Bergman
New member
I've no strong feelings either way - put up as many as you like for me, I was just trying to point out that cancellation is very unlikely to occur and why that is the case.
Radar Refector(s)
- Thread starter jimi
- Start date
charles_reed
Active member
Stealth aircraft
In fact that's almost precisely what is done - look closely (if you can get there without being jailed).
BTW military radar (even obsolescent 3rd world stuff) is very much more sensitive than x-band.
In fact that's almost precisely what is done - look closely (if you can get there without being jailed).
BTW military radar (even obsolescent 3rd world stuff) is very much more sensitive than x-band.
Bergman
New member
Re: Stealth aircraft
Very true
A trifle more sophisticated than 2 reflectors but principle same.
We could have saved them billions
1% commision do you?
Very true
A trifle more sophisticated than 2 reflectors but principle same.
We could have saved them billions
1% commision do you?
ccscott49
Active member
Tests' have shown and I repeat actual TESTS that two radar reflectors have the effect of minimsing the return signals in some directions! The theory is all very well, but it took the americans 30 years and millions of dollars to come up with stealth! I wonder why?? Radar reflectors have had huge amounts of money thrown at them, couple of thousand at least. Its hard enough to convince some people to haul one up to the spreaders, now you want two! That last bit was only joking!
brian_neale
New member
Think about this one, guys.
Sure, two reflectors will sometimes give reflections back that will cancel (reflections are in anti-phase, technically). Now, what are the conditions under which the signals are going to add together to make the return stronger? When they are in phase, of course, and by the nature of things that will happen exactly the same amount of time as the cancellation, on average. This is why it is so difficult to get accurate and repeatable radar reflector measurements - the physical movement in going from one extreme to the other is quite small (measured in centimetres). So, with two reflectors, when they are adding (and this need not be exact - they could be "not quite in phase") they will give a stronger return than just one reflector. But when they turn or move so as to start cancelling, the signal will be weaker than just one.
Best of all is a single, larger, reflector, which is designed so that it does not have multiple randomly-oriented reflecting elements pointing in any one direction.
Stealth aircraft technology is interesting here. Use flat panels - because the reflection comes off in a very narrow beam that is unlikely to be received at the same point from which it was sent; avoid right-angles, because their geometry is such as to send a reflection back in exactly the same direction as that from which it arrived; coat the aircraft with radar-absorbent paint so that the return signal is much weaker. These are reasons why aluminium foil, in sheets or crumpled, makes such poor reflectors in practice. Highly conductive, so all the signal bounces off, but flat sheets send it in the wrong direction, and crumpled sheets have nary a right-angle among all the creases so the return signal is scattered in all directions and becomes too weak to detect.
Sure, two reflectors will sometimes give reflections back that will cancel (reflections are in anti-phase, technically). Now, what are the conditions under which the signals are going to add together to make the return stronger? When they are in phase, of course, and by the nature of things that will happen exactly the same amount of time as the cancellation, on average. This is why it is so difficult to get accurate and repeatable radar reflector measurements - the physical movement in going from one extreme to the other is quite small (measured in centimetres). So, with two reflectors, when they are adding (and this need not be exact - they could be "not quite in phase") they will give a stronger return than just one reflector. But when they turn or move so as to start cancelling, the signal will be weaker than just one.
Best of all is a single, larger, reflector, which is designed so that it does not have multiple randomly-oriented reflecting elements pointing in any one direction.
Stealth aircraft technology is interesting here. Use flat panels - because the reflection comes off in a very narrow beam that is unlikely to be received at the same point from which it was sent; avoid right-angles, because their geometry is such as to send a reflection back in exactly the same direction as that from which it arrived; coat the aircraft with radar-absorbent paint so that the return signal is much weaker. These are reasons why aluminium foil, in sheets or crumpled, makes such poor reflectors in practice. Highly conductive, so all the signal bounces off, but flat sheets send it in the wrong direction, and crumpled sheets have nary a right-angle among all the creases so the return signal is scattered in all directions and becomes too weak to detect.
ccscott49
Active member
Brian, whats the point? As you say a properly constructed single reflector is best? Then you have answered the guys original question, sell it to somebody else for beer tokens! Especially at Christmas!
