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Encyclopedia > Circular polarization

In electrodynamics, circular polarization of electromagnetic radiation is a polarization such that the tip of the electric field vector, at a fixed point in space, describes a circle as time progresses. The name is derived from this fact. The electric vector, at one point in time, describes a helix along the direction of wave propagation (see the polarization article for pictures). The magnitude of the electric field vector is constant as it rotates. Circular polarization is a limiting case of the more general condition of elliptical polarization. The other special case is the easier-to-understand linear polarization. Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ... Electromagnetic radiation can be conceptualized as a self propagating transverse oscillating wave of electric and magnetic fields. ... In electrodynamics, polarization (also spelled polarisation) is a property of waves, such as light and other electromagnetic radiation. ... In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ... In electrodynamics, polarization (also spelled polarisation) is a property of waves, such as light and other electromagnetic radiation. ... In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation. ...


Circular (and elliptical) polarization is possible because the propagating electric (and magnetic) fields can have two orthogonal components with independent amplitudes and phases (and the same frequency).


A circularly polarized wave may be resolved into two linearly polarized waves, of equal amplitude, in phase quadrature (90 degrees apart) and with their planes of polarization at right angles to each other. In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation. ... Phase, from the Greek phasis, meaning appearance, has a number of related meanings in English. ... Quadrature, derived from Latin quadrare, is a term with various meanings: in astronomy, the line tangent to an objects orbit defines the objects quadrature. ...


Circular polarization may be referred to as right or left, depending on the direction in which the electric field vector rotates. Unfortunately, two opposing, historical conventions exist. In physics and astronomy, polarization is defined as seen from the receiver, such as a telescope or radio telescope. By this definition, if you could stop time and look at the electric field along the beam, it would trace a helix which is the same shape as the same-handed screw. For example, right circular polarization produces a right threaded (or forward threaded) screw. In the U.S., Federal Standard 1037C also defines the "handedness" of circular polarization in this manner. In electrical engineering, however, it is more common to define polarization as seen from the source, such as from a transmitting antenna. To avoid confusion, it is good practice to specify "as seen from the receiver (or transmitter)" when polarization matters. A black hole concept drawing by NASA. Physics (from the Greek, φυσικός (physikos), natural, and φύσις (physis), nature) is the science of the natural world dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. ... Lunar astronomy: the large crater is Daedalus, photographed by the crew of Apollo 11 as they circled the Moon in 1969. ... 50 cm refracting telescope at Nice Observatory. ... The 64 metre radio telescope at Parkes Observatory, New South Wales, Australia In contrast to an ordinary telescope, which produces visible light images, a radio telescope sees radio waves emitted by radio sources, typically by means of a large parabolic (dish) antenna, or arrays of them. ... Screws come in a variety of shapes and sizes for different purposes. ... Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ... Electrical engineers design power systems. ...


FM radio

The term "circular polarization" is often used erroneously to describe mixed polarity signals used mostly in FM radio (87.5 to 108.0 MHz), where a vertical and a horizontal component are propagated simultaneously by a single or a combined array. This has the effect of producing greater penetration into buildings and difficult reception areas than a signal with just one plane of polarization. FM radio is a broadcast technology invented by Edwin Howard Armstrong that uses frequency modulation to provide high-fidelity broadcast radio sound. ...


See also


  Results from FactBites:
 
Circular polarization selective surface made of resonant spirals - Patent 5280298 (2684 words)
A circular polarization selective surface as defined claim 3, wherein a number of the spirals are arranged parallel to each other in a single plane and all their central segments are parallel and perpendicular to the plane.
A circular polarization selective surface as defined claim 9, wherein a number of the spirals are arranged parallel to each other in a single plane and all their central segments are parallel and perpendicular to the plane.
A circular polarization selective surface as defined claim 14, wherein a number of the spirals are arranged parallel to each other in a single plane and all their central segments are parallel and perpendicular to the plane.
Polarization (330 words)
Light is linearly polarized when its E-field component is in a plane.
Circular and elliptical polarization occurs when two or more linearly polarized waves add together such that the E-field of the net wave rotates.
For elliptically polarized light both the magnitude and the direction of the E-field varies.
  More results at FactBites »

 
 

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