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. tworitdash

    A Continuity of a quantity in a conical system to determine the velocity

    My research is on radar images and the images are collected in several conical surfaces. These conical surfaces have the same origin, the same maximum length (max flare or max range), but different elevations angles. The images are collected on the surface of the cones only. I want to determine...
  2. D

    Why can't satellites be equipped with radar systems so that they can detect (and then avoid) impending collisions?

    Why can't satellites be equipped with radar systems so that they can detect (and then avoid) impending collisions?
  3. tworitdash

    I What is a distinct feature of an ambiguous result?

    This question comes from my experience in radar signal processing. As I am going more deep into the theory of sampling, statistical signal processing and estimation theory in general, I have a very silly but important mathematical question that I want to ask here. For example, we are estimating...
  4. J

    Wavelength / signal which would pass through concrete and rubble

    Greetings, Please imagine a huge pile of rubble, meters deep. Somewhere inside, there's a device emitting a certain signal. This signal can be picked up by a radar-like device which locates the origin of that signal, with the least interference from the pile of rubble, concrete blocks, metals...
  5. hagopbul

    I Can Ground Penetrating Radar Help Locate Earthquake Survivors?

    Hello : As the news coming from Syria and Turkey about earthquake devastation, is it possible to use ground penetrative radar or sound identification and wave frequency spectrum analysis to locate survivours ? The human sound are in the range of 20 kHz shouldnt we be able to use microphones...
  6. A

    Can a Jammer and Radar be Combined into One Device for Military Use?

    With this current war I'm thinking more about military electronics. I noticed that a lot of drones are used lately in various military exercises/conflicts as well as missiles. Most missiles except those that are "dumb" use some sort of radio communication. So there is the use of jammers or...
  7. L

    Can Radar Technology See Through Walls and Accurately Detect 3D Shapes?

    I was wondering if radar is safe, can it detect near objects (lets say 50 feet away) and does it accurately see 3D shapes? I am looking for a technology that could maybe supplement augmented reality in the sense that VR objects can be given GPS locations, but don't know if there is something in...
  8. Narayanan KR

    A Different Way to Achieve Electron Velocity Modulation in a Klystron

    Please Notice That the Toroid Coil is Outside the Discharge Tube and yet able to influence electrons moving inside the Tube.
  9. tworitdash

    Rotating radar time domain data

    I want to simulate the time domain data for a rotating radar. I assume that the space around the radar is filled up with a very big extended object and it moves with a constant speed in one direction. Picture attached.I don't take range information here. I am only concerned about the velocity as...
  10. P

    A Ground Penetrating Radar formula

    I am interested in the physics of ground penetrating radar. 1) Does anyone know where I can find a derivation of the formula in the attached jpg for the energy reflected? K=the dialectic constant. 2) An intuitive explanation of why the dialectic constant is important in determining the energy...
  11. B

    Orbit determination from radar readings of a satellite in orbit

    Hello everyone! This is from The Fundamentals of Astrodynamics Chapter 2 Questions. I'm doing this as a self-study (and never took Linear Algebra) so my "technique" might be a little sloppy 😖😖 Finding specific angular momentum Finding the orbital parameter Finding Eccentricity Vector...
  12. S

    Does a material change the direction of polarization of light?

    The polarization referes to the direction of the electric field of a light wave which is to be one direction. The unpolarized light interacts with a material in various ways such as reflection, scattering, refraction. and each of which can transform an unpolarized light into a vertically or...
  13. faiello

    Radar Reflection: Charged vs Non-Charged Objects

    A question I’ve been trying to figure out for the last 5 years with a friend of mine: Would the radar reflection from an object be different if the object is charged or not charged?
  14. LCSphysicist

    Doppler radar measurement by an aircraft

    u is the aircraft speed. c is light speed f is the initial frequency λ is the initial wavelength λ' is the apparent wavelength λƒ = u +λ'ƒ λƒ = u + (c/ƒ')*ƒ c = u + (c/ƒ')*ƒ u = c(1-(ƒ/ƒ')) u = 1500m/s The answer is half of it, where is my error?
  15. A

    Rotating waveguide antenna (rotating marine radar)

    I've seen these devices on shores as well as on ships , like a horizontal tube rotating slowly around it;'s axis. Now from what I know it's a type of radar, and unlike phased array it rotates it's beam physically by means of using a motor to rotate the antenna itself , what I want to know is...
  16. berkeman

    Is this officer checking his radar gun calibration incorrectly?

    I was watching "Northwest Law" last night (a TV show that follows Fish & Game Rangers in the Northwest), and when I saw an officer checking the calibration of their radar gun before using it on an ATV trail, I was very confused by it. He held it so that the tuning fork vibrated orthogonally to...
  17. G

    B Quantum radar and its implications

    https://www.popularmechanics.com/military/a28818232/quantum-radar/ https://www.asiatimes.com/2019/09/article/stealth-killer-quantum-radar-actually-works/?_=3274804 I don't know, whether the above sources are reliable, or not, that is why i ask. "Quantum radars involve pairing photon particles...
  18. Santilopez10

    Plane being tracked by radar

    I tried to workout the problem but I find motion in different coordinates systems a bit weird at the moment, so only thing I could do is realize that the x component of ##\vec r(t)## is: $$vt +x_0$$ but for simplicity we will use the initial condition ##x_0=0## so that ##t_0## is the moment the...
  19. U

    Radar Cross Section simulation with CST

    I'm trying to understand how CST measures the RCS of an object. If not specified by me, it gives me (with a very brief simulation even for complex objects) graphs, both 3D and 2D, entitled 'Bistatic RCS'. With this wording I think that there is an antenna in a different direction than the one...
  20. S

    How bad will the sale of the spectrum down to 24.25 GHz be for weather radar?

    I was reading this, and got concerned: https://slate.com/technology/2019/05/spectrum-auction-bandwidth-weather-forecasting-fcc-noaa.html
  21. C

    How Fast Was the Car Moving in the Radar Speed Trap Experiment?

    Homework Statement [Answer is V = 25m/s, however, how do I get that answer? Thank you!] A police cruiser sets up a novel radar speed trap, consisting of two transmitting antennas at the edge of a main north-south road. One antenna is 2.0 m [W] of the other. The antennas, essentially point...
  22. P

    Radar System Design: Reduce Power & Range for 1km Reach

    I have been reading up on clear-air pulsed radars and am wondering if it is possible to scale down a large radar system to one with reduced power and gain, but also greatly reduced range. Here are the specs for a large radar: Output power = 2.5 mega Watts Antenna gain = 47db. Range = 15km. If...
  23. R

    I Multiple hypothesis testing for radar tracking in clutter

    Hello All, The goal is to formulate a multiple hypothesis test for a radar tracking problem when false alarms are occurring and to apply a particle filter on this update step, however I first need to come to/understand the multiple hypothesis formulation in this problem. Say we are interested...
  24. R

    Probabilistic data association with a particle filter

    Homework Statement Hello everyone, I have to implement a probabilistic data association filter with a particle filter. I have already implemented a PDAF based on the Kalman filter. The assignment considers a radar (range,angle) tracker. With the state s containing the x, y position and the x...
  25. P

    Studying Textbook suggestions for LiDAR/Radar/RF Telemetry

    Previously I made this post, and soon after realized how woefully unprepared I am to approach such a topic. As stated in the post, I think my best use of time would be to gain background knowledge on the topic before attempting a project, but now I think I've found a better focus as to what...
  26. M

    Considering a career as Radar technician: cancer risk?

    I've done a good bit of online research and have concluded that both in the past and AFAIK currently there is a significant risk of cancer if I work for companies that make military or civilian radar systems. I'm looking at high powered systems for missle detection, defense radar of all types...
  27. J

    Radar Cross section Vs Reflection Coefficient

    I am working on HFSS and designing Antennas for LOW RCS , in all previous works they calculate the S11 parameter for the unit cell then make an array form this unit cell and calculate the RCS , my question is what is the relation between S11 and RCS and why we calculate S11 for the unit...
  28. M

    Calculate the Max Detection Radar Range

    Homework Statement I am asked to find the Max detection range of the following radar system: Transmitter Power, Pt = 10Kw RCS = 1 m sq. Frequency = 3Ghz Losses, Ls = 5dB radar dish radius, r = .5m Noise level, N = -140dbW SNR= 13 dB Homework Equations Radar Max range =...
  29. T

    Electronics 3D Printed 2.25 Ghz Microwave RADAR horn antenna

    So I printed this antenna with some conductive filament , however the microwaves seems to be going between the layers of the plastic. I surrounded it with Aluminum and still leaking, what can I do to fix it? Can conductive silver paint work?
  30. E

    RF and MW receivers' sensitivity

    I'm currently working on a novel RF and MW sensor and I wanted to know whether there is a paper that shows the current very best receiver sensitivity for a range of wavelengths in the RF-MW range in dBm preferably so I can directly compare to my device.
  31. R

    Help Identifying AESA Antenna Structure Type found in the F-35 aircraft

    This is the AN/APG-81 AESA Radar antenna by Northrop Grumman currently found in the F-35 (photo from wikipedia article). It seems to have a very different structure than past AESA/PESA antennas. For example the APG-68 from the F-16 looks a lot like stacked, slotted wave guides to me. So...
  32. gleem

    Patriot One Tech PatScan: AI-Driven Cognitive Microwave Radar Detection

    The company Patriot One Technologies is marketing a system called PatScan using AI and microwave technology to detected concealed weapons (gun, knives, explosives) without imaging (Cognitive Microwave Radar). https://patriot1tech.com/solutions/how-it-works/ Apparently it detects reflected...
  33. A

    Is there any way to modulate/change a radio wave reflection?

    Hi all, Is there any way to impart a transformation upon a radio wave's reflection from an object, such that the reflected wave is different from the original signal in some way (frequency, phase, etc.)? Not sure what this would require (maybe a constant and active coordinated interference...
  34. E

    High end Radar receiver sensitivities

    I am looking for what the high end radar receivers can achieve in terms of sensitivity? I have had trouble finding examples online, I have seen -100 to -103dBm as typical sensitivities, but I'm looking for the cutting edge stuff. I've also seen the GPS satellites also have a sensitivity of...
  35. M

    I Using trigonometry to create a radar for a game.

    I am making a video game using Game Maker Studio 2.0 and am making a radar. To give you some background, one object is obj_Player, and the other is obj_Sub. The radar gives the sub's position and distance from the player (center of radar). The first part of my radar works perfect. I normalized...
  36. J

    Pointer to data wanted please -- looking for a primer on phased array radar

    Fair warning: I can handle basic physics stuff, but probably nothing post-collegiate. :) Specifically, I'm looking for a primer on phased array radar that will tell me two things: 1) what are the practical physical (antenna) requirements for running a PAR system in the 800MHz/5GHz bands, and 2)...
  37. C

    B Radar & Jupiter Great Red Spot

    Ever since the first Pioneer spacecraft sent back closeup photos of Jupiter's Great Red Spot ("GRS") back in 1978(?), I noticed the GRS looks like a wave-cloud. There is a thick lip of wave-cloud on one side of the GRS, caused by air sweeping over an enormous volcano, it then bends around on...
  38. C

    I Relativistic doppler shift and radar

    Consider at stationnary radar at the origin ##z=0## and a target (speed ##v##) moving along the ##z## axis and away from the radar. The radar is sending plane waves (frequency ##f_i##) to the target and they come back to the radar (the radar is then both an emitter and a receiver). I am...
  39. L

    Does anybody know the sampling frequency of a cop radar?

    More specifically, does anybody know the sampling frequency of a mounted 360 degree cop radar? NOT a conical/directional hand-held radar gun.
  40. K

    Basic phased array radar questions

    So, I already understand that the maximum resolution of a radar system is λ R / L, where lambda is the wavelength, R is the range to the target, and L is the diameter of the antenna, and that for a phased array, L would be the maximum distance between antennas (correct me if I'm wrong :) ). But...
  41. K

    Difference between a clock and a series of radar pulses

    Homework Statement I have been working through “Basic Concepts in Relativity and Early Quantum Theory” by Resnick and Halliday. I've read about and done most of the problems about time-dilation, length-contraction, and Doppler effect. But then I got to problem 2-76, and I’ve been swirling in...
  42. P

    Radar and simple range problem

    Homework Statement Radar (radio wave) is placed 35m above sea level. Calculate working range of radar. Homework Equations So I have found various different formulas for range but they all are very complicated with respect to my example. I only have 1 known variable - height. The Attempt at...
  43. F

    B Locate and Eliminate Mosquitoes with Mosquito Radar

    I have difficulty finding the mosquitoes in my room so my electric swapper can't hit them.. is there any device that can find their exact location maybe some kind of mini radar.. what sensitivity before such radar can locate mosquitoes? Mosquitoes disturb my sleep at night.
  44. .Scott

    I Debunk these news stories (QM Radar)

    Normally when I cite something, it's to an article I consider credible, but this one is not: http://www.popularmechanics.com/military/research/a22996/china-quantum-stealth-radar/ The specific assertion in question is this paragraph: The article also asserts that Lockheed has patented this...
  45. penelopa

    I Radar Doppler effect: classical vs relativistic

    I think the relativity provides the Doppler shift (in a radar - double version) in a form: ##\frac{1-v}{1+v}## which is quite simple, as a square of a single Doppler: ##f' = f\sqrt{\frac{1-v}{1+v}}## But I never seen what is a classical version of this - what is a formula for a radar shift in...
  46. D

    Classical Wavelength, frequency, and radar

    I'm doing a high school paper on the effects of frequency alterations on a radar image. Can someone recommend a book which I can use?
  47. Steebly

    A radar device detects a rocket approaching directly from...

    Homework Statement A radar device detects a rocket approaching directly from east due west. At one instant, the rocket was observed 10 km away and making an angle of 30 degrees above the horizon. At another instant the rocket was observed at an angle of 150 degrees in the vertical east-west...
  48. kostoglotov

    A tuning fork measured by a police radar gun

    A police radar gun emits radio waves at 10.5 GHz, and measures the beats between this frequency and the returned waves to determine the speed of an object. It registers a tuning fork as "traveling" at 24.6 m/s. What is the frequency of the tuning fork. I can get the answer, but I don't...
  49. P

    Best material to reflect for 35GHz RF

    Hello everyone. This is my first post.. I have been given the task of building some large RF reflectors that will reflect 35GHz RF energy. Can anyone give me an idea of what material / thickness of material I could use. For an example.. Would a pyramid made from wooden pallets covered in...
  50. Spinnor

    Peanut-shaped near-Earth asteroid imaged by radar

    Why is the brightest part of the asteroid radar image below the upper edges? From, http://astronomynow.com/2015/08/03/peanut-shaped-near-earth-asteroid-1999jd6-imaged-by-radar/ Is it a software effect? I would naively think that the greatest radar intensity would be reflected from the parts...