Electrical engineering has many sub-disciplines, the most popular of which are listed below. Although there are electrical engineers who focus exclusively on one of these sub-disciplines, many deal with a combination of them. Sometimes certain fields, such as electronic engineering and computer engineering, are considered separate disciplines in their own right.
Power
Main article:
Power engineeringPower engineering deals with the
generation,
transmission and
distribution of
electricity as well as the design of a range of related devices. These include
transformers,
electric generators,
electric motors and
power electronics. In many regions of the world, governments maintain an electrical network called a
power grid that connects a variety of generators together with users of their energy. Users purchase electrical energy from the grid, avoiding the costly exercise of having to generate their own. Power engineers may work on the design and maintenance of the power grid as well as the power systems that connect to it. Such systems are called on-grid power systems and may supply the grid with additional power, draw power from the grid or do both. Power engineers may also work on systems that do not connect to the grid, called off-grid power systems, which in some cases are preferable to on-grid systems. The future includes Satellite controlled power systems, with feedback in real time to prevent power surges and prevent blackouts.
Control
Main article:
Control engineeringControl engineering focuses on the
modeling of a diverse range of
dynamic systems and the design of
controllers that will cause these systems to behave in the desired manner. To implement such controllers electrical engineers may use
electrical circuits,
digital signal processors,
microcontrollers and
PLCs (Programmable Logic Controllers).
Control engineering has a wide range of applications from the flight and propulsion systems of
commercial airliners to the
cruise control present in many modern
automobiles. It also plays an important role in
industrial automation.
Control engineers often utilize
feedback when designing
control systems. For example, in an
automobile with
cruise control the vehicle's
speed is continuously monitored and fed back to the system which adjusts the
motor's power output accordingly. Where there is regular feedback,
control theory can be used to determine how the system responds to such feedback.
Electronics
Main article:
Electronic engineeringElectronic engineering involves the design and testing of
electronic circuits that use the properties of
components such as
resistors,
capacitors,
inductors,
diodes and
transistors to achieve a particular functionality. The
tuned circuit, which allows the user of a
radio to
filter out all but a single station, is just one example of such a circuit. Another example (of a pneumatic signal conditioner) is shown in the adjacent photograph.
Prior to the second world war, the subject was commonly known as radio engineering and basically was restricted to aspects of communications and
radar,
commercial radio and
early television. Later, in post war years, as consumer devices began to be developed, the field grew to include modern television, audio systems,
computers and
microprocessors. In the mid to late 1950s, the term radio engineering gradually gave way to the name electronic engineering.
Before the invention of the
integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and
power and were limited in speed, although they are still common in some applications. By contrast,
integrated circuits packed a large number—often millions—of tiny electrical components, mainly
transistors, into a small chip around the size of a
coin. This allowed for the powerful
computers and other electronic devices we see today.
Microelectronics
Main article:
MicroelectronicsMicroelectronics engineering deals with the design of very small electronic circuit components for use in an
integrated circuit or sometimes for use on their own as a general electronic component. The most common microelectronic components are
semiconductor transistors, although all main electronic components (
resistors,
capacitors,
inductors) can be created at a microscopic level.
Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies,
compound semiconductors like gallium arsenide and indium phosphide) to obtain the desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of
quantum mechanics.
Signal processing
A
Bayer filter on a
CCD requires signal processing to get a red, green, and blue value at each pixel
Main article:
Signal processingSignal processing deals with the analysis and manipulations of
signals. Signals can be either
analog, in which case the signal varies continuously according to the information, or
digital, in which case the signal varies according to a series of discrete values representing the information. For analog signals, signal processing may involve the
amplification and
filtering of audio signals for audio equipment or the
modulation and
demodulation of signals for
telecommunications. For digital signals, signal processing may involve the
compression,
error detection and
error correction of digitally sampled signals.
Telecommunications
Main article:
Telecommunications engineeringTelecommunications engineering focuses on the
transmission of
information across a
channel such as a
coax cable,
optical fibre or
free space. Transmissions across free space require information to be encoded in a
carrier wave in order to shift the information to a
carrier frequency suitable for transmission, this is known as
modulation. Popular analog modulation techniques include
amplitude modulation and
frequency modulation. The choice of modulation affects the cost and performance of a system and these two factors must be balanced carefully by the engineer.
Once the transmission characteristics of a system are determined, telecommunication engineers design the
transmitters and
receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a
transceiver. A key consideration in the design of transmitters is their
power consumption as this is closely related to their
signal strength. If the signal strength of a transmitter is insufficient the signal's information will be corrupted by
noise.
Instrumentation engineering
Main article:
Instrumentation engineeringInstrumentation engineering deals with the design of devices to measure physical quantities such as
pressure,
flow and
temperature. The design of such instrumentation requires a good understanding of
physics that often extends beyond
electromagnetic theory. For example,
radar guns use the
Doppler effect to measure the speed of oncoming vehicles. Similarly,
thermocouples use the
Peltier-Seebeck effect to measure the temperature difference between two points.
Often instrumentation is not used by itself, but instead as the
sensors of larger electrical systems. For example, a thermocouple might be used to help ensure a furnace's temperature remains constant. For this reason, instrumentation engineering is often viewed as the counterpart of control engineering.
Computers
Main article:
Computer engineeringComputer engineering deals with the design of
computers and
computer systems. This may involve the design of new
hardware, the design of
PDAs or the use of computers to control an
industrial plant. Computer engineers may also work on a system's
software. However, the design of complex software systems is often the domain of
software engineering, which is usually considered a separate discipline.
Desktop computers represent a tiny fraction of the devices a computer engineer might work on, as computer-like architectures are now found in a range of devices including
video game consoles and
DVD players.