In simple terms and in detail, how does radar work? Any resources on the web that explains it nicely?
148430
A ultra-high frequency radio signal is generated by a magnitron transmitter tube.  A burst of signal is transmitted to a parabolic antenna which focuses the signal in one direction, through a hollow tube called a waveguide.  Just like a light is focused in a flashlight!\nFollowing the transmission the radar set goes into receive mode and receives the reflection of the transmitted signal.  The time delay represents the distance away from the transmitting / receiving antenna. The further away the longer it takes the signal to travel.  Now something will only be visable to radar if it is larger than a quarter wavelenth.  What this means to you in practical terms is this something can be so small that it cannot return a signal on some frequency!  So Radars that search for enemy aircraft have multiple frequencies so that they can detect multi-sized targets.  Aircraft when they come at you present a small target, although they are large.  Anyway Hope I have been of some use.\n\nHave a good day.\nIf you need more detail ask in additional details I can answer any specific.\n\nAPS
26442
Radar guns get two signals returned; one is the reflection from the target car, and the other is the reflection from everything around it (particularly from the road).  If the police car is not moving, then only the target car's reflection is Doppler shifted.  But if the police car is moving, then both the road reflection and the target car's reflection are Doppler shifted.  \n\nSome radar guns (called moving mode radar) can measure the difference in Doppler shift between these two signals, and thus measure the speed of the target car relative to the roadway.  Other radar guns (stationary mode) just pick the target car signal and will not work at all from a moving police car. If the police car were moving, a stationary mode radar will interpret the ground reflection as a target car reflection and will only report the police car's speed, regardless of what the target car is doing.  In otherwords, a policeman never just "adds his speedometer reading to the radar gun speed" as the previous answer said.\n\nThe important trick is that the target car must be moving either away form or towards the radar gun (whether stationary mode or moving mode), within about +/- 12 degrees, otherwise the radar gun will report a lower speed than the actual target car speed.
995173
Use an RF Spectrum Analyzer to detect and locate any device emitting a radio signal.  Spectrum analyzers tend to be extremely expensive and might have a lengthy learning curve if you're not familiar with radio physics.  There might be cheaper ways, but I doubt there is any other way that is as reliable as a spectrum analyzer.
734042
Try to watch here:\nhttp://www.radio-materiel.ch/new_design/radiomateriel/download/tps/tps.pdf
561483
Probably Radar - measuring the doppler shift (difference between transmitted frequency and reflexted frequency).\n\nDepending where you are, many police forces use laser systems these days. They are more precise and faster, but require someone to aim it at the target - not really suitable for a tennis ball!
895054
Guilty as charged. No twinkies for you. I recommend you slow down. Radar is only affected by angulation and then it is typically on your side, not mine.  Go pay your fine.
855420
I don't know of any drawbacks of having a radar. I am the Skywarn Coordinator in my City and I have a radar on my computer to give a more early warning for severe weather.\n\nI see what the NWS is seeing. When they spot something severe, it goes through a chain. Like from them to the broadcast media and so on, till it gets to you or your city to turn on their warning system.\n\nWhen I see it on radar, it comes straight from me to the city and they turn on the warning system. Its a good 2-4 min earily warning for us.
254943
If they can arrest a person on private property, why would they not be able to radar a person on private property? Granted, if on private property they are likely focused on the matter in the area, perhaps a domestic dispute, but why would there be an expectation of privacy when you pass private property, upon which a police officer, is via a car? \n\nNow, if you mean the whole area, including the road, is private property, then I would assume no, as the presence of the police must be based on cause, which could be as simple as a neighbor calling in about suspicious noises. However, once on the property, the police's powers, while possibly limited if they are present because of a search warrant, still exist in terms of monitoring and apprehension. If a person is speeding on the property, unless that speeding, or other type of driving, is lawful on the property, the police would have reason to use a radar gun, or just to detain the person and possibly arrest him. At the very least, the matter is best understood by knowing what kind of driving may be performed on what kind of property.   \n\nIn either case, my strong suspicion is that they can in some cases.
211329
ABOVE IS A TRAITOR,SCUM (TO YAHOO!)\n\nIF I LIVED IN  PEORIA ILLINOIS, UNITED STATES OF AMERICA NA , MY TRUE LOYALTIES WOULD LEAD ONE TO THE TRUE DOPPLER RADAR PLACE AND THAT IS  >>>>>>> Y A H O O  ! <<<<<<< WEATHER.  ALAS YAHOO! WEATHER, CAN ANSWER THIS QUESTION.\n\nWHY SEARCH FURTHER WHEN THE ANSWER IS UNDERNEATH YOUR NOSE!  \n\nOF COURSE YOU CAN GO TO THE FAA .GOV  AND THOSE OTHER UNNECESSARY SITES ---- GO TO YOUR AIRPORT SITE  AND SEE.\n\nHAVE FUN AND A GOOD DAY!\n\nYAHOO! IS ALL YOU NEED !\n\n\nAPS
154920
I think you're referring to the radar gun that is used to measure the speed of a pitcher's ball. Yes, they work.
21635
Meteorologists now use doppler radar to better define weather systems, especially rain clouds.  Theoretically this should permit more accurate seeding of clouds with silver iodide (from planes or the ground) to produce rain needed for crops.  At one time hurricanes were seeded with some success; but think of the lawsuits if they steered one your way and you lost your house!!!
607361
Actually NOAA has quite a handful of planes with high-quality radar, and they do use them in such projects.  I direct you to http://www.stormresearch.com/vortex/ for one such project, and http://www.ucar.edu/communications/newsreleases/2002/ihop.html for a more recent project on rain.\nI am currently related to a project looking at some high resolution Dopplar data from a hurricane a few years back while it was over the ocean.\n\nRegular WSR-88D Dopplar (the network the NWS uses) is decently effective at general alerting to possible tornadic storms... and it would be extremely expensive to send planes out all the time just for warning purposes (though there is a new test-project to setup a larger network of low cost radars to improve warnings a lot (http://www.casa.umass.edu/)).\n\nBut there are some things regular 88Ds can't give us, including:\n- better time and spatial resolution of features (we want to be near a tornado to get a more precise view of what it looks like, and WSR88Ds only update something like every 5 minutes because they scan the entire 360 degree sky)\n- the vertical wind fields.  You need at least two properly located radars to get the full 3-dimensional structure of winds... and this is crucial to understanding what's actually happening in a storm.\n\nSo, yes, portable Dopplars are very useful.  They also help us look at weather in places where we don't/can't have any fixed radars (like at sea or in mountain ranges).\nGenerally, portable radars on trucks will get us the same information, are much cheaper (and safer) to transport, you don't have to worry about removing the motion of the radar (planes are moving, trucks can be stopped), and you don't have as much trouble with beams hitting the ground... and thus most of our tornado information comes from truck-mounted radars like the famous Dopplar on Wheels (http://aaron.ou.edu/dow/dow.htm).  However, there are some reasons to use planes even in such experiments, including better upper-level resolution, the ability to reposition quicker, and the fact that trucks can only hold and power radars that are a cerain size.\n\nPlanes are indeed useful, and hopefully we'll continue to get better ones for research... as they really can provide quite a great suite of information (dropsondes (weather sensors that are dropped from airplanes) are also great because they give a rather quick profile of the atmosphere)!\n\nAwesome question!\n\nHope I helped answer things,\nGod bless,\nShane
359228
Yes it is used in radar scan converters.\nFor more details - http://www.cwcembedded.com/products/0/4/356.html
854507
HowStuffWorks.com is a resourceful website for these type of questions.\n\nhttp://home.howstuffworks.com/microwave.htm
1172796
I'm guessing that you are asking because you are looking to purchase.  With that it mind here is some info and I hope it helps!\n\nIn early radar detectors:\nS - Band Radar : operates at 2 - 4 GHz\nX - Band Radar : operates at 10.50-10.55 GHz (Not accurate below 20MPH)\nK - Band Radar : operates at 24.05-24.25 GHz\n\nIn modern radar/ladar detectors:\nKa - Band : operates at 33.4 - 36.0 GHz (has 13 200-MHz channels, can operate in “hop” mode)\nLadar : uses light emitted at 904 nm (typical)\n\nAdvantages of Radar\n*Very flexible - can be used in a number of ways (Stationary mode, Moving mode, Two Directional mode)\n*Beam spread can incorporate many targets\n*Can often select fastest target or best reflection\n*Still very reliable\n\nRadar Disadvantages\n*Time - Radar can take up to 2 seconds to lock on\n*Radar has wide beam spread (50 ft diameter over 200 ft range)\n*Cannot track if deceleration is greater than one mph/second\n*Large targets close to radar can saturate receiver\n*Hand-held modulation can falsify readings\n*More interference sources\n\nLadar Advantages\n*Faster lock-on time (less than 1/3 second)\n*Very narrow beam spread (less than 6 ft over 2000 ft range)\n*Better ability to track decelerating targets\n*Typically mounted, and aimed with optical targeting device\n*Fewer sources of interference\n*Much more difficult to detect\n\nProblems with Ladar\n*Particles (dust, water) in air can limit range\n*Rounded surfaces, the colors black, blue, and violet are poor reflectors\n*Can be difficult to track target\n*Alignment can cause severe error\n*Extreme sunlight can be damaging\n\nConclusions\n*Ladar is, in the correct environment, better suited for speed detection\n*Ladar is not perfect, however\n*There is still room for Radar patrolling\n*Both could be used in concert to achieve maximum detection capabilities
482962
Radar works because radio waves are reflected off of many objects. Stealth fighters are designed to hide from radar by minimizing the amount of radio waves reflected. I am sure a technologically advanced civilization could hide from our radar, however that would also imply that they want to. If they were trying to make contact, I am sure they could make sure we see them on radar.
617922
stealth technology is based on a number of things but the way it works is on fighter jets that are stealth there bodies are emitting a very low electrical current (lower than commercial planes) the stealth bombers that the American army uses the reason they are claimed to be undetectable to radar is because the current and exhaust in those are spread out on a very thin line from the rear of the plane which makes them virtually undetectable (although its been proven that they are not in fact undetectable just very hard to pick up on radar but yes the answer to you're question is stealth on planes works because the planes are made of a combination of highly sensitive metals which (soak up so to speak) the electrical current that radars emit to detect planes as for anything else stealth I'm not sure sorry...