Talk:Radio horizon

16 Jun 2005, Boon Phing write: I think the conversion here is more for optical horizon rather than radio horizon. aren't we suppose to use r = 4/3 r0 for earth radius?

then

D [NM] = 1.23 * sqrt(H [ft]) <= radio horizon

instead of

D [mi] = 1.23 * sqrt(H [ft]) <= optical horizon

Conversion

someone wrote: "GF: I believe that the conversion here from ft to meters is wrong. Should have taken the square root of the conversion factor?"

I agree.

Horizon (mi) = 1.23 * sqrt(Height (ft));

take an antenna 100 ft high. sqrt(100)=10; Horizon = 12.3 miles.

Horizon (km) = 1.6 km/mi * 1.23 * sqrt(3.28 ft/m) * sqrt(Height (m));

1.6 * 1.23 * 1.8113 = 3.5646384... chop precision, to get

therefore Horizon (km) = 3.56 * sqrt(Height (m));

also, "The ARRL Antenna Book gives a constant of 1.415 for weak signals during normal tropospheric conditions."

strangely, the ARRL Handbook condradicts this: 1.15 is the factor quoted there (page 21.20 of the 1999 edition.) so which is correct? Waveguy

Adding up horizons

We were learning this thoery at college today and a question came up that could not be answered: Why do you add the horizons of the two Antennas, if Antenna A has a horizon of 8 miles and the second 10 miles, why can they be more than 10 miles apart? How does the signal get from the horizon of the first (say 8 miles) and arrive 10 miles farther at the second atennna? --Crossmr 16:09, 18 April 2006 (UTC)

Because the top of antenna A can just barely see over the edge of the Earth that the tip of antenna B is showing. It cannot see the base of B. Both heights are needed. So they can be up to 18 miles apart for communications between A and B. Sagittarian Milky Way 18:13, 6 May 2007 (UTC)

Request rearrangement of article

Hello, I think this article should first give the exact formula of the radio horizon then the formula for the KM distance on the same line as the Miles distance. That would be clearer for our readers in the scientific community who mostly use the metric system. However, I do not have the time right now to do these modifications. I will probably do these modifications within a couple of days, if no one object this proposal. The best way to object my proposal is to reply to this message. Regards, Xionbox (talk) 04:10, 10 June 2010 (UTC)

Needs a diagram

One picture, etc. - maybe there's something on Commons, but even I can draw a circle with a couple of lines and some labels; and if no-one beats me to it, and I can't find anything on Commons, this is a reminder that this article needs a diagram. --Wtshymanski (talk) 17:06, 9 February 2011 (UTC)

Better yet, let's merge in Earth bulge which has the diagram and the maths. --Wtshymanski (talk) 17:24, 9 February 2011 (UTC)

• Oppose: I agree both subjects are related. But they are not identical. While this article concentrates on the propogation of the EM waves earth bulge treats the geometrical aspect and both subjects deserve separate articles. (If desired the file:Earthbulge.jpg can be added to this article). Nedim Ardoğa (talk) 13:30, 10 February 2011 (UTC)

That's surprising. It's the same topic - why are there two articles? It would be a better presentation to have all the maths and figures in one article. --Wtshymanski (talk) 20:07, 10 February 2011 (UTC)

This guy [1] talks about "earth bulge" and stresses the effect it has on atmosphere, not just geometry; since both effects are related, they should be discussed in a unified way. --Wtshymanski (talk) 15:54, 14 February 2011 (UTC)

• The article Earth bulge had been merged to this article two times without any serious reason except that a user wishes so. When an article merges into another one all past history of the merged article fades away. So I am definitely against merging articles. Besides this is not a high school text book which organises all related subjects under a single heading. This is encyclopedia and all different concepts deserve an article of their own. Nedim Ardoğa (talk) 19:27, 15 February 2011 (UTC)

The reason the articles were merged is that it's the same topic under two different names. The two pieces were incomplete and fragmetary; the combination, less so. The edit history of Earth bulge will remain as long as the redirect remains, so it's not lost ( just like this 5-year old merger [[2]]). An encyclopedia generally discusses a topic under one heading, not in separate fragments named as if by whoever came into the office that day. Can you illustrate by any references to sources that discuss "radio horizon" without mentioning "earth bulge" or the reverse? What do you think of merging all of this to Line-of-sight propagation? --Wtshymanski (talk) 19:50, 15 February 2011 (UTC)