Talk:Fresnel zone

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needs more reliable sources....--24.144.100.184 02:10, 2 November 2006 (UTC)

what's the unit of r ? what about the fomula in metric ?

I guessed it is "kilobarleycorns". Probably wrong, I suppose. What are the widths of the subsequent Fresnel zones, those "annular rings"? What are the widths at other than the halfway point?

What do "maximum obstruction" and "recommended obstruction" mean? Gene Nygaard 04:29, 4 May 2005 (UTC)

This article needs to be generalized to include the optics usage. (Yes, I know, sofixit and all that. I don't have time right now, so I'll just mention it here for now.)--Srleffler 04:07, 21 March 2006 (UTC)

Any idea why the formula for the radius on this page gives a different multiplier (43.3 instead of 72.6)? EdDavies 12:36, 3 April 2006 (UTC)

The link to "this page" above appears to be no longer reachable, but I've seen 43.3 elsewhere and had the same question. See this page instead. The 43.3 multiplier (for the radius in feet and distance in miles) may be the "obstacle-free radius", which is often taken as 60% of the Fresnel zone radius. Can someone verify this? 70.89.158.189 21:50, 25 October 2006 (UTC) Gerald Reynolds

[edit] General formula is fine, but numerical values only for optics in free-space

I haven't even checked the accuracy of those numerical prefactors, but people should be aware that the concept of a Fresnel zone applies as well to *any* wave phenomenon (my own familiarity with it is in acoustics). I'll change the article if and when I have time, but (1)it should be mentioned that those numerical values which people have been quibbling over are specific to optics in free-space---other values will show up for acoustics problems---still others for other wave-types in different media; or, (2) there should be *no* numerical values given, and simply stress that the formula yields different results based on wave- and media-type. --Smoo222 03:20, 21 March 2007 (UTC)smoo222

[edit] zone/region ?

Should this page make any distinction between "Fresnel zone" and "Fresnel region" (commonly used in antenna theory)?

In antenna theory, the Fresnel region generally refers to a radial range of distances between the reactive near field (~2*lambda?) of an aperture, and the Fraunhofer region (2*D^2/lambda, where D is the largest dimension of the aperture). Within the Fresnel region, the radiation pattern of the aperture varies significantly with radial distance since the multitude of sources that constitute a given aperture cannot yet accurately be approximated as having a common phase center.

69.137.170.154 23:42, 21 March 2007 (UTC)Bill Shultz