Friends, I want to ask, does anyone here know the maximum range of aircraft transponders in transmitting ADS-B signals? because I need this theoretical explanation about ADS-B for my thesis
If by theoretical explanation you mean a link budget, there are link budgets in this ITU document for satellite ADS-B links. https://www.itu.int/pub/R-REP-M.2413
Also, there is a long thread on here for range of terrestrial ADS-B .
https://discussions.flightaware.com/t/what-is-the-maximum-range-i-can-get/17248
Edit to add: In the last two posts of the above thread I calculated a link budget of a terrestrial ADS-B link.
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Theoretical explsnation & formuls are here:
https://discussions.flightaware.com/t/antenna-height-question/19510/4
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This may also help:
https://discussions.flightaware.com/t/antenna-height-increased-but-range-doesnt/31491/4
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Are you talking about real world conditions or theoretical free space, flat earth conditions using aerials made from unobtanium?
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(20 characters)
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Everyone has his own interpretition of “theoretical”.
My interoretation of theoretical is given below:
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Awesome. Another future “Dr.” that doesn’t know how to use a search engine?
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Maybe it’s for an MS degree. Also, some of the information you find on-line is wrong.
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Of course, range also goes out the window when you add local conditions as well. My graphs show my maximum range has been nearly 500nm.
@taniaachiever I hope you’ll be providing a link to this site and citing @abcd567 for his theoretical background in your thesis and including me for reminding you that unobtanium is the best material to build aerials with.
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True.It all comes down to the C/N you get at a receiver, where N is the noise from all sources.
That’s because as with many other things, there is a disparity between the use of the term by lay people and scientists. A theory in science is something which has been thoroughly tested as an explanation for a particular phenomenon. It is as close to science fact as you can get. In every day use, people often take it to mean something far less rigorous.
You often see people say things like ‘it’s only a theory’, but really the difference between observed phenomenon and something which is theoretical is often due to imprecise measurement, or the neglecting of some relevant factor or other. In their mind, this makes the theory less valid, when it should be the other way round. By the time something is called a theory, observed disagreements with it are usually down to that imprecision. Usually that is not a problem, because a close approximation is all that is necessary - case in point, the moon landings were conducted using Newtonian mechanics when special relativity is a much more complete description of motion. The extra precision just wasn’t needed.
Your example is good enough for an approximation of range, because it covers line of sight visibility. There are also other factors such as diffraction, scattering, tropospheric ducting and other atmospheric effects.
The reason I raise this is because @taniaachiever says they are writing a thesis - depending on what it is intended to cover, they might end up going down a rabbit hole of some quite complicated physics. If the focus is less on the academic side of radio propagation and more on the practical application of radio engineering to this particular feature of aviation, then empirical data and observation may well suffice.
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This is all a theory
Which is why I said ‘flat earth’ as a theoretical thing. Without the earth getting in the way, the RF would go a lot further 
I suppose the actual simple answer to the original question is “around 240nm” under normal real world conditions.
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For a terrestrial link. For a satellite link, depending on antennas, it can be much farther.
The obvious practical example here is the Aireon payloads on Iridium NEXT which are in a ~780km low earth orbit and can reliably see ADS-B (at least from top antennas) all the way down to the surface.
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