A pencil beam, narrow beam or pencil of rays is a beam of electromagnetic radiation, typically in the form of a narrow cone or cylinder.
Antennas which strongly bundle in azimuth and elevation are often described as "pencil-beam" antennas. For example a phased array antenna can send out a beam that is extremely thin. Such antennas are used for tracking radar.
In optics, the focusing action of a lens is often described in terms of pencils of rays. In addition to conical and cylindrical pencils, optics deals with astigmatic pencils as well.[1]
See also
References
- ^ Edward L, Nichols and William S. Franklin (1903). The Elements of Physics: A College Text-book. Macmillan Co. p. 77. http://books.google.com/books?id=WK0IAAAAIAAJ&pg=PA77&dq=pencil-of-rays++lens+astigmatic-pencil&lr=&as_brr=1&as_pt=ALLTYPES&ei=wVh-Saa6OZacyATy5oWrDg.
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