Path: utzoo!utgpu!water!watmath!clyde!att-cb!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!cornell!rochester!PT.CS.CMU.EDU!andrew.cmu.edu!il01+ From: il01+@andrew.cmu.edu (Ihor Andrew Lys) Newsgroups: sci.electronics Subject: Re: Robocop/ECM/ECCM/EW Message-ID: Date: 3 Apr 88 19:38:23 GMT References: <1342@titan.camcon.uucp> Organization: Carnegie Mellon University Lines: 27 In-Reply-To: <1342@titan.camcon.uucp> I found your post on diffration grating interesting. Its not a bad idea, and I thought I'd take some time to comment. The principles behind the technology seem sound. Its great for airplanes. No echo, no see, and you are essentially invisible. Traffic radar is a different story. Lets look at the principles behind each for the reason. I think you will agree that in principle the beam of a scanning radar system looks at only one spot at a time. It measures the amount of time it takes for a signal to reach the target and return. Traffic radar illuminates the road with a wide beam, and monitors the frequency shift due to the doppler effect of the returned signal. The fundamental difference is that traffic radar dosent care from where the signal came. Position radar does. The effect is that smokey will get some reflected energy from the car, that which bounces off of some other reflective object. The absence of a direct reflection does not prevent detection. It does severely decrease the range in certain situations. The vehicle does not have nearly as high a radar profile as it did before. The ultimate trick would be to absorb, not reflect the microwaves. It is a well known fact that this is possible, but again it is difficult. Water absorbs certain frequencies of microwaves, and this principle is used in the microwave oven. All you need to do is to find the appropriate molecule and paint it on the inside of your fiberglass body. Good luck. -il01 @andrew.cmu.edu -Ihor Lys