Presentation on the topic "radar". Our butts

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Goal: to determine the relationship between radio and radar, to find out how the radio signal propagates. Objectives: Find out when the first radio appeared and who invented it. Define radar and radio wave signal. Find out what determines the accuracy of radio wave measurements. Consider the areas of application of radar. Draw a conclusion about the propagation of the signal. Hypothesis: is it possible to control air traffic without knowing the principles of radar?

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Where did it all start? In 1888 German physicist Heinrich Rudolf Hertz experimentally proved the existence of electromagnetic waves. In his experiments he used a source electromagnetic radiation(vibrator) and a receiving element remote from it (resonator) that reacts to this radiation. The French inventor E. Branly repeated it in 1890. Hertz's experiments, using a more reliable element for detecting electromagnetic waves - a radio conductor. The English scientist O. Lodge improved the receiving element and called it a coherer. It was a glass tube filled with iron filings.

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The next step was taken by the Russian scientist and inventor Alexander Stepanovich Popov. In addition to the coherer, his device had an electric bell with a hammer that shook the tube. This made it possible to receive radio signals carrying information - Morse code. In fact, with Popov’s receiver, the era of creating radio equipment suitable for practical purposes began. Popov's radio receiver. 1895 Copy. Polytechnic Museum. Moscow. Popov radio receiver circuit

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Alexander Stepanovich Popov Born in 1859. In the Urals in the city of Krasnoturinsk. He studied at the elementary theological school. As a child, he loved making toys and simple technical devices. After graduating from general education classes, he entered the Faculty of Physics and Mathematics of St. Petersburg University. Having successfully graduated in 1882. University, A.S. Popov became a teacher at the Mine Officer Class in Kronstadt. Free time he devotes himself to physical experiments and study electromagnetic vibrations. As a result of numerous experiments, he invents the first radio receiver. May 7, 1895 Popov made a report at a meeting of the Russian Physicochemical Society. It was radio's birthday. In 1901 Popov became a professor at the St. Petersburg Electrotechnical Institute, and in 1905. he was elected director of this institute. He had to fight with tsarist officials for the demographic rights of students. This undermined the scientist’s strength and he died suddenly on January 13, 1906.

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Agree! That radio is not only radiotelephone and radiotelegraph communications, radio broadcasting and television, but also radiolocation, radio control and many other areas of technology that arose and are successfully developing thanks to the outstanding invention of A. S. Popov. What is radar?

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Radar

Radar – detection, precise determination of the location and speed of objects using radio waves. A radio wave signal is ultra-high frequency electrical oscillations propagated in the form of electromagnetic waves. The speed of radio waves, then where R is the distance to the target. The measurement accuracy depends on: The shape of the probing signal The energy of the reflected signal The type of signal The duration in time of the signal

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The use of radar in our time

Agriculture and forestry: determination of soil type, temperature, fire detection. Geophysics and geography: land use structure, transport distribution, searches for mineral deposits. Hydrology: the study of water surface contamination. Oceanography: determination of the topography of the surfaces of the bottom of seas and oceans. Military affairs and space research: flight support, detection of military targets.

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Radar (from the Latin words “radio” - radiate and “lokatio” - location) Radar - detection and precise determination of the position of objects using radio waves.

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In September 1922 in the USA, H. Taylor and L. Young conducted experiments on radio communications at decameter waves (3-30 MHz) across the Potomac River. At this time, a ship passed along the river, and the connection was interrupted - which prompted them to also think about using radio waves to detect moving objects. In 1930, Young and his colleague Hyland discovered the reflection of radio waves from an airplane. Soon after these observations, they developed a method of using radio echoes to detect aircraft. History of the development of radar A. S. Popov in 1897, during experiments on radio communication between ships, discovered the phenomenon of reflection of radio waves from the side of the ship. The radio transmitter was installed on the upper bridge of the transport "Europe", which was at anchor, and the radio receiver was installed on the cruiser "Africa". During experiments, when the cruiser "Lieutenant Ilyin" got between the ships, the interaction of the instruments stopped until the ships left the same straight line

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Scottish physicist Robert Watson-Watt was the first to build a radar installation in 1935 that could detect aircraft at a distance of 64 km. This system played huge role in protecting England from German air raids during the Second World War. In the USSR, the first experiments on radio detection of aircraft were carried out in 1934. Industrial production of the first radars put into service began in 1939. (Yu.B.Kobzarev). Robert Watson-Watt (1892 - 1973) History of the creation of radar (RADAR - an abbreviation for Radio Detection And Ranging, i.e. radio detection and ranging)

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Radar is based on the phenomenon of reflection of radio waves from various objects. Noticeable reflection is possible from objects if their linear dimensions exceed the electromagnetic wavelength. Therefore, radars operate in the microwave range (108-1011 Hz). And also the power of the emitted signal ~ω4.

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Radar antenna For radar, antennas are used in the form of parabolic metal mirrors, at the focus of which a radiating dipole is located. Due to the interference of waves, highly directional radiation is obtained. It can rotate and change its angle, sending radio waves in different directions. The same antenna is automatically connected alternately with the pulse frequency to the transmitter and to the receiver.

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Operation of the radar The transmitter generates short pulses of alternating current microwave (pulse duration 10-6 s, the interval between them is 1000 times longer), which through the antenna switch enters the antenna and is emitted. In the intervals between emissions, the antenna receives the signal reflected from the object, while connecting to the receiver input. The receiver performs amplification and processing of the received signal. In the very simple case the resulting signal is fed to a beam tube (screen), which displays an image synchronized with the movement of the antenna. A modern radar includes a computer that processes the signals received by the antenna and displays them on the screen in the form of digital and text information.

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S is the distance to the object, t is the time of propagation of the radio pulse to the object and back. Determining the distance to the object Knowing the orientation of the antenna during target detection, its coordinates are determined. By changing these coordinates over time, the speed of the target is determined and its trajectory is calculated.

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Radar reconnaissance depth The minimum distance at which a target can be detected (the round trip signal propagation time must be greater than or equal to the pulse duration) The maximum distance at which a target can be detected (the round trip signal propagation time must not be greater than the pulse repetition period) - pulse duration T-period of pulse repetition

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Using signals on radar screens, airport dispatchers control the movement of aircraft along air routes, and pilots accurately determine flight altitude and terrain contours, and can navigate at night and in difficult weather conditions. Aviation Radar Applications

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Main task- monitor the airspace, detect and track the target, and, if necessary, direct air defense and aviation at it. The main application of radar is air defense.

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Cruise missile (unmanned aircraft single launch) Control of the rocket in flight is completely autonomous. The operating principle of its navigation system is based on comparing the terrain of a specific area where the missile is located with reference maps of the terrain along its flight route, previously stored in the memory of the on-board control system. The radio altimeter ensures flight along a predetermined route in terrain following mode by accurately maintaining the flight altitude: above the sea - no more than 20 m, above land - from 50 to 150 m (when approaching the target - decrease to 20 m). Correction of the missile's flight path during the cruising phase is carried out according to data from the satellite navigation subsystem and the terrain correction subsystem.

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Stealth technology reduces the likelihood that the aircraft will be located by the enemy. The surface of the aircraft is assembled from several thousand flat triangles made of a material that absorbs radio waves well. The locator beam falling on it is scattered, i.e. the reflected signal does not return to the point from where it came (to the enemy radar station). The plane is invisible

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One of important methods Reducing accidents is to control the speed limit of vehicles on the roads. American police used the first civilian radars to measure vehicle speed at the end of World War II. Now they are used in all developed countries. Radar for measuring vehicle speed

At school and institute they explained to us that if a ship flies from the Earth at sub-light speed, light from the Earth comes to it with increasing delay, and on the ship it seems that time (all processes) on Earth is slowing down... And it turns out that Einstein is only saying about the illusion of “slowing down” and “accelerating” time for different observers.

Here it turns out that as much as time “slowed down” when moving away from the Earth, it also “accelerated” when returning to Earth. If in the first case the signal caught up with the ship for five seconds, now the signal meets the ship earlier by the same 5 seconds. There is no Einstein with his relativity here.
Replace Earth with Moscow in your story, spacecraft- by train, destination - Vladivostok, signals - by telephone calls. And it will immediately become clear that there is no smell of the theory of relativity here. Although there really is some effect, it is completely insignificant in comparison with the fiction that appears in your legend.

So, what is real? In reality, there are a lot of experiments that tested SRT. I chose the simplest and most understandable one. Actually, I did not find a report on this experiment. But I believe that this is indeed a hundred thousand times more accurate than the 1938 experiment.

Canadian physicists asked to use the accelerator at the Max Planck Institute (there is one in Germany). The essence of the experiment: lithium ions are excited by a laser and then the frequency of radiation of these ions is measured. We call frequency the number of “humps,” roughly speaking, of an emitted wave per unit time. First, the frequency is measured in a stationary (laboratory) reference frame. Get the value f 0. The ions are then accelerated in an accelerator. If Einstein's theory correctly predicts time dilation, then in a time of, say, 2 s in a laboratory system, only 1 s can pass in a system moving at a certain speed. By exciting moving lithium ions, we obtain in this case the radiation frequency f 1, half the size f 0. This is actually what the Canadians did. And they found a deviation from the theory of less than one ten-millionth of a second.

But that's not what we're interested in. The background of the philosophical criticism of STR, GTR, quantum mechanics. Studying the current “commentators” of the persecution of physics in the USSR, one gets the impression that Soviet physicists We weren’t up to speed in that same physics. The real problem was that 20th century physics found itself in a state where “matter disappeared, only equations remained.” In other words, physics refused to look for models of material reality, and having received equations that quite successfully described the processes, it simply began to invent their interpretations. And this point was understood equally well by both physicists of the USSR and physicists of the West. Neither Einstein, nor Bohr, nor Dirac, nor Feynman, nor Bohm... no one was satisfied with this situation in theoretical physics. And Soviet criticism often took Made-in-Ottedov’s arguments.

I will try to illustrate what is meant by the physical model of STR, for example, in contrast to its mathematical model, built by Lorentz and Poincaré, and in a more accessible form - by Einstein. As an example, I chose the model of Gennady Ivchenkov. Let me emphasize that this is an illustration only. I do not undertake to defend its truth. Moreover, Einstein’s SRT is quite physically impeccable.

Let's look at Einstein's solution first. According to SRT, time flows slower in a moving system than in a stationary one:

Then the frequency of oscillations (no matter what) in a moving system (measured by a stationary observer) will be less than in a stationary one:

Where ω ν is the frequency of oscillations in a moving system, and ω 0 - motionless. Thus, measuring the frequency of radiation coming to a stationary observer from a moving system, in relation to the frequencies ω ν / ω 0 you can calculate the speed of the system. Everything turns out simple and logical.

Ivchenkov model

Let us assume that two identical charges of the same size (for example, two electrons) interact, moving relative to the laboratory coordinate system in the same direction with the same speed V at a distance r parallel to each other. It is obvious that in this case the Coulomb forces will push away the charges, and the Lorentz forces will attract them. In this case, each charge will fly in the magnetic field created by the second charge.

The total force (sometimes called the Lorentz force, since he was the first to derive it) is described by the formula

Consequently, the Lorentz force of attraction of moving charges (the second part of the formula), which became currents during movement, will be equal (in scalar form):

Coulomb force, repulsive electric charges will be equal to:

And the speed of the charges, at which the attractive force is equal to the repulsive force, will be equal to:

Therefore, when V< C Coulomb forces predominate and flying charges are not attracted, but repelled, although the repulsive force becomes less than the Coulomb force and decreases with increasing speed V according to dependency:

This formula can be presented differently:

So, we have obtained the dependence of the interaction force of moving charges in a laboratory system. Next, let's take into account general view equation of vibrations, without going into the specifics of it (in this case, we can keep in mind the de Broglie model for the ground and first excited states of the hydrogen atom).

F = — ω 2 m q

those. the radiation frequency for a fixed electron mass and its “displacement” is proportional to the square root of the force modulus. In our model, the details of the structure of the atom are not important to us; it is only important for us to know what will be observed in the laboratory frame of reference with the relationship between the forces of charge interaction obtained above. Thus,

which coincides with Einstein's conclusion:

MIB is not a “legend”. This is how the theory of relativity was explained to us at school.

The same thing happens not only with light, but also with sound waves.

So I’m telling you how you were “taught.” Or how did you “learn”? You are talking about the Doppler effect, and the theory of relativity is based on the equality of inertial reference systems and on the finiteness of the maximum speed of interactions. It is these two provisions that give rise to geometry with the Lorentz group.

As far as I have read, the Michelson-Morphy experiment was repeated only once due to its complexity. In the USA in the mid-20th century.

But that’s not the point... the point is the physical (philosophical) interpretation of the STR equations.

Not Morphy, but Morley.

Below is a list of related articles. In the context of physics, the last two articles are the most interesting. In the context of philosophy, there is nothing sensible - you yourself demonstrate who, how and what “philosophy” and “physics” taught you.

But why would sand fall slower in a moving train, if Einstein himself wrote that the basic premise of his theory is that physical processes in all inertial reference frames proceed the same way.

Hmmm... How everything is running...

Let's start from the beginning, with Newton's Principia. The fact that physical processes in all inertial frames of reference proceed in the same way is the discovery of Galileo, not Newton, and especially not Einstein. However, Newton has a three-dimensional Euclidean space parameterized by the variable t . If we consider this construction as a single space-time, we obtain the parabolic geometry of Galileo (i.e., a geometry different from both flat Euclidean and hyperbolic Lobachevsky and spherical Riemann). Important feature Newtonian mechanics - an infinite speed of interaction is allowed. This corresponds to the group of Galilean space-time transformations.

Now Maxwell. The equations of electrodynamics do not allow an infinite speed of interactions; electromagnetic fields propagate at a finite speed - the speed of light With . This gives rise to an unpleasant fact: Maxwell's equations are not transformed by the Galilean group, or, as they say, are not invariant with respect to this group, which sharply weakens their cognitive value unless some specific group is found for them, passing in the limit With → ∞ to the Galilean group. In addition, we want to preserve the principle of causality, i.e. to avoid a situation where in one frame of reference an event has already occurred, but in others either has not yet occurred, or has occurred even earlier. Essentially, the equality of the speed of light in all inertial frames of reference is a consequence of the principle of causality. Hence the requirement arises that there should be a certain quantity, a certain invariant, identical in all inertial frames of reference. Such an invariant turned out to be the expression

s 2 = r 2 - (ct) 2

(I don’t write in differentials so as not to scare you). This value is called interval. As you can see, this is simply the hypotenuse of a four-dimensional triangle with three real (spatial) legs and one imaginary (temporal) one. Here With — maximum interaction speed (we accept it equal speed light, but physicists have reason to doubt that interactions with higher speeds do not exist).

The interval connects a pair of events in any inertial reference frame (IFR) and is the same for the same pair of events in all reference frames (IFR). Next is a matter of technology. When moving from one ISO to another, the spatial and time coordinates are transformed by the Lorentz group, leaving the interval invariant. Lorentz transformations are a group of rotations of our triangle in 4-dimensional space-time in such a way that all 4 coordinates change x, y, z, ict , but the length of the hypotenuse s remains constant.

When striving With → ∞ Lorentz transformations turn into Galilean transformations.

Somewhere on the fingers. If you missed anything or expressed yourself inaccurately, call and ask.

History of the development of radar A. S. Popov in 1897, during experiments on radio communication between ships, discovered the phenomenon of reflection of radio waves from the side of the ship. The radio transmitter was installed on the upper bridge of the transport "Europe", which was at anchor, and the radio receiver was installed on the cruiser "Africa". During experiments, when the cruiser “Lieutenant Ilyin” got between the ships, the interaction of the instruments stopped until the ships left the same straight line. In September 1922 in the USA, H. Taylor and L. Young conducted experiments on radio communications at decameter waves (3-30 MHz) across the Potomac River. At this time, a ship passed along the river, and the connection was interrupted - which prompted them to also think about using radio waves to detect moving objects.

Scottish physicist Robert Watson-Watt was the first to build a radar installation in 1935 that could detect aircraft at a distance of 64 km. This system played a huge role in protecting England from German air raids during the Second World War. In the USSR, the first experiments in radio detection of aircraft were carried out in the Industrial production of the first radars put into service began in 1939. Robert Watson-Watt (gg.) History of the creation of radar (RADAR is an abbreviation for Radio Detection And Ranging, i.e. radio detection and ranging)

Radar is based on the phenomenon of reflection of radio waves from various objects. Noticeable reflection is possible from objects if their linear dimensions exceed the electromagnetic wavelength. Therefore, radars operate in the microwave range (Hz). And also the power of the emitted signal ~ω 4.

Cruise missile Control of the missile in flight is completely autonomous. The operating principle of its navigation system is based on comparing the terrain of a specific area where the missile is located with reference maps of the terrain along its flight route, previously stored in the memory of the on-board control system. The radio altimeter ensures flight along a predetermined route in terrain following mode by accurately maintaining the flight altitude: above the sea - no more than 20 m, above land - from 50 to 150 m (when approaching the target - decrease to 20 m). Correction of the missile's flight path during the cruising phase is carried out according to data from the satellite navigation subsystem and the terrain correction subsystem.

One of the important methods of reducing accidents is to control the speed limit of vehicles on the roads. American police used the first civilian radars to measure vehicle speed at the end of World War II. Now they are used in all developed countries. Radar for measuring vehicle speed

Application in space In space research, radars are used to control flight and track satellites, interplanetary stations, and when docking ships. Radar of the planets made it possible to clarify their parameters (for example, distance from the Earth and rotation speed), the state of the atmosphere, and to map the surface.

Radar

Radar - detection and precise determination of the position of objects using radio waves.

A.S. Popov In 1895, the outstanding Russian scientist Alexander Stepanovich Popov, within the walls of the Mine Officer Class in Kronstadt, discovered the possibility of using electromagnetic waves for practical purposes of communication without wires. The significance of this discovery, which represents one of the greatest achievements of world science and technology, is determined by its exceptionally wide use in all areas of national economic life and by all branches of the Armed Forces. Invention by A.S. Popov opened a new era in the use of electromagnetic waves. It resolved the issue of communication not only between stationary but also between moving objects and at the same time prepared the way for a number of discoveries that made possible the widespread use of radio in all areas of science and technology.

The history of the creation of radar Scottish physicist Robert Watson-Watt was the first in 1935. He built a radar installation capable of detecting aircraft at a distance of 64 km. This system played a huge role in protecting England from German air raids during the Second World War. In the USSR, the first experiments on radio detection of aircraft were carried out in 1934. Industrial production of the first radars adopted for service began in 1939. Robert Watson-Watt (1892 -1973)

radar is based on the phenomenon of reflection of radio waves from various objects. Noticeable reflection is possible from objects in that case. If their linear dimensions exceed the length of the electromagnetic wave. Therefore, radars operate in the microwave range, as well as the power of the emitted signal

Determining the distance to an object Knowing the orientation of the antenna during target detection, its coordinates are determined. By changing these coordinates over time, the speed of the target is determined and its trajectory is calculated.

Application of radar

Radar for measuring vehicle speed One of the important methods of reducing accidents is to control the speed of vehicles on the roads. American police used the first civilian radars to measure vehicle speed at the end of World War II. Now they are used in all developed countries.