What is Radar: Definition and 155 Discussions

Radar (properly R.A.D.A.R. or RADAR, for Radio Detection and Ranging) is a detection system that uses radio waves to determine the distance (range), angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the object(s). Radio waves (pulsed or continuous) from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.
Radar was developed secretly for military use by several nations in the period before and during World War II. A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution. The term RADAR was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging". The term radar has since entered English and other languages as a common noun, losing all capitalization. During RAF RADAR courses in 1954/5 at Yatesbury Training Camp "radio azimuth direction and ranging" was suggested. The modern uses of radar are highly diverse, including air and terrestrial traffic control, radar astronomy, air-defense systems, antimissile systems, marine radars to locate landmarks and other ships, aircraft anticollision systems, ocean surveillance systems, outer space surveillance and rendezvous systems, meteorological precipitation monitoring, altimetry and flight control systems, guided missile target locating systems, self-driving cars, and ground-penetrating radar for geological observations. High tech radar systems are associated with digital signal processing, machine learning and are capable of extracting useful information from very high noise levels.
Other systems similar to radar make use of other parts of the electromagnetic spectrum. One example is LIDAR, which uses predominantly infrared light from lasers rather than radio waves. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents.

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  1. G

    Is a matched filter the key to optimal radar performance?

    can anyone please explain me matched filter in detail ? my understanding is as follows ( in case of a radar). u transmit a signal and during reception have a filter in ur receiver which continously checks in the received echoes whether the echo has the same shape of the transmitted pulse. is...
  2. D

    Anyone know how I can build a FM radar gun?

    Well here are a couple of things I would like to know. Thanks in advance! how to build a Frequency-Modulated Radar gun. or how to build a Frequency-Modulated transmitter and reciever or where i can get either of these :D Thanks again!
  3. A

    Frequency & Wavelength of Radar & Sonar: Get Answers Here!

    Can anyone tell me what frequency and Wavelength Radar and Sonar work in. I think Radar have a frequency of 300giga hertz (UHF), wavelength 0.1 Sonar is somewhere between wavelength 100k - 10k metres, frequency 3k - 30k hertz. Please help me thanks,
  4. E

    Calculating Radar Cross Section

    I am trying to write a program to numerically calculate RCS using geometrical optics (or some form of it). Basically my idea was to cast a bunch of rays from an emitting object (in my code it is a 1 m^2 plate), find where they intersect a surface, reflect the rays off of this surface and see if...
  5. H

    To find speed of a plane when position of radar is given

    Homework Statement A plane flying at a constant velocity v (parallel to x-axis) at a height h = 8 km is being tracked by a radar located at origin. if the angle A is decreasing at the rate of 0.025 rad/s, the velocity of the plane when A = 60 degrees is: (A is the angle made by the...
  6. V

    What is the physics behind radar

    what is the physics behind radar
  7. P

    RADAR SPEED CAMERAS and HOT DAYS

    Hi all Is it possible that a RADAR speed camera, (the type that bounces off the road and is reflected off the vehicle and then the doppler shift represents the vehicle speed) can be affected by a raise in surface temperatue on a very hot day(40 degrees C plus, poster is in Australia) I...
  8. G

    How is aviation radar able to track objects in three dimensions simultaneously?

    I understand the theory of radar but not aviation radar. It is my understanding they can find an objects position in the x, y, and z axis simultaneously. How does that work?
  9. B

    Need help rewiring radar detector

    Hey guys, I'm a first timer here, and need just easy pieces of advice. I'm pretty into cars and have a decent electrical knowledge behind my mechanical know how, just not with reading schematics. Recently, my 12V socket died and I finally have an excuse to hardwire my Escort Passport...
  10. J

    Polarizing radar waves with egg slicers

    If I bought a radar gun, a radar detector, and three egg slicers, should I be able to demonstrate the three polarizer crossed polarization tricks? TIA, Jim Graber
  11. U

    Academic areas to focus on to become a radar engineer

    Hi, This is my first post but I've perused the forums often enough before (usually while I should be studying instead!). I'm 26 and in my second year of a 4 year Electrical Engineering degree (late starter). I am currently intrigued by radar and how to engineer machines to detect and track an...
  12. D

    Radar Range from I/Q samples

    I was given a set of I/Q data points by my professor and asked to find the range of the target. How would one approach such a problem?
  13. L

    Solve Stationary Radar Homework: Find Ship's Velocity

    Homework Statement A stationary radar operator determines that a ship is 12 km south of him. An hour later the same ship is 10 km southeast. If the ship moved at constant speed and always in the same direction, what was its velocity during this time? This is so easy but I am just so...
  14. O

    The Doppler Effect of radar gun

    Homework Statement You are in charge of calibrating the radar guns for a local police department. One such device emits microwaves at a frequency of 2.15 GHz. During the trials, these waves are reflected from a car moving directly away from the stationary emitter. You detect a frequency...
  15. A

    The doppler radar trap paradox on the path to gravity.

    Hello All, I have been challenged by a friend to look into Gravitational waves and some questions he has about them -- but I have always been a slow starter. Took physics with SR in college, got my BSEE, happily can build analog circuitry of all kinds -- but found that certain questions about...
  16. O

    Calculating beamwidth of a radar

    beamwidth = 60(lamda) / area i knw lamda = c x f how do i find the area ? and also what is c and f in relation to radar?
  17. H

    Ultrasonic Radar: How to Build & Use on a Computer

    how do you make a ultrasonic radar to use on a computer? help please
  18. J

    Calculating Distance Change of Plane from Radar Station

    Q) a plane is flying horizontally at an altitude of 1.5 miles and a speed of 400 mph. it is on a linear path that will take it directly over a radar station. find the rate at which the distance from the plane to the radar station is changing when the plane is exactly 2.5 miles from the station...
  19. I

    What happens when a wave's wavelength is compressed by moving objects?

    Homework Statement A radar beam has a wavelength of .02 m. The frequency is 17500 Hz. What would be its echo frequency if a rocket 60km away is moving at 500m/s and the radar is coming from a jet moving at 310m/s towards the rocket which is aimed at it? (b) Would the rocket appear red shifted...
  20. M

    Radar? Sonar? Solve A Mystery Please

    I have a strange mystery. My house sings! I am wondering if anyone can take a guess at what could cause this. I have occasional insomnia, which leaves me lying there in bed in the wee hours of the night when it is dead silent. Well, this morning was one of those. I woke up around 1:00 am...
  21. P

    Projectile motion radar antenna

    Homework Statement A radar antenna is tracking a satellite orbiting the earth. At a certain time, the radar screen shows the satellite to be 162 km away. The radar antenna is pointing upward at an angle of 62.3 degrees from the ground. Find the x and y component(in km) of the position of...
  22. C

    What Damage Can Infrared Rays, Radar Waves, FM Waves, etc. Do To The Body?

    What damage to the body can infrared rays, radar waves, FM waves, TV waves, "shortwav What damage to the body can infrared rays, radar waves, FM waves, TV waves, "shortwave" waves, and AM waves do? I have to do a physics project on causes of cancer, based on a physics standpoint. I have an...
  23. E

    Calculating Wave Packet Length & Frequency for Radar Transmitter

    Homework Statement A radar transmitter used to measure the speed of pitched baseballs emits pulses of 2.0cm wavelength that are .25micros in duration. (a) what is the length of the wave packet produced? (b)to what frequency should the receiver be tuned? (c) What must be the minimum...
  24. J

    Latest word from Lewis, Francis et all on radar ranging

    Holy smokes, just when we needed it, http://arxiv.org/PS_cache/arxiv/pdf/0805/0805.2197v1.pdf" is the latest paper hot off the press from Lewis, Francis, Barnes, Kwan & James, "Cosmological Radar Ranging in an Expanding Universe." This is mandatory reading for everyone interested in expanding...
  25. A

    Doppler Radar Relative Velocities

    Homework Statement A radar at rest emits microwaves at a frequency of 1.63 GHz onto a truck moving away from the radar. There is a frequency difference between the received and sent frequencies of 281 Hz. What is the velocity of the truck? Homework Equations f(obs)=f(sent)*[(v+/-observer...
  26. J

    Mapping a building for use in game (RADAR?)

    Hi guys I hope I'm in the right subforum. I was thinking of a way to map a house or outside area with radar or some other method, and then using that info to create a map for a game. So my question is, what are the different methods available for sensing the surrounding area and creating a...
  27. C

    Designing an Ultrasonic Range Finder with a PIC Microcontroller

    Hi I am designing a ultrasonic range finder. I am part of design group with the challenge of building a robot that can find its way through a known course. I found some circuits avaliable on the net. There is a section on the transmitter circuitry that confuses me. I am using microcontroller...
  28. K

    MATLAB Bistatic Radar: Seeking Assistance with MATLAB Design

    hi, I'm working on bistatic radar as part of my final year project. i'm using MATLAB software to implement my design and have a small problem in assuming bistatic RCS.. i got the formula from a book but the derivation was omited. any help in this area or anything related to bistatic radar...
  29. C

    Ultrasonic Radar Circuit for High School MITES Project

    I am in high school and I am doing an altrasonic circuit for my MITES project. I am using this schematic for it, but I read a lot of complaints about it on this website so I was woundering if there was a better one I could use. This is the one I am using...
  30. A

    How Can I Integrate an Ultrasonic Radar with My Computer for Motion Detection?

    I'm new to this forum, and I'm a Computer Engineer who recently have a lot of passion for circuits. Can anyone help me with a Ultrasonic Radar with can be worked in unison with my Computer to detect any movement. Thankyou all for helping me in advance
  31. K

    What is the equation for finding the maximum frequency in a towed-array sonar?

    Homework Statement A towed - array sonar comprises 100 transducers equally spaced at every 3m and towed behind a ship so the array stays just below the surface of the water (effectively horizontal). An adjustable phase delay can be introduced for each transducer, allowing the sonar beam to be...
  32. G

    How does radar find the position of an object?

    How does radar find the position of an object? And how does radar make an image? Isn't the reicever a dish so wouldn't only be able to receive magnitude related information like a microphone does with sound?
  33. Q

    Volunteer radar gunslingers nail speeders

    http://www.usatoday.com/news/nation/2007-10-22-radar_N.htm Just read this on yahoo. I don't know about you guys, but a 'warning letter' isn't going to stop me from going 50 in a 30.
  34. L

    Why is Speed Checked by Radar on Some Roads?

    I've driven down a road that had this sign before, but I don't understand what the process is. My girlfriend who's much more familiar with that road than I am said she didn't understand it either because her mother speeds down that road all the time and never gets a speeding ticket. So what...
  35. B

    Borehole / Ground penetrating radar research opportunities

    Hi Members I am preparing to do a presentation on possible research opportunities in ground penetrating radar before an Industry and academic audience. Anyone with information as to what is lacking or needs improvement in current BH or GPR research in the context of Data analysis (processing...
  36. O

    Discovering the Wonders of Radar: A Closer Look at How it Works

    Hey I've been wondering for a while about radar. I believe it works by bouncing a radio signal off an object and receiving the reflected radiowave at a receiver, right? My question is.. since Radar works at (i believe) short distances measured in miles... wouldn't the time it took the...
  37. B

    Radar echo and clock synchronization

    Please help me in the folowing problem: It is well known that the radar echo (police radar) establishes a relationship between the period T(e) at which a stationary observer emits successive light signals and the period T(r) at which he receives them back after reflection on an object that...
  38. C

    MATLAB Radar Books: Analysis & Design w/ Matlab

    Hi, I am trying to learn about radar principles and functions. Although I have some DSP and communication background, it is still a very difficult subject by itself. I am trying to learn the basic stuffs such as MTI, doppler radar, tracking, pulse compression, probability of false alarm and...
  39. D

    Solving Plane Displacement Using Radar Data

    Okay, this should really be a fairly easy problem and my work is below this question: "A radar station detects an airplane approaching directly from the east. At first observation, the range to the plane is d1 = 384 m at 40° above the horizon. The airplane is tracked for another 123° in the...
  40. S

    Amplifiers used in Radar Immunization ?

    amplifiers used in Radar Immunization ?? HI Guys! well! i have read somewhere that the waves generated by a primary radar adversley affect the electronic components of the vehicles that travel in the vicinty of the airport. To immunize these effects, TWT amplifiers and Class C amplifiers are...
  41. I

    Doppler Radar - Bandwidth, Continuous Wave or Pulse?

    Doppler Radar?? Please can someone help me with doppler radar...need to know bandwidth?? Is it usually continuous wave or pulse?? or can it be both?? pretty much just after some general knowledge on doppler radar? thanks in advance!
  42. J

    Creating Personal Radar: Software or Sensors?

    Would it be possible for me to make a sort-of personal radar program for my laptop which would hook up to my comp via USB or something and which would display objects on my screen like people moving, etc? Actually, it's probably more like a visual motion detection software program, but...
  43. L

    Powerful Radar Requirements: An Overview

    What requirements does a radar need to meet in order to be recognized as a powerful radar?
  44. H

    RADAR - Radio Detection and RangingCan we use the same technique on

    RADAR - Radio Detection and Ranging . Can we use the same technique on a smaller scale :rolleyes: ? I mean to measure the relative velocity between two vehicles :smile: ? Are there any good sources on internet where I can get information in detail about the working of RADAR system...
  45. R

    Do circuits need to be used in Radar related hardware?

    Do circuits need to be used in Radar related hardware?
  46. P

    Can a radar detect a plastic object?

    can a radar detect a plastic object? could the uhf and microwave signals be reflected by the target if it's made of plastic material? please give justifications :smile: thanks.
  47. R

    Courses for Radar engineering

    What courses do I have to take and focus on if I want to be a Radar engineer?
  48. O

    Understanding Radar Guns and Speed Measurement with STR

    Hello everyone, I was just thinking about something...A police radar gun measures the speed of an object by the change in frequency of the reflected wave. For example...we might have a gun sending out a series of radio waves towards an object moving toward us like this... GUN...
  49. C

    Radar Detectors in Australia: Truth or Scare Tactic?

    I was reading something today about it being stupid to own a radar detector in Australia because the police carry radar detector detectors with them. Is this even possible? I would have assumed that radar detectors don't send out a signal of sorts but only attempt to detect incoming radar...
  50. V

    How is the target detected in a tracking radar?

    How is the target detected in a tracking radar?
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