Encyclopedia of Remote Sensing

2014 Edition
| Editors: Eni G. Njoku

Radiation, Polarization, and Coherence

Reference work entry
DOI: https://doi.org/10.1007/978-0-387-36699-9_145

Definition

Radiation. The process of electromagnetic energy propagation from the source.

Polarization. A property of electromagnetic waves to describe the orientation of their oscillations.

Coherence. A property of electromagnetic waves that enables stationary interference.

Radiation

Radiation of energy characterizes a source in an unbounded space. To illustrate the radiation mechanisms and the dependence of the radiation on the source, first consider the case of a single wire, where there is no radiation if a charge is not moving or charge is moving with uniform velocity along a straight and infinite wire, whereas there is radiation if the wire is deformed in certain ways (curved, bent, truncated, discontinuous) or charge is oscillating (Balanis, 1997). Next consider another simple case of current I forming an electric dipole of moment Il by extending over an incremental length l, the results of which can be readily extended to general source distributions. For simplicity, current...
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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.Zhejiang UniversityHangzhouPeople's Republic of China