Practical conic sections : the geometric properties of ellipses, parabolas and hyperbolas by Unknown

Author:Unknown
Language: eng
Format: epub
Published: 2021-08-22T16:00:00+00:00

Although it is customary to use symmetrical parabolic reflectors whose vertex is at the center of the dish, we are not limited to this configuration. The laws of reflection from the surface of a paraboloid apply to all parts of the curve. Any portion of the curve may be used as long as the receiver or source of energy (light, radio, sound, and so on) is at the focus (Figure 5-14). The advantage of an offset feed is that the source will not be in the way of the energy path. The disadvantage is that the efficiency of utilization of the reflective surface area decreases rapidly when we get beyond the focal width of the paraboloid. At the focal width, the efficiency is reduced to 70.7%. This may not be a significant problem with small reflectors for radar and optics, but it becomes quite serious when we consider large parabolic reflectors used for concentrating solar energy. Such reflectors would require approximately 50% more reflective material at the focal width than at the vertex to intercept a given amount of incident sunlight. Because of this, it is best to design reflectors to be rather shallow, having a diameter less than four times the focal length.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.