The data are coded into Dibit by a circuit generating:

• A data signal l(in-phase) consisting in voltage levies con-esponding to the value of the first

bit of the considered pair, for duration equal to 2 bit intervals.

" A data signal Q(in-quadrature) consisting in voltage levies corresponding to the value of the

first bit of the considered pair, for duration equal to 2 bit intervals.

Circuit:



The block diagram of the modulator used on the module is shown in the figure, four 500kH:,

sine carriers, shifted between them of 90deg are applied to modulator, the data (signal I & Q)

reach the modulator from the dibit generator. The instantaneous value uf I anc.l Q data bit

generates a symbol. Since I and Q can take either 0 or I value, maximum 4 possible symbols

can be generated (00, 01, 10 and 11 ). According to the symbol generated one of the four-sine

carrier \vill be selected. The relation between the symbol generated and sine carrier is shown

in table.



A receiver for the QPSK signal is shown in fog, .synchronous detection is required and

hence. i.t is necessary to locally regenerate the carriers, the scheme for carrier regeneration is

similar to that employed in BPSK. In that earlier case we squared the incoming signal,

extracted _the waveform at twice the carrier frequency by filtering and recovered the carrier

by frequency dividing by two.1n the present case, it is required that the incoming signal be

raised to the fourth pover after which filtering recovers a waveforms at four times the

carrier.The incoming signal also applied to the sampler followed by an sadder and envelope

detectors. Two adders add the sampled QPSK signal, sampled by the clock having different

phases. At the output of added ti1e signals consisting the envelope corresponds to the 1 and Q

bit. Envelope detector then filters the high frequency components and recovers I and Q bits

having exactly same phase and frequency compared to transmitter 1 or Q bit. These I & Q

bits then applied to data decoder logic to recover the original NRZ-L data pattern.

Procedure:

NOTE: KEEP THE SWITCH FAULTS IN OFF.POSJTION

1. Refer the block diagram and carry out the following connections and S\vitch setting:;.

2. Connect power supply in proper polarity to the kits ADCL-02 & ADCL-03 and

switch it ON.

3. Select data pattern of simulated data using switch SW 1.

4. Connect SDA TA generated to DAT AIN of the NRZ-L CODER

5. Connect NRZ-L DATA to DA TA IN of the DIBIT CONVERSION.

6. Connect SCLOCK to CLK IN of the DIBIT CONVERSION.

7. Connect the dibit data I & Q bit to control in out C 1 and C2 CARRIER

MODULATOR

respectively.

NOTE: adjust I & Q as shown in waveform by operating RST switch on ADCL02

before connecting it to C 1 & C2.

8. Connect carrier components to input of CARRIER MODULA TOR as follows:



i.S!N I to TN I

ii.SIN 2 to IN 2

iii.SIN 3 to IN 3

iv.S1N 4 to IN 4

9. Connect QPSK modulated signal MODOUT on ADCL-02 to the MOD IN of the

QPSK DEMODULATOR on ADCL-03. NOTE: Adjust Recovered I & Q bit on ADCL 03 as

per ADCL -02 by RST Switch on ADCL-03.

10. Connect 1 BJT, Q BIT.& CLK OUT outputs of QPSK Demodulator to I BIT IN, Q-BIT

&CLK IN posts of data decoder respectively.

11 . Observations on ADCL-02 KIT:

a. lnout NRZL Data at DATA INPUT.

b. Canier frequency SIN 1 TO SIN 4.

c. DiBIT pair generated data I bit & Q bit at DlBIT CONVERSION.

d. QPSK modulated signal at :tv10D OUT.

12. Observations on ADCL-02 KIT:

a. Output of first squarer at SQUARER 1.

b. Output of second squarer at SQUARER 2.

c Four sampling clocks at the output of SAMPLING CLOCK GENER.A.. TOR

d. Two adder outputs at the output of ADDt:R.

e. Recovered data bits (I & Q) at the output of ENVELOPE DETECTORS.

f. Recovered NRZL data from I & Qbits at the output of DATA DECODER.

Result:



ANALOG AND DIGITAL (WITH TDM) COMMUNICATION

LINK USING OPTICAL

Setting Up of Fibre Optic Analog Link:

Block Diagram:

Aim: To Study a 650nm Fibre optic analog link

Components Required: Fibre optic trainer, CRO, connecting probe, Fibre optic wire

Theorv: Fibre optic link can be used for transmission of digital as well as analog

signals.Basically a Fibre optic link contains three main elements, a transmitter, an optic Fibre

and a receiver. The transmitter module takes the input signal in the electrical form and then

transforms it into optical energy containing the same information

Transmitter:

Fibre optic transmitters are typically composed of a buffer, driven ::md optical source. The

buffer provides both an electrical connection and Isolation between the transmitter and the

electrical system supplying the data.

Fibre optic link:

Emitter and detector circuit on board from the Fibre optic link this section provide the light

source for the optic Fibre a11d t'.1e light detector at the far end of the Fibre optics links. The

optic Fibre plugs into the connectors provided in this part of the board The comparator circuit

PLL, LPF AC amplifier circuit from receiver on the board. It is able to do the modulation

process in order to recover the original information signal.

Procedure:






Connect I kHz Sine wave output of emitter l's input

Connect the Fibre optic cable between emitter output and detectors input


• Comparator l's outut to AC amplifier I's input

4. On the board, switch emitter 1 's driver to digital mode.


6. J'vlonitor both the inputs to comparator 1. Slowly adjust the comparators bias preset, until

DC

7. Observe the input to emitter 1 with the· output from AC amplifier 1 and note that the two

signals are same.

Result:

Setting Up of Fibre Optic Analog Link:

Aim: To Study a 650nm Fibre optic digital link

Components Required: Fibre optic trainer, CRO, connecting probe, Fibre optic wire

Theorv: Fibre optic link can be used for transmission of digital as well as analog signals.

Basically a Fibre optic link contains three main elements, a transmitter, an optic Fibre and a


transforms it into optical energy containing the same information.

Transmitter:

Fibre optic transmitters are typically composed of a buffer, driven and optical source. The

buffer provides both an electrical connection and Isolation betvveen the transmitter and the

electrical system supplying the data.

Fibre optic link:

Emitter and detector circuit on board from the Fibre optic link this section provide· the light

source for the optic Fibre and the light detector at the far end of the Fibre optics links. The

optic Fibre plugs into the connectors provided in this part of the board.



Receiver:

The comparator circuit PLL, LPF AC amplifier circuit from receiver on the board. It is able

to do the modulation process in order to recover the original information signal.




Connect !kHz Square wave output of emitter 1 's input

Connect the Fibre optic cable between emitter output and detectors input


Comparator 1 's output to AC amplifier I's input



6. Monitor both the inputs to comparator 1 (tp 13 & 14). Slowly adjust the comparators bias

preset, until DC level on the input lies mid way between the high and low level of the signal

on the positive input (tp 14).

7. Observe the input to emitter l(tp 5) with the output from AC amplifier l(tp 28) and note

that

the two signals are same.

Result:



7. MEASUREMENT OF BENDING LOSSES AND

NUMERICAL APERTURE OF A GIVEN OPTICAL FIBRE.

Study of Bending Losses:

Aim: To study loss using 1 m Fibre optic cable

Theorv: In optical Fibre wire, whenever the condition of angle of incidence of the incident

light

is bended the losses are introduced due to refraction of light. This occurs when Fibre is

subjected

to bending lower radius of curvature more or less.

Procedure:

1. Repeat al I the steps from 1 to 6 of digital I ink using Im cable.

2. Ensure that all S\Vitched faults are off.

3. Make the follo\ving connections.

4. Connect the 1 kHz sine \Vave output to emitter l's input.



5. Connect the Fibre optic cable between emitter output and detector input.

6. Detector l's output to AC amplifier l's input

7. On the board, switch emitter l's driver to analog mode.

8.Observe the input to emitter with the output from AC amplifier & note the signals are same.

Tabular Column

First Bending:

Second Morning:

Third Binding:

Result:



Measurement of Numerical Aperture:

Aim: To measure the numerical aperture of Fibre

Components: Fibre optic cable, screen, trainer kit.

Theorv: Numerical aperture refers to the wave angle of which the light incident on the Fibre

end

is totally internally reflected and is transmitted properly along the Fibre. It s formed by the

relation of this angle of the Fibre optic in the con'e of acceptance of the Fibre.

Procedure:

1. Connect pm:Ver supply to the board.



2. Connect the frequency generator of 1 kHz sine wave output to input of the emitter circuit.

Adjust its amplitude to 5Yp-p

3. Connect one end of Fibre optic cable to the output socket of emitter l circuit either to other

end of Numerical aperture measurement.

4. Hold the white screen having facing the Fibre such that it cut face is perpendicular to the

axis of Fibre.

5. Hold the white screen with four concentric circles (10, 15, 20, 25)mrn ck11neter, vertically

at the suitable distance to n1Jke :':'.d spot of the Fibre coincide with 10rnm circle.

6. Record the distance of screen from the Fibre end and note the diameter of the spot.

7. Compute the numerical aperture from the formula given below:

8. Vary the distance between the screen and optic cable and make it coincide with one of the

concentric circles. Note the distance.

9.Tabulate the various distance and diameter of the circles made on the white screen and

compute the numerical aperture from formula given above.

TABULAR COLUMN

Formula: W = (MR+PN)/4



MEASUREMENT OF FREQUENCY, GUIDE WAVELENGTH,

POWER, VSWR AND ATTENUATION IN A MYCROWAVE TEST

BENCH

To set the square wave and measurement of frequency,VSWR and

attenuation:

Measurement of Power and VSWR:



Calculations:

Frequency:

Guided wavelength:

Tabular Column:

s.No Power MSR CVD R=MSR+(CVD*L.C)

Calculations:



Aim: To conduct an experiment to obtain guide wavelength,frequency,power

and attenuation in a microwave test bench.

Components required: Attenuator, frequency meter,isolator,oscillator,

detector,klystron power supply,vswr meter and CRO.

Theory:



10. DIRECTIVITY AND GAIN OF AN ANTENNA

Aim: To measure the directivity and gain of antenna's standard dipole.

Components Required: Power supply, microwave source (VCO), 6dB attenuator,

Transmitting

antenna, Rotatable Test Antenna, Detector, Active filterm VSWR meter, CRO.

Procedure:

1. Set up the system as shown in block for a standard dipole antenna

2. Keeping the voltage at minimum, switch ON the power supply.

3.Vary the power supply voltage and check the output for different VCO frequencies.

4. Keeping at the resonant frequceny , calculate and keep the minimum distance for field

between the transmitting and receiving antenna using the formula: S = 2d0.0 where cl is the

broader dimension of the antenna.

5 Keeping the line of sight properly (0° at the tum table). Tabulate the output obtained.

6. Rotate the tum table in clock wise and anto clock-\vise for different angle of deflection and

tabulate the output for every angle(E~).

7. Plot a graph: angle Vs output

8 Find the half power beam with (HPBW) from the points where the power half (3dB points

or 0.707\i points)

9. Directivity of the antenna can be calculated using the formula 45253 I (HPBW)4 where

HPBW is the half power beam width in degrees. En and E < >> are the output signals

measured at the receiving antenna for 00 and for different angles respectively

10. Gain of the antenna can be calculated using the formula.

Circuit Diagram



Tabular Column:

11. DETERMINATION OF COUPLING AND ISOLATION

CHARACTERISTICS OF A

STRIPLINE (OR MICROSTRIP) DIRECTIONAL COUPLER

Aim: Determination of coupling and Isolation characteristics of a stripline

Components required: Power supply, Microwave source, attenuator, detector, active filter,

VSWR or CRO

Procedure:

1. Set up the system as sho\vn in figure

2. Keeping the voltage at minimum, Switch On the po\Ver supply.

3. lnsert a 50ohm transmission line and check for the output at the end of the system using a

CRO/VSWR meter/ F power meter

4. Vary the power supply voltage and check the output for different VCO frequencies.

5. Keep the VCO frequency constant, note down the output. This value can be taken as the

input to the power divider.

6.Replace the 50ohm transmission line with the Wilkinson power divider.

7. Tabulate the output at port2,3 and 4.

8. Calculate insertion loss and coupling factor in each coupled arm.

9. Calculate the isolation between port 3 and 4 by feeding the input to port 3 and

measure

10. Output at port by terminating port I and port 2.

11. Repeat the experiment for different VCO frequencies .

Result:



12.MEASUREMENT OF RESONANCE CHARACTERISTICS

AND DIELECTRIC CONSTANT

Tabular Column





Aim: To measure the resonance characteristic characteristics of a mycrostrip Ring Resonator

and Determination of Dielectric constant of the substrate.

Apparatus: Power supply, attenuator, detector, active filter, CRO, metal Zig

Procedure:

1.Connect 6dB attenator to RF output in C-band solid state source with power supply order to

control noise.

2. Also connect an 6dB attenuator to detector also.

3. In order to gain proper sine wave tune voltage and gain.

4. Once we get sine wave, place a ring resonator in metal zig. Then place metal zig between

supply and detector.

5. Now adjust voltage and gain in order to get a sine wave.

6. Now tabulate the values of voltage obtained from CRO and frequency which is obtained

from power supply.



7. This is the procedure for ring resonator in air. Now cover the ring resonator with a material

on metal zig and follow the same procedure to get dielectric.

13.Power Division and Isolation characteristics o(a microstrip 3dB power

divider

Block Diagram

To check sine wave:

Block Digram to power arms

Calculation:

Power at arm2: P1-P2

Power at arm3:p1-p3

Power at arm1:P2-P3



Aim: To measure the power division and isolation characteristics of rnicrostrip power

divider.

Apparatus: Power supply, attenuators, detector, active filter, CRO, metal zig, VSWR, 50ohm

mismatch terminals.

Procedure:

1.First check only for sine wave without connecting the metal zig and set the frequency as

5gHz. 2. Now remove the connection to CRO and connect it to VSWR.

3. Set the VSWR to 0.

4. Connect the metal zig also.

5. If p2 is considered as output then p3 is connected to 50ohm mismatch terminator and

vice-versa.

6. p I is always considered as input.

7. Calculate the power arm 2 and 3 and isolation which should be zero.

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