Ground plane
Encyclopedia
In electrical engineering
, a ground plane is an electrically conductive surface
.
, a ground plane structure or relationship exists between the antenna
and another object, where the only structure of the object is a structure which permits the antenna to function as such (e.g., forms a reflector or director for an antenna). This sometimes serves as the near-field
reflection
point for an antenna, or as a reference ground
in a circuit
.
There are a variety of ground planes, including drooping ground planes, and flat circular ground plane antennas. A ground
plane may consist of a natural surface, such as the Earth
(or ocean
) (or salt marsh
) or an artificial surface of opportunity (such as the roof of a motor vehicle). A ground plane can also be a specially designed artificial surface (such as the radial elements of a quarter-wave ground plane antenna). Artificial (or substitute) grounds (e.g., ground planes) concerns the grounding structure for the antenna and includes the conductive structure used in place of the earth and which grounding structure is distinct from the earth.
Essentially, the ground plane acts as the "missing half" of a dipole two element, half wave long, center fed antenna. It can be thought of as the "return current" path for the radiating antenna. The efficiency of a ground plane can be measured in ohms as the loss component (i.e., fewer ohms are better) of an antenna's total input impedance. In VHF (30 to 300 MHz or wavelengths 10 to 1 meter) used in mobile communications, the metal of a car body begins to act as an efficient quarter-wavelength groundplane. By the upper VHF and UHF frequencies (300 to 3000 MHz), the car or truck body ground plane can be several wavelengths long, making an "ideal and lossless" groundplane.
assembly is a layer of copper
that appears to most signals as an infinite ground
potential. This helps reduce noise
and helps ensure that all integrated circuit
s within a system compare different signals' voltage
s to the same reference potential
.
It also serves to make the circuit design easier, allowing the designer to ground anything without having to run multiple tracks; the component needing grounding is routed directly to the ground plane on another layer.
Ground planes can also be placed on adjacent layers to power planes creating a large parallel plate capacitor
that helps filter the power supply
.
Ground planes are sometimes split and then connected by a thin trace. This allows the separation of analog and digital sections of a board or the inputs and outputs of amplifiers. The thin trace has low enough impedance
to keep the two sides very close to the same potential while keeping the ground currents of one side from impacting the other.
Websites
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...
, a ground plane is an electrically conductive surface
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...
.
Radio antenna theory
In telecommunicationTelecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
, a ground plane structure or relationship exists between the antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
and another object, where the only structure of the object is a structure which permits the antenna to function as such (e.g., forms a reflector or director for an antenna). This sometimes serves as the near-field
Near and far field
The near field and far field and the transition zone are regions of the electromagnetic radiation field that emanates from a transmitting antenna, or as a result of radiation scattering off an object...
reflection
Reflection (physics)
Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...
point for an antenna, or as a reference ground
Ground (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
in a circuit
Telecommunication circuit
A telecommunication circuit is any line, conductor, or other conduit by which information is transmitted.A dedicated circuit, private circuit, or leased line is a line that is dedicated to only one use...
.
There are a variety of ground planes, including drooping ground planes, and flat circular ground plane antennas. A ground
Ground (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
plane may consist of a natural surface, such as the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
(or ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
) (or salt marsh
Salt marsh
A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...
) or an artificial surface of opportunity (such as the roof of a motor vehicle). A ground plane can also be a specially designed artificial surface (such as the radial elements of a quarter-wave ground plane antenna). Artificial (or substitute) grounds (e.g., ground planes) concerns the grounding structure for the antenna and includes the conductive structure used in place of the earth and which grounding structure is distinct from the earth.
Essentially, the ground plane acts as the "missing half" of a dipole two element, half wave long, center fed antenna. It can be thought of as the "return current" path for the radiating antenna. The efficiency of a ground plane can be measured in ohms as the loss component (i.e., fewer ohms are better) of an antenna's total input impedance. In VHF (30 to 300 MHz or wavelengths 10 to 1 meter) used in mobile communications, the metal of a car body begins to act as an efficient quarter-wavelength groundplane. By the upper VHF and UHF frequencies (300 to 3000 MHz), the car or truck body ground plane can be several wavelengths long, making an "ideal and lossless" groundplane.
Printed circuit boards
A ground plane in PCBPrinted circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
assembly is a layer of copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
that appears to most signals as an infinite ground
Ground (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
potential. This helps reduce noise
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
and helps ensure that all integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s within a system compare different signals' voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
s to the same reference potential
Electric potential
In classical electromagnetism, the electric potential at a point within a defined space is equal to the electric potential energy at that location divided by the charge there...
.
It also serves to make the circuit design easier, allowing the designer to ground anything without having to run multiple tracks; the component needing grounding is routed directly to the ground plane on another layer.
Ground planes can also be placed on adjacent layers to power planes creating a large parallel plate capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
that helps filter the power supply
Power supply
A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
.
Ground planes are sometimes split and then connected by a thin trace. This allows the separation of analog and digital sections of a board or the inputs and outputs of amplifiers. The thin trace has low enough impedance
Electrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...
to keep the two sides very close to the same potential while keeping the ground currents of one side from impacting the other.
See also
- List of electronics topics
- Power planePower planeIn printed circuit board design, a power plane is the counterpart to the ground plane and behaves as an AC signal ground, whilst providing DC voltage for powering circuits mounted on the PCB.- Uses :...
- MicrostripMicrostripMicrostrip is a type of electrical transmission line which can be fabricated using printed circuit board technology, and is used to convey microwave-frequency signals. It consists of a conducting strip separated from a ground plane by a dielectric layer known as the substrate. Microwave components...
and StriplineStriplineStripline is a transverse electromagnetic transmission line medium, that was invented by Robert M. Barrett of the Air Force Cambridge Research Centre in the 1950s.- Description :... - Line-of-sight propagationLine-of-sight propagationLine-of-sight propagation refers to electro-magnetic radiation or acoustic wave propagation. Electromagnetic transmission includes light emissions traveling in a straight line...
- Radio electronicsRadio electronics*For the magazine, see Radio-ElectronicsRadio electronics is the sub-field of electrical engineering concerning itself with the class of electronic circuits which receive or transmit radio signals....
and Radio propagationRadio propagationRadio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere... - Printed circuit board millingPrinted circuit board millingPrinted circuit board milling is the process of removing areas of copper from a sheet of printed circuit board material to recreate the pads, signal traces and structures according to patterns from a digital circuit board plan known as a layout file...
- Antenna tunerAntenna tunerAn antenna tuner, transmatch or antenna tuning unit is a device connected between a radio transmitter or receiver and its antenna to improve the efficiency of the power transfer between them by matching the impedance of the equipment to the antenna...
- Salisbury screenSalisbury screenThe Salisbury screen, invented by American engineer Winfield Salisbury in 1952, was one of the first concepts in radar absorbent material, later known as "stealth technology", used to prevent enemy radar detection of military vehicles. It was first applied to ship radar cross section reduction...
External articles
References and citations- Groundplane antenna model FA-2 from the book PRACTICAL ANTENNA DESIGN second edition, Philippine copyright, 1990, 1994 by Elpidio C. Latorilla
Websites
- John Whitmore, sci.electronics > What is a PCB with a Ground plane?. August 11, 1992.
- Amateur Quarter Wave Ground Plane Antenna Calculator. Computer Support Group, Inc., 2006.
- What is a Ground Plane? Criterion Cellular, 2006.