Question Bank
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
UNIT I TIME VARRYING FIELDS AND MAXWELL’S EQUTIONS
PART A
State pointing theorem.
Write the point form and integral form of maxwell’s equation using faradays Law
Write the point form and integral form of maxwell’s equation using ampere Circuital law
Write the point form and integral form of maxwell’s equation using electric And magnetic gauss
law
Define pointing vector.
Define Instantaneous average vector
Define complex pointing vector
State Faraday’s law
State Lenz’s law.
What is Lorentz law of force?
PART B
1. With necessary explanation ,derive the Maxwell’s equation in differential and integral forms for
Static fields.(16)
2. Write faraday’s law in differential and integral forms and explain faradays experiments(8)
3. An electric field in the medium which is source free is given by E=1.5 cos(108 𝑡 − 𝛽𝑧)𝑎
⃗⃗⃗⃗𝑥 V/m.Find
B,H and D.Assume 𝜀𝑟 = 1, 𝜇𝑟 = 1, 𝜎 = 0. (8)
⃗ = 𝐸𝑚 /𝜇0 cos x cos t ⃗⃗⃗⃗
4. Do the fields 𝐸⃗ = 𝐸𝑚 sin 𝑥 sin 𝑡 ⃗⃗⃗⃗
𝑎𝑦 𝑎𝑛𝑑 𝐻
𝑎𝑧 satisfy Maxwell’s Equation? (8)
5. Explain briefly about the Transformer e.m.f and derive an expression for it.(8)
6. Derive the wave equations for electric and magnetic fields .(8)
7. Derive poynting theorem .(8)
8. State and derive the maxwell’s equations for free space in integral form and point form for time
varying field.(8)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
UNIT II TRANSMISSION LINES
PART A
What is the characteristic impedance of T and π symmetrical network?
If the short circuit impedance is 100Ω and open circuit impedance is 400Ω, what is the
characteristic impedance of symmetrical network?
What are the primary and secondary constants of a transmission line?
Write the condition for a distortion less line.
What is called as infinite line?
Define propagation constant.
Mention the relation between characteristic impedance and primary constant of a transmission
line.
When does reflection take place on a transmission line?
Define reflection coefficient.
Define SWR.
Write the equation of SWR in terms of reflection coefficient.
What are constant S circles?
Explain how smith chart can be used as an admittance chart.
What are the advantages of double stub over single stub matching?
What is stub matching?
Give the names of circles on Smith chart.
Mention two applications of Smith chart
List the advantages of Smith Chart.
What are limitations of single stub matching?
Why short circuit is preferred over open circuited stub?
Distinguish between single and double stub matching.
What is the importance of a quarter wave line?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
PART B
Explain in detail about characteristic impedance of symmetrical network. (16)
Discuss the properties of symmetrical network. (16)
Derive the condition to be satisfied for a distortion less line. (16)
Develop the differential equations governing the voltage and current at any point on a uniform
line. Solve these to obtain the Vand I in terms of the load current and voltage. Derive an
expression for the reflection coefficient in terms of Z0 and ZR. (16)
Describe a voltage and current equation on the dissipation less line. (16)
Discuss how smith chart is constructed and explain its application. (16)
Explain in detail about single stub matching. (16)
Explain in detail about double stub matching. (16)
Explain, with diagrams, the method of deriving constant S circles and constant βx circles used for
impedance determination. (16)
A dipole antenna whose input impedance is 100Ω is to be matched at a frequency of
100MHz to a transmission line having characteristic impedance of 600 by means of
short circuit stub. Determine the location and length of the stub. (16)
Explain in detail about quarter wave transmission line and its impedance matching? (16)
A lossless transmission line with Z0=75 Ω and electric length l=0.3λ is terminated
with a complex load impedance of ZR=40+j20 Ω. Determine reflection coefficient
and VSWR of line. (16)
Consider the line with Z0-100 Ω terminated by an unknown impedance.The SWR=2.5
and first voltage minimum at 16cm from termination when the frequency is 100MHz.
determine the terminating impedance by use of smith chart assuming the line is placed
in free space. (16)
On a transmission line a standing wave pattern is observed and the voltage
standing wave ratio is found to be 3.0 and it is also noted that two successive
voltage minima are 30cm apart. The first voltage minimum is found to be 12cm
from the load. The length of the line is 85.2cm and the Zo is 200 Ω. (16)
Determine the SWR, characteristic impedance of the quarter wave transformer,
and the distance the transformer must be placed from the load to match a 75 Ω
transmission line to a load ZL=25-j50 Ω. (16)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
UNIT III THE UNIFORM PLANE WAVE
PART A
Mention the properties of uniform plane wave.
Write down the wave equation for E and H in free space.
Write down the wave equation for E and H in a conducting medium
Define intrinsic impedance or characteristic impedance.
Calculate the characteristic impedance of free space.
Define skin depth
Define Pointing vector.
State Poynting Theorem.
What is lossy dielectric medium?
Define Polarization
Define Circular Polarization
Define Elliptical polarization
Define Linear Polarization
For a loss dielectric material having μr=1,ε r=48, σ=20s/m.calculate the Propagation constant at a
frequency of 16 GHz
PART B
1. (a) Calculate the attenuation constant and phase constant for the
uniform plane wave with the frequency of 10GHz in a medium for
which μ=μ0, εr=2.3 and σ=2.54x10-4Ω/m.
(8)
(b) Derive the expression for the attenuation constant ,phase constant
and intrinsic impedance for a uniform plane wave in a good conductor.
(8)
2.
Discuss about the reflection of plane waves by a perfect dielectrics.
(8)
3.
Discuss about linear and circular polarization.
(8)
4.
Derive wave equation in phasor form and also derive for α,β ٧ and η
(16)
5.
Derive suitable relations for integral and point forms of poynting theorem.
(16)
6. A plane wave propagating through a medium with εr = 8, µr = 2 has E = 0.5 sin
(108 t – βz )
z V/m.
Determine
(i)
β
(ii)
The loss tangent
(iii)
Wave impedance
(iv)
Wave velocity
(V)
H field
UNIT IV TRANSMISSION AND REFLECTION OF PLANE WAVES AT BOUNDARIES
PART A
1.Brief about the intrinsic impedance of a perfect dielectric medium.
2.What is Brewster angle?
3. Define the term intrinsic impedance.
4.What is uniform plane wave.
5.What is loss tangent?
6.Define plane of incident
7.Explain snell’s law of refraction.
PART B
1.
2.
3.
4.
5.
6.
7.
1.
2.
Briefly explain about the wave incident
(i) Normally on perfect conductor
(8)
(ii) Obliquely to the surface of perfect conductor.
(8)
Assume that Eland H waves, traveling in free space, are normally
Incident on the interface with a perfect dielectric with εr=3 .calculate
the magnitudes of incident, reflected and transmitted E and H waves
at the interface.
3.
(8)
A uniform plane wave of 200 MHz, traveling in free space
Impinges
normally on a large block of material having εr =4 , μr =9 and
σ =0. Calculate transmission and reflection co efficient of interface.
(8)
UNIT V WAVE GUIDES AND CAVITY RESONATORS
PART A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
What are guided waves?
What is TE wave or H wave?
What is TM wave or E wave?
What is cut off frequency?
What is TEM wave or principal wave?
Differentiate TE and TM waves.
Why are rectangular waveguides preferred over circular waveguides?
Mention the applications of waveguides.
Why waveguide is taken circular or rectangular form?
What is the resonant frequency of a microwave resonator?
Why transmission line resonator is not usually used as a microwave resonator?
Why rectangular or circular cavities can be used as microwave resonator?
What is the dominant mode for a rectangular resonator?
Define Q of a waveguide.
PART-B
1) Derive the electromagnetic field expression for TM waves guide by a parallel plane perfectly
conducting structure. (16)
2) Starting from Maxwell’s equations, explain how a wave propagates in between two infinite parallel
planes. (16)
3) Derive the electromagnetic field expression for TE waves guide by a parallel conducting plane. (16)
4) Explain the characteristics of TE and TM waves. (16)
5) Derive the field expressions for TEM waves guided by a parallel conducting plane. (16)
6) Bring out the differences between TE, TM and TEM waves. (16)
7) A parallel plane waveguide consists of two sheets of good conductor separated by 10cm. find the
propagation constant at frequencies of 100MHz and 10GHz,
when the waveguide is operated in TE10 mode. Does the propagation takes place in each case. (16)
8) A pair of perfectly conducting planes is separated by 8cm in air. For frequency of
5000MHz with the TM1 mode excited find the following:
Cut-off frequency
Characteristic impedance
Attenuation constant for f=0.95fc
Phase shift
Phase velocity and group velocity Wavelength measured along the guiding walls (16)
9) consider a parallel plate waveguide with plate separation 20cm with the TE10 mode excited at 1GHz.
Find the propagation constant, the cut-off frequency and guide wavelength assuming εr=4 for medium of
propagation in the guide. (16)
10) A uniform plane wave propagates in a lossless medium whose εr=4, µr=1 in the Z direction. Assume
that Ex is sinusoidal with a frequency of 100MHz and has a maximum value of 1m/V at t=0 and z=1/8m.
Write down the instantaneous expression for E and H for any t and z. (16)
11) Derive expression for the field components of TE10 waves in a rectangular Waveguide. Sketch the
field distribution. (16)
12) Derive the expressions for the field component of TM waves in a rectangular waveguide. (16)
13) Derive an expression for the cut-off frequency for the TE10 mode for a rectangular Waveguide. (16)
14) Derive expressions for the field components of TE waves in a circular waveguide. (16)
15) Derive an expression for the attenuation factor in a circular waveguide for TE and TM modes. (16)
16) Derive expressions for the field components of TE and TM waves in a rectangular Cavity resonator.
(16)
17) Given a circular waveguide used for a signal at a frequency of 11GHZ propagated in the TE01 mode
and the internal diameter is 4.5cm.calculate: Cut-off wavelength (ii) guide wavelength
Group velocity (iv) phase velocity and (v)Characteristics impedance (16)
18) A circular waveguide has an internal diameter of 5cm. calculate the cut-off Frequencies for the first
four modes of TE and TM waves. (16)
19) An air filled circular waveguide having an inner radius of 1cm is excited in dominant mode at 10GHZ.
Find (a) the cut-off frequency of the dominant mode at 10 GHZ. (b) The guide wavelength and (c) wave
impedance. Also find the bandwidth for the operation in the dominant mode only. (16)
20) Find the resonant frequencies of the first five lowest modes of an air filled rectangular Cavity of
dimensions 5cm*4cm*2.5cm. (16)