Code: D-07 Jun 2003 Subject: NETWORK AND TRANSMISSION LINES
Time: 3 Hours Max. Marks: 100
NOTE: There are 11 Questions in all.
· Question 1 is compulsory and carries 16 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
· Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.
· Any required data not explicitly given, may be suitably assumed and stated.
Q.1 Choose the correct or best alternative in the following: (2x8)
a. To calculate Thevenin’s equivalent value in a circuit
(A) all independent voltage sources are opened and all independent current
sources are short circuited.
(B) both voltage and current sources are open circuited.
(C) all voltage and current sources are shorted.
(D) all voltage sources are shorted while current sources are opened.
b. A 26 dBm output in watts equals to
(A) 2.4W. (B) 0.26W.
(C) 0.156W. (D) 0.4W.
c. The Characteristic Impedance of a low pass filter in attenuation Band is
(A) Purely imaginary. (B) Zero.
(C) Complex quantity. (D) Real value.
d. The real part of the propagation constant shows:
(A) Variation of voltage and current on basic unit.
(B) Variation of phase shift/position of voltage.
(C) Reduction in voltage, current values of signal amplitude.
(D) Reduction of only voltage amplitude.
e. The purpose of an Attenuator is to:
(A) increase signal strength. (B) provide impedance matching.
(C) decrease reflections. (D) decrease value of signal strength.
f. In Parallel Resonance of :
R – L – C circuit having a R – L as series branch and ‘C’ forming
parallel branch. Tick the correct answer only.
(A) Max Impedance and current is at the frequency that of resonance.
(B) Value of max Impedance = L / (CR).
(C) Branch currents are 180 Degree phase shifted with each other.
(D) 
.
g. In a transmission line terminated by characteristic impedance, Zo
(A) There is no reflection of the incident wave.
(B) The reflection is maximum due to termination.
(C) There are a large number of maximum and minimum on the line.
(D) The incident current is zero for any applied signal.
h. For a coil with inductance L and resistance R in series with a capacitor C has
(A) Resonance impedance as zero.
(B) Resonance impedance R.
(C) Resonance impedance L/CR.
(D) Resonance impedance as infinity.
PART I
Answer any THREE Questions. Each question carries 14 marks.
Q.2 a. State and prove Millman Theorem. (7)
b. Give its applications. (7)
Q.3 a. Design a prototype lowpass filter (L.P.F.),
assuming cut off frequency 
. (7)
b. State advantages of m-derived networks in case of filters. (7)
Q.4 For a series R – L – C circuit in resonance, derive values of ‘Resonant Frequency’, ‘Q’ of the circuit, current and impedance values at resonance.
Give the significance of Q. Why is it called Quality Factor? (14)
Q.5 Write short notes on:
(i) Compensation Theorem.
(ii) Stub matching.
(iii) Star delta conversion. (14)
Q.6 a. What is an Attenuator? Classify and state its applications. (7)
b. Open and short circuit impedances of a transmission line at 1.6 KHz are
900 
and
400 
.
Calculate the characteristic Impedance of
the Line. (7)
PART II
Answer any THREE Questions. Each question carries 14 marks.
Q.7 a. What is Line Loading? Why is it required? State methods of loading a transmission line. (7)
b. Define ‘h’ parameters? Give their application. (7)
Q.8 Design a “Symmetrical Bridge” – T attenuator
having attenuation of 40 dB and design impedance of 600 
.
(14)
Q.9 a. Derive the relationships between Neper and Decibel units. (4)
b. Explain the terms VSWR and Image Impedance. (5)
c. State the relationship between reflection Coefficient ‘K’ and voltage standing wave ratio. (5)
Q.10 a. Explain Poles and Zeros of a network function. (7)
b. Derive equation for resonant Frequency of an antiresonant circuit. (7)
Q.11 a. Define unit step, ramp and impulse function. Derive the Laplace transforms
for these functions. (7)
b. What is convolution in time domain? What is the Laplace transform of convolution of two time domain functions. (7)
JUNE / 2003
Code: D-07 Dec 2003 Subject: NETWORK AND TRANSMISSION LINES
Time: 3 Hours Max. Marks: 100
NOTE: There are 11 Questions in all.
· Question 1 is compulsory and carries 16 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
· Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.
· Any required data not explicitly given, may be suitably assumed and stated.
Q.1 Choose the correct or best alternative in the following: (2x8)
c. Laplace transform of a unit Impulse function is
(A) s. (B) 0.
(C) 
. (D)
1.
b. Millman’s theorem is applicable during determination of
(A) Load current in a network of generators and impedances with two output terminals.
(B) Load conditions for maximum power transfer.
(C) Dual of a network.
(D) Load current in a network with more than one voltage source.
c. Asymmetrical two port networks have
(A) 
(B)
(C) 
(D)
d. An attenuator is a
(A) R’s network. (B) RL network.
(C) RC network. (D) LC network.
e. A pure resistance, 
when connected at
the load end of a loss-less 100 
line produces a VSWR of 2. Then is
(B) 50 only. (B)
200 only.
(C)
50 or
200 . (D)
400 .
f. The reflection coefficient of a transmission line with a short-circuited load is
(A) 0. (B)
.
(C)
. (D)
.
g. All pass filter
(E) passes whole of the audio band.
(F) passes whole of the radio band.
(G) passes all frequencies with very low attenuation.
(H) passes all frequencies without attenuation but phase is changed.
h. A series resonant circuit is inductive at f = 1000 Hz. The circuit will be capacitive some where at
(A) f > 1000 Hz.
(B) f < 1000 Hz.
(C) f equal to 1000 Hz and by adding a resistance in series.
(D) f = 1000+ fo ( resonance frequency)
PART I
Answer any THREE Questions. Each question carries 14 marks.
Q.2 a. State and prove the superposition theorem with the help of a suitable network. (8)
b. Find
the power dissipated in 8 resistor in the circuit shown below
using Thevenin’s theorem.
|
(6)
Q.3 a. Derive the expression for characteristic impedance of a symmetrical Bridged-T-network. (8)
d.
Design an asymmetrical T-network shown below having 
(6)
Q.4 a. Define the h-parameters of a two port network. Draw the h-parameter equivalent circuit. Where are the h-parameters used mostly? (6)
b. Calculate the transmission parameters of the network shown below. Also verify the reciprocity & symmetricity of the network.
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(8)
Q.5 a. Design a symmetrical bridged-T attenuator shown
below use necessary assumptions for simplification.
where 
is
the characterstic impedance and 
is the attenuation constant. (6)
b. In
a symmetrical T-network, if the ratio of input and output power is 6.76.
Calculate the attenuation in Neper & dB. Also design this attenuator
operating between source and load resistances of 1000 . (8)
Q.6 a. What are the disadvantages of the prototype filters? How are they removed in composite filters? (8)
b. Determine
the Laplace transform of the function 
, where 
is a constant. (6)
PART II
Answer any THREE Questions. Each question carries 14 marks.
Q.7 a. Draw the equivalent circuit of a section of transmission line. Explain primary and secondary parameters. (6)
b. Derive the expressions for characteristic impedance and propagation constant of a transmission line. (8)
Q.8 a. Describe various types of losses in a transmission line. How these losses are reduced? (8)
b. Find the image impedances of an asymmetrical-
(pi) network. (6)
Q.9 a. A low-loss coaxial cable of characteristic impedance
of 100 is
terminated in a resistive load of 150 . The peak voltage across the load is
found to be 30 volts. Calculate,
(i) The reflection coefficient of the load,
(ii) The amplitude of the forward and reflected voltage waves and current waves.
(iii) and V.S.W.R. (8)
b. In Laplace domain a function is given by
where 
are constants. Show by initial value
theorem
(6)
Q.10 a. Three series connected coupled coils are shown below in Fig.
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Calculate
(i) The total inductance of these coils.
(ii) The coefficient of coupling between coils 
and 
, coils
&
and coils 
and 
.
It is given that 
(7)
b. It
is required to match 300 load to a 400 transmission line,
to reduce the VSWR along the line to 1.0. Design a quarter-wave transformer
at 100 MHz. (7)
Q.11 a. Check, if the driving point impedance Z (s), given below, can represent a passive one port network.
(i) 
(ii) 
Also specify proper reasons in support of your answer. (8)
b. A network function is given below
Obtain the pole-zero diagram (use graph paper). (6)
DEC./2003
Code: D-07 Jun 2004 Subject: NETWORK AND TRANSMISSION LINES
Time: 3 Hours Max. Marks: 100
NOTE: There are 11 Questions in all.
· Question 1 is compulsory and carries 16 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
· Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.
· Any required data not explicitly given, may be suitably assumed and stated.
Q.1 Choose the correct or best alternative in the following: (2x8)
e. Compensation theorem is applicable to
(A) non-linear networks. (B) linear networks.
(C) linear and non-linear networks. (D) None of the above.
b. Laplace transform of a damped sine wave 
is
(E) 
. (B)
.
(C) 
. (D)
.
c. A network function is said to have simple pole or simple zero if
(A) the poles and zeroes are on the real axis.
(B) the poles and zeroes are repetitive.
(C) the poles and zeroes are complex conjugate to each other.
(D) the poles and zeroes are not repeated.
d. Symmetrical
attenuators have attenuation 
given by
(A)
. (B)
.
(C) 
. (D) 
.
e. The velocity factor of a transmission line
(C) is governed by the relative permitivity of the dielectric.
(D) is governed by the skin effect.
(E) is governed by the temperature.
(F) All of the above.
f.
If is
attenuation in nepers then
(A) attenuation in dB = / 0.8686. (B)
attenuation in dB = 8.686 .
(C)
attenuation in dB = 0.1 . (D) attenuation in
dB = 0.01 .
g. For
a constant K high pass 
-filter, characteristic impedance 
for f < 
is
(I) resistive. (B) inductive.
(C) capacitive. (D) inductive or capacitive.
h. A delta
connection contains three impedances of 60 each. The impedances of equivalent
star connection will be
(E) 15 each. (B)
20 each.
(C) 30 each.
(D) 40 each.
PART I
Answer any THREE Questions. Each question carries 14 marks.
Q.2 a. State the Millman theorem and prove its validity by taking a suitable example. (8)
b. For the network of Figure 1, replace the parallel combination of impedances with the compensation source. (6)
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Q.3 a. State the advantages of using Laplace transform in networks. Give the ‘s’ domain representations for resistance, inductance and capacitance. (7)
f.
Determine the elements of a ‘T’ – section which is equivalent to
a -
section. (7)
Q.4 a. Discuss the characteristics of a filter. (8)
b. Find by convolution integral of the Laplace inverse of 
taking
as first
function and 
as
the second function. (6)
Q.5 a. Find the sinusoidal steady state solution 
for a series RL
circuit. (8)
b. Given two capacitors of 1
each and coil L of 10mH,
Compute the following :
(i) Cut-off frequency and characteristic impedance at infinity frequency for a HPF.
(ii) Cut-off frequency and characteristic impedance at zero frequency for an LPF.
Draw the constructed sections of filters from these elements. (6)
Q.6 Write notes on any TWO of the following :-
(i) Dumped and distributed elements.
(ii) Criteria for stability from pole and zero plot.
(iii) Transmission parameters. (7+7)
PART II
Answer any THREE Questions. Each question carries 14 marks.
Q.7 Define input impedance of a transmission
line. Derive an expression for the input impedance of a line and show that 
for a lossless line
is 
. (14)
Q.8 a. Differentiate between attenuator and amplifier. List the practical applications of attenuators. (6)
b. In a transmission line the VSWR is given as 2.5.
The characteristic impedance is 50 and the line is to transmit a power of
25 Watts. Compute the magnitudes of the maximum and minimum voltage and
current. Also determine the magnitude of the receiving end voltage when load
is 
. (8)
Q.9 Compute the values of resistance, inductance
and capacitance of the series and shunt elements of a ‘T’ network of 10 Km line
having a characteristic impedance of 
ohms and propagation constant of 
per loop Km at a
frequency of 
Draw
the ‘T’ network from the calculated values. (14)
Q.10 a. Explain the terms Image impedance and Insertion loss. (6)
b. Explain the basis for construction of Smith chart. Illustrate as to how it can be used as an admittance chart. (8)
Q.11 a. What is resonance? Why is it required in certain electronic circuits? Explain in detail. (6)
b. Design an unbalanced - attenuator with loss of 20 dBs to
operate between 200 ohms and 500 ohms. Draw the attenuator. (8)
JUNE/2004
Code: D-07 Dec 2004 Subject: NETWORK AND TRANSMISSION LINES
Time: 3 Hours Max. Marks: 100
NOTE: There are 11 Questions in all.
· Question 1 is compulsory and carries 16 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
· Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.
· Any required data not explicitly given, may be suitably assumed and stated.
Q.1 Choose the correct or best alternative in the following: (2x8)
g. Which one of the following is a passive element?
(A) A BJT. (B) An Inductor.
(C) A FET. (D) An Op-amp.
b. Millman theorem yields
(F) equivalent resistance of the circuit.
(G) equivalent voltage source.
(H) equivalent voltage OR current source.
(I) value of current in milliamperes input to a circuit from a voltage
source.
c. The z-parameters of the shown T-network at Fig.1 are given by
|
(A) 5, 8, 12, 0
(B) 13, 8, 8, 20
(C) 8, 20, 13, 12
(D) 5, 8, 8, 12
d. To a highly inductive circuit, a small capacitance is added in series. The angle between voltage and current will
(A) decrease. (B) increase.
(C) remain nearly the same. (D) become indeterminant.
e. The equivalent inductance of
Fig.2 at terminals 
is equal to
(G) 
(H) 
(C) 
(D) 
f. The
characteristic impedances 
of a transmission line is given by,
(where R, L, G, C are the unit length parameters)
(A) 
(B) 
(C)
(D)
g. The relation between
for the given symmetrical lattice
attenuator shown in Fig.3 is
(J) 
(K) 
(L) 
(M) 
h. If Laplace transform of x(t) = X(s), then Laplace transform of x(t-t0) is given by
(F) 
(B)
(C) 
(D)
PART I
Answer any THREE Questions. Each question carries 14 marks.
Q.2 a. The
current in a conductor varies according to the equation 
Find the total charge in coulomb that passes through the conductor. (7)
b. A
current I = 10t A flows in a condenser C of value 10 
. Calculate the voltage,
charge and energy stored in the capacitor at time t= 1 sec. (7)
Q.3 a. Define Laplace transform of a time function x(t) u(t). Determine Laplace transforms for
(i) 
(the impulse function)
(ii) u(t) (the unit step function)
(iii) tn eat, n +ve integer (7)
h. Find the Inverse Laplace transform for
(i) 
(ii) 
(3+4)
Q.4 For the circuit shown, at Fig.4 the switch K is closed at t=0. Initially the circuit is fully dead (zero current and no charge on C). Obtain complete particular solution for the current i(t). (14)
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Q.5 a. Derive necessary and sufficient condition for
maximum power transfer from a voltage source, with source impedance 
, to a load 
. What is the value
of the power transferred in this case? (7)
b. By using Norton’s theorem, find the current in
the load resistor
for
the circuit shown in Fig. 5. (7)
Q.6 a. Differentiate between Bilateral and Unilateral elements with suitable examples. (7)
b. Determine
the ABCD parameters for the -network shown at Fig.6. Is this network
bilateral or not? Explain. (7)
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PART II
Answer any THREE Questions. Each question carries 14 marks.
Q.7 a. Determine the relationship between y-parameters and ABCD parameter for 2-Port networks. By using these relations determine y-parameters of circuit given in Fig.7 and then deduce its ABCD parameters. (7)
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b. What is the significance of poles and zeros in
network functions. What is the criteria of stability of a network? For the
transform current 
, plot its poles and zeros in s-plane
and hence obtain the time domain response. (7)
Q.8 Solve the differential equation given below and determine the steady state solutions.
(i)
(ii) 
(7+7)
Q.9 Determine the condition for resonance for the
parallel circuit as shown in Fig.8. Determine it’s
(i) resonant frequency 
(3)
(ii) impedance z (j
) at (3)
(iii) half power bandwidth (4)
(iv) quality factor of the circuit. (4)
Q.10 a. For the case of distributed parameters, determine the expressions for:
(i) Characteristic impedance ()
(ii) Propagation constant (
)
(iii) Attenuation and phase constants 
(7)
b. A
transmission line is terminated by an impedance 
. Measurements on the line show that
the standing wave minima are 105 cm apart and the first minimum is 30 cm from
the load end of the line. The VSWR is 2.3 and is 300 . Find the value of 
. (7)
Q.11 Write short notes on any TWO of the following:
a. Low-pass filter and its approximation/design.
b.
T and - attenuators.
c. Single stub matching in transmission line.
d. H-parameters, its relations with z-parameters and y-parameters. (2x7=14)