## Wave Transmission and Fiber Optics

Semester 1

This course starts with a basic coverage of the electromagnetic theory that is required for understanding the behavior of waves in various mediums. It continues with the fundamentals of wave propagation and waveguiding of all kinds; the essentials of propagation along optical fibers; and the concepts underlying integrated optics systems. It details the theoretical analyses of various transmission line including twisted wire pairs, coaxial cables, and traces on printed circuits boards. A study of antennas and their interfacing to transmission line is included. A thorough analysis is done on the theory of fiber optic and dielectric transmission medium with extended discussions on their practical application. The theory and operation of practical fiber optic communication system, its signals and its components are studied.

Syllabus:
• The electromagnetic wave and field energetics:
• Maxwell’s equations in integral and differential forms, the electromagnetic wave, electric power density, Poynting’s theorem, field energetics. Complex fields, polarization – linear and circular. Group velocity, dispersion relation, wave velocities, complex Poynting’s theorem, complex permittivity, load impedance.
• Waves in conducting media and across interfaces:
• Wave equation in conductors; Waves in good insulators, waves in good conductors, transition frequencies; boundary conditions, normal incidence with matched impedances, impedance mismatch, reflection and transmission coefficients, energy transmission and reflection, insulator-conductor interfaces, antireflection coating. Oblique waves as non-uniform transverse waves, Snell’s law, TE and TM polarization, Brewster angle, power conservation. Reactive impedances, total internal reflection (TIR), TIR for TE and TM polarizations. Skin effect in co-axial conductors.
• Transmission lines:
• Non-uniform waves, electrostatic solutions, coaxial line, voltage and current waves, characteristic impedance, mismatched loads, standing waves ratio, impedance measurements, reflection coefficients, input impedance of a line, the Smith Chart, transmission and reflection coefficients (S21 and S11), half-wave and quarter-wave transformers, matching stubs, transmission lines on printed circuit boards – microstrip, co-planar, slot line; EMI from PCBs, impedance matching in high speed circuits.
• Waveguides:
• Generalized non-uniform wave, Helmholtz solution, TE and TM waves, rectangular waveguides, cut-off frequencies, power flow, group and phase velocities in waveguide, cylindrical waveguides, Bessel function
• Antennas:
• The elementary dipole, near and far field, radiated power, radiation resistance, radiation pattern, power gain, effective aperture. The half-wave dipole and other harmonics, effects of ground reflection, directors and reflectors, Yagi antennas. Travelling wave antennas, V-antennas, Loop antennas, patched antennas, phased-array antennas, and trend in modern antenna designs. Matching antenna and transmission line, T-Match, Gamma match and Delta match.
• Dielectric cylinders and optical fibers:
• Step-index fiber, hybrid modes, Derivation of characteristic equation, HE and EH modes, TE and TM modes, Dominant mode
•  Practical versions of optical fibers:
• Numerical aperture, LP modes, Single-mode fiber, attenuation, material and multimode dispersion, graded-index fibers, wave launching, mode coupling.
• Fiber optic communication systems design:
• System components; signal measurements, chromatic dispersion – the eye diagram, optical return loss; optical circuits and components.
Evaluation:

One 2-hour final exam                                      60%

Two 1-hour in-course tests (20% each)           40%

Learning Objectives:

After completing this course, students should be able to:

• Apply Maxwell’s equation to analyze wave behavior in various transmission media
• Optimize a transmission media for efficient signal transfers
• Calculate characteristic impedances of transmission lines, waveguides and antennas
• Design impedance matching networks for optimal interface between transmission lines and antennas
• Use Smith chart for impedance characterization
• Explain how the choice of PCB trace designs affects high frequency performance and EMI
• Assess a medium for its ability to transmit or block electromagnetic waves
• Specify fiber optic cables for selected light transmission modes and distortion levels
• Describe the basic components of a fiber optic communication system
ELET2480

Text Books:

Magnusson, P. C.,  Weisshaar, A., Tripathi, V. K. &  Alexander, G. C. (2000) Transmission lines and wave propagation – 4th Edition. CRC Press. ISBN:  978-0849-30269-5

Crisp, J. & Elliot, B. (2005) Introduction to fiber optics -3rd Edition. Nunes. ISBN: 0 7506 67567

Reference Text :

Diament, P. (1990) Wave transmission and fiber optics. Prentice Hall international paperback Editions. ISBN: 9780023287619

Internet Resources:

Tutorials on transmission line and impedance matching

Understanding EM wave propagation

Designing fiber optic system

Course Code:
ELET3470
Credits:
3 Credits
Level:
Level 3
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