MIKHAILOV, Andrei Borisovich (Telmana str, 52-160St.Petersburg, 2, 19313, RU)
POPOV, Aleksei Leonidovich (Vostochnaya str, 11-15Bzhedukhovskaya,Belorechensky raio, Krasnodarsy region 5, 32561, RU)
MIKHAILOV, Andrei Borisovich (Telmana str, 52-160St.Petersburg, 2, 19313, RU)
Claims
1. The tag for radio-frequency identification consists of body, identification microchip and microstrip antenna matched with it, including lower conducting layer and upper conducting layer. Identification microchip outputs are connected directly to lower and upper conducting layers. Identification microchip with complex impedance (10í30) - j(410í430) ohm is matched with complex impedance of microstrip antenna within the range 0,86í0,9 of its resonance frequency and tag operating range is 865í869,65 MHz. At that lower and upper conducting layers have air space between them and body comprises base and hollow cover trimmed in circumferential direction. Base has columns, lower conducting layer is fixed directly to the base, and upper conducting layer is fixed to the columns.
2. Tag according to Claim 1, characterized in that subjects, that lower and upper conducting layers are made of copper or its alloy and installed parallel, and identification microchip is installed between conducting layers. 3. Tag according to Claim 1,2, characterized in that subjects, that lower and upper conducting layers are implemented as copper plates 0,5 mm.
4. Tag according to Claim 1,2 characterized in that subjects, that lower conducting layer and upper conducting layer are fixed to the base and two cylindrical columns respectively by means of mounting elements. 5. Tag according to Claim 1,2 characterized in that subjects, that the base is made flat and the cover is implemented as tetrahedral pyramid of trapezoidal cross- section.
6. Tag according to Claim 1,2 characterized in that subjects, that lower conducting layer area is larger than the area of upper conducting layer. |
THE TAG FOR RADIO-FREQUENCY IDENTIFICATION Field of the Invention
The invention refers to radio engineering and is intended for radio-frequency identification of objects (goods, products, structures) of different purpose and receiving of information about them.
Prior Art
There is a tag for radio-frequency identification consisting of identification microchip and antenna connected to it, comprising two symmetrical plate elements (US N° 6,147,606 G08B 13/14, 2000). Imperfection of this device is that if it is installed on metallic surface reading distance will be decreased.
There is a device for radio-frequency identification of consisting of identification microchip and microstrip antenna connected to it, containing lower conducting layer, upper conducting layer and dielectric layer located between them (US JM° 6215402 G08B 13/14, 2001).
The construction of this device provides significant increase in directivity. Such tags are particulary intended for installation on metallic surfaces.
Imperfection of this device is overall size and necessity for additional matching circuit between microchip and antenna. In this case substrate of radio- frequency dielectric is used for installation of antenna and matching circuit. Additional matching circuit can contain both lumped elements and be implemented as sections of microstrip lines, which sophisticate tag construction and increase its size.
There is also a tag for radio-frequency identification of containing identification microchip and microstrip antenna matched with it, including lower conducting layer and upper conducting layer. Outputs of identification microchip are connected directly to the upper and lower conducting layers, identification microchip has complex impedance (10í30) - j(410í430) ohms, it is matched with complex impedance of microstrip antenna within the range of 0,86í0,9 of its resonance frequency and tag operating range makes up 865í869,65 MHz (RU Ns
62723,27.04.2007, prototype).
Imperfections of this device are weak protection of antenna from external action, low reliability of mounting of conducting layers in case of foamed dielectric use, necessity for use of dielectric layer increasing tag cost in case of high-quality radio-frequency dielectric use. Summary of the invention
Engineering problem is creation of effective tag for radio-frequency identification and extension of means of radio-frequency identification.
The result ensuring solving the set problem solving lies in providing of reliable protection of antenna from external action (in particular, from vandalism), improving of mounting of conducting layers reliability, admitting separation of conducting layers only with air, allowing exclusion of dielectric layer, increasing of stability of tag characteristics within a wide temperature range, decreasing of its cost.
The tag for radio-frequency identification consists of body, identification microchip and microstrip antenna matched with it, including lower conducting layer and upper conducting layer. Identification microchip outputs are connected directly to lower and upper conducting layers. Identification microchip with complex impedance (10í30) - j(410í430) ohm is matched with complex impedance of microstrip antenna within the range 0,86í0,9 of its resonance frequency and tag operating range makes up 865í869,65 MHz. At that lower and upper conducting layers have air space between them and body comprises base and hollow cover trimmed in circumferential direction. Base has columns, lower conducting layer is fixed directly to the base, and upper conducting layer is fixed to the columns.
In particular cases lower and upper conducting layers are made of copper or its alloy and installed parallel and identification microchip is installed between conducting layers, e.g. lower and upper conducting layers are implemented as copper plates 0,5 mm thick.
It is preferable that lower conducting layer and upper conducting layer are fixed to the base and two cylindrical columns respectively with mounting elements, base is flat, cover is implemented as tetrahedral pyramid of trapezoidal cross-section and lower conducting layer area is larger than the area of upper conducting layer.
Detailed Description of the Invention
Figure 1 shows tag for radio-frequency identification in section, figure 2 - tag with body cover removed, figure 3 - 3D view of tag in the body, figure 4 - diagram of dependency of return loss on frequency, figure 5 — diagram of dependency of antenna resistance and reactance on frequency.
The tag for radio-frequency identification consists of body, identification microchip 1 (e.g. Philips UCODE) and microstrip antenna matched with it, including lower conducting layer 2 and upper conducting layer 3. Identification microchip 1 outputs are connected directly to upper and lower conducting layers 2, 3. Identification microchip 1 has complex impedance within the range (10í30) - j(410í430) ohms and is matched with complex impedance of microstrip antenna within the range 0,86í0,9 of its resonance frequency. Tag operating range is 865í869,65 MHz. Lower and upper conducting layers 2, 3 are made of copper and installed with space between them. Body is implemented as the base 4 and hollow cover 5 trimmed in circumferential direction. The base 4 is implemented with columns 6, 7. The lower conducting layer 2 is fixed directly to the base 4 and upper conducting layer 3 is fixed to the columns 6, 7.
Lower and upper conducting layers 2, 3 are installed parallel, identification microchip is installed between conducting layers. Lower and upper conducting layers 2, 3 are implemented as copper plates 0,5 mm thick.
Lower conducting layer 2 and upper conducting layer 3 are fixed to the base 4 and two cylindrical columns 6, 7 respectively with mounting elements 8.
The base 4 is made flat and the cover 5 is implemented as tetrahedral pyramid of trapezoidal cross-section.
Lower conducting layer 2 area is larger than the area of upper conducting layer 3.
The base 4 is implemented with openings 9 for mounting on identified object (not illustrated), located outside perimeter trimmed with the cover 5. Identification microchip 1 connected directly to tag antenna (layers 2, 3) has complex impedance within the range Zj 0 =(10í30) - j(410í430) ohm, consisting of
resistance Rj c and reactance Xj c . Matching and maximum effective transfer of power from antenna to identification microchip 1 are reached provided that complex impedance of identification microchip Zj c and antenna Z A are complex conjugated
Z ic = Z* A (figure 5). Range of matching frequency 0,86í0,9 of resonance frequency is determined experimentally. Matching frequency range of tag antenna with identification microchip 1 is limited by frequencies where return loss does not exceed -20 dB, this conforms to current conditions of tag use (figure 4).
Range of matching on return loss level no more than -20 dB lies within the range 846í886 MHz, that makes up 0,86í0,9 of resonance frequency if antenna resonance frequency is 982 MHz. Tag operating band lies within the matching range and return loss within tag operating band does not exceed -33 dB.
When identification microchip impedance is changed within the range
Zi c =(10í30) - j(410í430), return loss within the range 0,86í0,9 of resonance frequency will not exceed -20 dB, thus frequency band of integrated circuit matching having complex impedance within the range Zj c =(10í30) - j(410í430) with antenna impedance on return loss level -20 dB makes up 0,86í0,9 of resonance frequency.
The given tag is intended for frequency band 865í869,65 MHz, specified by European standards ETSI EN 300-220, ETSI EN 302-208.
Figure 4 shows dependency of return loss on frequency. Thus return loss value is laid off Y-direction on a logarithmic scale.
Figure 5 shows dependency of real and imaginary part of antenna complex impedance on frequency relative to point of connection of integrated circuit. Thus values Ra as active part and Xa as reactive part of antenna complex impedance are laid off Y-direction and expressed in ohms.
Dimension of tag in body: length 182 mm, width 25 mm, height 17 mm. The tag operates as follows.
For identification of objects with metallic surfaces the concerned party, e.g. product manufacturer or trade organization, provides each object (goods, product,
structure etc.) with tag of radio-frequency identification during its production, handing over to trade organization or its selling.
Microstrip antenna (layers 2, 3) provides receiving of signal from external readout device and reverse transfer of individual information which is contained in identification microchip within the range of 10 m if using reader with power 2 W and antenna with circular polarization and 8 dBi gain connected to it. When being outside the limit of matching range readout distance is decreased more than two times. This fact does not allow using of tag in modern identification systems.
If real and imaginary part of identification microchip complex impedance is changed within the specified range, return loss will not exceed -20 dB. In view of matching deterioration, when being outside the specified interval return loss exceeds -20 dB. This fact also does not allow using of tag in modern identification systems.
The cover 5 and base 4 provide reliable protection of antenna from external action (in particular, from vandalism). The openings 9 provide reliable mounting of tag on an object. The columns 6, 7 and mounting elements 8 provide reliability of fixing of conducting layers 2, 3 and allow separation of conducting layers 2, 3 only with air. This allows exclusion of dielectric layer, increasing stability of tag characteristics within a wide temperature range, decreasing its cost.
Industrial Applications The given invention is implemented by means of universal equipment widely spread in mechanical engineering for production of radio engineering equipment and facilities of automatic control and inspection.
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