PHY3126 Electromagnetic Waves

1999-2000

Code: PHY3126
Title: Electromagnetic Waves
Instructors: Prof. J.R. Sambles and Dr W.G. Parker
HE credits: 10
ECTS credits: 5
Availability: unrestricted
Level: 3
Prerequisites: Electromagnetic Fields (PHY2206)
Corequisites: none
Background Assumed: Electricity and Magnetism (PHY1004), Mathematics II (PHY1016) and Electromagnetic Fields (PHY2206)
Duration: Semester I
Directed Study: 22 lectures
Private Study: 78 hours
Supports Programme Aims: 1, 2 and 5
Supports Programme Objectives: none

Assessment Methods

One 90-minute examination

Rationale

The first part of the module discusses the solution of Maxwell's equations with particular emphasis on the plane-wave solutions and their polarization characteristics. In the second part of the module the relevance of these solutions to electronic communications sytems is discussed and developed. The module illustrates the principal features of analogue and digital modulation techniques and assesses the relative advantages and disadvantages of common systems in practical TV, radio and telephony.

Intended Learning Outcomes

Students will be able to:

• describe all the fundamental aspects of electromagnetic wave progapagation;
• use Maxwell's equations and appropriate vector mathematics to solve problems in a variety of situations (as outlined in the syllabus below and the lectures);
• assess the relative merits of different communication techniques, such as fibres, radio, land-line links;
• discuss the relative merit of different modulation techniques;
• solve simple problems involving different modulation techniques;
• explain the operation of microwave sources.

Teaching and Learning Methods

Lectures are given at two per week for ten weeks with two problems classes

Transferable Skills

Knowledge of the technology and fundamental physics underlying modern telecommunications systems.

Assignments

None, the students are given example problems.

Module Text

Reitz J.R., Milford F.J. and Christy R.W. (1993), Foundations of Electromagnetic Theory (4^th edition), Addison-Wesley (UL: 530.141 REI)

Supplementary Reading

Not applicable

Syllabus Plan and Content

Part A (8 lectures, 1 problems class)

1. Maxwell's Equations
   1. The equation of continuity, displacement-current density
   2. Maxwell's equations for the electromagnetic field, constitutive equations
2. Electromagnetic Waves
   1. Electromagnetic waves in free space
   2. Plane waves and polarization
   3. Plane waves in free space and in isotropic insulating media, dispersion
   4. Energy in electromagnetic waves and the Poynting vector
   5. Plane waves in conductors and the skin effect, waves in plasmas

Part B (12 lectures, 1 problems class)

1. Signals and Channels
   1. Basic features of a communication link
   2. Examples of signals in the time and frequency domains
   3. Communication channels; practical features of common examples, twisted-pair and co-axial cables, optical, fibres, free space
   4. Overview of telecommunications world-wide.
2. Sinusoidal Carrier Modulation
   1. Double-sideband suppressed-carrier amplitude modulation (DSB-SC-AM)
   2. Double- and single-sideband amplitude modulation(DSB-AM, SSB-AM)
   3. Vestigial-sideband modulation (VSB-AM)
   4. Frequency and phase modulation (FM, PM)
   5. Spectral occupancy of amplitude-modulated signals
   6. Frequency-division multiplex (FDM) transmission
   7. Some features of demodulation techniques
3. Pulse-Carrier-Modulation and Digital-Modulation Techniques
   1. Modulation and demodulation using a pulsed carrier; spectral aspects, pulse amplitude modulation (PAM)
   2. The sampling theorem, aliassing
   3. Pulse modulation schemes based on frequency, phase and width of carrier (PFM, PPM, PWM)
   4. Time-division multiplex (TDM) transmission
   5. General comparison of analogue/binary signal modulation systems
   6. Pulse-code modulation (PCM); quantization, sampling, encoding and noise
   7. Application of nonuniform quantization
   8. Differential PCM (DPCM) and delta modulation (DM)
   9. Introduction to special aspects of data communications
   10. Descriptions of elementary modulation techniques; amplitude, frequency and phase shift keying (ASK, FSK, PSK), and relation to conventional analogue techniques
   11. Brief survey of advanced techniques
4. Active Microwave Devices
   1. Practical context in communications; problems of conventional circuitry and devices at microwave frequencies
5. Vacuum-Tube Devices
   1. Principles of velocity modulation; the klystron oscillator and travelling-wave amplifiers (TWT)
   2. Pulses and high-power applications; the magnetron
6. Solid-State Devices
   1. The Gunn diode
   2. Transferred electron effect; charge accumulation in semiconductors
   3. Bulk negative differential resistivity
   4. Materials; J, E characteristics
   5. Modes of operation; accumulation-layer mode, transit-time dipole-layer mode, quenched dipole-layer mode, limited space-charge-accumulation mode
   6. Characteristics of operation of impact avalanche and transit-time diode (IMPATT diode)

Feedback to Students

Students are given example sheets and the full answers are provided in the problems classes.

Feedback from Students

Feedback from students on the module is gathered via the standard student representation mechanisms.