Properties of microwave waves

In modern life, ultrahigh-frequency waves are used very actively. Take a look at your cell phone - it operates in the microwave range.

All technologies such as Wi-Fi, wireless Wi-Max, 3G, 4G, LTE (Long Term Evolution), Bluetooth short-range radio interface, radar and radio navigation systems use ultra-high frequency (microwave) waves.

Microwaves have found application in industry and medicine. In another way, microwave waves are also called microwaves. The operation of a household microwave oven is also based on the use of microwave radiation.

Microwave- these are the same radio waves, but the wavelength of such waves ranges from tens of centimeters to a millimeter. Microwaves occupy an intermediate position between ultrashort waves and infrared radiation. This intermediate position also affects the properties of microwaves. Microwave radiation has the properties of both radio waves and light waves. For example, microwave radiation has the qualities of visible light and infrared electromagnetic radiation.

LTE mobile network station

Microwaves, which have a wavelength of centimeters, can cause biological effects at high radiation levels. In addition, centimeter waves pass through buildings worse than decimeter waves.

Microwave radiation can be concentrated into a narrow beam. This property directly affects the design of receiving and transmitting antennas operating in the microwave range. No one will be surprised by the concave parabolic antenna of satellite television, which receives a high-frequency signal, like a concave mirror collecting light rays.

Microwaves, like light, travel in a straight line and are blocked by solid objects, similar to how light does not pass through opaque objects. So, if you deploy a local Wi-Fi network in an apartment, then in the direction where the radio wave encounters obstacles in its path, such as partitions or ceilings, the network signal will be less than in the direction that is freer from obstacles.

Radiation from GSM cellular base stations is quite strongly attenuated by pine forests, since the size and length of the needles are approximately equal to half the wavelength, and the needles serve as a kind of receiving antennas, thereby weakening the electromagnetic field. Dense tropical forests also affect the weakening of station signals. As the frequency increases, the attenuation of microwave radiation increases when it is blocked by natural obstacles.

Cellular communications equipment can even be found on power poles.

The propagation of microwaves in free space, for example, along the surface of the earth, is limited by the horizon, in contrast to long waves that can circle the globe due to reflection in the layers of the ionosphere.

This property of microwave radiation is used in cellular communications. The service area is divided into cells in which there is a base station operating on its own frequency. The neighboring base station operates on a different frequency so that nearby stations do not interfere with each other. Next comes the so-called radio frequency reuse.

Since the station's radiation is blocked by the horizon, it is possible to install a station operating at the same frequency at some distance. As a result, such stations will not interfere with each other. It turns out that the radio frequency band used by the communication network is saved.

GSM base station antennas

Radio frequency spectrum is a natural, limited resource, like oil or gas. The distribution of frequencies in Russia is handled by the State Commission on Radio Frequencies - SCRF. In order to obtain permission to deploy wireless access networks, real “corporate wars” are sometimes waged between mobile network operators.

Why is microwave radiation used in radio communication systems if it does not have the same propagation range as, for example, long waves?

The reason is that the higher the frequency of the radiation, the more information can be transmitted with its help. For example, many people know that fiber optic cable has an extremely high information transmission speed of terabits per second.

All high-speed telecommunications highways use fiber optics. The carrier of information here is light, the frequency of the electromagnetic wave of which is disproportionately higher than that of microwaves. Microwaves, in turn, have the properties of radio waves and propagate unhindered in space. Light and laser beams are highly scattered in the atmosphere and therefore cannot be used in mobile communication systems.

Many people have a microwave oven (microwave) in their kitchen, which is used to heat food. The operation of this device is based on the polarization effects of microwave radiation. It should be noted that heating of objects with the help of microwave waves occurs to a greater extent from the inside, in contrast to infrared radiation, which heats the object from the outside inward. Therefore, you need to understand that heating in a conventional and microwave oven occurs differently. Also microwave radiation, for example, at a frequency 2.45 GHz is capable of penetrating several centimeters into the body, and the heating produced is felt at a power density of 20 – 50 mW/cm 2 when exposed to radiation for several seconds. It is clear that powerful microwave radiation can cause internal burns, since heating occurs from the inside.

At a microwave operating frequency of 2.45 Gigahertz, ordinary water can absorb the energy of microwave waves as much as possible and convert it into heat, which is what actually happens in a microwave.

While there is ongoing debate about the dangers of microwave radiation, the military already has the opportunity to test the so-called “ray gun” in practice. Thus, in the United States, a device has been developed that “shoots” a narrowly directed microwave beam.

The installation looks like something like a parabolic antenna, only not concave, but flat. The diameter of the antenna is quite large - this is understandable, because it is necessary to concentrate microwave radiation into a narrowly directed beam over a long distance. The microwave gun operates at a frequency of 95 Gigahertz, and its effective “firing” range is about 1 kilometer. According to the creators, this is not the limit. The entire installation is based on an army humvee.

According to the developers, this device does not pose a mortal threat and will be used to disperse demonstrations. The power of the radiation is such that when a person enters the focus of the beam, he experiences a strong burning sensation on his skin. According to those who were exposed to such a beam, the skin seemed to be heated by very hot air. In this case, a natural desire arises to hide, to escape from such an effect.

The operation of this device is based on the fact that microwave radiation with a frequency of 95 GHz penetrates half a millimeter into the skin layer and causes local heating in a fraction of a second. This is enough for the person under the gun to feel pain and burning on the surface of the skin. A similar principle is used to heat food in a microwave oven, only in a microwave oven the microwave radiation is absorbed by the food being heated and practically does not leave the chamber.

At the moment, the biological effects of microwave radiation are not fully understood. Therefore, no matter what the creators say that a microwave gun is not harmful to health, it can cause harm to the organs and tissues of the human body.

It is worth noting that microwave radiation is most harmful to organs with slow heat circulation - these are the tissues of the brain and eyes. Brain tissue does not have pain receptors, and it will not be possible to feel the obvious effects of radiation. It’s also hard to believe that a lot of money will be allocated for the development of a “demonstrator repeller” - $120 million. Naturally, this is a military development. In addition, there are no special obstacles to increasing the power of the high-frequency radiation of the gun to such a level when it can already be used as a destructive weapon. Also, if desired, it can be made more compact.

The military plans to create a flying version of the microwave gun. Surely they will install it on some drone and control it remotely.

Harm from microwave radiation

Documents for any electronic device that is capable of emitting microwave waves mention the so-called SAR. SAR is the Specific Absorption Rate of Electromagnetic Energy. In simple terms, this is the radiation power that is absorbed by living tissues of the body. SAR is measured in watts per kilogram. So, for the USA the permissible level has been determined to be 1.6 W/kg. For Europe it is slightly larger. For the head 2 W/kg, for other parts of the body 4 W/kg. In Russia, more stringent restrictions apply, and permissible radiation is measured in W/cm 2. The norm is 10 μW/cm2.

Despite the fact that microwave radiation is generally considered non-ionizing, it is worth noting that in any case it affects any living organisms. For example, the book “The Brain in Electromagnetic Fields” (Yu. A. Kholodov) presents the results of many experiments, as well as the thorny history of introducing standards for exposure to electromagnetic fields. The results are quite interesting. Microwave radiation affects many processes occurring in living organisms. If interested, read it.

From all this follows a few simple rules. Talk on your cell phone as little as possible. Keep it away from the head and important parts of the body. Don't sleep with your smartphone in your arms. Use a headset if possible. Stay away from cellular base stations (we are talking about residential and work areas). It is no secret that mobile communication antennas are placed on the roofs of residential buildings.

It is also worth “throwing a stone at the garden” of mobile Internet when using a smartphone or tablet. If you are surfing the Internet, the device constantly transmits data to the base station. Even if the radiation power is small (it all depends on the quality of communication, interference and distance of the base station), then with prolonged use a negative effect is guaranteed. No, you won't go bald or start to glow. There are no pain receptors in the brain. Therefore, he will eliminate “problems” “to the best of his ability and capabilities.” It will just be more difficult to concentrate, fatigue will increase, etc. It’s like drinking poison in small doses.

The range of radio emission is the opposite of gamma radiation and is also unlimited on one side - from long waves and low frequencies.

Engineers divide it into many sections. The shortest radio waves are used for wireless data transmission (Internet, cellular and satellite telephony); meter, decimeter and ultrashort waves (VHF) occupy local television and radio stations; short waves (HF) are used for global radio communications - they are reflected from the ionosphere and can circle the Earth; medium and long waves are used for regional radio broadcasting. Ultra-long waves (ELW) - from 1 km to thousands of kilometers - penetrate salt water and are used for communication with submarines, as well as for searching for minerals.

The energy of radio waves is extremely low, but they excite weak vibrations of electrons in a metal antenna. These vibrations are then amplified and recorded.

The atmosphere transmits radio waves with a length from 1 mm to 30 m. They make it possible to observe the nuclei of galaxies, neutron stars, and other planetary systems, but the most impressive achievement of radio astronomy is record-breaking detailed images of cosmic sources, the resolution of which exceeds a ten-thousandth of an arc second.

Microwave

Microwaves are a subband of radio emission adjacent to the infrared. It is also called ultra-high frequency (microwave) radiation because it has the highest frequency in the radio range.

The microwave range is of interest to astronomers because it detects the relict radiation remaining from the time of the Big Bang (another name is the microwave cosmic background). It was emitted 13.7 billion years ago, when the hot matter of the Universe became transparent to its own thermal radiation. As the Universe expanded, the CMB cooled and today its temperature is 2.7 K.

CMB radiation comes to Earth from all directions. Today, astrophysicists are interested in inhomogeneities in the sky glow in the microwave range. They are used to determine how clusters of galaxies began to form in the early Universe in order to test the correctness of cosmological theories.

But on Earth, microwaves are used for such mundane tasks as heating breakfast and talking on a cell phone.

The atmosphere is transparent to microwaves. They can be used to communicate with satellites. There are also projects for transmitting energy over a distance using microwave beams.

Sources

Sky Reviews

Microwave sky 1.9 mm(WMAP)

The cosmic microwave background, also called the cosmic microwave background radiation, is the cooled glow of the hot Universe. It was first discovered by A. Penzias and R. Wilson in 1965 (Nobel Prize 1978). The first measurements showed that the radiation is completely uniform throughout the sky.

In 1992, the discovery of anisotropy (inhomogeneity) of the cosmic microwave background radiation was announced. This result was obtained by the Soviet satellite Relikt-1 and confirmed by the American COBE satellite (see Sky in the infrared). COBE also determined that the spectrum of the cosmic microwave background radiation is very close to that of the blackbody. The 2006 Nobel Prize was awarded for this result.

Variations in the brightness of the cosmic microwave background radiation across the sky do not exceed one hundredth of a percent, but their presence indicates subtle inhomogeneities in the distribution of matter that existed at an early stage of the evolution of the Universe and served as the embryos of galaxies and their clusters.

However, the accuracy of the COBE and Relict data was not enough to test cosmological models, and therefore in 2001 a new, more accurate WMAP (Wilkinson Microwave Anisotropy Probe) apparatus was launched, which by 2003 had built a detailed map of the intensity distribution of the cosmic microwave background radiation across the celestial sphere. Based on these data, cosmological models and ideas about the evolution of galaxies are now being refined.

CMB arose when the age of the Universe was about 400 thousand years and, due to expansion and cooling, it became transparent to its own thermal radiation. Initially, the radiation had a Planck (blackbody) spectrum with a temperature of about 3000 K and accounted for the near-infrared and visible ranges of the spectrum.

As the Universe expanded, the cosmic microwave background radiation experienced a red shift, which led to a decrease in its temperature. Today the temperature of the cosmic microwave background radiation is 2.7 TO and it falls in the microwave and far-infrared (submillimeter) ranges of the spectrum. The graph shows an approximate view of the Planck spectrum for this temperature. The spectrum of the cosmic microwave background radiation was first measured by the COBE satellite (see Sky in the infrared), for which the Nobel Prize was awarded in 2006.

Radio sky on wave 21 cm, 1420 MHz(Dickey & Lockman)

Famous spectral line with wavelength 21.1 cm is another way to observe neutral atomic hydrogen in space. The line arises due to the so-called hyperfine splitting of the main energy level of the hydrogen atom.

The energy of an unexcited hydrogen atom depends on the relative orientation of the spins of the proton and electron. If they are parallel, the energy is slightly higher. Such atoms can spontaneously transform into a state with antiparallel spins, emitting a quantum of radio emission that carries away a tiny excess of energy. This happens to an individual atom on average once every 11 million years. But the huge distribution of hydrogen in the Universe makes it possible to observe gas clouds at this frequency.

Radio sky on wave 73.5 cm, 408 MHz(Bonn)

This is the longest wavelength of all sky surveys. It was performed at a wavelength at which a significant number of sources are observed in the Galaxy. In addition, the choice of wavelength was determined by technical reasons. To construct the survey, one of the world's largest full-rotating radio telescopes was used - the 100-meter Bonn radio telescope.

Terrestrial Application

The main advantage of a microwave oven is that over time the food is heated throughout the entire volume, and not just from the surface.

Microwave radiation, having a longer wavelength, penetrates deeper than infrared radiation under the surface of products. Inside food, electromagnetic vibrations excite rotational levels of water molecules, the movement of which mainly causes heating of food. In this way, microwave (microwave) drying of food, defrosting, cooking and heating takes place. Also, alternating electric currents excite high frequency currents. These currents can occur in substances where mobile charged particles are present.

But sharp and thin metal objects cannot be placed in a microwave oven (this especially applies to dishes with metal decorations coated with silver and gold). Even a thin ring of gold plating along the edge of the plate can cause a powerful electrical discharge that will damage the device that creates the electromagnetic wave in the furnace (magnetron, klystron).

The operating principle of cellular telephony is based on the use of a radio channel (in the microwave range) for communication between the subscriber and one of the base stations. Information is transmitted between base stations, as a rule, via digital cable networks.

The range of the base station - the size of the cell - is from several tens to several thousand meters. It depends on the landscape and on the signal strength, which is selected so that there are not too many active subscribers in one cell.

In the GSM standard, one base station can support no more than 8 telephone conversations simultaneously. During mass events and natural disasters, the number of callers increases sharply, this overloads base stations and leads to interruptions in cellular communications. For such cases, cellular operators have mobile base stations that can be quickly delivered to areas with large crowds of people.

There is a lot of controversy about the possible harm of microwave radiation from cell phones. During a conversation, the transmitter is in close proximity to the person's head. Repeated studies have not yet been able to reliably register the negative effects of radio emissions from cell phones on health. Although the effects of weak microwave radiation on body tissue cannot be completely ruled out, there is no cause for serious concern.

Television images are transmitted on meter and decimeter waves. Each frame is divided into lines along which the brightness changes in a certain way.

The transmitter of a television station constantly broadcasts a radio signal of a strictly fixed frequency, it is called the carrier frequency. The receiving circuit of the TV is adjusted to it - a resonance arises in it at the desired frequency, which makes it possible to pick up weak electromagnetic oscillations. Information about the image is transmitted by the amplitude of the oscillations: large amplitude means high brightness, low amplitude means a dark area of ​​the image. This principle is called amplitude modulation. Sound is transmitted similarly by radio stations (except FM stations).

With the transition to digital television, the rules for image encoding change, but the very principle of the carrier frequency and its modulation remains the same.

Parabolic antenna for receiving a signal from a geostationary satellite in the microwave and VHF ranges. The principle of operation is the same as that of a radio telescope, but the dish does not need to be made movable. At the time of installation, it is directed to the satellite, which always remains in one place relative to earthly structures.

This is achieved by placing the satellite into a geostationary orbit at an altitude of about 36 thousand. km above the Earth's equator. The period of revolution along this orbit is exactly equal to the period of rotation of the Earth around its axis relative to the stars - 23 hours 56 minutes 4 seconds. The size of the dish depends on the power of the satellite transmitter and its radiation pattern. Each satellite has a primary service area where its signals are received by a dish with a diameter of 50–100 cm, and the peripheral zone, where the signal quickly weakens and an antenna of up to 2–3 may be required to receive it. m.

Who invented microwaves and how did it all end?

The first microwave ovens were invented by German scientists commissioned by the Nazis. This was done in order not to waste time on cooking and not to carry heavy fuel for stoves during the cold Russian winters. During operation, it turned out that food prepared in them had a negative effect on the health of soldiers and their use was abandoned.

In 1942-1943, these studies fell into the hands of the Americans and were classified.

At the same time, several microwave ovens fell into the hands of the Russians and were carefully studied by Soviet scientists in B Belarusian Radio Technological Institute and in closed research institutes of the Urals and Novosibirsk (Drs. Luria and Perov). In particular, their biological effect was studied, that is, the influence of microwave radiation on biological objects.

Result:

The Soviet Union passed a law prohibiting the use of microwave ovens due to their biological hazard! The Soviets have issued an international warning about the health and environmental hazards of microwave ovens and other similar electromagnetic devices.

These data are a little alarming, aren't they?

Continuing their work, Soviet scientists examined thousands of workers who worked with radar installations and received microwave radiation. The results were so severe that a strict radiation limit was set at 10 microwatts for workers and 1 microwatt for civilians.

Operating principle of a microwave oven:

Microwave radiation, Microwave radiation (microwave radiation)- electromagnetic radiation, including the centimeter and millimeter range of radio waves (from 30 cm - frequency 1 GHz to 1 mm - 300 GHz).

Microwaves are a form of electromagnetic energy, just like light waves or radio waves. These are very short electromagnetic waves that travel at the speed of light (299.79 thousand km per second). In modern technology, microwaves are used in microwave ovens, for long-distance and international telephone communications, transmission of television programs, and operation of the Internet on Earth and via satellites. But microwaves are best known to us as a source of energy for cooking - the microwave oven.

Each microwave oven contains a magnetron, which converts electrical energy into a microwave electric field of 2450 MHz or 2.45 GHz, which interacts with water molecules in food. Microwaves attack water molecules in food, causing them to spin millions of times per second, creating molecular friction that heats the food.

What is the harm of a microwave?

For those who know about the harmful effects of mobile phones, it should be clear that a mobile phone operates at the same frequencies as a microwave oven. For those who are not familiar with this information, please read the information “The Impact of Mobile Phones on Humans”.

We will talk about four factors that indicate that microwaves are harmful.

Firstly, these are electromagnetic radiations themselves, or rather their information component. In science it is called a torsion field.

It has been experimentally established that electromagnetic radiation has a torsion (information) component. According to research by specialists from France, Russia, Ukraine and Switzerland, it is torsion fields, and not electromagnetic ones, that are the main factor in the negative impact on human health. Since it is the torsion field that transmits to a person all the negative information that causes headaches, irritation, insomnia, etc.

In addition, we must not forget about temperature. Of course, this applies to long periods of time and constant use of the microwave.

The most harmful to the human body, from a biological point of view, is high-frequency radiation in the centimeter range (microwave), which produces electromagnetic radiation of the highest intensity.

Microwave radiation directly heats the body, blood flow reduces heating (this applies to organs rich in blood vessels). But there are organs, such as the lens, that do not contain blood vessels. Therefore, microwave waves, i.e. significant thermal effects lead to clouding of the lens and its destruction. These changes are irreversible.

Electromagnetic radiation cannot be seen, heard or clearly felt. But it exists and affects the human body. The exact mechanism of action of electromagnetic study has not yet been studied. The influence of this radiation does not appear immediately, but as it accumulates, so it can be difficult to attribute a particular disease that suddenly appears in a person to the devices with which he was in contact.

Secondly, this is the effect of microwave radiation on food. As a result of the influence of electromagnetic radiation on a substance, ionization of molecules is possible, i.e. an atom can gain or lose an electron, and this changes the structure of the substance.

Radiation leads to the destruction and deformation of food molecules. Microwaves create new compounds that do not exist in nature, called radiolytics. Radiolytic compounds create molecular rot - as a direct consequence of radiation.

• Microwaved meats contain Nitrosodienthanolamines, a well-known carcinogen;
• Some amino acids in milk and cereals have become carcinogens;
• Defrosting frozen fruits in microwave ovens converts their glucosides and galactosides into particles containing carcinogenic elements;
• Even very short microwave irradiation of raw vegetables converts their alkaloids into carcinogens;
• Carcinogenic free radicals are formed in microwaved plants, especially root vegetables;
• The value of food decreases from 60% to 90%;
  
• The biological activity of vitamin B (complex), vitamins C and E, and also in many minerals disappears;
• Alkaloids, glucosides, galactosides and nitrilosides are destroyed to varying degrees in plants;
• Degradation of nucleoproteins in meat. Robert Becker in his book ‘Electricity of the Body’, citing research by Russian scientists, describes diseases associated with microwave ovens.

Data:

Some of the amino acids L-proline, which are part of mother's milk, as well as in infant formula, are converted under the influence of microwaves into d-isomers, which are considered neurotoxic (deform the nervous system) and nephrotoxic (poisonous to the kidneys). It is a tragedy that many children are fed on artificial milk substitutes (baby formula), which are made even more toxic by microwave ovens.

A short-term study showed that people who ate microwaved milk and vegetables had changes in their blood composition, decreased hemoglobin and increased cholesterol, while people who ate the same food, but prepared in a traditional way, did not change their body condition.

Hospital patient Norma Levit underwent a simple knee operation, after which she died from a blood transfusion. Usually the blood is warmed before a transfusion, but not in a microwave oven. This time, the nurse heated the blood in the microwave, unaware of the danger. Microwave-tainted blood killed Norma. The same thing happens with food that is heated and cooked in microwaves. Although the trial took place, newspapers and magazines did not talk about this case.

Researchers at the University of Vienna have found that heating with microwaves disrupts the atomic order of amino acids. According to the researchers, this is of concern because these amino acids are incorporated into proteins, which they then structurally, functionally and immunologically alter. Thus, proteins - the basis of life - are changed in food by microwaves.

Third, Microwave radiation leads to weakening of the cells of our body.

In genetic engineering, there is such a method: in order to penetrate a cell, it is lightly irradiated with electromagnetic waves and this weakens the cell membranes. Since the cells are practically broken, the cell membranes cannot protect the cell from the penetration of viruses, fungi and other microorganisms, and the natural self-healing mechanism is also suppressed.

Fourth, a microwave oven creates radioactive decay of molecules with the subsequent formation of new alloys unknown to nature, as usual with radiation.

Doesn’t the harm of a microwave seem so unrealistic now?

The influence of microwave radiation on human health

As a result of eating microwaved food, the pulse and blood pressure first decrease, and then nervousness, high blood pressure, headaches, dizziness, eye pain, insomnia, irritability, nervousness, stomach pain, inability to concentrate, hair loss, increased incidence of appendicitis occur. , cataracts, reproductive problems, cancer. These chronic symptoms are exacerbated by stress and heart disease.

Consumption of food irradiated in a microwave oven contributes to the formation of an increased number of cancer cells in the blood serum.

According to statistics, in a large number of people, food irradiated in a microwave oven causes tumors resembling cancer in the stomach and digestive tract, in addition, a general degeneration of peripheral cellular tissue with permanent disruption of the functions of the digestive and excretory system.

Thus, food altered by microwaves harms the human digestive tract and immune system and can ultimately cause cancer.

In addition, we must not forget about electromagnetic radiation itself. This is especially true for pregnant women and children.

The circulatory system, endocrine system, brain, eyes, immune and reproductive systems are most susceptible to the influence of electromagnetic fields.

As for pregnant women, you need to be extremely careful. Unlimited “walks” through electromagnetic fields during pregnancy can lead to spontaneous abortions, premature births, and the appearance of congenital malformations in children.

Read more about the influence of electromagnetic fields in the section “The influence of electromagnetic radiation on humans”.

The purpose of this site is not to intimidate. We warn you.

Nobody says that tomorrow you will have mental disorders or, God forbid, they will discover something in your brain.

The harm of microwave radiation depends on its intensity and exposure time. Modern microwave ovens will not be able to kill you... tomorrow or in a year...

Scientists talk about the consequences in 10-15 years.

What does this mean?

1. If you are 20-25 today, then while still a young person (up to 35-40 years old), you risk remaining disabled, or giving birth to a disabled person, or not giving birth to one at all, significantly shortening the life span of yourself and your child.

2. If you are around 30-40, then you may not see your grandchildren or risk a painful old age. In addition, you influence the development and even the lives of your children.

3. If you are about 50 or older, refer to point 2. This applies to you too.

Do you need this?

Isn't it better to protect yourself from electromagnetic radiation and refuse to eat food from the microwave?

Good afternoon, dear Khabrovsk residents.

This post will be about the undocumented functions of the microwave oven. I'll show you how many useful things you can do if you use a slightly modified microwave in an unconventional way.

The microwave contains a generator of microwave waves of enormous power.

I open the case

In this video I want to show what this voltage can do:

Antenna for magnetron

Now all the radiation is directed in the right direction. Just in case, I decided to test the effectiveness of this antenna. I took a lot of small neon bulbs and laid them out on a plane. When I brought the antenna with the magnetron on, I saw that the lights were lighting up exactly where needed:

Unusual experiences

Using non-ionizing radiation from a magnetron, plasma can be obtained. In an incandescent lamp brought to the magnetron, a brightly glowing yellow ball, sometimes with a purple tint, like ball lightning, lights up. If you do not turn off the magnetron in time, the light bulb will explode. Even an ordinary paper clip turns into an antenna under the influence of microwaves. An EMF of sufficient strength is induced on it to ignite an arc and melt this paper clip. Fluorescent lamps and housekeepers light up at a fairly large distance and glow right in your hands without wires! And in a neon lamp, electromagnetic waves become visible:

I want to reassure you, my readers, that none of my neighbors suffered from my experiments. All the closest neighbors fled the city as soon as fighting began in Lugansk.

Safety precautions

Unusual uses of the magnetron

These are not all possible applications that I have tested. Experiments continue and soon I will write an even more unusual post. Still, I want to point out that using a microwave like this is dangerous! Therefore, it is better to do this in cases of extreme necessity and while observing safety rules when working with microwaves.

That's all for me, be careful when working with high voltage and microwaves.

Androsova Ekaterina

I. Microwave radiation (a little theory).

II. Impact on humans.

III. Practical application of microwave radiation. Microwave ovens.

1. What is a microwave oven?

2. History of creation.

3. Device.

4. The operating principle of a microwave oven.

5. Main characteristics:

a. Power;

b. Internal coating;

c. Grill (its varieties);

d. Convection;

IV. Research part of the project.

1. Comparative analysis.

2. Social poll.

V. Conclusions.

Download:

Preview:

Project work

in physics

on the topic of:

“Microwave radiation.
Its use in microwave ovens.
Comparative analysis of furnaces from different manufacturers"

11th grade students

GOU secondary school "Losiny Ostrov" No. 368

Androsova Ekaterina

Teacher – project leader:

Zhitomirskaya Zinaida Borisovna

February 2010

Microwave radiation.

Infrared radiation- electromagnetic radiation occupying the spectral region between the red end of visible light (with a wavelengthλ = 0.74 µm) and microwave radiation (λ ~ 1-2 mm).

Microwave radiation, Ultrahigh frequency radiation(microwave radiation) - electromagnetic radiation including the centimeter and millimeter range of radio waves (from 30 cm - frequency 1 GHz to 1 mm - 300 GHz). High-intensity microwave radiation is used for non-contact heating of bodies, for example, in everyday life and for heat treatment of metals in microwave ovens, as well as for radar. Low-intensity microwave radiation is used in communications, mainly portable (walkie-talkies, latest generation cell phones, WiFi devices).

Infrared radiation is also called “thermal” radiation, since all bodies, solid and liquid, heated to a certain temperature, emit energy in the infrared spectrum. In this case, the wavelengths emitted by the body depend on the heating temperature: the higher the temperature, the shorter the wavelength and the higher the radiation intensity. The radiation spectrum of an absolutely black body at relatively low (up to several thousand Kelvin) temperatures lies mainly in this range.

IR (infrared) diodes and photodiodes are widely used in remote controls, automation systems, security systems, etc. Infrared emitters are used in industry for drying paint surfaces. The infrared drying method has significant advantages over the traditional convection method. First of all, this is, of course, an economic effect. The speed and energy consumed during infrared drying is less than the same indicators with traditional methods. A positive side effect is also the sterilization of food products, increasing the corrosion resistance of painted surfaces. The disadvantage is the significantly greater unevenness of heating, which is completely unacceptable in a number of technological processes. A special feature of the use of IR radiation in the food industry is the possibility of penetration of an electromagnetic wave into capillary-porous products such as grain, cereals, flour, etc. to a depth of up to 7 mm. This value depends on the nature of the surface, structure, material properties and frequency characteristics of the radiation. An electromagnetic wave of a certain frequency range has not only a thermal, but also a biological effect on the product, helping to accelerate biochemical transformations in biological polymers (starch, protein, lipids).

Impact of microwave radiation on humans

The accumulated experimental material allows us to divide all the effects of microwave radiation on living beings into 2 large classes: thermal and non-thermal. The thermal effect in a biological object is observed when it is irradiated with a field with a power flux density of more than 10 mW/cm2, and tissue heating exceeds 0.1 C, otherwise a non-thermal effect is observed. If the processes occurring under the influence of powerful electromagnetic fields of microwaves have received a theoretical description that is in good agreement with experimental data, then the processes occurring under the influence of low-intensity radiation have been poorly studied theoretically. There are not even hypotheses about the physical mechanisms of the impact of low-intensity electromagnetic studies on biological objects of different levels of development, from a single-celled organism to humans, although individual approaches to solving this problem are being considered

Microwave radiation can affect human behavior, feelings, and thoughts;
Affects biocurrents with a frequency from 1 to 35 Hz. As a result, disturbances in the perception of reality, increased and decreased tone, fatigue, nausea and headache occur; Complete sterilization of the instinctive sphere is possible, as well as damage to the heart, brain and central nervous system.

ELECTROMAGNETIC RADIATIONS IN THE RADIO FREQUENCY RANGE (RF EMR).

SanPiN 2.2.4/2.1.8.055-96 Maximum permissible levels of energy flux density in the frequency range 300 MHz - 300 GHz depending on the duration of exposure When exposed to radiation for 8 hours or more, MPL - 0.025 mW per square centimeter, when exposed to 2 hours, MPL - 0.1 mW per square centimeter, and for exposure of 10 minutes or less, MPL - 1 mW per square centimeter.

Practical application of microwave radiation. Microwave ovens

A microwave oven is a household electrical appliance designed for quickly cooking or quickly heating food, as well as for defrosting food, using radio waves.

History of creation

American engineer Percy Spencer noticed the ability of microwave radiation to heat food when he worked at the Raytheon company. Raytheon ), which manufactures equipment for radars. According to legend, when he was conducting experiments with another magnetron, Spencer noticed that a piece of chocolate in his pocket had melted. According to another version, he noticed that a sandwich placed on the switched-on magnetron became hot.

The patent for the microwave oven was issued in 1946. The first microwave oven was built by Raytheon and was designed for rapid industrial cooking. Its height was approximately equal to human height, weight - 340 kg, power - 3 kW, which is approximately twice the power of a modern household microwave oven. This stove cost about $3,000. It was used mainly in soldiers' canteens and canteens of military hospitals.

The first mass-produced household microwave oven was produced by the Japanese company Sharp in 1962. Initially, demand for the new product was low.

In the USSR, microwave ovens were produced by the ZIL plant.

Microwave oven device.

Main components:

1. microwave source;
2. magnetron;
3. magnetron high-voltage power supply;
4. control circuit;
5. a waveguide for transmitting microwaves from the magnetron to the chamber;
6. a metal chamber in which microwave radiation is concentrated and where food is placed, with a metallized door;
7. auxiliary elements;
8. rotating table in the chamber;
9. circuits that provide security (“blocking”);
10. a fan that cools the magnetron and ventilates the chamber to remove gases generated during cooking.

Principle of operation

Magnetrons convert electrical energy into a high-frequency electric field, which causes water molecules to move, which leads to heating of the product. The magnetron, creating an electric field, directs it along a waveguide into the working chamber in which the product containing water is placed (water is a dipole, since the water molecule consists of positive and negative charges). The effect of an external electric field on the product leads to the fact that the dipoles begin to polarize, i.e. The dipoles begin to rotate. When the dipoles rotate, frictional forces arise, which turn into heat. Since polarization of dipoles occurs throughout the entire volume of the product, which causes its heating, this type of heating is also called volumetric heating. Microwave heating is also called microwave heating, meaning the short length of electromagnetic waves.

Characteristics of microwave ovens

Power.

1. The useful or effective power of a microwave oven, which is important for heating, cooking and defrosting, ismicrowave power and grill power. As a rule, the microwave power is proportional to the volume of the chamber: this microwave and grill power should be sufficient for the amount of food that can be placed in a given microwave oven in the appropriate modes. Conventionally, we can assume that the higher the microwave power, the faster heating and cooking occurs.
2. Maximum power consumption- electrical power, which should also be taken into account, since electricity consumption can be quite high (especially in large microwave ovens with grill and convection). Knowing the maximum power consumption is necessary not only to estimate the amount of electricity consumed, but also to check the possibility of connecting to existing outlets (for some microwave ovens, the maximum power consumption reaches 3100 W).

Internal coatings

The walls of the microwave oven's working chamber have a special coating. There are currently three main options: enamel coating, specialty coatings and stainless steel coating.

1. Durable enamel coating, smooth and easy to clean, found in many microwave ovens.
2. Special coatings, developed by microwave oven manufacturers, are advanced coatings that are even more resistant to damage and intense heat and are easier to clean than conventional enamel. Special or advanced coatings include LG's "antibacterial coating" and Samsung's "bioceramic coating".
3. Stainless steel coating- extremely resistant to high temperatures and damage, especially reliable and durable, and also looks very elegant. Stainless steel lining is typically used in grill or convection microwave ovens that have multiple high-temperature settings. As a rule, these are stoves of a high price category, with a beautiful external and internal design. However, it should be noted that keeping such a coating clean requires some effort and the use of special cleaning products.

Grill

Heating element grill. outwardly resembles a black metal tube with a heating element inside, located in the upper part of the working chamber. Many microwave ovens are equipped with a so-called “moving” heating element (TEN), which can be moved and installed vertically or inclined (at an angle), providing heating not from above, but from the side.
The movable heating element grill is especially convenient to use and provides additional opportunities for preparing dishes in grill mode (for example, in some models you can fry chicken in a vertical position). In addition, the inner chamber of a microwave oven with a movable heating element grill is easier and more convenient to clean (as is the grill itself).

Quartz Quartz grill located at the top of the microwave oven, and is a tubular quartz element behind a metal grid.

Unlike a heating element grill, a quartz grill does not take up space in the working chamber.

The power of a quartz grill is usually less than that of a grill with a heating element; microwave ovens with a quartz grill consume less electricity.

Ovens with a quartz grill roast more gently and evenly, but a grill with a heating element can provide more intense operation (more “aggressive” heating).

There is an opinion that a quartz grill is easier to keep clean (it is hidden in the upper part of the chamber behind a grill and is more difficult to get dirty). However, we note that over time, grease splatters, etc. They may still get on it, and it will no longer be possible to simply wash it, like a heating element grill. There is nothing particularly terrible about this (grease splashes and other contaminants will simply burn off the surface of the quartz grill).

Convection

Microwave ovens with convection are equipped with a ring heating element and a built-in fan (usually located on the back wall, in some cases at the top), which evenly distributes the heated air inside the chamber. Thanks to convection, food is baked and fried, and in such an oven you can bake pies, bake chicken, stew meat, etc.

Research part of the project

Comparative analysis of microwave ovens from different manufacturers
Social survey results

comparison table

A social survey was conducted among high school students.

1. Do you have a microwave oven?

2. Which company? What model?

3. What is the power? Other characteristics?

4. Do you know the safety rules when handling a microwave oven? Do you comply with them?

5. How do you use a microwave oven?

6. Your recipe.

Precautions when using a microwave oven.

1. Microwave radiation cannot penetrate metal objects, so you should not cook food in metal containers. If the metal utensils are closed, then the radiation is not absorbed at all and the oven may fail. Cooking in an open metal container is possible in principle, but its efficiency is an order of magnitude less (since radiation does not penetrate from all sides). In addition, sparks may occur near the sharp edges of metal objects.
2. It is undesirable to place dishes with a metal coating (“golden border”) in a microwave oven - a thin layer of metal has a high resistance and is highly heated by eddy currents, this can destroy the dishes in the area of ​​the metal coating. At the same time, metal objects without sharp edges, made of thick metal, are relatively safe in the microwave.
3. You cannot cook liquids in hermetically sealed containers or whole bird eggs in a microwave oven - due to the strong evaporation of the water inside them, they will explode.
4. It is dangerous to heat water in the microwave, because it is capable of overheating, that is, heating above the boiling point. A superheated liquid can then boil very sharply and at an unexpected moment. This applies not only to distilled water, but also to any water that contains few suspended particles. The smoother and more uniform the inner surface of the water container, the higher the risk. If the vessel has a narrow neck, then there is a high probability that when it starts boiling, superheated water will spill out and burn your hands.

CONCLUSIONS

Microwave ovens are widely used in everyday life, but some buyers of microwave ovens do not know the rules for handling microwave ovens. This can lead to negative consequences (high dose of radiation, fire, etc.)

Main characteristics of microwave ovens:

1. Power;
2. Availability of grill (heating element/quartz);
3. Presence of convection;
4. Internal coating.

The most popular are microwave ovens from Samsung and Panasonic with a power of 800 W, with a grill, costing about 4000-5000 rubles.