The energy of the electromagnetic field

Action DC sources, which are described below, based on the use of so-called free energy all the way , i.e. the energy of radio waves strong local radio station. Such sources can be powered transistor radios (1 ... 3 transistors). It was held this experience. Far from the city at a height of 4 m suspended wire antenna length of about 30 m. 9 ohm load was isolated DC power of 0.9 mW. When the transmitter power of 1 kW and an operating frequency of 1.6 MHz is located about 2.5 km. At times the filter capacitor (idling) were recorded voltage of about 5 V. These results are obtained only with a large antenna aimed at the transmitter.

In practice are used other more effective schemes. There are three ways to power the receiver from the rectified voltage tion HF radio. The first is that the receiving station is carried out on two antennas. Radio signals received by the second antenna is converted into direct current, which is used to power the receiver. Another method uses a single antenna and a part of captured its energy diverted to the converter circuit. In the latter method uses two antennas: one antenna - the reception who listen to the radio, and the second receives another radio station, which are converted into voltage.

In any case, the minimum RF power voltage required for operation of the receiver is equal to 50 mW. It is only enough to odnotranzistornyh receivers (or transmitters).If necessary receiver our current (eg, 1 mA at a voltage of 3V), then the required power RF voltage increases to 3 mW, and the value to be taken as an average. The fact that at a distance of 20 ... 30 km from the station "Warsaw II» (818 kHz), you can still get a little power rectified current of about 9 mW, indicates the prospects of such experiments.

The simplest wireless radio receiving circuit shown in Fig. 6.3 a-c. It can take a local radio station, for example, the same "Warsaw II» and simultaneously use its energy to convert to emf DC. To receive radio waves with a frequency above 50 MHz, ie. E. VHF transmitter signals (eg, television), the RF voltage converter must have a special dish - folded dipole (dipole) . This antenna can simultaneously operate both in the medium range of the receiver, and the power supply. If the energy of a single vibrator is insufficient, then the multiple antennas of this type (Fig. 6.3, d) connected in series (to increase voltage or in parallel (to increase the current).

With the antenna shown in Fig. 6.3 d, catch ing the energy of radio waves 50-kW transmitter operating in the range of 50 ... 250 MHz, received DC power about 3 mW.The antenna was located at a distance of 1.5 km from the transmitter. Fig. 6.3, and e is a diagram of a receiver with two antennas, one of which (VHF) power supply is used. Medium-receiver can operate with any antenna, while the power supply to the energy must come from the high frequency oscillations of the dipole antenna. In switch position 1, the device acts as B1 switch actuated nym modulated RF signal, in position 2 as a receiver.

An interesting example of the use of radio wave energy to power the radio can serve as a circuit shown in Fig. 6.3 g. This beacon (land, river or sea), which included a signal transmitter mounted on a motor vehicle, boat, aircraft or glider. Request signal trigger transmitter buoy, response signals which are used for the definition of its location. Signal devices of this type make it easy to search for people lost in the sea, the mountains, dense forests, etc. They are part of the equipment of tourists and alpinistov.Umeloe energy use radio waves enable apparently significantly reduce the size of hearing aids, receiver, remote control devices , toys, etc.

It should, however, say that experiments have shown that results when the receiver power from the rectified RF voltage can be achieved only by using only carefully tuned antenna zazemlenie.Drugoy drawback is that the value of the rectified voltage depends on the depth of modulation of the carrier frequency during the reception . It works best receiver circuit is shown in Figure 6.3, which was rectified RF voltage received radiostan of the miniature is used to recharge nickel-cadmium batteries at a time when the receiver is not working. At a distance of 20 km from the station "Warsaw 1" and the length of the external antenna receiver 40 m current battery charge voltage of 2.5 V is 5 mA. This almost makes up for charging electricity consumption during the hour-long operation of the receiver.

The electromagnetic field energy source
Fig. 6.3. Power radio energy of the electromagnetic field: a ... c- receiver for receiving transmissions in the range of powerful radio stations AM; g - in the receiver with a rectifier, a rechargeable battery (The switch is shown in the position of "charge"); d - a set of FM antennas, feeder straightener: e -receiver switch; f - automatic buoy lighthouse.