PANIMALAR ENGINEERING COLLEGE

Transcription

1 PANIMALAR ENGINEERING COLLEGE (A CHRISTIAN MINORITY INSTITUTION) JAISAKTHI EDUCATIONAL TRUST ACCREDITED BY NATIONAL BOARD OF ACCREDITATION (NBA) BANGALORE TRUNK ROAD, VARADHARAJAPURAM, NASARATHPET, POONAMALLEE, CHENNAI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING ADDITIONAL LAB COURSE EC TRANSMISSION LINES AND WAVEGUIDES III ECE - V SEMESTER LAB MANUAL (07 08 ODD SEMESTER) Panimalar Engineering College

2 DEPARTMENT OF ECE VISION To emerge as a entre of exellene in providing quality eduation and produe tehnially ompetent Eletronis and Communiation Engineers to meet the needs of industry and Soiety. MISSION M: To provide best failities, infrastruture and environment to its students, researhers and faulty members to meet the Challenges of Eletronis and Communiation Engineering field. M: To provide quality eduation through effetive teahing learning proess for their future areer, viz plaement and higher eduation. M3: To expose strong insight in the ore domains with industry interation. M4: Prepare graduates adaptable to the hanging requirements of the soiety through lifelong learning. PROGRAMME EDUCATIONAL OBJECTIVES. To prepare graduates to analyze, design and implement eletroni iruits and systems using the knowledge aquired from basi siene and mathematis.. To train students with good sientifi and engineering breadth so as to omprehend, analyze, design and reate novel produts and solutions for real life problems. 3. To introdue the researh world to the graduates so that they feel motivated for higher studies and innovation not only in their own domain but multidisiplinary domain. 4. Prepare graduates to exhibit professionalism, ethial attitude, ommuniation skills, teamwork and leadership qualities in their profession and adapt to urrent trends by engaging in lifelong learning. 5. To pratie professionally in a ollaborative, team oriented manner that embraes the multiultural environment of today s business world. Panimalar Engineering College

3 PROGRAMME OUTCOMES. Engineering Knowledge: Able to apply the knowledge of Mathematis, Siene, Engineering fundamentals and an Engineering speialization to the solution of omplex Engineering problems.. Problem Analysis: Able to identify, formulate, review researh literature, and analyze omplex Engineering problems reahing substantiated onlusions using first priniples of Mathematis, Natural sienes, and Engineering sienes. 3. Design / Development of solutions: Able to design solution for omplex Engineering problems and design system omponents or proesses that meet the speified needs with appropriate onsiderations for the publi health and safety and the ultural, soietal, and environmental onsiderations. 4. Condut investigations of omplex problems: Able to use Researh - based knowledge and researh methods inluding design of experiments, analysis and interpretation of data, and synthesis of the information to provide valid onlusions. 5. Modern tool usage: Able to reate, selet and apply appropriate tehniques, resoures, and modern Engineering IT tools inluding predition and modeling to omplex Engineering ativities with an understanding of the limitations. 6. The Engineer and soiety: Able to apply reasoning informed by the ontextual knowledge to aess soietal, health, safety, legal and ultural issues and the onsequent responsibilities relevant to the professional Engineering pratie. 7. Environment and sustainability: Able to understand the impat of the professional Engineering solutions in soietal and environmental ontext, and demonstrate the knowledge of, and need for sustainable development. 8. Ethis: Able to apply ethial priniples and ommit to professional ethis and responsibilities and norms of the Engineering pratie. 9. Individual and Team work: Able to funtion effetively as an individual, and as a member or leader in diverse teams, and in multidisiplinary settings. 0. Communiation: Able to ommuniate effetively on omplex Engineering ativities with the Engineering ommunity and with soiety at large, suh as, being able to omprehend and write effetive reports and design doumentation, make effetive presentations, and give and reeive lear instrutions.. Projet Management and Finane: Able to demonstrate knowledge and understanding of the engineering and management priniples and apply these to one s own work, as a member and leader in a team, to manage projets and in multidisiplinary environments.. Life long learning: Able to reognize the needs for, and have the preparation and ability to engage in independent and life-long learning in the broadest ontest of tehnologial hange. Panimalar Engineering College 3

4 PROGRAMME SPECIFIC OUTCOMES. Graduates should demonstrate an understanding of the basi onepts in the primary area of Eletronis and Communiation Engineering, inluding: analysis of iruits ontaining both ative and passive omponents, eletroni systems, ontrol systems, eletromagneti systems, digital systems, omputer appliations and ommuniations.. Graduates should demonstrate the ability to utilize the mathematis and the fundamental knowledge of Eletronis and Communiation Engineering to design omplex systems whih may ontain both software and hardware omponents to meet the desired needs. 3. The graduates should be apable of exelling in Eletronis and Communiation Engineering industry/aademi/software ompanies through professional areers. 4. The graduates should be apable of exelling in Eletronis and Communiation Engineering industry/aademi/software ompanies through professional areers. COURSE OBJECTIVES:. To gain knowledge of passive reative filter response. To understand the harateristis of a o-axial line 3. To have exposure of measuring line parameters pratially COURSE OUTCOMES: Students will be able. To understand the harateristis of filter and transmission lines. To measure parameters of transmission line and waveguide. COURSE CO-ORDINATORS:. Dr.D.Selvaraj / Professor / ECE / Panimalar Engineering College - Chennai. Mrs.D.Nithya / Assistant Professor (Grade ) / ECE / Panimalar Engineering College - Chennai Panimalar Engineering College 4

5 LIST OF EXPERIMENTS Ex.No. Name of the Experiment Page No.. Determination of primary and seondary onstants of a oaxial line. Measurement of attenuation in a o-axial line 3. Measurement of ut off frequeny of a o-axial line 4 4. Determination of SWR and Refletion oeffiient of a oaxial line 5. Determination of line parameters using Smith hart software Design and simulation of onstant k, m-derived and omposite filters using Ciruit maker Design and simulation of onstant k, m-derived and omposite filters using Proteus VSWR and Refletion oeffiient measurement using Slotted line Measurement of frequeny and wavelength of dominant TE mode in Retangular waveguide Study of waveguide omponents 4 Panimalar Engineering College 5

6 Figure : Determination of primary and seondary onstants of a o-axial line. Panimalar Engineering College 6

7 DETERMINATION OF PRIMARY AND SECONDARY CONSTANTS OF A CO-AXIAL LINE EX.NO : DATE : Aim: To determine primary and seondary onstants of a 00m o-axial line. Apparatus required: Aessories: Proedure:. 0 MHZ Dual trae osillosope. 3 MHz funtion generator 3. LCR meter 4. Transmission line trainer. Path ord. CRO and LCR probes. Adjust Ri and RL for 8and 68respetively with the help of LCR meter.. Make the onnetions as shown in figure. 3. Both the indutane and the ohmi resistane of the line are measured in series by short-iruiting end of eah setion of the line and onneting the measuring instruments to the start of the line. The apaitane and the ondutane are measured in parallel by operating on eah setion of the open line as shown in Figure. 4. Using LCR meter, measure the values of primary onstants R, L, G and C at eah setion of the line. 5. Calulate Seondary onstants using the formula; R jl Z 0 and ( R jl)( G jc) G jc Panimalar Engineering College 7

8 (a) (b) () Figure : (a) Mathed line (b) Short ended line () Open ended line Panimalar Engineering College 8

9 Tabulation: Length (m) Primary onstants Seondary onstants R L G C Z Result: The measured Primary and seondary onstants of a o-axial line are as follows; Panimalar Engineering College 9

10 Figure 3: Measurement of attenuation of a o-axial line. Panimalar Engineering College 0

11 MEASUREMENT OF ATTENUATION OF A CO-AXIAL LINE EX.NO : DATE : Aim: To measure attenuation of a o-axial line at different length. Apparatus required:. 0 MHZ Dual trae osillosope. 3 MHz funtion generator 3. Digital multimeter 4. Transmission line trainer Aessories:. Path ord. CRO and LCR probes Proedure:. Adjust Ri and RL for 8and 68respetively with the help of DMM.. Make the onnetions as shown in Figure Set the sine wave frequeny to approximately 0 KHz and level to V. 4. Measure signal level at 5m, 50m, 75m and 00m lengths at mathed ondition. Tabulate as below; V 0 Length (m) Input voltage (V) Output voltage (V) 0log ( db) Vi 5.Try the same with open ended and short ended line. Sample tabulation (Mathed Line): Length (m) Input voltage (V) Output voltage (V) V 0 0log ( db) Vi Result: The measured values of attenuation at different length are as follows; Panimalar Engineering College

12 Figure 4: Measurement of ut off frequeny of a o-axial line. Panimalar Engineering College

13 MEASUREMENT OF CUT OFF FREQUENCY OF A CO-AXIAL LINE EX.NO : 3 DATE : Aim: To measure ut off frequeny of a o-axial line at different lengths. Apparatus required:. 0 MHZ Dual trae osillosope. 3 MHz funtion generator 3. Digital multimeter 4. Transmission line trainer Aessories:. Path ord. CRO and LCR probes Proedure:. Adjust Ri and RL for 8and 68respetively with the help of DMM.. Make the onnetions as shown in figure Set the sine wave level in funtion generator to.4 V. 4. Connet CRO probe at the terminals of 5m line. 5. Vary the frequeny of generator gradually keeping the input amplitude onstant till the voltage at the terminal of 5m line is 0.99 V. (This an be alulated using the 0 formulav 0 V i 0, where = -3 db). 6. Note this frequeny on osillosope. This is known as ut off frequeny f of a 5m long o-axial line. 7. Repeat the same proedure for finding ut off frequeny of 50m, 75m and 00m line and tabulate the values as shown below; Panimalar Engineering College 3

14 Input voltage = (V) Length (m) Output voltage = (V) Cut off frequeny (Hz) Sample tabulation: Input voltage =.4 V Output voltage = 0.99V Length (m) Cut off frequeny (Hz) KHz KHz KHz KHz Result: The measured ut off frequeny of a o-axial line at different length is as follows; Panimalar Engineering College 4

15 DETERMINATION OF STANDING WAVE RATIO AND REFLECTION COEFFICIENT OF A CO-AXIAL LINE EX.NO : 4 DATE : Aim: To determine standing wave ratio (SWR) and Refletion oeffiient of a o-axial line. Apparatus required: Aessories: Proedure:. 0 MHZ Dual trae osillosope. 3 MHz funtion generator 3. Digital multimeter 4. Transmission line trainer. Path ord. CRO and LCR probes. Adjust Ri and RL for 8and 68respetively with the help of DMM.. Make the onnetions as shown in figure Set sine wave frequeny to 0KHz and level to.4 V. 4. Measure voltage at the terminals of 0m, 5m, 50m, 75m and 00m mathed line. 5. Find Vmax and Vmin 6. Calulate SWR and k using the formula; Panimalar Engineering College 5 V max S and 7. Repeat the same for open ended and short ended line. Sample tabulation: (i) For mathed line V i =.4 V Length (m) Output voltage (V) V min S k S

16 Figure 5: Determination of SWR and refletion oeffiient of a 00m o-axial line. Panimalar Engineering College 6

17 S V V max min k S S.5 (ii) For Open iruit line V i =.4 V Length (m) Output voltage (V) S V V max min k S S 3 (iii) For Short iruit line V i =.4 V Length (m) Output voltage (V) Result: The measured standing wave ratio and refletion oeffiient of a o-axial line at different length is as follows; Panimalar Engineering College 7

18 DETERMINATION OF LINE PARAMETERS USING SMITH CHART SOFTWARE EX.NO : 5 DATE : Aim: Proedure: (i) (ii) (iii) To determine line parameters using Smith hart software (Ketab). Calulation of admittane. Loate the given normalized load impedane point and let it be P.. With O as enter and OP as radius draw a irle. This irle is alled S irle. 3. The diametrially opposite end of impedane gives the value of admittane. Therefore draw a line OP and extend it to ut the other end of the irle at point Q. This point gives the value of normalized load admittane. Calulation of Standing wave ratio. Loate the given normalized load impedane point and let it be P.. With O as enter and OP as radius draw a irle. This irle is alled S irle. 3. The right hand intersetion of S irle and the horizontal axis gives the value of standing wave ratio. Calulation of Refletion oeffiient. Loate the given normalized load impedane point and let it be P.. Draw a line OP and extend this line to ut the Angle of refletion oeffiient irle at point P. 3. Point P orresponds to angle of refletion oeffiient. 4. Measure the line length of OP and OP 5. Find the ratio of OP to OP. This gives the magnitude of refletion oeffiient. k OP OP Panimalar Engineering College 8

19 (iv) Calulation of input / sending end impedane. Loate the given normalized load impedane point and let it be P.. With O ad enter and OP as radius draw a irle. Draw a line OP and extend it to ut the wavelength towards the generator irle at point P 3. Shift P point to the given length of the transmission line in lokwise diretion. Let this point be Q. 4. Draw a line joining O and Q. The line OQ intersets irle at point Q. This point gives the value of normalized input impedane. (v) Single stub mathing. Calulate the normalized load admittane using the formula, Loate this point and mark it as Q.. With O as enter and OQ as radius, draw a irle. y r Z 0. Z 3. Draw Unity irle. (A irle passing through enter point (,0) is alled unity irle). 4. The irles interset at points. Find the st intersetion point of the irles while moving point Q in lokwise diretion. 5. This point an be represented as B, whih gives the point where stub is loated. 6. To find loation of the stub l s : Calulate the distane between Q and B by extending the lines OQ and OB to ut the wavelength towards generator irle. 7. To find length of the stub l t ; Find the suseptane orresponding to point B. Mark the opposite suseptane and let it be R. The distane between the short iruit (Right end) and the point R gives the value of l t. Exerises:. Calulate standing wave ratio of a line having normalized impedane.64 j.4 R. Find refletion oeffiient of a line whih has normalized impedane. j0.8 Panimalar Engineering College 9

20 3. A transmission line has Z 0 of 300 and terminated in a load impedane of50 j 50. Calulate input impedane at a distane of 0. from the load. 4. An RF transmission line with Z 0 of 300 is terminated in an impedane of This load is to be mathed to the transmission line by using a short iruit stub. Determine the length and loation of the stub. RESULT: The parameters of transmission line were determined using Smith hart software. Panimalar Engineering College 0

21 DESIGN AND SIMULATION OF CONSTANT k, m-derived AND COMPOSITE FILTER USING CIRCUIT MAKER EX.NO : 6 DATE : AIM: To simulate passive reative filters Constant k, m derived and omposite low pass and high pass filters using Ciruit maker. PROCEDURE: Ciruit maker is a simple but powerful omputer-aid iruit analysis tool that an do both transient, frequeny response, and bias analysis. The program has a wide seletion of devie models that inlude ICs and disrete devies. This proedure will explain how to find the frequeny response of filters using Ciruit maker. Finding Ciruit Frequeny Response. Draw the iruit. Eah omponent must have a designation (R, C et) and value. The omponents an be seleted from the left panel. Use the signal generator omponent for the signal soure. This omponent an be found by seleting Analog in the left panel and then selet Instruments and Signal Gen.. Under the Simulation, menu seletion, analog mode should be heked. To set the type of analysis, under Simulation, selet analyses setup. The sreen below should appear. Enable the frequeny response alulation by heking the AC enabled hek-box. 3. Cliking the AC button brings up another sreen that allows the frequeny range and number of analysis points to be set. Set the desired frequeny range and total number of analysis points. Panimalar Engineering College

22 4. Clik on the Run Analysis button to start the simulation. 5. Use the Probe tool to selet the voltage to display on the frequeny response plot. (i) To design and simulate onstant k LPF for 400 impedane having its ut off frequeny at 000 Hz. Design: Rk = 400 and f = 000 Hz Rk 400 L L = 7. 3mH ; 63.66mH f 000 C = F R f k Shemati: R7 400 L7_ L mH C_ L mH L6_ V -/V V_ C 0.795uF R4 400 khz Simulated waveform: Panimalar Engineering College

23 (ii) To design and simulate onstant k HPF for 500 impedane having its ut off frequeny at 300 Hz. Design: Rk = 500 f = 300 Hz Rk 500 L = 7. 3mH 4 f C = F 4R f ; C 0.38 F k Shemati: R 500 C 0.384uF C 0.384uF V -/V khz L 7.3mH R 500 Simulated waveform: (iii)to design and simulate m-derived LPF for 600 impedane having its ut off frequeny at 5000 Hz and infinite attenuation frequeny at 650 Hz. Design: Rk = 600 f = 5000 Hz f = 650 Hz Rk 600 L = 38. mh f 5000 Panimalar Engineering College 3

24 C = R f k 600 f 5000 m f 650 mc F ml.46mh m L 0. 8mH 4m 0.06 F Shemati: R8 600 L4_ L4.46mH L4_ L8.46mH L8_ V4 -/V V4_ C uF L9_ R9 600 khz L9 0.8mH Simulated waveform: (iv) To design and simulate m-derived HPF for 600 impedane having its ut off frequeny at 38.3 Hz and infinite attenuation frequeny at 300 Hz. Design: Rk = 600 f = 38.3 Hz f = 300 Hz Rk 600 L = 50 mh 4 f C = 4R f k 0.46 F Panimalar Engineering College 4

25 m C m f f.45f L 4m 898.mH L 5.6 mh m m Shemati: V -/V R 600 C.45uF L 5mH R 600 khz L 898.mH L3 898.mH (v) To design a low pass omposite filter to meet the following requirements: f = 000 Hz f = 050 Hz Rk = 500 Design: Step : Constant k LPF: Rk = 500 and f = 000 Hz Rk 500 L = mH f 000 Panimalar Engineering College 5 C = 0.38 F R k f Step : m-derived LPF: Rk = 500 f = 000 Hz f = 050 Hz Rk 500 L = mH f 000 C = R f k F 000

26 f 000 m 0.95 f 050 Step 3: m-derived filter with m = 0.6; Rk = 500 f = 000 Hz f = 050 Hz Rk 500 L = mH f 000 C = 0.38 F R f k V3 -/V khz Shemati: R6 500 L mH C uF L9 4.44mH L mH L mH C3 0.38uF L4 8.73mH L3 8.73mH C6 0.07uF L 86.7mH L 3.874mH A C uF L0 4.44mH R5 500 Simulated waveform: Result: Thus Passive reative filters Constant k, m-derived and omposite low and high pass filters were designed and simulated using iruit maker. Panimalar Engineering College 6

27 DESIGN AND SIMULATION OF CONSTANT k, m-derived AND COMPOSITE FILTER USING PROTEUS EX.NO : 7 DATE : AIM: To simulate passive reative filters Constant k, m derived and omposite low pass and high pass filters using Proteus. PROCEDURE: Step : Open a new projet under shemati ategory in Proteus 8 professional software Step : Selet the required omponents and onnet them using wires Step 3: Selet SINE funtion generator and voltage probe and plae them in input and output terminals respetively. Step 4: Plae Frequeny blok and edit properties of all the seleted omponents and devies. Step 5: Simulate the shemati and observe filter response in Frequeny blok. (i) To design and simulate onstant k LPF for 400 impedane having its ut off frequeny at 000 Hz. Design: Rk = 400 f = 000 Hz L = C = Rk 400 L 7. 3mH ; 63.66mH f 000 R f k F 000 Panimalar Engineering College 7

28 Shemati: R 400 L 63.66mH L 63.66mH R() R 400 R() C 0.795uF Simulated waveform: (i) To design and simulate onstant k HPF for 600 impedane having its ut off frequeny at 000 Hz. Design: Rk = 600 f = 3000 Hz Rk 600 L = 3. 87mH 4 f C = 0.37 F 4R f k Panimalar Engineering College 8

29 Shemati: C C 0.37uF 0.37uF R() R 600k C() L 3.87mH Simulated waveform: (ii) To design and simulate m-derived LPF for 400 impedane having its ut off frequeny at 000 Hz and infinite attenuation frequeny at 00 Hz. Design: Rk = 400 f = 000 Hz f =00 Hz f 000 m 0.46 f 00 Rk 400 ml L = 7. 3mH ; 6.48mH f 000 Panimalar Engineering College 9

30 C = R f k m L 63. 7mH 4m Shemati: F ; mc 0.33 F R L 6.48mH L 6.48mH R() 400 R 400 R() C 0.33uF L3 63.7mH Simulated waveform: (iii)to design and simulate m-derived HPF for 600 impedane having its ut off frequeny at 4000 Hz and infinite attenuation frequeny at 3600 Hz. Design: Rk = 600 ; f = 4000 Hz; f = 3600 Hz Rk 600 L = H 4 f C = F 4R f m k f f Panimalar Engineering College 30

31 Shemati: R C C uF 0.63uF R() R() L mH R 500 C uF Simulated waveform: (iv) To design a low pass omposite filter to meet the following requirements: f = 000 Hz f = 050 Hz Rk = 500 Design: Step : Constant k LPF: Rk = 500 and f = 000 Hz Rk 500 L = mH f 000 C = 0.38 F R k f Step : m-derived LPF: Rk = 500 ; f = 000 Hz; f = 050 Hz Rk 500 L = mH f 000 C = 0.38 F R f k Panimalar Engineering College 3

32 m f f Step 3: m-derived filter with m = 0.6 Rk = 500 ; f = 000 Hz;; f = 050 Hz Rk 500 L = mH f 000 C = 0.38 F R k f Shemati: C() L 3.874mH L 39.75mH L mH L4 8.73mH L5 8.73mH L mH C4() C 0.095uF C 0.38uF C3 0.07uF C uF L7 86.7mH L8 4.44mH L9 4.44mH Simulated waveform: Result: Thus Passive reative filters Constant k, m-derived and omposite low and high pass filters were designed and simulated using Proteus. Panimalar Engineering College 3

33 VSWR AND REFLECTION COEFFICIENT MEASUREMENT USING SLOTTED LINE EX.NO : 8 DATE : AIM : mathed load To measure the Voltage Standing Wave-Ratio and Refletion Co-effiient for EQUIPMENTS REQUIRED: Klystron Power Supply, Klystron Tube with Klystron Mount, Isolator, Variable Attenuator, Frequeny Meter, Slotted Setion, Tunable Probe, S.S.Tuner, Mathed Termination, Waveguide Stands, VSWR Meter, CRO, Cables and Aessories. THEORY : The eletromagneti field at any point of transmission line may be onsidered as the sum of two traveling waves: the Inident Wave propagates from generator and the refleted wave propagates towards the generator. The refleted wave is set up by refletion of inident wave from a disontinuity on the line or from the load impedane. The magnitude and phase of refleted wave depends upon amplitude and phase of the refleting impedane. The super position of two traveling waves, gives rise to standing wave along with the line. The maximum field strength is found where two waves are in phase and minimum where the two waves add in opposite phase. The distane between two suessive minimum is half the guide wavelength on the line. The ratio of eletrial field strength of refleted and inident wave is alled refletion oeffiient. Hene VSWR denoted by S is S V V max min V V i i V r V r Where V i Inident Voltage V r Refleted Voltage Panimalar Engineering College 33

34 BLOCK DIAGRAM: Klystron Power Supply Tunable Probe VSWR Meter Klystron Mount Isolator Variable Attenuator Frequeny Meter Slotted Setion S.S. Tuner TABULATION: Mathed Termination REPELLER VOLTAGE: FREQUENCY: VERNIER SCALE READING (m) VSWR S REFLECTION COEFFICIENT S k= S PROCEDURE:. Set the omponents and equipment as shown in figure.. Before swithing ON the power supply keep the ontrol knobs of Klystron power supply as below. Meter swith OFF position Mod seletor swith AM position AM Frequeny & Amplitude - Mid position Beam voltage Fully antilokwise Refletor voltage Fully lokwise Panimalar Engineering College 34

35 Standby swith ON position 3. Keep the ontrol knob of VSWR meter as below Input swith Low Impedane SWR Range swith 40dB Meter swith Normal Gain (ourse & Fine) Mid position. 4. Initially set the variable attenuator for maximum attenuation. 5. Rotate the knob of frequeny meter at maximum position. 6. Swith ON the Klystron power supply, VSWR meter and ooling fan. 7. Turn the meter swith of power supply to beam voltage position and set the beam voltage at 300V with the help of beam voltage knob. 8. Adjust the refletor voltage to get some defletion in VSWR meter. 9. Maximize the defletion with AM amplitude and frequeny ontrol knob of power supply. 0. Tune the plunger of klystron mount for maximum defletion.. Tune the probe for maximum defletion in VSWR.. Tune the frequeny meter knob to get dip on the VSWR sale, and note down the frequeny diretly from the frequeny meter. 3. Keep the depth of pin of S.S.Tuner to around 3 4mm and lok it. 4. Move the probe along with slotted line to get maximum defletion. 5. Adjust VSWR meter gain ontrol knob suh that the meter indiates.0 on the normal upper SWR sale. 6. Move the probe to next minima point note down the SWR = S 0 on the sale. Also note down the probe position, let it be d. S 7. Calulate the Refletion Coeffiient k = S + RESULT: Thus VSWR and Refletion Co-effiient was measured using unknown load. Panimalar Engineering College 35

36 MEASUREMENT OF FREQUENCY AND WAVELENGTH OF DOMINANT TE MODE IN RECATNGULAR WAVEGUIDE EX.NO : 9 DATE : AIM : To determine frequeny and wavelength of dominant TE mode in a retangular waveguide. EQUIPMENTS REQUIRED: Gunn Power Supply, Gunn Osillator, PIN Modulator, Isolator, Variable Attenuator, Frequeny Meter, Slotted Setion, Tunable Probe, Mathed Termination, Movable short, Waveguide Stands, VSWR Meter, CRO, Cables and Aessories. THEORY: For dominant TE 0 mode in retangular wave-guide λo, λg and λ are related as 0 g For TE mn mode in retangular waveguide. λ = / [(m/a) + (n/b) ] For dominant TE0 mode we have, λ = / [(/a) + (0/b) ] = a Thus, λg = λo/ [-( λo/a) ], λg = / [(/λo) -(/a) ] /( λo) = / [(/ λg) + (/a) ] /( λo ) = /(λg ) + (/a ) Panimalar Engineering College 36 were λo is free spae wavelength λg is guide wavelength λ is ut off wavelength For TE 0 mode, λ = a were a is broad dimension of waveguide. The following relationship an be proved = f λ were is veloity of light and f is frequeny. For an air filled hallow pipe waveguide; g 0 0

37 f = / λo = [(/ λg) + (/a) ] The wavelength λg an be measured as twie the distane between minima in the standard wave pattern. PROCEDURE :. Set the omponents and equipment as shown in figure.. Before swithing ON the power supply keep the ontrol knobs of Gunn power supply as below. Gunn bias and PIN bias knob Fully antilokwise Meter swith Voltage position. Seletor swith INT position Mod Frequeny knob Any position. 3. Keep the ontrol knob of VSWR meter as below Input swith Low Impedane SWR Range swith 40dB Meter swith Normal Gain (ourse & Fine) Mid position. 4. Initially set the variable attenuator for maximum attenuation. 5. Rotate the knob of frequeny meter at maximum position. 6. Set the mirometer of Gunn osillator for required frequeny of operation. 7. Swith ON the Gunn power supply, VSWR meter and ooling fan. 8. Rotate PIN bias knob to around maximum position 9. Inrease the Gunn bias voltage ontrol knob up to 7 volts. 0. Tune the mirometer of Gunn osillator for maximum defletion in VSWR meter.. Tune the frequeny meter knob to get a dip on VSWR sale and note down the frequeny diretly from the frequeny meter.. Replae the termination with movable short, and detune the frequeny meter. Panimalar Engineering College 37

38 BLOCK DIAGRAM: Gunn Power Supply Mathed Termination Gunn Osillator PIN Modulator Isolato r Variable Attenuato Frequeny Meter Slotted Setion VSWR Meter Tunable Probe TABULATION: FREQUENCY BY DIRECT METHOD: INDIRECT METHOD: Frequeny Vernier Distane b/w Guide Free spae (GHz) sale reading two minima d (m) Wavelength λg = d (m) wavelength λo = /f f g a Panimalar Engineering College 38

39 3. Move the probe along with slotted line, the defletion in VSWR meter will vary. Move the probe to a minimum defletion position. To get aurate reading, it is neessary to inrease the VSWR range db to higher position. Note and reord the probe position. 4. Move the probe next minimum position and reord the probe position again. 5. Calulate the guide wavelength as twie the distane between two suessive minimum positions obtained as above. 6. Measure the wave-guide inner broad dimension a whih will be around.86mm for X-band. 7. Calulate the frequeny by following equation. f 0 g a RESULT : Thus the frequeny and wavelength in a retangular waveguide on TE0 mode is determined. Frequeny by diret method : Frequeny by indiret method: Free spae wavelength (λo) : Guide wavelength (λg) : Panimalar Engineering College 39

40 STUDY OF WAVEGUIDE COMPONENTS EXP.NO : 0 DATE : Aim: To study different types of waveguide omponents Gunn osillator Gunn osillators or transferred eletron devie osillators are a heap soure of mirowave power and omprise of Gunn diode or transferred eletron devie (TED) as their major omponent. In these devies, the Gunn diode will be plaed in a resonant avity and omprises of two major omponents viz., (i) A DC bias and (ii) A tuning iruit. The resonant frequeny of gunn osillator is given as f n l where, n is the number of half-waves whih an fit into the avity for a given frequeny. This n ranges from to l/t d where t d is the time taken by the gunn diode to respond to the hanges in the applied voltage. Gunn diode osillators are extensively used as radio transmitters and reeivers, veloitydeteting sensors, parametri amplifiers, radar soures, traffi monitoring sensors, motion detetors, remote vibration detetors, rotational speed tahometers, moisture ontent monitors, mirowave transeivers (Gunnplexers) and in the ase of automati door openers, burglar alarms, polie radars, wireless LANs, ollision avoidane systems, anti-lok brakes, pedestrian safety systems, et. Isolator Mirowave Isolator is a passive, non-reiproal devie with three or more ports used to transmit mirowave energy in a speifi diretion. This Mirowave Isolator is used to prevent refleted mirowave energy from the magnetron preventing exessive magnetron heating or molding. Mirowave Isolator is a irulator with an absorbing load, attahing to Panimalar Engineering College 40

41 the port used to transmit the refleted energy that is generated from the magnetron and is transmitted to the load port and absorbed. This Teleommuniation Equipment is widely used in teleommuniation, test equipment, eletroni warfare, radar and avioni systems. Slotted setion Slotted lines are used for mirowave measurements and onsist of a movable probe inserted into a slot in a transmission line. They are used in onjuntion with a mirowave power soure and usually, in keeping with their low-ost appliation, a low ost Shottky diode detetor and VSWR meter rather than an expensive mirowave power meter.slotted lines an measure standing waves, wavelength, and, with some alulation or plotting on Smith harts, a number of other parameters inluding refletion oeffiient and eletrial impedane. Frequeny meter A frequeny meter is an instrument that displays the frequeny of a periodi eletrial signal. Various types of frequeny meters are used. Many are instruments of the defletion type, ordinarily used for measuring low frequenies but Panimalar Engineering College 4

42 apable of being used for frequenies as high as 900 Hz. These operate by balaning two opposing fores. Changes in the frequeny to be measured ause a hange in this balane that an be measured by the defletion of a pointer on a sale. Fixed and Variable attenuators The attenuators are basially passive devies whih ontrol power levels in mirowave system by absorption of the signal. Attenuator whih attenuates the RF signal in a waveguide system is referred as waveguide attenuator. There are two main types fixed and variable. Phase shifters A phase shift module is a mirowave network module whih provides a ontrollable phase shift of the RF signal. Phase shifters are used in phased arrays. Phase Shifters are a ritial omponent in many RF and Mirowave systems. Appliations inlude ontrolling the relative phase of eah element in a phase array antenna in a RADAR or steerable ommuniations link and in anelation loops used in high linearity amplifiers. Panimalar Engineering College 4

43 Diretional ouplers A diretional oupler is a devie with whih it is possible to measure the inident and refleted wave separately. i. It onsists of two transmission lines the main arm and auxiliary arm, eletro-magnetially oupled to eah other. The power entering the main arm gets divided between port and 3 and almost no power omes out in port 4. Power entering at port is divided between port and 4. E plane Tee It is a three port devie port one and port two are ollinear arms and port 3 is E arm. A retangular slot is ut along with broader side dimension of along wave length and the side arm is attahed forms e plane tee. Port one and Port two will have phase shift of 80 degrees. H plane Tee Panimalar Engineering College 43

44 A waveguide tee in whih the axis of its side arm is shunting the E-field or parallel to the H-field of the main guide is alled H plane tee. Magi Tee It is a four port devie port one and port two are ollinear arms port 3 is H-arm and port 4 is E-arm in this magi tee if any two ports are perfetly math to the juntion then the remaining two ports are automatially math to the juntion. Panimalar Engineering College 44