Talk:Radar cross section

message: This statement (in the first paragraph) is spurious:
"The RCS of a target object is equal to the cross-sectional area of a perfectly conducting sphere that would produce the same magnitude of reflection as that observed from the target object."
It is only correct (or, at least, approximately so) in the high-ka limit. A clear way to demonstrate its invalidity is to ask "What is the RCS of a perfectly conducting sphere?" By the definition given above, it must be, at all frequencies/wavelengths, \pi a^2, the cross-sectional area of the sphere. But, of course, in the resonance region the RCS of a sphere is not constant; it wobbles about the high-ka limit. And in the low-ka limit the RCS falls precipitously.
The correct definition for RCS is stated later in the article: \sigma = 4\pi P_backscatter / P_intercepted
:You are correct. I made some changes to the article to clarify that the RCS is the same as a sphere only when the target spans several wavelengths. =Axlq 18:50, 5 July 2007 (UTC)
thread_title:  Spurious definition of RCS 

message: Wikipedia isn't just for specialists in... god knows what it's called "Radarography" lol, it's for uneducated people to educate themselves too. Now I've been reading up on radars at HowStuffWorks.com and I still don't understand this article. I know essentially that a large RCS means a big blip on the radar screen at home receiving its "rays" or whatever, that bounced off a plane it zapped for example. But I didn't learn that from here, take for instance the opening line. It says;
Radar cross section (RCS) describes the extent to which an object reflects an incident electromagnetic wave.  It is a measure of the strength of the radar signal backscattered from a "target" object for a given incident wave power.
WTF is a "incident electromagnetic wave"?, I know "electromagnetic" is linked but it doesn't explain this incident wave thing. What's backscattering? Then it hits you with a "given incident wave power"!
Now I know the opening line has been the subject of some debate recently, but it's not just the opening line. Perhaps we could save the formula in the definitions section for the calculation section, and an example of RCS would be very very helpful. I think we should try and explain the basic concept in very basic terms to dummies like me, in the opening paragraph. Then the rest of the article can be used for all the factual encyclopaedic knowledge. Please don't think stupid of me, I just don't know about radars. I'd love it if someone could send me a condescending dummed down explanation of RCS please, then perhaps we could work together to make the article a bit more easy to understand.Ryan4314 (talk) 21:24, 1 January 2008 (UTC)
thread_title:  Article is too hard to understand 

message: Somehow the current article misses a major usage by radar and ECM designers & analysts: the use of dBsm (which has no article at present) to express the measured RCS. There's one implied calculation in the RCS article when it mentions reducing detection range by shrinking the RCS, but the actual math is omitted. Using dBsm instead of a straight ratio could make it more understandable, if the two-way radar range equation is brought into it. Also, the image given at the top of the article of an aircraft RCS has no units shown; I bet they are dBsm though. Please consider adding this kind of info, and an article on dBsm that links to both RCS and decibel. I've just posted something similar on the decibel article talk page.
Reference: dBsm@everything2.com
138.163.0.42 (talk) 18:20, 8 July 2008 (UTC)
thread_title:  dBsm 

message: sir,
i want to know about more .
on that topics
because no person clear the concept what actually it is
i have to many question
like
on what it depend?
and more.............
plsssssss
suggest me more idea about that.  —Preceding unsigned comment added by 117.197.17.67 (talk) 16:07, 14 October 2008 (UTC)
thread_title:  radar cross section 

message: Hi, I noticed that the definition of RCS on this page is currently not correct.
It says:  "Radar cross section of an object is defined as: The cross sectional area of a conductive sphere that would reflect as much energy as the object in question."
However, conductive spheres have nothing to do with RCS.  A more correct definition might go like:
"RCS is the area required to intercept the transmitted power density at the target such that when the total intercepted power is re-radiated isotropically, the power density actually observed at the receiver is produced."
The major issue here is that the sigma/(4 pi r^2) term in the radar equation implies that the scattered power is radiated isotropically -- and a sphere (PEC or otherwise) definitely does not scatter incident plane wave power isotropically.
Also, I am pretty sure the simple definition of sigma as 4 pi Pbackscatter/Pintercepted cannot be correct because it is not dimensionally correct -- sigma has the units of area (i.e., meters squared).
I have a 1970 copy of Radar Handbook edited by M.I. Skolnick handy, and I will quote section 27-2 (which describes a monostatic case with G = Gr = Gt):
"sigma = ((4 pi)^3 r^4 Pr)/(Pt G^2 lambda^2)"
.
.
.
"...and radar cross section has the dimensions of area.  The concepts embodied in the above definition are those employed in formulating the radar-range equation for received power and area as follows:
1. The establishment of local power density at the target by the transmitter and its antenna.  This is represented by the factor G Pt / (4 pi r^2) and is measured in watts per unit area.
2. The capture of a portion of the incident flux and its reradiation to account for a dimensionless factor sigma/(4 pi r^2).  A hypothetical area sigma is defined in terms of isotropic reradiation to yield the observed power flux density at the receiver."  —Preceding unsigned comment added by Double helix (talk • contribs) 05:59, 27 February 2009 (UTC)
replies: text: You have my blessing to fix it then, but for the love of god keep it simple. This is meant to be an encyclopaedia for people who don't know about these things. I have no idea what you just said, nor what the current article is talking about (see my above thread). Ryan4314  (talk) 15:14, 27 February 2009 (UTC)
thread_title:  Definition of RCS on this page is not correct 

message: In the last paragraph of the "Definition" section of this article, there seem to be two mutually exclusive statements back-to-back: 
"... RCS is an extremely valuable concept because it is a property of the target alone..." 
"... RCS is a strong function of the orientation of the radar and target, or, for the bistatic, a function of the transmitter-target and receiver-target orientations."
From the first statement, it appears that RCS is a constant for the specific airframe (independent of orientation, velocity, etc.). From the second, it seems that it is changed by external factors. I don't know which is right, so somebody who knows, please look into this. 
Side note, I've always understood that relative velocity is a big factor in detection by modern radars. Targets which move more quickly relative to the radar source are more easily discovered. Is the velocity factored into the Pt? 75.170.61.39 (talk) 21:44, 11 May 2009 (UTC)
thread_title:  Seemingly contradictory sentences 

message: Hey folks, I removed:
"Informally, the RCS of an object is the cross-sectional area of a perfectly reflecting sphere that would produce the same strength reflection as would the object in question. (Bigger sizes of this imaginary sphere would produce stronger reflections.) Thus, RCS is an abstraction: The radar cross-sectional area of an object does not necessarily bear a direct relationship with the physical cross-sectional area of that object but depends upon other factors."
from the article because it is wrong in general.  Please do not put this wrong info back in the article.  RCS has nothing to do with perfectly conducting spheres, real or imagined.  If you look at a Mie series, which is an analytical solution for the RCS of a sphere, at high frequencies the RCS does approach the geometrical cross section of the sphere.  But when the sphere is not many wavelengths in radius, this is not true, and thus the statement I removed is false.  —Preceding unsigned comment added by 68.35.14.57 (talk) 03:13, 1 February 2010 (UTC)
replies: text: The wikipedia is based on reliable sources. You are not a reliable source, you're just an insulting opinionated anonymous coward who is probably going to get suspended soon.- Wolfkeeper 12:26, 1 February 2010 (UTC)
thread_title:  Definition Wrong (Again) 

message: Well, it looks like you're pretty good at name calling, yourself.  I will now enlighten you with a citation.  According to Balanis, Advanced Engineering Electromagnetics, John Wiley & Sons, 1989, section 11.3, p. 577, "The echo area or RCS is defined as the area intercepting the amount of power that, when scattered isotropically, produces at the receiver the power density that is equal to the density scattered by the actual target."  This is a standard graduate engineering E&M text.  Note that Balanis does not say anything about spheres.  That's because defining RCS this way is wrong.  Not "informal", but wrong.  As has now been noted several times, the fact that the RCS of a sphere approaches its geometrical cross section at high frequencies is basically a mathematical coincidence and does not imply much about the nature or definition of RCS.  For example, the RCS of an airplane does not approach its geometrical cross section at high frequencies.  If it did, the F-117 would've been worthless and the only recourse for RCS reduction would be to build a smaller airplane.
So I'm growing tired of arguing with you.  If you want to be a stubborn bully and keep this plainly wrong definition here, then that's fine by me.  But it's a little like seeing someone throw a piece of trash down on the ground in a public park.  No, it doesn't really hurt me that much, but it does make the world a worse place for everyone.
I'm not worried about being banned since I'm on DHCP.  Take care, and I hope you never have to do any calculations of RCS that matter in the real world.  —Preceding unsigned comment added by 68.35.14.57 (talk) 04:34, 4 February 2010 (UTC)
thread_title:  Definition Still Wrong... 

message: The current lead seems a bit unwieldy with the bulleted list and equations. here is a possible re-write: . With no objections, I will add this to this article in a couple weeks or so. Mysticdan (talk) 18:33, 16 December 2016 (UTC)
thread_title:  possible lead re-write