Electric power transmission without wires - from the beginning to the present

The transmission of electricity without wires is a method of transmitting electrical energy without using conductive elements in an electrical circuit.

At the end of the 19th century, the discovery that a bulb could be made to glow with electricity caused an explosion of research aimed at finding the best way to transmit electricity.


Wireless energy was also actively studied in the early 20th century, when scientists paid great attention to the search for various ways of wireless energy transmission. The purpose of the research was simple - to generate an electric field in one place so that it could then be detected by its devices at a distance. At the same time, attempts were made to supply energy at a distance not only to highly sensitive sensors for voltage detection, but also to significant energy consumers. So, in 1904 at the exhibition of St. Louis World's Fair was awarded a prize for the successful launch of a 0.1-horsepower aircraft engine, carried out at a distance of 30 m.
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The “electricity” gurus are known to many (William Sturgeon, Michael Faraday, Nicolas Joseph Callan, James Clerk Maxwel, Heinrich Hertz, Mahlon Loomas, etc.), but few know that the Japanese researcher Hidetsugu Yagi used a self-developed antenna to transmit energy. In February 1926 he published the results of his research, in which he described the structure and method of tuning the Yagi antenna.



Note: I deliberately did not mention about Tesla Nikola (Nikola Tesla) : it was written a lot and a lot.

Very serious work and projects were carried out in the USSR in the period 1930-1941 and in parallel at Drittes Reich . Naturally, mainly for military purposes. Naturally, mainly for military purposes: the defeat of enemy personnel, the destruction of military and industrial infrastructure, etc.
In the USSR, serious work was also being done on the use of microwave radiation to prevent surface corrosion of metal structures and products.
But this is a separate story. Again you have to climb into the dusty attic.

One of the greatest Russian physicists of the last century, the Nobel Prize winner, Academician Peter Leonidovich Kapitsa devoted part of his creative biography to exploring the prospects for using microwave oscillations and waves to create new and highly efficient energy transfer systems. In 1962, in the preface to his monograph, he wrote

"... I want to remind you that electrical engineering, before coming to the service of the power industry, in the last century dealt widely only with telecommunication issues (telegraph, signaling, etc.). It is likely that history will repeat: now the electronics are mainly used for radio communication purposes, but its future lies in solving major energy problems . "

From the long list of fantastic technical ideas implemented in the twentieth century, only the dream of wireless transmission of electric energy continued to remain unfulfilled. Detailed descriptions of the energy rays in science fiction novels teased engineers with their obvious need, and at the same time the practical complexity of implementation.
But the situation gradually began to change for the better.

In 1964, an expert in the field of microwave electronics, William C.Brown, first tested a device (helicopter model) capable of receiving and using microwave energy in the form of direct current, thanks to an antenna array consisting of half-wave dipoles, each of which is loaded on high-efficiency Schottky diodes.

In 1964, William C. Brown demonstrated on the CBS channel in the Walter Cronkite News program his model of a helicopter, which received enough energy to fly from a microwave radiator.


Already by 1976, William Brown transferred the power of 30 kW to the microwave beam at a distance of 1.6 km with an efficiency of more than 80%.

The tests were conducted in the laboratory and commissioned by Raytheon Co.
Read in detail (in English):
Microwave Power Transmission - IOSR Journals
The microwave powered Helicopter. William C. Brown. Raytheon Company.

In 1968, the American space research expert Peter E. Glaser proposed to place large solar panels in a geostationary orbit, and transfer the energy (5-10 GW) generated by them to the Earth’s surface with a well-focused microwave beam. , then convert it into DC or AC energy at a technical frequency and distribute to consumers.


Such a scheme made it possible to use an intense flux of solar radiation existing in a geostationary orbit (~ 1.4 kW / sq. M.) And transmit the received energy to the Earth's surface continuously, regardless of the time of day and weather conditions [2-12]. Due to the natural inclination of the equatorial plane to the ecliptic plane with an angle of 23.5 degrees, the satellite located in the geostationary orbit is illuminated by solar radiation flow almost continuously except for short periods of time near the days of the spring and autumn equinox, when this satellite falls into the Earth’s shadow. These periods can be accurately predicted, and in total they do not exceed 1% of the total duration of the year.

The frequency of electromagnetic oscillations of the microwave beam should correspond to the ranges that are allocated for use in industry, research and medicine. If this frequency is chosen to be 2.45 GHz, then meteorological conditions, including dense clouds and heavy precipitation, have practically no effect on the efficiency of energy transfer. The range of 5.8 GHz is tempting because it makes it possible to reduce the size of the transmitting and receiving antennas. However, the influence of meteorological conditions here requires further study.

The current level of development of microwave electronics suggests a rather high value of the efficiency of microwave energy transfer from the geostationary orbit to the Earth's surface - about 70-75%. The diameter of the transmitting antenna is usually chosen to be 1 km, and the terrestrial rectenna is 10 km x 13 km in size for a latitude of 35 degrees. SCES with an output power level of 5 GW has a radiated power density in the center of the transmitting antenna of 23 kW / sq. M, in the center of the receiving - 230 W / sq. M.


Various types of solid-state and vacuum microwave generators for the SCES transmitting antenna were investigated. William Brown showed, in particular, that magnetrons well mastered by industry and intended for microwave ovens can also be used in SCES transmitting antenna arrays if each of them is provided with its own negative feedback circuit in relation to the external clock signal (so called Magnetron Directional Amplifier (MDA).

Rektenna is a highly efficient receiving-transforming system, however, the low-voltage diodes and the need for their sequential switching can lead to avalanche-like breakdowns. A cyclotron energy converter makes it possible to substantially eliminate this problem.

The SCES transmitting antenna can be a reverse-re-emitting active antenna array based on slotted waveguides. Its coarse orientation is carried out mechanically; for accurate guidance of the microwave beam, the pilot signal emitted from the receiving center is used and analyzed on the surface of the transmitting antenna by the network of relevant sensors.

From 1965 to 1975 A scientific program led by Bill Brown was successfully completed, demonstrating the possibility of transmitting 30 kW of power over a distance of more than 1 mile with an efficiency of 84%.

In 1978–1979, the first government research program aimed at determining the SCES perspectives was carried out in the United States under the leadership of the Department of Energy (DOE) and NASA (NASA).

In 1995-1997, NASA again returned to the discussion of the prospects of SCES, based on the progress of technology achieved by that time.


Research was continued in 1999–2000 ( Space Solar Power (SSP) Strategic Research & Technology Program ).

The most active and systematic research in the field of SCES was conducted by Japan. In 1981, under the guidance of professors M.Nagatomo (Makoto Nagatomo) and S.Sasaki (Susumu Sasaki), the Institute of Space Research of Japan began research on the development of a prototype SCES with a power level of 10 MW, which could be created using existing launch vehicles. Creating such a prototype allows you to gain technological experience and prepare the basis for the formation of commercial systems.


The project was named SCES2000 (SPS2000) and received recognition in many countries around the world.

In 2008, Marin Soljačić, an associate professor at the department of physics at the Massachusetts Institute of Technology (MIT), was awakened from sweet sleep by insistent squeaking of a mobile phone. “The phone did not stop talking, demanding that I set it to charge,” says Soldzhachich. Tired and unwilling to get up, he began to dream that the phone, once at home, would start charging by itself .

So WiTricity and WiTricity corporation appeared.


In June 2007, Marin Soljačić and several other researchers at the Massachusetts Institute of Technology reported on the development of a system in which a 60-watt light bulb was supplied from a source located at a distance of 2 m, and the efficiency was 40%.


According to the authors of the invention, this is not a “pure” resonance of coupled circuits and is not a Tesla transformer with inductive coupling. The radius of power transmission today is just over two meters, in the future - up to 5-7 meters.
In general, scientists tested two fundamentally different schemes.
1. In an induction coil or electrical transformer that have a metal or air core, energy is transmitted by a simple electromagnetic coupling, called magnetic induction. Using this method, the transmission and production of energy became possible at a considerable distance, but to obtain significant voltage in a similar way it was necessary to arrange two coils very closely.
2. If magnetic resonance coupling is used, where both inductors are tuned to mutual frequency, considerable energy can be transferred to a considerable distance.

Similar technologies are frantically developed by other companies: Intel has demonstrated its WREL technology with an efficiency of up to 75% energy transfer. In 2009, Sony showed off TV without a network connection. Only one circumstance is alarming: regardless of the method of transmission and technical tricks, the energy density and field strength in the premises must be high enough to power the devices with a capacity of several tens of watts. According to the developers themselves, there is no information on the biological effects on humans of such systems. Given the recent appearance, and a different approach to the implementation of energy transfer devices, such studies are still coming, and the results will not appear soon. And we can judge their negative impact only indirectly. Something will disappear again from our dwellings, such as cockroaches.

In 2010, Haier Group, a Chinese home appliance maker, unveiled its unique product at CES 2010 - a fully wireless LCD TV based on research by Professor Marina Solyachicha on wireless power transmission and wireless home digital interface ( WHDI ).

In 2012-2015 Engineers at the University of Washington have developed technology to use Wi-Fi as an energy source to power portable devices and charge gadgets. The technology is already recognized by Popular Science magazine as one of the best innovations of 2015. The widespread adoption of wireless data transmission technology has in itself produced a real revolution. And now it was the turn of the wireless transmission of energy over the air, which the developers at the University of Washington called PoWiFi (from Power Over WiFi).


At the testing stage, researchers were able to successfully charge small-capacity lithium-ion and nickel-metal hydride batteries. Using the Asus RT-AC68U router and several sensors located at a distance of 8.5 meters from it. These sensors just convert the energy of an electromagnetic wave into a direct current with a voltage from 1.8 to 2.4 volts, necessary for powering microcontrollers and sensor systems. The peculiarity of the technology is that the quality of the working signal does not deteriorate. Just reflash the router and you can use it as usual, plus supply power to low-power devices. At one of the demonstrations, a small covert surveillance camera with low resolution was successfully powered, located more than 5 meters from the router. Then 41% was charged fitness tracker Jawbone Up24, it took 2.5 hours.

Tricky questions about why these processes do not adversely affect the quality of the network communication channel, the developers responded that this is possible due to the fact that the flash router, during its operation, sends energy packets to the channels that are not transmitting information. They came to this decision when they discovered that during periods of silence energy simply flows out of the system, and in fact it can be sent to power low-power devices.

During the research, the PoWiFi system was placed in six houses, and they suggested that residents use the Internet as usual. Download web pages, watch streaming video, and then tell you what's changed. As a result, it turned out that network performance did not change at all. That is, the Internet worked as usual, and the presence of the added option was not noticeable. And these were only the first tests, when a relatively small amount of energy was collected over Wi-Fi .

In the future, the PoWiFi technology can fully serve to power the sensors built into home appliances and military equipment in order to control them wirelessly and carry out remote charging / recharging.

Energy transfer for UAVs is most relevant (most likely already using the PoWiMax technology or from the aircraft radar of the carrier):



→ LOCUST - Swarming Navy Drones
→ The Pentagon successfully tested a swarm of 103 UAVs
→ Intel ran a drone show during Lady Gaga's performance during the break in the US Super Bowl

For a UAV, the negative of the inverse square law (isotropic-emitting antenna) partially “compensates” for the antenna beam width and the radiation pattern:



After all, an airborne radar antenna in a pulse can emit an energy of EMR below 17 kW.

This is not a cellular connection — where a cell should provide 360 ​​degree endpoint connectivity.
Suppose this variation:
The aircraft carrier (for Perdix) this F-18 has (now) radar AN / APG-65:

maximum average radiated power of 12000 W

or in the future will have AN / APG-79 AESA:

in the impulse should produce under 15 kW of energy EMP

This is quite enough to prolong the active life of Perdix Micro-Drones from the current 20 minutes to an hour, and maybe more.

Most likely, the Perdix Middle drone will be used, which the radar of the fighter will radiate at a sufficient distance, and it in turn will “distribute” energy to the younger brothers Perdix Micro-Drones for PoWiFi / PoWiMax, simultaneously exchanging information with them (flight-pilot, targets, swarm coordination).

Maybe soon it will come to charging cell phones and other mobile devices that are in range of Wi-Fi, Wi-Max or 5G?

Afterword: 10-20 years, after the widespread introduction into the everyday life of numerous electromagnetic microwave emitters (Mobile phones, Microwave ovens, Computers, WiFi, Blu tools, etc.) suddenly cockroaches in big cities suddenly turned into a rarity! Now the cockroach is an insect that can be found only in the zoo. They suddenly disappeared from the houses that they had so loved before.


TARAKANI CARL!
These monsters, the leaders of the list of "radio-resistant organisms" shamelessly capitulated!
reference
LD 50 - the average lethal dose, that is, the dose kills half of the organisms in the experiment; An LD 100 - lethal dose kills all organisms in the experiment.

Who's next in line?

The permissible radiation levels of mobile base stations (900 and 1800 MHz, the cumulative level from all sources) in the sanitary-residential zone in some countries are noticeably different:
Ukraine: 2.5 µW / cm². (the toughest sanitary standard in Europe)
Russia, Hungary: 10 µW / cm².
Moscow: 2.0 mWW / cm². (the norm existed until the end of 2009)
USA, Scandinavian countries: 100 µW / cm².
Temporarily permissible level (VDU) of mobile radio telephones (MRI) for users of radio telephones in the Russian Federation is 10 mW / cm² (Section IV - Hygienic requirements for mobile radio stations SanPiN 2.1.8 / 2.2.4.1190-03 "Hygienic requirements for placement and operation land mobile radio communications ” ).
In the USA, the Certificate is issued by the Federal Communications Commission (FCC) for cellular devices, the maximum SAR level of which does not exceed 1.6 W / kg (and the absorbed radiation power is reduced to 1 gram of human organ tissue).
In Europe, according to the International Commission on Non-Ionizing Radiation Protection Directive (ICNIRP), the SAR value of a mobile phone should not exceed 2 W / kg (the absorbed radiation power is reduced to 10 grams of human tissue).
Relatively recently, a level of 10 W / kg was considered to be a safe SAR level in the UK. The same roughly picture was observed in other countries.
The maximum SAR value (1.6 W / kg) adopted in the standard cannot even be safely referred to as “hard” or “soft” norms.
The standards for determining the SAR value adopted in the USA and in Europe (all the rationing of microwave radiation from cell phones, which is referred to, is based only on the thermal effect, that is, associated with the heating of tissues of human organs).
FULL CHAOS.
Medicine has not yet given a clear answer to the question: is mobile / WiFi harmful and to what extent?
And what about the wireless power transmission of microwave technologies?
Here the power is not watts and miles watts, but already kW ...

Note: A typical WiMAX base station emits power at approximately +43 dBm (20 W), and a mobile station usually transmits to +23 dBm (200 mW).