EC6503 - Transmission lines and Waveguides Question bank with Anna University questions

1. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 1
EC6503 – TRANSMISSION LINES AND WAVEGUIDES
QUESTION BANK
UNIT IV - FILTERS
PART A
1. A constant-k T section high pass filter has a cut off frequency of 10 KHz. The design
impedance is 600 ohms. Determine the value of L.
(Nov/Dec 2016, Apr/May 2017(R8), May/June 2013)
2. Define propagation constant of a transmission line.
(Nov/Dec 2016, Apr/May 2017(R8), Nov/Dec 2012)
3. What are the major drawbacks of a constant-k prototype filter?
(Apr/May 2017(R13), May/June 2016 (R13), Dec/Jan 2016, Apr/May 2015,
May/June 2012)
4. Sketch an m-derived band pass section. (Apr/May 2017(R13))
5. Why a composite filter is designed and what are the sections of a composite filter?
(May/June 2016 (R13))
6. Determine the value of L required by a constant-k T-section high pass filter with a cut
off frequency of 1 KHz and design impedance of 600Ω.
(Nov/Dec 2015 (R13), Nov/Dec 2013)
7. What are the advantages of m-derived filters?
(Nov/Dec 2015 (R13)), May/June 2014, Nov/Dec 2013)
8. What is constant-k filter? Why it is called prototype filter section?
(Nov/Dec 2014(R8))
9. A prototype LPF is to be designed which must have Ro = 600Ω, fc = 1 KHz. Find filter
elements [L and C]. (Nov/Dec 2014(R8))
10.Determine the value of L required by a constant-k T-section high pass filter with a cut
off frequency of 1.5 KHz and design impedance of 500Ω. (May/June 2014(R8))
11.A constant-k T section high pass filter has a cut off frequency of 10 KHz. The design
impedance is 600 ohms. Determine the value of L. (May/June 2013(R8))
12.Write the relationship between neper and decibel. (May/June 2012(R8)))
PART B
1. What is m-derived filter? Draw a m-derived T-section and π section low pass filter and
explain the analysis of m-derived low pass filter with respect to attenuation, phase
shift and characteristic impedance with frequency profile respectively.(16m)
(Nov/Dec 2016(R13))
2. What is composite filter? Design a constant-K low pass filter (T and π section) and
having cut-off at which 2.5 KHz and design resistance R0 is 700Ω. Also find the

2. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 2
frequency at which this filter produces attenuation of 19.1 dB. Find its characteristic
impedances and phase constant at pass band and stop or attenuation band.(16m)
(Nov/Dec 2016(R13))
3. (a) Derive the design equations of a constant-k low pass filter.(8m)
(b) A π section filter network consists of series arm inductance of 20mH and two shunt
capacitor of 0.16 µF each. Calculate the cut off frequency, attenuation and phase shift
at 15 KHz. What is the value of nominal impedance in the pass band? (8m)
(May/June 2016 (R13))
4. Design a low pass composite filter to meet the specifications fc = 2000 Hz, f∞ = 2050
Hz, Rk = 500Ω. (16m) (May/June 2016 (R13))
3. (a) Explain the operation and design of constant-k T-section band elimination filter
with necessary equations and diagrams.(8m)
(b) Design a constant-k band pass filter (both π and T sections) having a design
impedance of 600Ω and cut off frequencies of 1KHz and 4KHz.(8m)
(Nov/Dec 2015 (R13), Nov/Dec 2013)
4. (a) Design an m-derived T-section low pass filter having cut off frequency of 1 KHz.
Design impedance is 400Ω and the resonant frequency is 1100Hz (4m)
(Nov/Dec 2013(R8))
(b) Derive the equations for the characteristic impedance of symmetrical T and π
networks. (6m)
(c) Discuss the properties of symmetrical network in terms of characteristic impedance
and propagation constant. (6m) (Nov/Dec 2015 (R13))
5. (a) Derive the expressions for the characteristic impedance of symmetrical T and π
networks. (12m)
(b) Bring out the relationship between decibel and Neper (4m)
(Dec/Jan 2016, May/June 2013)
6. Derive and draw the m-derived T and π section for low pass and high pass filter.
(16m) (Apr/May 2015(R8))
7. Derive characteristic impedance, inductance, capacitance and cut off frequency for
constant-k low pass and constant-k high pass filters, also draw their reactance curves.
(16m) (Apr/May 2015(R8))
8. Design a constant-k band pass filter deriving expressions for the circuit components. A
constant- k high pass filter cuts off at the frequency of 2300 Hz. The load resistance is
500Ω. Calculate the values of the components used in the filter.(16m)
(Nov/Dec 2014(R8))
9. Design a composite high pass filter to operate into a load of 600Ω and have a cut off
frequency of 1.2 KHz. The filter is to have one constant-k section, one m- derived
section with f∞=1.1 KHz and suitably terminated half section. Discuss the merits and
demerits of m-derived filter and crystal filter.(16m) (Nov/Dec 2014(R8))

3. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 3
10. (a) Draw and explain the design and operation of m-derived T-section and pass filter
with necessary equations and diagrams.(8m)
(b) Design constant-k band stop filters (both π and T sections) for the cut off
frequencies of 2 KHz and 6 KHz. The design impedance is 500 Ω. (8m)
(May/June 2014(R8))
11.Design an m-derived low pass filter with a cut off frequency of 2 KHz. Design
impedance is 500Ω and m = 0.4. Consider a π section for your calculation. (8m)
(May/June 2014(R8))
12. Obtain the design equations for m-derived
i. Band pass filters
ii. Band elimination filters (May/June 2013(R8))
13.(a) Explain the properties and characteristic impedance of symmetrical networks. (6m)
(b) Design T and π section low pass filter which has series inductance 80mH and shunt
capacitance 0.022µF. Find the cut off frequency and design impedance (10m)
(Nov/Dec 2012(R8))
14.What are the advantages of m-derived filters? Design an m-derived low pass filter (T
and π section) having design resistance R0=500Ω, cut off frequency fc = 1500Hz and
infinite attenuation frequency f∞.(16m) (Nov/Dec 2012(R8))
15.(a) Calculate the value of inductor and capacitor of a prototype constant k low pass
filter composed of π section to operate with a terminating load of 600 ohms and to
have cut off frequency of 3 KHz. (8m)
(b) Construct a band stop constant-k filter. (8m) (May/June 2012(R8))

4. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 4
UNIT I – TRANSMISSION LINE THEORY
PART A
1. A transmission line has Z0 = 745∟120
Ω and is terminated in ZR = 100 Ω. Calculate
the reflection factor. (Apr/May 2017(R13))
2. Define Smooth line. (Apr/May 2017(R13))
3. Write the need of inductance loading of telephone cables.
(Apr/May 2017(R8), Nov/Dec 2013(R8))
4. A transmission line has a characteristic impedance of 400Ω and is terminated by a
load impedance of (650-j475) Ω. Determine the reflection coefficient.
(Apr/May 2017(R8), May/June 2014(R8), Nov/Dec 2013(R8))
5. What is meant by distortionless line? (Nov/Dec 2016(R13), Nov/Dec 2015(R13))
6. Find the characteristic impedance of a line at 1600 Hz if ZOC = 750∟-300
Ω and ZSC =
600-∟200
Ω. (Nov/Dec 2016(R13))
7. A lossless transmission line has a shunt capacitance of 100 pF/m and a series
inductance of 4 µH/m. Calculate the characteristic impedance. (May/June 2016 (R8))
8. A transmission line has a characteristic impedance of 300 Ω and is terminated in a
load of (150 + j150) Ω. Calculate the reflection coefficient. (May/June 2016 (R8))
9. What is Characteristic impedance? (May/June 2016 (R13), May/June 2013(R8))
10.Define Reflection loss? (May/June 2016 (R13))
11.Find the reflection coefficient of a 50 Ω transmission line when it is terminated with
the load impedance of 60+j40Ω. (Nov/Dec 2015(R13), May/June 2013(R8))
12.What is the drawback of using ordinary telephone cables? (Apr/May 2015(R8))
13.Define the term insertion loss. (Apr/May 2015(R8), May/June 2014(R8))
14.Define the wavelength of the line. (Nov/Dec 2014(R8))
15.What is the significance of reflection coefficient? (Nov/Dec 2014(R8))
16.At a frequency of 80MHz, a lossless transmission line has a characteristic impedance
of 300Ω and a wavelength of 2.5m. Find L and C. (Nov/Dec 2012(R8))
17.Draw the equivalent circuit of a unit length of a transmission line.(May/Jun2012(R8))
18.What is meant by infinite line? (May/June 2012(R8))
PART B
1. (a) Discuss the general solution of a transmission line in detail.(10m)
(Or) Obtain the expression for current and voltage at any point along a line which is
terminated in Z0.
(May/June 2016 (R13), Apr/May 2015(R8), Nov/Dec 2014(R8), May/June
2014(R8), Nov/Dec 2013(R8), May/June 2013(R8), May/June 2012(R8))
(b) A generator of 1.0 volt, 1000 cycles, supplies power to a 100 mile open wire line
terminated in Z0 and having the following parameters: Series resistance R = 10.4

5. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 5
Ω/mile, Series inductance L = 0.00367 H/mile, Shunt Capacitance G= 0.8 x 10-6
mhos/mile and capacitance between conductors C = 0.00835 x 10-6
F/mile. Find the
characteristic impedance, propagation constant, attenuation constant, phase shift
constant, velocity of propagation and wavelength.(also find the received power) (6m)
May/June 2016 (R13), (May/June 2012(R8)), (Apr/May 2017(R13)
2. (a) Discuss in detail about lumped loading and derive the Campbell’s equation. (8m)
(b) A 2 meter long transmission line with characteristic impedance of 60+j40 Ω is
operating at ω = 106
rad/sec has attenuation constant of 0.921 Np/m and phase shift
constant of 0 red/m. If the line is terminated by a load of 20+j50Ω, determine the input
impedance of this line. (8m) (Apr/May 2017(R13), Nov/Dec 2015(R13))
3. Prove that an infinite line equal to finite line terminated in its characteristic
impedance. (6m) (May/June 2016 (R13))
4. (a) Explain in detail about the reflection on a line not terminated by its characteristic
impedance Z0. (8m) (May/June 2013(R8), Nov/Dec 2012(R8))
(b) Derive the condition for minimum attenuation in a distortionless line. (8m)
((Nov/Dec 2016(R13))
5. A Communication line has L = 3.67 mH/Km, G = 0.08 x 10-6 mhos/km, C = 0.0084
µF/km and R = 10.4 ohms/km. Determine the characteristic impedance, propagation
constant, velocity of propagation, sending end current and receiving end current for
given frequency of f = 1000 Hz, Sending end voltage is 1 volt and transmission line
length is 100 kilometers.(16m) ((Nov/Dec 2016(R13))
6. (a) Explain in detail about the waveform distortion and also derive the condition for
distortionless line.(10m) (May/June 2013(R8))
(b) Derive the expressions for the input impedance of open and short circuited
lines.(6m) (Nov/Dec 2015(R13), Nov/Dec 2012(R8), May/June 2012(R8))
7. (a) A parallel wire transmission line is having the following parameters at 5KHz.
Series resistance (R = 2.59 x 10-3
Ω/m), Series inductance (L = 2µH/m) , Shunt
Conductance (G = 0 mho/m) and capacitance between conductors (C = 5.66 nF/m).
Find the characteristic impedance, attenuation constant, Phase shift constant, velocity
of propagation and wavelength. (10m) (Nov/Dec 2015(R13))
8. A telephone cable 64 km long has a resistance of 13 Ω/km and a capacitance of 0.008
µF/km. Calculate attenuation constant, velocity, and wavelength of the line at 1000
Hz. (6m) (Apr/May 2015(R8))
9. (a) Explain about different types of transmission line (8m)
(b) Discuss the following: Reflection loss and Return loss (8m)
(Apr/May 2015(R8))
10.For a transmission line terminated in Z0, prove that 𝑍0 = √ 𝑍 𝑂𝐶 𝑍𝑆𝐶 . The following
measurements are made on a 25km line at a frequency of 796 Hz. ZSC = 3220∟-79.290
Ω, ZOC = 1301∟76.670
Ω. Determine the primary constants of the line.

6. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 6
(Nov/Dec 2014(R8))
11.(a) What are the types of waveform distortion introduced by a transmission line?
Derive the conditions for the distortionless operation of a transmission line. (10m)
(Nov/Dec 2013(R8))
(b) The constants of a transmission line are R = 6 Ω/km, L = 2.2 mH/km, C = 0.005
µF/km, G = 0.25 x 10-3
mhos/km. Calculate the attenuation constant (α) and phase
constant (β) at 1000 Hz. (6m) (May/June 2014(R8))
12.A transmission line has a characteristic impedance of (683-j138)Ω. The propagation
constant is (0.0074+j0.0356)Ω per km. Determine the values of R and L of this line if
the frequency is 1000 Hz. (6m) (May/June 2014(R8))
13.A transmission line has L = 10 mH/m, C = 10-7
F/m, R = 20 Ω/m and G = 10-5
mhos/m. Find the input impedance at a frequency of (
5000
2𝜋
)Hz if the line is very
long.(6m) (Nov/Dec 2013(R8))
14.The characteristic impedance of a uniform transmission line is 2309.6 Ω at 800 Hz. At
this frequency the propagation constant is 0.054(0.0366+j0.999) per/km. Determine R
and L. (6m) (Nov/Dec 2013(R8))
15.A cable has the following parameters:
R = 48.75 ohm/km, L = 1.09 mH/km, G = 38.75 µmho/km, C = 0.059 µF/km.
Determine the characteristic impedance, propagation constant, and wavelength for a
source of f = 1600 Hz and ER = 1V. (May/June 2013(R8))
Explain the concept of reflection on a line not terminated in its characteristic
impedance, Z0. (May/June 2013(R8))
16.Explain the condition for distortionless line. Characteristic impedance for a
transmission line at 8MHz is (40-2j) ohm and the propagation constant is (0.01 +
j0.18) per meter. Find the primary constants.(16m) (Nov/Dec 2012(R8))

7. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 7
UNIT II – HIGH FREQUENCY TRANSMISSION LINES
PART A:
1. Define Standing Wave Ratio. (May/June 2013(R8), (Apr/May 2017(R13))
2. A Lossless line has a characteristic impedance of 400Ω. Determine the standing wave
ratio if the receiving end impedance is 800+j0.0Ω (Apr/May 2017(R13))
3. Express standing wave ration in terms of a reflection coefficient. (Apr/May 2017(R8))
4. Write the expression for input impedance of open and short circuited dissipation less
line. (Nov/Dec 2016(R13))
5. Calculate standing wave ratio and reflection coefficient on a line having the
characteristic impedance Z0 = 300Ω and terminating impedance in ZR = 300+j400Ω.
(Nov/Dec 2016(R13))
6. A transmission line has a characteristic impedance of 300Ω and is terminated in a load
of (150+j150) Ω. Calculate the reflection coefficient. (May/Jun 2016(R8))
7. What is meant by a dissipationless line? (May/Jun 2016(R8))
8. What are the assumptions to simplify the analysis of line performance at high
frequencies? (May/Jun 2016(R13))
9. Write the expression for standing wave ratio in terms of reflection coefficient?
(May/Jun 2016(R13))
10.Write the expression for VSWR in terms of
i. The reflection coefficient
ii. VSWR in terms of ZL and Z0. (Nov/Dec 2012(R8), (Nov/Dec 2015(R8))
11.What is the significance of Reflection coefficient? (Nov/Dec 2015(R8))
12.How will you make standing wave measurements on coaxial line?
(Apr/May 2015(R8))
13.Define the term insertion loss. (May/Jun 2014(R8), (Apr/May 2015(R8))
14.List the parameters of open wires at high frequencies. (Nov/Dec 2014(R8))
15.A line having the characteristic impedance of 50 ohms is terminated in load impedance
(75+j75)Ω. Determine the reflection coefficient. (Nov/Dec 2014(R8))
16. Give the equations for the characteristic impedance and propagation constant of a
dissipationless line. (May/Jun 2014(R8))
17.A loss transmission line has a characteristic impedance of 400Ω and is terminated by a
load impedance of (650 – j475)Ω. Determine the reflection coefficient.
(Nov/Dec 2013(R8))
18.Write the conditions to be satisfied by a dissipationless line. (Nov/Dec 2013(R8))
19.Find the reflection coefficient of a 50 ohm transmission line when it is terminated by a
load impedance of 60+j40ohms. (May/June 2013(R8))
20.Write the relationship between SWR and reflection coefficient.
(May/Jun 2012(R8))

8. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 8
PART B:
1. Discuss in detail about the voltages and currents on the dissipation less line.(16m)
(Apr/May 2017(R13))
2. (i) Derive the expression that permit easy measurements of power flow on a line of
negligible losses.
(ii) A radio frequency line with Z0 = 70Ω is terminated by ZL = 115 – j80Ω at λ = 2.5
m. Find the VSWR and the maximum and minimum line impedances.
(Apr/May 2017(R13))
3. Derive an expression for the input impedance of dissipation less lines. Deduce the
input impedance of open and short circuited dissipation less lines.(10m)
(Nov/Dec 2013(R8)), May/Jun 2014(R8),Apr/May 2017(R8))
4. (i) Describe an experimental setup for the determination of VSWR of RF
transmission.(8m)
(ii) Briefly explain on:
(a) Standing Waves
(b) Reflection losses (Nov/Dec 2016(R13))
5. (a) Derive an expression for the input impedance of a dissipationless line and also find
the input impedance is maximum and minimum at a distance ‘s’.(8m)
(b) Find the sending end impedance for a HF line having the characteristic impedance
of 50Ω. The line of length (1.185λ) and is terminated in a load of (110+j80)Ω. (8m)
(Nov/Dec 2016(R13))
6. (i) Derive the line constants of a zero dissipationless line.
(ii) A line with zero dissipation has R= 0.006 Ω/m, C = 4.45 pF/m and L = 2.5 µH/m.
if the line is operated at 10MHz, find R0, α, β, λ, v. (May/Jun 2016(R13))
7. (i) Discuss in detail about the variation of input impedance along with open and short
circuit lines with relevant graphs.
(ii) A lossless line has a standing wave ratio of 4. The R0 is 150 ohms and the
maximum voltage measured in the line is 135V. Find the power delivered to the load.
(May/Jun 2016(R13))
8. Explain the parameters of open wire line and coaxial cable at RF. Mention the
standard assumptions made for radio frequency line.
(Nov/Dec 2014(R8), (Nov/Dec 2015(R8))
9. (i) Explain about different types of transmission line.(8m)
(ii) Discuss the following: reflection loss and return loss. (8m)
(Apr/May 2015(R8), (Nov/Dec 2015(R8), (Nov/Dec 2014(R8))
10.Write a brief note on impedance measurement of transmission line.
(May/Jun 2014(R8))
11.A 30 m long lossless transmission line with Z0 = 50 Ω operating at 2 MHz is
terminated with a load ZL = 60 + 40j Ω. If U = 0.6C on the line, find

9. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 9
a. Reflection coefficient (5m)
b. Standing wave ratio (5m)
c. Input impedance (6m) (Nov/Dec 2012(R8))
12.A low loss transmission line of 100 ohms characteristic impedance is connected to a
load of 200ohm. Calculate the voltage reflection coefficient and the standing wave
ratio. (May/Jun 2012(R8))
13.Discuss the theory of open and short circuited lines with voltage and current
distribution diagram and also get the input impedance expression.
(May/Jun 2012(R8))

10. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 10
UNIT III – IMPEDANCE MATCHING IN HIGH FREQUENCY LINES
PART A:
1. List the applications of a Quarter-wave line.
(Apr/May 2017(R13), Apr/May 2017(R8)))
2. Why a short circuited stud is ordinarily preferred to an open circuited stub?
(Apr/May 2017(R13))
3. Give the applications of eight wave line. (Nov/Dec 2015(R13),Nov/Dec 2016(R13))
4. Distinguish between Single stub and Double stub matching in a transmission line.
(Nov/Dec 2015(R13)),Nov/Dec 2016(R13))
5. Mention the drawbacks of single stub matching.
(May/Jun 2012(R8), May/Jun 2014(R8), May/Jun 2016(R8))
6. Why a quarter wave line is considered as a impedance inverter? Justify.
(May/Jun 2016(R13))
7. What is a stub? Why it is used between transmission lines? (May/Jun 2016(R13))
8. List the applications of smith chart. (Apr/May 2015(R8))
9. Design a quarterwave transformer to match the load of 200Ω to a source resistance
500Ω. The operating frequency is 200 MHz. (May/Jun 2013(R8))
10.Mention the significance of λ/4 line. (Nov/Dec 2012(R8))
PART B:
1. A 300Ω transmission line is connected to a load impedance of 450-j600Ω AT 10MHz.
Find the position and length of a short circuited stub required to match the line using
smith chart. (16m).(Nov/Dec 2015(R13), Apr/May 2017(R13), Apr/May 2017(R8)))
2. (i) A Load impedance of 90-j50Ω is to be matched to a line of 50Ω using single stub
matching. Find the length and position of the stub. (10m)
6. (ii) Design a quarter wave transformer to match a load of 200Ω to a source resistance
of 500Ω. The operating frequency is 200 MHz (6m)
(May/Jun 2016(R13), (Apr/May 2017(R13))
3. Discuss the principle of double stub matching with neat diagram and expressions.
(May/Jun 2014(R8), Nov/Dec 2015(R13), Apr/May 2017(R8))
4. (i) Determine the length and location of a single short circuited stub to produce an
impedance match on a transmission line with characteristic impedance of 600Ω and
terminated in 1800Ω. (8m)
(ii) Explain the operation of quarter wave transformer and mention its important
applications. (8m) (Nov/Dec 2016(R13))
5. (i) Find the sending end impedance of the line with negligible losses when
characteristic impedance is 115+j75Ω, length of the line is 1.183 wavelengths by using
smith chart. (10m)

11. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 11
(ii) Explain the significance of smith chart and its application in a transmission line.
(6m)
7. A line having the characteristic impedance of 50Ω is terminated in load impedance [75
+ j75] Ω. Determine the reflection coefficient and voltage standard wave ratio.
Mention the significance and application of smith chart.
(Nov/Dec 2014(R8)),Nov/Dec 2015(R8))
8. (i) Prove that the input impedance of a quarterwave line is Zin = R02
/ZR.
(May/Jun 2016(R13))
9. (i) What is quarter wave line?
(ii) A 75Ω lossless transmission line is to be matched with a 100-j80 Ω load using
single stub. Calculate the stub length and its distance from the load corresponding to
the frequency of 30 MHz using smith chart. (Nov/Dec 2015(R13))
10.(i)Discuss the applications of quarter wave line.
(ii) Design a single stub match for a load of 150 + j225 ohms for a 75 ohms line at 500
MHz using smith chart. (Apr/May 2015(R8))
11.Explain double stub matching on a transmission line and derive the expression and
length of the stub used for matching on a line. (Apr/May 2015(R8))
12.A single stub is to match a 300Ω line to a load of (180 + j120)Ω. The wavelength is 2
meters. Determine the shortest distance from the load to the stub location and proper
length of the short circuited stub using the relevant formula. (May/Jun 2014(R8))
13.A lossless line in air having a characteristic 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.
(Nov/Dec 2013(R8))
14. A 300Ω transmission line is connected to a load impedance of (450 + j600)Ω at 10
MHz. Find the position and length of the short circuited stub required to match the line
using smith chart. (Nov/Dec 2013(R8))
15.Design a single stub matching network (use smith chart) for a transmission line
functioning at 500 MHz terminated with a load impedance ZL = 300 + j250 ohms with
a characteristic impedance Z0 = 100 ohms. Use short circuited shunt stubs. Determine
VSWR before and after connecting the stubs. (May/Jun 2013(R8))
16.The input impedance of a λ/8 long 50Ω transmission line are Z1 = 25 + j100Ω, Z2 =
10 – j50Ω, Z3 = 100 + j0Ω, and Z4 = 0 + j50Ω, when various load impedances are
connected at the other end. In each case, determine the load impedance and the
reflection coefficient at the input and load ends. (May/Jun 2013(R8))
17.Discuss the following
a. Impedance Matching
b. Single and Double stub matching. (Nov/Dec 2012(R8))

12. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 12
18.(i) An ideal lossless transmission line of characteristic impedance 60Ω is terminated in
a load impedance ZL. Give the value of input impedance of a line when ZL = 0, ∞, and
60Ω.
(ii) Write the concept of single and double stub matching. (May/Jun 2012(R8))
19. A 100 ohm, 200 m long lossless line operates at 10 MHz and is terminated to an
impedance of 50 – j200 ohm, the transit time is 1µs. Determine the length and location
of the short circuited stub line. (May/Jun 2012(R8))

13. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 13
UNIT V – WAVEGUIDES AND CAVITY RESONATORS
PART A:
1. Calculate cut off frequency of a rectangular waveguide whose inner dimensions are a =
2.5 cm and b = 1.5 cm operating at TE10 mode. (Apr/May 2017(R13)
2. Enumerate the parameters describing the performance of a cavity resonator
(Apr/May 2017(R13))
3. A rectangular waveguide with a 5 cm x 2 cm cross is used to propagate TM11 mode at
10 GHz. Determine the cut off wavelength.
(Nov/Dec 2014(R8), Apr/May 2017(R8), Nov/Dec 2015(R13))
4. Mention the application of resonant cavities. (Nov/Dec 2014(R8), Apr/May 2017(R8))
5. A wave is propagated in the dominant mode in a parallel plane waveguide. The
frequency is 6 GHz and the plane separation is 4 cm. Calculate the cut-off wavelength
and the wavelength in the waveguide. (Apr/May 2017(R8))
6. Write the applications of cavity resonators. (Nov/Dec 2013(R8),Nov/Dec 2015(R13))
7. What are the dominant mode and degenerate modes in rectangular waveguides?
(Apr/May 2015(R8))
8. Justify, why TM01 and TM10 modes in rectangular waveguide do not exist.
(Nov/Dec 2016(R13))
9. An air-filled rectangular waveguide for inner dimensions 2.286 x 1.016 in centimetres
operates in the dominant TE10 modes. Calculate the cut-off frequency and phase
velocity of a wave in the guide at a frequency of 10GHz. (Nov/Dec 2016(R13))
10.What are the characteristics of TEM waves? (Apr/May 2015(R8))
11.A Rectangular waveguide has the following dimensions l = 2.54 cm, b = 1.27 cm, and
thickness = 0.127 cm. Calculate the cut off frequency for TE11 mode.
(Apr/May 2015(R8))
12.State the significance of dominant mode of propagation. (Nov/Dec 2014(R8))
13.What are the advantages and applications of cylindrical waveguides?
(May/Jun 2014(R8))
14.Mention the different types of guide termination. (May/Jun 2014(R8))
15.A wave is propagated in a parallel plane waveguide. The frequency is 6Ghz and the
plane separation is 3 cm. Determine the group and phase velocities for dominant mode.
(Nov/Dec 2013(R8))
16.Define TEM waves. (Nov/Dec 2013(R8))
17.A rectangular waveguide with a = 7 cm, and b = 3.5 cm is used to propagate TM10 at
3.5 GHz. Determine the guided wavelength. (Nov/Dec 2013(R8))
18.What is degenerate mode in a rectangular waveguide? (May/Jun 2013(R8))
19.State the characteristics of TEM waves. (May/Jun 2013(R8))
20.Write Bessel’s function of first kind of order zero. (May/Jun 2013(R8))

14. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 14
21.Compare TE and TM mode. (Nov/Dec 2012(R8))
22.What is the dominant TE and TM mode in rectangular waveguide?
(Nov/Dec 2012(R8))
23.How to design an air filled cubical cavity to have its dominant resonant frequency at 3
GHz? (Nov/Dec 2012(R8))
24.Write Maxwell’s equations? (May/Jun
2012(R8))
25.What is meant by dominant mode? What is the dominant mode for parallel plate wave
guide? (May/Jun 2012(R8))
26.Write the expression for the wave impedance and guide wavelength for TEM mode?
(May/Jun 2012(R8))
27.What is the dominant mode of a rectangular waveguide? Why? (May/Jun 2012(R8))
PART B:
1. Derive the field components of Transverse Electric wave in rectangular waveguide.
(16m) (Apr/May 2017(R13))
2. When dominant mode is transmitted through a circular waveguide, the wavelength
measured is to be 13.33 cm. The frequency of the microwave signal is 3.75 GHz.
Calculate the cut off frequency, inner radius of the guide, phase velocity, phase
constant, wave impedance, bandwidth for operation in dominant mode only. (16m)
(Apr/May 2017(R13))
3. A Rectangular waveguide with dimensions a = 2.5 cm, b = 1cm is to operate below 15
GHz. How many TE and TM modes can the waveguide transmit if the guide is filled
with a medium characterized by σ = 0, ϵ = 4ϵ0, µr = 1? Calculate the cut off frequencies
of the modes.(16m) (Apr/May 2017(R8))
4. Explain in detail
i. Excitation of Waveguides (8m)
ii. Resonant Cavities (8m) (Apr/May 2017(R8))
5. Derive an expression for the transmission of TE waves between parallel perfectly
conducting planes for the field components. (Nov/Dec 2016(R13))
6. (i) Write a brief note on circular cavity resonator and its applications.
(ii) A TE11 wave is propagating through a circular waveguide. The diameter of the guide
is 10 cm and the guide is air filled. Given X11 = 1.842.
a) Find the cut off frequency
b) Find the wavelength λg in the guide for a frequency of 3 GHz.
c) Determine the wave impedance in the guide. (Nov/Dec 2016(R13))
7. Discuss the characteristics of TE and TM waves and also derive the cut off frequency
and phase velocity from the propagation constant.
(May/Jun 2013(R8), Apr/May 2015(R8))

15. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 15
8. A rectangular air filled copper waveguide with a α = 2.28 cm and b = 1.01 cm cross
section and l = 30.48 cm is operated at 9.2 GHz with a dominant mode. Find the cut off
frequency, guide wavelength, phase velocity and characteristic impedance.
(Nov/Dec 2014(R8))
9. Explain the principles of the following
i. Excitation of Waveguides
ii. Guide termination and resonant cavities (Nov/Dec 2014(R8))
10.Discuss the transmission of TM waves between parallel perfectly conducting planes
with necessary expressions for the field components. Discuss the characteristics of TE
and TM waves between the parallel planes. (May/Jun 2014(R8))
11.(i) Describe the propagation of TE waves in a rectangular waveguide with necessary
expressions for the field components.(10m)
(ii) An air filled rectangular waveguide of dimensions a = 6 cm and b = 4 cm operates in
the TM11 mode. Find the cut off frequency, guide wavelength and phase velocity at a
frequency of 3 GHz.(6m) (Nov/Dec 2013(R8),May/Jun 2014(R8))
12.(i) Describe the principle and operation of the rectangular cavity resonator with relevant
expressions.(10m)
(ii) Give a brief note on excitation of modes in rectangular waveguides. (6m)
(May/Jun 2014(R8))
13.(ii) An air filled rectangular waveguide of dimensions a = 4 cm and b = 3 cm operates in
the TM11 mode. Find the cut off and characteristic wave impedance at a frequency of 9
GHz.(4m) (Nov/Dec 2013(R8))
14.(i)Explain briefly the propagation of TM waves in a circular waveguide with necessary
expressions for the field components.(10m)
(ii) Give a brief note on excitation of modes in rectangular waveguides.
(Nov/Dec 2013(R8))
15.Derive the expression for the field strengths of TE waves between a pair of perfectly
conducting planes of infinite extent in the Y and Z directions. The plates are separated
in X direction by ‘a’ meter. (May/Jun 2013(R8))
16.A pair of parallel perfectly conducting planes is separated by 7 cm in air and carries a
signal with frequency of 6 GHz in TE1 mode. Find
i. Cut off frequency
ii. Phase constant
iii. Attenuation constant and phase constant for f = 0.8fc
iv. Cut off wavelength (May/Jun 2013(R8))
17.Derive the expression for the field components of TE and TM waves in a circular
waveguide.(16m) (May/Jun 2013(R8))
18.(i) A rectangular cavity resonator excited by TE101 mode at 20 GHz has the dimensions
a =2 cm, b = 1 cm. Calculate the length of the cavity.(8m)
(ii)With neat diagrams, explain the concepts of excitation of modes.(8m)

16. R. Beulah Merlin, AP/ECE,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY Page 16
(May/Jun 2013(R8))
19. Explain the concept of transmission of TM waves and TEM waves between parallel
plates.
(Nov/Dec 2012(R8))
20.Derive the field expression for TM wave propagation in rectangular waveguide stating
the necessary assumptions. (Nov/Dec 2012(R8))
21.(i) Explain the concept of excitation of waveguides. (8m)
(ii) Discuss the structure, advantage and disadvantage of resonant cavities. (8m)
(Nov/Dec 2012(R8))
22.(i) Discuss the characteristics of TM waves in circular waveguides.
(ii) A 10 GHZ signal is to be transmitted inside a hollow circular conducting pipe.
Determine the inside diameter of the pipe line such that its lowest cut off frequency is
20% below this signal frequency. (May/Jun 2012(R8))
23.(i) Discuss the principle of rectangular cavity resonator.
(ii) Determine the dominant mode and their frequencies is an air filed rectangular cavity
resonator for a>b>d, a>d>b and a=b=d where a, b, d are dimension is the x, y, z
directions respectively. (May/Jun 2012(R8))
24.(i) Discuss the transmission of TE waves between parallel planes.
(ii) Sketch the field lines of TE1 mode in parallel plane waveguides
(May/Jun 2012(R8))