# Set No. 1 - ?· Code No: R05220404 Set No. 1 II B.Tech II Semester Supplimentary Examinations, Aug/Sep…

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<ul><li><p>Code No: R05220404 Set No. 1</p><p>II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007ELECTROMAGNETIC WAVES AND TRANSMISSION LINES</p><p>( Common to Electronics &amp; Communication Engineering and Electronics &amp;Telematics)</p><p>Time: 3 hours Max Marks: 80Answer any FIVE Questions</p><p>All Questions carry equal marks </p><p>1. (a) State and explain Coulombs law using vector form of Coulomb?s force ex-pression.</p><p>(b) Find the force on a charge of -100mC located at P (2, 0, 5) in free space dueto another charge 300 C located at Q (1, 2, 3).</p><p>(c) State and express Gausss law in both integral and differential forms. [8+4+4]</p><p>2. (a) Obtain an expression for differential magnetic field strength dH due to differ-ential current element I dl at the origin in the positive Z- direction.</p><p>(b) Find the magnetic field strength, H at the centre of a square conducting loopof side 2a in Z=0 plane if the loop is carrying a current , I, in anti clock wisedirection. [6+10]</p><p>3. (a) What is the inconsistency of Amperes law?</p><p>(b) A circular loop conductor of radius 0.1m lies in the z=0plane and has a resis-tance of 5 given B=0.20 sin 103 t az T. Determine the current [8+8]</p><p>4. (a) Explain the propagation of wave in a loss less medium.</p><p>(b) A uniform plane wave at a frequency of 1GHz is travelling in a large block ofTeflon ( r = 2.1, r = 1and = 0). Determine V, , and [8+8]</p><p>5. (a) What is Total Internal Reflection on the basis of EM theory of light and whatare its applications.</p><p>(b) An EM wave traveling in air is incident normally on a boundary between airand a dielectric having permeability same as free space and permittivity as 4.Prove that one-ninth of the incident power is reflected and eight-ninths of itis transmitted into the second medium. [8+8]</p><p>6. (a) Explain about attenuation in parallel-plate wave guides. Also draw attenu-ation versus frequency characteristics of waves guided between parallel con-ducting plates.</p><p>(b) A parallel plate wave guide made of two perfectly conducting infinite planesspaced 3 cm apart in air operates at a frequency of 10 GHz. Find the maximumtime average power that can be propagated per unit width of the guide forTE1andTM1 modes. [8+8]</p><p>1 of 2</p></li><li><p>Code No: R05220404 Set No. 1</p><p>7. (a) Explain the meaning of the terms characteristic impedance and propagationconstant of a uniform transmission line and obtain the expressions for themin terms of Parameters of line?</p><p>(b) A telephone wire 20 km long has the following constants per loop km resistance90 , capacitance 0.062 F , inductance 0.001H and leakage = 1.5 x 106</p><p>mhos. The line is terminated in its characteristic impedance and a potentialdifference of 2.1 V having a frequency of 1000 Hz is applied at the sendingend. Calculate :</p><p>i. The characteristic impedance</p><p>ii. Wavelength.</p><p>iii. The velocity of propagation [8+8]</p><p>8. (a) Describe all the characteristics of UHF Lines?</p><p>(b) Explain the significance and design of single stub impedance Matching. Dis-cuss the Factors on which stub length depends. [6+10]</p><p>2 of 2</p></li><li><p>Code No: R05220404 Set No. 2</p><p>II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007ELECTROMAGNETIC WAVES AND TRANSMISSION LINES</p><p>( Common to Electronics &amp; Communication Engineering and Electronics &amp;Telematics)</p><p>Time: 3 hours Max Marks: 80Answer any FIVE Questions</p><p>All Questions carry equal marks </p><p>1. (a) State and prove Gausss law. Express Gausss law in both integral and differ-ential forms.</p><p>(b) Discuss the salient features and limitations of Gausss law .</p><p>(c) Derive Poissons and Laplaces equations starting from Gausss law. [6+4+6]</p><p>2. (a) Obtain an expression for differential magnetic field strength dH due to differ-ential current element I dl at the origin in the positive Z- direction.</p><p>(b) Find the magnetic field strength, H at the centre of a square conducting loopof side 2a in Z=0 plane if the loop is carrying a current , I, in anti clock wisedirection. [6+10]</p><p>3. (a) Write down Maxwell?s equations in their general integral form. Derive thecorresponding equations for fields varying harmonically with time</p><p>(b) In free space D = Dm sin (t + z) ax use Maxwell?s equations to find B.[8+8]</p><p>4. (a) Derive wave equations for sinusoidal time variations</p><p>(b) A 100v/m plane wave of frequency 300 MHz travels in an infinite, losslessmedium having r = 1, r = 9 = 0 write the complete time domainexperements for E and H field vectors. [8+8]</p><p>5. An EM wave in dielectric medium 1 (1, 0) impinges obliquely on a boundary planewith dielectric medium 2 (2, 0). Let 1, t denote the incident and refraction an-gles respectively and show that for perpendicular polarization, reflection coefficientis equal to</p><p>sin(ti)sin(t+i)</p><p>and transmission coefficient is</p><p>2 sin t cos isin(i+t)</p><p></p><p>6. Derive the expressions for the E and H field components for TE waves in a parallelplane wave guide, using Maxwell?s equations approach. </p><p>1 of 2</p></li><li><p>Code No: R05220404 Set No. 2</p><p>7. (a) What is meant by the polarization of wave? When is the wave linearly polar-ized and circularly polarized?</p><p>(b) A traveling wave has two linearly polarized components Ex = 2 Cos wt andEy =3Cos (wt + /2)</p><p>i. what is the axial ratio.</p><p>ii. What is the tilt angle of the major axis of the polarization ellipse?</p><p>iii. What is the sense of rotation? [8+8]</p><p>8. (a) Derive the expression for the input impedance of a transmission line of lengthL</p><p>(b) Explain the application of smith?s chart. [8+8]</p><p>2 of 2</p></li><li><p>Code No: R05220404 Set No. 3</p><p>II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007ELECTROMAGNETIC WAVES AND TRANSMISSION LINES</p><p>( Common to Electronics &amp; Communication Engineering and Electronics &amp;Telematics)</p><p>Time: 3 hours Max Marks: 80Answer any FIVE Questions</p><p>All Questions carry equal marks </p><p>1. (a) Derive an expression for the electric field intensity due to a finite length linecharge along the z-axis at an arbitrary point Q(x, y, z).</p><p>(b) Find the force on a 100C charge at (0, 0, 3)m if four like charges of 20Care located on x and y axes at 4m. [8+8]</p><p>2. (a) Find magnetic field strength, H, on the Z- axis at a point P(0,0,h), due to acurrent carrying circular loop, x2 + y2 = A2 in Z=0 plane.</p><p>(b) Find the total magnetic flux crossing a surface, = 2, 1 2 and 0 </p><p>Z 5 due to a vector magnetic potential A = (2/4).z webers/m [8+8]</p><p>3. (a) Obtain the integral form of Maxwell?s equation from amperes circuital law inthe generalized form</p><p>(b) Determine the total magnetic flux through the rectangular loop shown inthe figure 3. The source of the magnetic field is the long straight conductorcarrying a current I [8+8]</p><p>Figure 3</p><p>4. A 3 GHz uniform plane wave propagates through rexolite in the positive Z-directionthe E-field at Z = 0 is 100 6 00v/m</p><p>(a) Calculate the RMS value and phase of E at Z=4 cm</p><p>(b) Calculate the total attenuation in dB over a distance of 6 wave langths.For rexolite r=2.54 and tan =0.0005 [8+8]</p><p>5. Write short notes on the following</p><p>1 of 2</p></li><li><p>Code No: R05220404 Set No. 3</p><p>(a) Surface Impedance</p><p>(b) Brewster angle</p><p>(c) Total Internal Reflection [5+5+6]</p><p>6. (a) Define and explain the significance of the following terms as applicable toparallel plane guides:</p><p>i. Wave impedance</p><p>ii. Phase and group velocities</p><p>iii. Principal wave and its characteristics [10+6]</p><p>(b) Explain the factors on which cut off frequency of a parallel plate wave guidedepend.</p><p>7. (a) List out types of transmission lines and draw their schematic diagrams.</p><p>(b) Draw the directions of electric and magnetic fields in parallel plate and coaxiallines</p><p>(c) A transmission line in which no distortion is present has the following pa-rameters Zo = 60, = 20mNP/m, V = 0.7V0. Determine R, L, G, C andwavelength at 0.1GHz. [5+5+6]</p><p>8. (a) A dipole antenna is fed by a transmission line having Zo = 60. The sourceimpedance is 600. If the length of the line is 10, determine antenna im-pedance.</p><p>(b) Describe how matching is achieved using single stub matching. What are theadvantages and disadvantages compared to double-stub matching. [8+8]</p><p>2 of 2</p></li><li><p>Code No: R05220404 Set No. 4</p><p>II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007ELECTROMAGNETIC WAVES AND TRANSMISSION LINES</p><p>( Common to Electronics &amp; Communication Engineering and Electronics &amp;Telematics)</p><p>Time: 3 hours Max Marks: 80Answer any FIVE Questions</p><p>All Questions carry equal marks </p><p>1. (a) What is capacitance? Differentiate between isotropic and anisotropic materi-als.</p><p>(b) Calculate the capacitance of a parallel-plate capacitor with a dielectric, micafilled between plates. r of mica is 6. The plates of the capacitor are squarein shape with 0.254cm side. Separation between the two plates is, 0.254cm.</p><p>(c) As an example of the solution of Laplaces equation, derive an expressionfor capacitance of a parallel plate capacitors. Make necessary assumptions.[4+6+6]</p><p>2. (a) Derive equation of continuity for static magnetic fields.</p><p>(b) Derive an expression for magnetic field strength, H, due to a current carryingconductor of finite length placed along the y- axis, at a point P in x-z planeand r distant from the origin. Hence deduce expressions for H due to semi-infinite length of the conductor. [6+10]</p><p>3. (a) Explain faraday?s law for time varying fields.</p><p>(b) Verify that the displacement current in the parallel plate capacitor is the sameas the conduction current in the connecting wires. [8+8]</p><p>4. (a) Explain skin depth and derive expression for depth of penetration for goodconductor</p><p>(b) Find r, r and for a material in which at 100MHz, uniform plane wave has = 2N/m = 1m and || = 200ohm. [8+8]</p><p>5. An EM wave in dielectric medium 1 (1, 0) impinges obliquely on a boundary planewith dielectric medium 2 (2, 0). Let 1, t denote the incident and refraction an-gles respectively and show that for perpendicular polarization, reflection coefficientis equal to</p><p>sin(ti)sin(t+i)</p><p>and transmission coefficient is</p><p>2 sin t cos isin(i+t)</p><p></p><p>1 of 2</p></li><li><p>Code No: R05220404 Set No. 4</p><p>6. (a) Define and explain the significance of the following terms as applicable toparallel plane guides:</p><p>i. Wave impedance</p><p>ii. Phase and group velocities</p><p>iii. Principal wave and its characteristics</p><p>(b) Explain the impossibility of TEM wave propagation in wave guides. [8+8]</p><p>7. (a) Explain the meaning of the terms characteristic impedance and propagationconstant of a uniform transmission line and obtain the expressions for themin terms of Parameters of line?</p><p>(b) A telephone wire 20 km long has the following constants per loop km resistance90 , capacitance 0.062 F , inductance 0.001H and leakage = 1.5 x 106</p><p>mhos. The line is terminated in its characteristic impedance and a potentialdifference of 2.1 V having a frequency of 1000 Hz is applied at the sendingend. Calculate :</p><p>i. The characteristic impedance</p><p>ii. Wavelength.</p><p>iii. The velocity of propagation [8+8]</p><p>8. (a) What is the significance of standing wave ratio in a transmission line? Calcu-late the Reflection coefficient and VSWR for a 50 lines, terminated with</p><p>i. matched Load</p><p>ii. Short circuit</p><p>iii. +j50 loads</p><p>iv. -j50 load</p><p>(b) A 50 Omega transmission line is terminated by an unknown impedance. TheVSWR is 4 and the first minimum is formed at 2 cm from the load end. Thefrequency of operation is 1 GHz. Design a single stub line matching for theAbove conditions. [8+8]</p><p>2 of 2</p></li></ul>