Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!asuvax!hrc!godzilla!dalyb From: dalyb@godzilla.UUCP (Brian Daly) Newsgroups: sci.electronics Subject: Re: radar cracks windshield Summary: I doubt it! Message-ID: <49b3c6da.1423f@godzilla.UUCP> Date: 9 Apr 90 16:33:23 GMT References: Organization: gte Lines: 29 In article , jjoshua@topaz.rutgers.edu (Jon Joshua) writes: > > Date - 1980. Person is driving a '79 Monte Carlo through town. All > of a sudden the windshield cracks. It was not caused by a kid > throwing rocks because the crack was rather straight. Anyway the > person pulls off the road and a cop pulls up a few seconds later. The > cop had been using radar and the windshield had a built in antenna > wire. > > Could radar hitting the wires in the glass cause them to resonate so > much that the glass cracked? > I doubt that the electromagentic energy emitted by the police radar would have the effect that is mentioned here. First, the power output of a radar gun is relatively low. Following the inverse square law, the amount of energy received at the car would be a fraction of the radiated energy. This would hardly be enough energy to crack a car window (did you ever see how hard it is to crack tempered glass?). Second, since the wavelength of a radar signal is very small, a car antenna (wire) is not an effecient antenna for the microwave radar signal. Thus, not much of the radar signal will be received by the car antenna. -- Brian K. Daly WB7OML @ AG Communication Systems, Phoenix, Arizona UUCP: {...!ames!ncar!noao!asuvax | uunet!zardoz!hrc | att}!gtephx!dalyb Phone: (602) 582-7644 FAX: (602) 582-7111 ~