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Sea Kayaks Techniques Bulletin Board
Re: debatable...
Posted By: Jerry In Response To: debatable... (Christian H)
Date: Saturday, 23 December 2000, at 12:49 p.m.
: See notes in original text
: Kayakers and kayaks are generally organic "radar translucent"
: material. Metal is a much better reflector of radar waves than plastic, a
: human body, water etc. Only rock comes close, but might be a bit heavy as
: a radar reflector!Not exactly, some materials that kayaks are made of are not transparent they're absorbant. Kevlar and to a certain extent fiberglass absorb most if not all the radiation that come into contact with it. However, the gelcoat and fasteners reflect a lot of energy back, not to mention anything that might be strapped on deck. Plastic is to a large degree transparent (RADAR energy passes through it), however, the contents inside of the kayak are quite reflective, stuff like stoves, pots and pans, tent poless etc.... will most likely reflect enough energy back to the receiving antenna.
The material of the objected being painted on RADAR doesn't have as big an impact as the angle of it. The more 90 degree angles or better on an object, the better it's reflectivity. If you look at the F-117 fighter you'll notice that it's made of metal. However, there isn't one angle over 90 degrees on the whole darn plane. In fact I don't think there's anything over 45 degrees. And the plane probably has more metal on it that a thousand kayaks could have, yet its reflectiveness is less than that of a bumble bee.
: Yes, the aluminum foil may work well. "Chaff" used as radar jamming
: decoys in arial warfare is made up of fine strips of aluminum foil. The
: reflections from these clouds of chaff produce tremendous return, albeit
: largely due to the wide dispersion of the individual aluminum bits.Sort of, Chaff is actually fine strips of aluminum foil cut into different lengths, and widths. The length and width of a chaff foil determine the frequency that the energy will be reflected back. As a wave leaves the transmitting antenna, strikes an object, and returns back to the receiving antenna its frequency changes slightly (the doppler effect). Most antennas are designed to pick up return energy across a spectrum of frequency's. However, if the chaff is of the wrong width or length it can alter the energy frequency to a point that the receiving antenna won't even be able to detect the energy's return. So most chaff is cut into different lengths and widths to cover a pretty broad spectrum of freqs.
While it's not used to jam it is used as a decoy in electronic warfare. It's typical employment is used to confuse enemy warheads. The human operator and most anybody else for that matter is capable enough to be able to see through the chaff and can see the actual target. On RADAR chaff shows up as a giagantic cloud, which might be a problem. Meanwhile an actual target looks a little like a bananna. So if you do decide to try something like that all you might end up doing is confusing the operator into thinking that all they're seeing is a huge clound. The second problem is that chaff really needs a few minutes from the point that it's launched to when it disperses enough to do some real good. Thirdly chaff can stay afloat for hours, so if there's any low flying aircraft they might be endangered by foreign object damage. And fourthly, it's probably illeagle as it can interfer with local air traffic RADAR and local air traffic.
A bit
: of aluminum foil on your hat may improve chances of detection. It would
: also keep those alien rays from reading your thoughts! 8-)Remember to keep the shinny side out.
: Here's where we differ. I have used a thin "whip" antenna as a
: suspender for a radar reflector. The thick end was loosely placed in a rod
: mount behind the cockpit. Were I to flip it would fall out under it's own
: weight (tether to boat!), or will be easily dislodged by the paddler
: should it remain in place. I also have no reservations rolling with the 6'
: pole in place, as it's water resistance is not that great.On of the problems with that, and this is pretty indictative of all boats is that the reflector itself probably bobs around a bit due to wave action. Remember that the energy has to get reflected back to the source inorder to be seen. If it's a little rough out there then the bobing of the reflector might actually cause the return energy to return straight up into space or down into the water because of the angle of a constantly moving reflector. However, it can also work both ways and more energy can be reflected bacause of a bobing moving boat and you'll return more energy, thus creating a bigger return. But keep in mind that this can happen to the biggest freighter or the smallest kayak, it really depends on the seas.
Peace and happy holidays
Jerry
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