Applications of the microwires

Codification method using bistable magnetic microwires.

One of the applications is based on wide range of coercivity obtained in microwires. It was realized in the method of magnetic codification using magnetic tags. The tag contains several microwires with well-defined coercivities, all of them characterized by a rectangular hysteresis loop. Once the magnetic tag submitted to the AC magnetic field, each particular microwire remagnetizes at different magnetic field giving rise to an electrical signal on a detecting system [1]. The extended range of switching fields obtained in Fe-rich microwires gives a possibility to use a big number of combinations for magnetic codification.

This method is basically related with such magnetic characteristics of the material as the amplitude of the voltage pulse at remagnetization and the voltage pulse duration (sec). In order to achieve good sensibility and easy detection, it has to have a large amplitude and short duration. Nevertheless, switching field fluctuations can deteriorate large number of encoding combinations because of the overlapping of the switching field values.

The other problem related with the identification of the goods is an effect of the spatial orientation of the marker. Such problem can be resolved by the introduction of the marker of reference, but remagnetization process of the single wires under the different applied magnetic field orientation should be studied.

[1]V. Larin, A. Torcunov, S. Baranov, M. Vázquez, A. Zhukov and A. Hernando, Method of magnetic codification and marking of the objects, Patent (Spain) No P 9601993 (1996).

Absorbing at RF and shielding materials and products.

Physical origins of the microwires applications for the shielding

      

During incidence of electromagnetic wave on the interface of two media the part of electromagnetic wave is reflected from the surface, another part penetrates and is extended inside another medium, the third interacts with the medium and is absorbed (it is converted in heat-).The value of shielding according to the power can be expressed through the shielding constant KS, which can be written down in the form:

Ks = Pr/Ps (1)

Where:Pr- the power of the incident wave;Ps.the power of the transmitted wave. Since electromagnetic wave contains electrical and magnetic component, interaction of electromagnetic wave and medium can have electrical nature, the case of conducting or dielectric medium, and also magnetic nature, in the case of the medium, whose magnetic permeability is more than 1. Glass coated microwire from different alloys have the high magnetic permeability in the region of frequencies up to 12 GHz.

On the basis of the theoretical conclusions and calculations for the effective shielding from the electromagnetic radiation in different cases the shielding of different constructions/designs can be used for example:

1. For the shielding of the objects, inside which it is not located the sources of electromagnetic radiation, constructions/designs and devices, which require protection from the external sources of electromagnetic radiation, it is expedient to use the shielding reflectors containing microwire from the conducting materials (copper, silver, alloys on their basis). Depending on the type of the shielded object the shielding can be flexible and elastic, for example the tissues, containing microwire; rigid plastic, polymeric, glass or paper articles.
2. For the shielding of the everyday and working rooms, in which besides protection from the external radiation sources is required the suppression of electromagnetic radiation and re-emission of internal radiation source reasonable to use reflecting- absorbing shielding, which contain microwire with high impedance at the operating frequencies of source. For example, in the rooms, where works the powerful HF source of emission it is reasonable to use the materials, which contain the microwire, which has the resonance frequency of the absorption of the working source.
3. For the shielding of human (service personnel) working in the conditions of the increased level of electromagnetic radiation it is reasonable to use the reflecting- absorbing multilayer electromagnetic screens, whose outer layer reflects the incident electromagnetic wave, and the internal absorbs the past and the re-reflection waves.
   

Radio masking products

Radio masking flexible, volumetric coating is destinated for radio and optical (visual) masking of stationary targets. Article is the volumetric woven net, prepared from the high-strength synthetic threads, which contain microwire and possessing the radar transmitter properties. Net is made from the incombustible materials and can be colored. Technical specifications:

• Damping level with the reflection of the incident electromagnetic wave is not less than 20 dB in the arbitrary polarization and the direction in the range of frequencies from 0,8 to 12 GHz.
• Range of operating temperatures from minus 60 to + 100 °S.
• Mass 1 m2 not more than 5 kg.
• Materials used in the article are not combustible and do not separate/liberate toxic substances at high temperatures.
• Product stably from the mashing possesses the water-repellent properties.
• Product can be prepared any color on the demand of customer.(from the white to the black). The dimensions of product are determined by customer. On the perimeter the product is supplied with the high-strength cord, which makes it possible to fasten it on the object.

Shielding tissues and non-woven materials at radio frequencies.

Modern telecomuncations, radio-electronic devices, household and industrial electronic and electrical devices create powerful electromagnetic radiation over a wide range of frequencies. This emission in many instances negatively affects the vitally important human organs, creates interferences for the work of electronic devices and instruments and of computer systems.The standards, which limit the level of electromagnetic fields in the working and public rooms, limitations in the retention time of people in the zone of the increased electromagnetic radiations, are introduced in many countries. Requirements on the level of the spurious radiation of instruments and devices are also introduced. During the construction of radio-electronic devices the tasks in the guarantee of external and internal electromagnetic compatability appear. Tissues from the shielding materials are intended for the shielding of the electromagnetic radiation:

• weakening the level of electromagnetic radiation in the habitable and working rooms;
• the protection of people, which work in vicinity of the sources of electromagnetic radiation;
• improvement in the electromagnetic compatability of electronic devices and devices.

Tissue shielding represents tissues consisting of the natural or synthetic threads, which contain glass-coated microwire. Consumer properties of such tissue does not differ from the usual, that not containing microwire. Level of shielding in the range 0, 8- 24 GHz is at least 30 dB.

Sensors and actuators

Pressure transducers

Pressure transducers are based on the use stress effect and are intended for measuring the alternal and static pressures of media with the temperature from minus 196 to + 450 °S in reservoirs and tubes of different diameter. Main parameters of the transducers:

• the range of the measurements of pressures (MPa) by 0,4; 0,6; 1,0; 1,6; 2,5; 4; 6; 10; 16; 25; 40; 100; 160; 250; 400
• accuracy (% from the range of output signal) 0,16; 0,25; 0,4
• the temperature range of the measured medium from - 196 to + 450° C
• the temperature range of environment from minus 40 to 80 °C
• output signal
  • 0 - 5 v
  • 0 - 5 mA
  • 4 - 20 mA
• the voltage of supply (direct current) is
  • 12 v
  • ±12 v
• the output resistance of sensor 600 Ohm
• additional temperature error is not more than 0,05%/10 °C
• the natural frequency of converter, depending on the range of measurement by 0,08-10 kHz

Transducer consists of the sensor and electronic component. Sensor is connected with the block by the sectional or nondetachable cable with a length of from 0,6 to 2,5 m. Transducer is characterized by the absence of the membrane, increased reliability and possibility of measuring the pressure in the tube without a change in the form of tube and speed of flow.

Coaxial microwire

Coaxial microwire is glass coated microwire having continuous metallic coating outside.The thickness of coating composes 0,1-1 m, resistance to 5-50 k , the material of coating : Au, Pt, AG.

Micro-cable, which consists of several coaxial and usual microwires of the glass or varnish isolation.Fields of application:

• small high-frequency communication lines for the intra-computer application;
• the matched high-frequency communication lines for the intra-modular compounds and the connections inside the integrated SHF circuits.
• microelectrodes for the output of the potentials of living tissues and cells.

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