SPPU Electronics and Telecom Engineering (Semester 5)

Electromagnetics and Transmission Lines

May 2017

Electromagnetics and Transmission Lines

May 2017

Solve any one question from Q.1(a,b,c) &Q.2(a,b,c)

1(a)
Derive the expression for electric filed intensity \(\bar{E} \)/ at a point 'P' due to infinite line charge with uniform line charge density 'ρ'

_{ L}.
6 M

1(b)
Derive the electrostatic boundary condition between two dielectric media.

8 M

1(c)
Find \(\bar{H} \)/ at point P(2, 3, 4) caused by a current filament of 12A in a \( \hat{a_{y}}\)/ direction on y axis and extending from y = 0 to y = 8.

6 M

2(a)
Derive relation between \(\bar{E} \)/ and V. Also state significance to potential gradient.

8 M

2(b)
Find the capacitance of parallel plate capacitor containing two dielectrics, \(\varepsilon _{r1}=1.5 \ \ \text{and}\ \ \varepsilon _{r2}=3.5, \)/ each comprising one half the volumes as shown in figure. Here area of plates A = 2m

!mage

^{2}and d = 10^{-3}m.!mage

6 M

2(c)
State and prove Ampere's Law and apply the same for infinite sheet of current.

6 M

Solve any one question from Q.3(a,b) &Q.4(a,b)

3(a)
Write Maxwell's equations for static and time varying fields in point and integral forms.

8 M

3(b)
State and prove Poying theorem. Interpret each them.

8 M

4(a)
What do you mean by uniform plane wave? Obtain equation of wave travelling in free space in terms of \(\bar{E} \)/.

8 M

4(b)
The magnertic filed of an EM wave in free space is given by \(\vec{H}=0.5\epsilon _{0}\cos \left ( \omega t-100z \right )\hat{a}_{y}\frac{A}{m}. \)/ Findthe electric field intensity and displacement current density.

8 M

Solve any one question from Q.5(a,b) &Q.6(a,b)

5(a)
State primary and secondary constants of transmission lines. Derive the relationship between primary and secondary constants of transmission line.

8 M

5(b)
The characteristic impedance of the uniform transmission line is 2040Ω at a frequency of 800Hz, At this frequency, the propagation constant is 0.054 ∠ 87.9°. Determine R, L. G, C, α and β

8 M

6(a)
Explain the phenomenon of reflection of transmission line and hence defien reflection coefficient.

8 M

6(b)
Derive the expression for characteristic impedance (Z

_{0}and propagation constant in terms of primary constants of transmission lines.
10 M

Solve any one question from Q.7(a,b) &Q.8(a,b)

7(a)
What is impedance matching? Explain necessity of it. What is stub matching? Explain signle stub matching with merits and demerits.

10 M

7(b)
A 50Ω line is terminated by a load impedance of (75 - j69) Ω. The line is 3.5 meter long and is excited by 50 Mhz source. Propagation velocity is 3×10

^{8}m/sec. Find the input impedance, reflection coefficient, VSWR, position of minimum voltage.
8 M

8(a)
What is mean by distortionless line? Derive the expression for characteristic impedance and propagation constant for it.

10 M

8(b)
A transmission line has a characteristic impedance of 300Ω and terminated n a load Z

i)VSWR

ii) Reflection Coefficient.

iii) Input impedance at a distance 0.1λ from load.

iv) Input admitance from 0.1λ from load.

_{L}= 150+j150Ω. Find the following using smith chart.i)VSWR

ii) Reflection Coefficient.

iii) Input impedance at a distance 0.1λ from load.

iv) Input admitance from 0.1λ from load.

8 M

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