Questions tagged [radar]

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What is the difference between radar cross section and intensity/amplitude?

I've been tasked with simulating a radar system, and I think I understand the problem, except I'm supposed to be providing the outputs in both radar cross section and amplitude. What's the difference? ...
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Can radar detect electrical fields?

Can we create a radar image of electrical fields, or this is even possible? Do we need a detector opposite the emitter or does reflection work? (see figure.1)
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Can I track hypersonic missiles with heat sensors? [closed]

On a video, it is said that hypersonic missiles create an plasma layer that scatters radar waves, therefore hard to detect And then, on another video, it demonstrates anti-ballistic missile system ...
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How does interferometric SAR determine position of the reflecting object?

I'm interested to know how synthetic-aperture radar functions. The Wikipedia article for Synthetic-aperture radar, subheading Interferometry says: If the two samples are obtained simultaneously (...
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Why do metallic objects reflect radar?

We learn that EM waves cause the electrons in a conductor to move around. For example, air to ground radar shows the ocean as having few returns compared to land. Water molecules absorb the energy. ...
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Why do pulsed signals have a bandwidth but continuous wave signals do not?

A continuous wave signal of 'f' kHz will appear on a receiver plot tuned in at f kHz and nothing else, ie it is 1 Hz wide. However, apparently this is not the case with pulsed signals and I'm ...
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Radar pulse width, peak power and relation to maximum range

The textbook I'm using to understand radar is explaining the 'pulse width dilemma'. It says that shorter pulse widths can resolve targets that are close together; however, because there is a limit to ...
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Location of first null off boresight, in ant pattern of 2 element phased array antenna, in radians as a function of wavelength and distance?

Does it make sense that the first null off boresight of a 2-element phased array antenna, where each element is isotropic, in-phase, and separated by a distance $d$ (where $d$ is much greater than the ...
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Is there any kind of "radar" system That can detect electrical fields / electricity

I may be using improper terms here, but Is there any kind of "radar" / non-contact system That can detect electrical fields / electricity? see fig for clarification to what I'm talking about....
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Through-metal-wall Ultrasound sensor imaging?

A while ago, MIT published a paper that used a radar sensor to take a low-res image, and then they trained an AI model to convert the image into a human skeleton for through-wall human pose detection. ...
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4 answers
95 views

Is there an alternative to radio waves that can go through metallic objects?

Radar can pass through materials such as paper, wood, glass, brick, and concrete, but it reflects off of metal. Is there an alternative to radar that can pass through metal substances? If not, is it ...
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Doubt in radar question

This is a question(2.25) from introduction to radar systems by Merrill Skolnik 3rd edition. Plot the single-scan probability of detection as function of range, assuming a constant cross-section target ...
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Doppler Effect and Radar Sensors

Radar sensors make use of the Doppler effect to measure the radial velocity of an object. The radar's Tx antennas emit an electromagnetic wave which travels to the moving objects, is reflected and the ...
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Radar lobes vs forever propagating waves

I'm trying to learn some more about radar and I'm confused about "lobes". My understanding of EM radiation is that it radiates forever or until something physical blocks it, but directional ...
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FMCW radar scattering direction from a special case of a rough dielectric surface

I have some misunderstandings about radar backscatter from rough dielectric surfaces and was hoping somebody could enlighten me. I have one specific question first concerning a thought experiment. A ...
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Will a sheet of carbon atoms reflect radio waves?

I am working out some details in a SciFi novel. I'm thinking of having spec ops who would use a device that could manipulate carbon atoms to form and maintain large, rigid, one-atom thick carbon ...
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How did early radar determine range/ distance precisely?

Wikipedia talks about precise timing of the returned radar pulse, with an animation of a clock. But they didn't have atomic clocks and such before or during WWII. So how did they determine distances ...
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Radar Wave Reflection -- How can we justify coherent radar?

How can we model a radar wave's reflection from a target? Will the phase of the return be different from the signal that gets sent out? For instance, suppose our radar was transmitting the following ...
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Energy in radar equation

In the book Skolnik, Introduction to Radar Systems, ed. 2, pag. 52 (sec. Transmitter Power) the radar equation in its simplest form is initially cited: $$R_{\max}=\left[\frac{P_t G A_e \sigma }{(4 \...
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Is Sentinel able to obtain wave spectrum by interferometric Data?

I have recently read many articles on recovering wave spectrum from the AT-INSAR image spectrum (through interferometric images). However, it is not clear to me whether Sentinel is a viable option, ...
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4 answers
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Painting a vehicle black to avoid radar detection: a bad idea?

A lot of people on the Radar Detector & Laser Jammer Forum are trying to paint their cars in the deepest black to avoid getting a speed ticket by making their vehicle stealthier for incoming radar ...
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Why aren't extremely-low-frequency (ELF) radio waves used for underwater radar?

Since extremely-low-frequency radio waves are used by submarines for some simple, low-transmission-rate communications, why can't those same wavelengths be used for submarine radar? It may not be ...
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Loss of beam power over astronomical distances

pardon my choice of words, but English isn't my native language, so I might use the wrong terms at some places. Beside this, I do have a hypothetical situation which might be a bit off reality (...
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2 answers
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Why does a sonar or radar's frequency correlate with its resolution?

A sonar's (or radar's) frequency determines its limit on the smallest size that it can detect and its resolution. I've heard that it's due to aliasing, if so, please explain the reason behind it a ...
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-1 votes
1 answer
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Can radar detect dumb bombs in freefall mode? [closed]

Can gravity bombs dropped from an aircraft be detected by radar and intercepted with a missile to prevent detonation on ground impact? Is there currently such a system? Edit: Its a military/defence ...
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Why do sensors that emit higher frequency signals give more accurate data?

I am doing a technical presentation about RADAR and LiDAR. I understand that LiDAR is several times more accurate and capable of producing really detailed 3-D maps of their surroundings, while RADARs ...
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2 votes
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Radar Antenna Quantity and functional performance

Millimeter wave radar SoC (system on a chip) are evolving from 4 to 72 antennas on a single chip. Is there a simple (ELI5) explanation as to why 72 antennas (vs 4) are desirable? My intuition ...
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L-band for search radars?

I'm making my way through the Linesman-related section's of Gough's Watching the Skies. Linesman was developed to counter the carcinotron jammer. The main solution was the Type 85, which had 12 ...
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1 answer
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Does Radar detect objects or has point cloud

Many times in literature I read that Radar is used to detect objects. How does this work? Are reflections from objects with Radar not point reflections? And how does Radar know that all reflections ...
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How does increasing conductivity increases radar cross section?

This is for the context of radar detection. I am trying to figure out exactly why increasing the conductivity of a metallic object increases its radar cross section. I've been directed to looking at ...
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1 vote
1 answer
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When using radar in space to find asteroids is it helpful to know the distance? Or do you just need the direction?

Couldn't they just send out the largest sounding pulse in a given direction that they could safely generate, and if there is anything in that direction no matter if it's by Jupiter or pluto as long as ...
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Bistatic radar equation for moving objects

From my understanding, and correct me if I'm wrong, the bistatic radar equation assumes that the transmitter and the receiver are separated by a distance $L$, and that the transmitter and receiver are ...
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Why can we not measure the distance to the Sun directly using Radar?

My question is specifically WHY CAN WE NOT USE Radar to measure the distance to the Sun? What is the reason for that? Sorry if this is a lame question, I'm not an expert on these things and just ...
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Is there a way to recalculate radar detection range given the old and new probability of detection and false alarm?

I'm reading through some radar books and I'm trying to find out if there's an easy method or equation to recalculate radar detection range given only the original radar detection range, original ...
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1 vote
1 answer
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Why is my reasoning to derive the bistatic radar equation wrong?

The ideal effective antenna aperture is calculated from $A_{eff}=G\lambda^2/4\pi$, G being the antenna gain. Why is it that in a bistatic radar setup with a transmitter and receiver fixed on the ...
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2 votes
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Doppler radar electric field expressions

Consider the right handed coordinate system $(x,y,z)$ in which a stationnary radar is positioned at the origin and a metallic plate (initial position $z_0$) that is moving along the $z$ axis with ...
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Doppler Cone: What exactly is it?

I'm trying to understand Synthetic Aperture Radar (SAR). It appears that it makes use of what's called a "Doppler cone". I understand Doppler frequency shifts of light, but I'm not sure what the cone ...
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1 vote
1 answer
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Radar: frequency and target size

I am wondering if there is a general rule of thumb in the radar world for what frequency you should pick to detect targets of a certain size. For instance, if one had two radars set up - one for ...
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1 answer
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What exactly is an "instrumentation radar"? [closed]

I am coming across this term "instrumentation radar" without exactly defining it but with adjectives like high performance, mono pulse etc. But what exactly is an instrumentation radar?
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5 votes
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What happens to a radar signal when it meets with a superconductor? [duplicate]

A radar system has a transmitter that emits radio waves called a radar signal, consisting of electromagnetic radiation. What happens when it meets with a strong superconductor, considering the fact ...
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2 votes
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Wavelength, frequency, and radars [closed]

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?
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2k views

Why does this radar speed sign show a decreasing speed, despite the fact that I'm accelerating? [closed]

Everyday when I'm going back home from college, I pass by this big radar speed sign and I've noticed that it does a peculiar thing. The sign is placed on a downward slope of the street. So say I'm ...
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8 votes
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Is radar-style 'pulse coding' (stretch, amplify, interact, and then compress) used in the optical domain?

Chirped Pulse Amplification (CPA) is an optics technique for producing short laser pulses at intensities which are high enough that the gain medium would destroy itself through nonlinear phenomena ...
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2 answers
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Does radar affect magnetism?

Does radar affect magnetism? Let's say I have two magnets, one is suspending the other. Would radar affect the magnetic field?
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1 vote
2 answers
397 views

Why can't LIDAR be implemented with traditional antennae?

In robotics, LIDAR and RADAR are both used for obstacle detection. The data they produce are very similar, but they do have different qualities (LIDAR is more precise but less robust). There are many ...
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1 answer
355 views

Why would a sweeping LIDAR or RADAR beam not produce an artificial Doppler shift?

Assuming a bi-static Radar or LIDAR with a stationary transmitter and a stationary target and a stationary receiver, with a sweeping RADAR/LIDAR beam reflecting off a stationary target: Why would the ...
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1 vote
2 answers
112 views

Radars on Space Ships

If a radar (say, an x-band radar similar in size to that of a modern fighter aircraft) was carried by a spaceship, would the radar have a greater range in vacuum of space than it has in atmosphere?
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1 answer
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Simple explanation of Coherent integration radar

I have a physics background, and I'm reading some physics data analysis papers where they keep throwing around the term coherent integration. I've done the google search, but the best answer I could ...
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3 answers
938 views

Chaff-RF Relationship?

What is the relationship between chaff length and the frequency it is meant to interfere with? I've read that specific lengths of chaff are more effective as a countermeasure for specific frequencies,...
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1 answer
905 views

Radar Vs. Sonar

What is the true difference between radar and sonar? My understanding is that radar uses a reflected EM wave, while sonar uses a compression (shock wave) of the material it's in. (It compresses water, ...
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