VELAMMAL ENGINEERING COLLEGE, CHENNAI-66 DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

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1 VELAMMAL ENGINEERING COLLEGE, CHENNAI-66 DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING TUTORIAL SHEET- 1, 2, 3, 4 & 5 UNIT 1 TRANSMISSION LINE THEORY 1. A transmission line has a characteristic impedance of 600 ohm. Determine magnitude of reflection of coefficient if the receiving and impedance is (650-j 475) ohm.c A transmission line has a characteristic impedance of 400 ohm and is terminated by a load impedance of (650 - J475) ohm. Determine the reflection coefficient.c Find the characteristics impedance of a line at 1600Hz if Z oc = ohm and Z sc = ohm.c A parallel wire transmission line is having the following line parameters at 5KHz. Series resistance R=2.59x10-3 Ω/m, series inductance L=2µH/m, shunt conductance G=0 Ʊ/m and capacitance between conductors C=5.56 nf/m. Find the characteristics impedance, attenuation constant, phase shift constant, velocity propagation and wavelength.c A generator of 1V, 1000 Hz supplies power to a 100km open wire line terminated in Z o and having the following parameters. R=10.4 Ω/km, G=0.8x10-6 Ʊ/km, L= H/km and C= µf/km. Calculate Z o, α, β, λ, v and also find the received power.c A 2m long transmission line with characteristics impedance of 60+j40 ohm is operating at ω=10 6 rad/sec has attenuation constant of nep/m and phase constant of 0 rad/m. If the line is terminated by a load of 20+j50 ohm, determine the input impedance of this line.c The characteristics impedance of a 805m long transmission line is Ω, attenuation constant is 74.5x10-6 nepers/m and the phase shift constant is 174x10-6 rad/m at 5KHz. Calculate the line parameters R, L, G, C and phase velocity on the line.c A 10% voltage drop across in 2Km of a uniformly loaded transmission line terminated by its characteristic impedance and there is a phase change of 20 over the same distance at a frequency of 796 Hz. Find the value of the line attenuation in db/km, β in rad/km and the velocity of propagation.c303.1

2 UNIT-2 HIGH FREQUENCY TRANSMISSION LINE 1. A lossless transmission has a shunt capacitance of 100pF/m and a series inductance of 4μH/m. Evaluate the characteristic impedance. C Determine the values of VSWR in the case of (a) Z R = 0 and (b) Z R = Z 0 C Calculate standing wave ratio and K on a line having the characteristics impedance Zo=300Ω and terminating impedance in Z R =300+j400Ω.C A line with zero dissipation has R=0.006 ohm/m, C=4.45 pf/m, L=2.5µH/m If the line is operated at 10MHz find Ro, α, β, λ and v.c A lossless line has a standing wave ratio of 4. The Ro is 150 ohm and the maximum voltage measured in the line is 135V. Find the power delivered to the load. C A lossless line in air having a characteristics impedance of 300Ω is terminated in unknown impedance. The first voltage minimum is located at 15cm from the load. The standing wave ratio is 3.3. Calculate the wavelength and terminated impedance. C Find the sending end line impedance for a HF line having characteristics impedance of 50 ohm. The line is of length 1.185λ and is terminated in a load of 110+j80Ω.C A lossless transmission line with Ro=75Ω and of electrical length s=0.3ω is terminated with load impedance of Z R =40+j20Ω. Determine the reflection coefficient at load, SWR of the line and input impedance of the line. C303.2 UNIT 3 IMPEDANCE MATCHING IN HIGH FREQUENCY LINES 1. An ideal lossless quarter wave line of characteristic impedance 60 ohm is terminated in a load impedance of the line when Z R. Given the value of the input impedance of the line when Z R =0, and 60Ω. C Design a quarter wave transformer to match a load of 200 ohm to a source resistance 500 ohm, the operating frequency is 200MHz. C A 75Ω line feeds an inductive load Z R =18.75+j56.25Ω. Design a double stub tuner to match this load to the line using smith chart. C303.3

3 4. A low loss line with R 0 =70Ω is terminated at an impedance of Z R =115-j80Ω. The wavelength of transmission line is 2.5m. Using smith chart find the following. (i)load admittance (ii)swr (iii)maximum and minimum line impedance (iv)distance between the load and first voltage minimum. C Determine length and location of a single short circuited stub to produce an impedance match on a transmission line with characteristics impedance of 600 Ω and terminated in 1800Ω using smith chart. C Determine the standing wave ratio, characteristics impedance of a quarter waves transformer and the distance of the transformer must be placed to achieve a smooth line with R 0 =50Ω with a load impedance Z R =30+j40Ω. C A 300 ohm line feeding an antenna has a standing wave ratio of 4 and the distance from the load of the first voltage minima is 28cm. If the frequency is 150MHz, design single stub matching system. C A 75Ω lose less transmission line is to be matched with a 100-j80Ω load using single stub. Calculate the stub length and its distance from the load corresponding to the frequency of 30MHz using smith chart. C A lossless line in air having a characteristic impedance of 300 ohms is terminated by unknown impedance. The first voltage minimum is located at 15 cm from the load the standing wave ratio is 3.3. Calculate the wavelength and terminating impedance. C303.3 UNIT 4PASSIVE FILTERS 1. A constant-k T-section high pass filter has a cutoff frequency of 10 KHz. The design impedance is 600 ohms. Determine the value of L and C. C Determine the value of L required by a constant-k T section high pass filter with a cut off frequency of 1KHz and design impedance of 600Ω. C A line is connected of T-section of pure resistances. Calculate characteristics impedance if each series arm is 50Ω and shunt arm is 5000Ω. C Find the resonant frequency of a band pass filter which has lower cut off frequency of 2700Hz and upper cut off frequency of 5100Hz. C Design a prototype band elimination filter for the following specifications R K =400Ω, lower cut off frequency 1250Hz and upper cut off frequency 2000Hz. C303.4

4 6. Design m-derived high pass filter π section to work into the load of 600Ω with cut off frequency of 1000/π Hz and peak attenuation frequency is 300Hz.C A π section low pass filter network consists of a series arm inductance of 20mH and two shunt capacitor of 0.16µF each. Calculate the cut off frequency, attenuation and phase shift at 15KHz. What is the value of nominal impedance in the pass band?c Design low pass composite filter to meet the following specifications f c =2000Hz, f =2050Hz, R K =500Ω. C (i) Design constant-k band pass filter (both T and π sections) having a design impedance of 600Ω and cut off frequencies of 1KHz and 4KHz.(ii) Design an m-derived T section low pass filter having cut off frequency of 1KHz. Design impedance is 400Ω and the peak attenuation is 1100Hz. C303.4 UNIT 5 WAVEGUIDES AND CAVITY RESONATORS 1. A rectangular waveguide of cross section 5cm x 2cm is used to propagate TM 11 mode at 10GHz. Determine the cut-off wavelength. C An air filled rectangular waveguide of inner dimensions x in centimeters operates in the dominant TE 10 mode. Calculate the cut-off frequency and phase velocity of a wave in the guide at a frequency of 7GHz. C A rectangular air filled copper waveguide with dimension 0.9 inch x 0.4 inch cross section and 12 inch length is operated at 9.2GHz with a dominant mode. Find cut-off frequency, guide wavelength, phase velocity, characteristics impedance and group velocity. C A pair of perfectly conducting planes is separated by 8cm in air. For a frequency of 5000MHz with the TM 1 mode excited find the following (a)cut -off frequency (b)characteristics impedance (c)attenuation constant for f=0.95fc (d)phase constant (e)phase velocity and group velocity (f)wavelength measured along the guided walls (g)cut-off wavelength and (h)angle of incidence.c Given cylindrical waveguide with f=11ghz in TE 11 mode and internal diameter 4.5cm. Find λ c, λ g, v g, v ph and Z TE. C A TE 11 wave is propagated through a circular waveguide. The diameter of the guide is 10cm and the guide is air filled. Given X 11 =1.842 (a) Find the cut off frequency (b) Find

5 the wavelength λg in the guide for a frequency of 3GHz. (c)determine the wave impedance in the guide. C For a frequency of 10GHz and plane separation of 5cm in air, find the cut off frequency, cut off wavelength, phase velocity and group velocity. C Calculate the resonant frequency of an air filled rectangular resonator of dimensions a=2cm, b=4cm, and d=6cm operating in TE 101 mode. C303.6

EC6503 Transmission Lines and WaveguidesV Semester Question Bank

EC6503 Transmission Lines and WaveguidesV Semester Question Bank UNIT I TRANSMISSION LINE THEORY A line of cascaded T sections & Transmission lines General Solution, Physicasignificance of the equations 1. Derive the two useful forms of equations for voltage and current