Polished hood

That's the spirit.

 

Emissivity doesn't matter in radio waves, at least not as much as you are making it out. Sure, you will deflect a good portion of the signal, but keep in mind the scale of what we are talking about. Just because when you run your hand over it it doesn't feel glass smooth, doesn't mean there isn't a very VERY large amount of that surface that is providing a surface perpendicular to the incoming signal. And like I said, you would have to absorb every single photon of the incoming laser for it not to reflect back. If you can see the dot, the device can see the dot.

There is also PRF and Modulation. You could slow that signal as much as you want, the underlying information in that signal can't be changed. And the problem most people have is that they see a drawing of a waveform, and they think that is the actual representation of the waves in the air without reference markers to show them what the amplitude and frequency is. Do any of you know just how fast microwaves pulse? We're talking Gigahertz, BILLIONS of times per SECOND.
I think it is time to add PRF and Modulation to my Radar Blog thing.

 

With regards to what part of the EM spectrum? If you are telling me that flat black lacquer finish is somehow this magical void for EM radiation, then no, I wont even consider doublechecking. Yes, the rougher the surface, the less reflected signal is returned...obviously. What I'm saying is this, you are sending out billions of waves in a 1second pulse. That wave isn't some 1 demensional vector of light, it has a width and height and length. Wave patterns are going to have volume. When a volume of EM radiation strikes an object, yes, there will be deflected information, but microwave radiation really doesn't give ten ****s about what color your surface is. Information still gets back to the receiver and is still going to be processed. Especially with what is probably a 1W transmitter, and fired within a 1 mile range. For visible light spectrum and probably a good part of the IR subset, yeah, you can absorb lots of it with flat black paint. But the surface of your car is just a couple millimeters of paint on a metal or plastic surface.

If you want to stop radar from detecting you as a car, you will need some way of completely attenuating the signal at < or = 1 mile. Stealth countermeasures don't work for cars vs. cops at 1 mile distances. Preach flat black coatings all you want. I'm telling you that there is no substance available to you that you can spray on your car to defeat laser and radar detection systems.

And regardless, the best you can hope to achieve is to reduce your object's signature. That doesn't matter to a cop's radar gun, because a radar gun's job isn't to determine if you are a car or not. It's job is to determine the speed of the object in the crosshairs. That's why you can use them to determine how fast some kid is pitching a baseball. All it knows is that the object in it's ROI is travelling at X speed relative to it. In radar, there are usually two types, search radar and tracking radar. Search radar is used to find objects that are of a certain signature size, speed and heading. Tracking arrays are usually mechanically pointed at objects acquired by a search system. With regards to police radar guns, the cop's eyes are the search system, he see's your car coming down the freeway...that is acquisition...he see's your object, and can tell that by it's size and shape, it is a car. So, first you have to defeat or hinder the ability of the search system to identify you as an object of interest. A black car, flat or glossy, at 1 mile on an open interstate, surrounded by green grass and trees, and a blue sky, isn't going to pass that test. Regardless, once the cop has "acquired" you as a target, he is going to then point his radar tracking device at you. He already knows you are a car, so any countermeasures you have to reduce your car's profile are now pointless, as it didn't defeat acquisition. All he has to do is keep you inside of the radar device's receive aperature long enough to collect a few pulses of data that he's sent at you. Now we play the odds game...even if you have coated your car in graphite and ferrous materials, about 1/4 of an inch thick, and then on top of that, you've put up little graphite pyramids all over your car that form 90* angles with their adjacent pyramids on all sides, you still WILL NOT absorb all sent radiaton, nor will you entirely deflect all radiation. You will still have at least one surface somewhere on your car that forms a perpendicular plane to the incoming radiowaves and on that surface, you will not absorb every single radiowave as you are not a blackhole. You may gain a fraction of a second of time, as the receiver of teh device may filter results. But it'll see enough of them that it WILL detect you, and it WILL give the police your speed.

Again, as I said before, emissivity doesn't matter with regards to this scenario. If the cop had to physically see the laser dot on your car to get a reading, then yeah, flat black your car...he will have trouble seeing it at 1 mile. But that is because he is using eyes, not a detector array that is made to see just the wavelengths that the emitter is firing off. I don't know how the laser system works with regard to things like PRF and if it uses any kind of modulated information. So I can't comment there.

And I'll tell you right now, that if the US Navy knew that this magical flat black paint existed, then our ships wouldn't be painted light, semi gloss "haze gray."