Radar invisible car?

Discussion in 'General Science & Technology' started by Communist Hamster, Aug 31, 2005.

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  1. Nasor Valued Senior Member

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    False. Laser jammers are illegal in many states.
     
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  3. Stryder Keeper of "good" ideas. Valued Senior Member

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    Or better still watch your speed, save your money from not getting tickets or buying jammers and spend it on hiring out a race track for the day with a bunch of other motorists. You'd be surprised how much fun you can have legally wearing your tyres out and socialising at the same time.
     
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  5. Buffalo Roam Registered Senior Member

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    Really? :roflmao: don't know much about stealth technology do you?
     
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  7. speedvillain Registered Member

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    Responding to the Idiot

    If this is true than why does the police dept. spends tons of money on radar equipment. I just can't imagine a cop fighting a speeding ticket in court by saying I saw him speeding with no proof.
     
  8. speedvillain Registered Member

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    Active Radar Jammer

    Does anyone know where you can get an active radar jammer. They are very hard to find considering they are illegal. However, they are out there and I was wondering if anyone had any idea. Btw do not reply to this post if you don't know but want to submit your thoughts about the legal issues and the do's and don't cause no one cares. If building one is an option i'm up for it..
     
  9. Echo3Romeo One man wolfpack Registered Senior Member

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    You could build one using a pair of Gunnplexers. Look for surplus motion detectors and door openers, like you'd find at a supermarket. They'll typically have output powers from the tens to hundreds of mW (higher is better for ECM purposes). Get a K and Ka band Gunnplexer to be sure (X band speed radars are rare these days, and antennas and waveguide for ~10 GHz stuff is quite large and awkward).

    Powering up a Gunnplexer is as simple as putting a DC biasing voltage (typically 8-10V) across the diode, but you need to make sure you're forward biasing it, which can be tricky as Gunn diodes have no polarity and reverse biasing them can blow the junction. An easy way to run a Gunnplexer in a vehicle would be to use a LM7808 regulator to produce 8VDC from the car's electrical system.

    Once you power the Gunnplexers up you'll need to tune them to the police radar frequency within their design ranges. If you've got an oscilloscope that will reach into the SHF spectrum, or a downconverter and a less expensive everyday o-scope, that will work. Or you can use a spectrum analyzer, or even a diagnostic tool the police themselves use. Physically tuning a Gunnplexer involves advancing or backing off a small allen bolt from the cavity, which changes its resonance and thereby also the oscillating frequency of the diode. Match their center frequencies to that which are used by police radars.

    The Gunnplexers should come with small horn antennas attached, but if not you can find some on ebay or possibly at a ham radio flea market. At this point all you need to do is give them sufficient mounting and power in your vehicle, and test them to see if they work. If you want to get really crazy, you could get a reflex klystron or TWT from a higher powered search radar or terrestrial microwave comm gear. Those have output powers measuring into the hundreds of watts PEP.

    I've heard of the commercially-available "jammers" and also of their uselessness. I would never trust anything sold commercially, as it would be illegal under US Federal law to even manufacture such a thing, if it worked. The FCC requires all RF devices be registered before manufacture is authorized. Further, RF devices that produce interference with lawful RF devices (including speed radar) are categorically unlawful to sell, much less actually use in criminal activity (interfering with police business, producing unlawful RF emissions, etc.) I've thought it would be cool to try to make one of my own as described above, just to see if it works, but haven't ever had the motivation to. No way I'd spend hundreds of dollars on some other asshole's black box that I know does nothing, when I could make something myself that at least might work.
     
  10. codanblad a love of bridges Registered Senior Member

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    in australia they use sensors in the road.
     
  11. Nasor Valued Senior Member

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    Uhh...you do realize, don't you, that cops have been writing people speeding tickets for as long as cars have existed. Radar/laser speed guns are a relatively recent invention. I don't know about everywhere, but I in my state part of a police officer's training involves estimating how fast a car is going when it passes them. They're required to be able to accurately estimate it to within some fairly narrow range, something like +/- 5 mph. I've been told it's actually not that hard once you spend a little time practicing it. Police don't generally need any physical evidence that someone committed a crime; they can just say they saw person X doing action Y, and that's good enough for the courts.
     
  12. Echo3Romeo One man wolfpack Registered Senior Member

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    Yeah, this is the standard everywhere in the US, afaik.

    For another means of estimating, on highways they'll also put white lines perpendicular to the road at set intervals. An airborne observer in a helo or light airplane will use a stopwatch to time a car as it clears the lines and calculate its speed, then handoff the info to a patrol officer for the interception.

    IMO, it's a waste of time to try to defeat radar and LIDAR, as they're really just there for redundancy and some form of physical evidence for the officer's case.
     
  13. longhorntexas Registered Member

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    As far as I know

    I don't presume to be expert, but I am pretty sure stealth plane doesn't actually absorb radar, but rather it traps the radar within it's structure / in direction other than where the radar is coming from.
     
  14. Montec Registered Senior Member

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    There are two different methodologies to stealth.
    One is to reflect the incoming radar away from the transmitting radar.
    The other is to use RAM materials or paint. IE use a high resistance, small diameter, iron alloy wire cut into segments that have a dipole length equal to the frequency of the incoming radar. Embed this wire into paint and you have a stealth paint job for that frequency. I believe this technique is used in Japan to paint the bridges so that ship radar will see other ships and not the bridges.

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  15. dscharenbroch Registered Member

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    luvmyctsvcoupe

    About 8-10 years ago, someone built a stealth car. It was featured in one of the popular car magazines, Road & Track, Car & Driver, Motor Trend, or Hot Rod, etc. I don't rember which. It was tested somewhere out west, Arizona, Utah or Navada. They tested it against state police radar. The car performed flawlessly. It was invisible on radar. I have searched the Net but have not found the article yet. If you really need to know, write the editors about their archive articles on stealth cars.

    I have a CTS-V Coupe that has been modified. It produces 650 HP. It is black on black with black tinted windows. I am not interested in a stealth vehicle since it would ruin the beauty of the design & :shrug::shrug::shrug:appearence. Good luck on the quest. There is a stealth car out there somewhere.
     
  16. HEZ-BALLER Registered Member

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    I DONT KNOW IF I UNDERSTAND,

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    :shrug:THE RADAR ABSORBING MATERIAL IS RADIO-ACTIVE ?
     
  17. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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  18. wlminex Banned Banned

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    . . .haven't read all of these posts . . . but I once had an idea to use an array of corner-reflectors (e.g., the front grill assembly) to overwhelm radar returns to the source . . . I hear that police radar detectors are designed to recieve only very weak return (reflected) signals. Also, I went to court once on a speeding violation and argued (successfully) that unless the radar source were 'calibrated' for temperature (inside the police vehicle - i.e., if air conditioner was on or off), that simple metal shrinkage or expansion (due to cooling or heating) at the radar emanation source would alter the radar signal produced by the device and could produce erroneous results. Both the court and the patrol officer were intrigued by the concept and I was asked to explain in more detail. I got the violation dismissed and in a friendly conversation with the officer afterward, he said he had not ever considered such a phenomenon. Worked for me . . . .!
     
    Last edited: Oct 9, 2011
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