Circular polarization: Difference between revisions

Revision as of 17:08, 15 May 2006

Revision as of 05:42, 11 June 2006

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A circularly polarized wave may be resolved into two [[linear polarization|linearly polarized]] waves, of equal amplitude, in [[Quadrature_phase|phase quadrature]] (90 degrees apart) and with their planes of polarization at right angles to each other.

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 <i>''receiver</i>'', 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 <i>''source</i>'', 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.

== FM radio ==