CN102509893B - Equated symmetrical type open-circuit coaxial antenna - Google Patents
Equated symmetrical type open-circuit coaxial antenna Download PDFInfo
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- CN102509893B CN102509893B CN201110347270.6A CN201110347270A CN102509893B CN 102509893 B CN102509893 B CN 102509893B CN 201110347270 A CN201110347270 A CN 201110347270A CN 102509893 B CN102509893 B CN 102509893B
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Abstract
The invention discloses an equated symmetrical type open-circuit coaxial antenna, which is applied on the radio frequency identification technical field. The equated symmetrical type open-circuit coaxial antenna comprises a receiving unit and a power feeding unit, wherein the receiving unit uses an equated coaxial cable structure, the total distribution capacitance of the coaxial cable is decomposed into a plurality of segmentary distributed capacitances in serial connection, thus the total distribution capacitance is reduced, the resonance frequency of a coil is increased and the perimeter limit of the coaxial cable open-circuit antenna is broken, therefore the antenna covers larger ranges and farther reading distance; the power feeding unit feeds the power for the receiving unit in a not-balanced way; the antenna is completely symmetrical relative to the reference position, so as to not only completely suppressing the common mode interference but also transit the not balanced feed structure to the balanced antenna. The equated symmetrical type open-circuit coaxial antenna is applied in the long-distance high frequency radio frequency identification system, so as to effectively improve the system performance and reduce the system cost.
Description
Technical field
The present invention relates to REID field, relate in particular to a kind of Equated symmetrical type open-circuit coaxial antenna.
Background technology
In intelligent book shop, Meeting Signature, motion timing, access control and attendance, jewelry management, in the thing network sensing layer technology of the applications such as concerning security matters asset management, the long thing network sensing layer technology that is considered to tool prospect apart from high-frequency radio frequency recognition technology, here high frequency refers to the frequency range of 3MHz to 30MHz, the electromagnetic wave of this frequency range wavelength is in a vacuum 10 to 100 meters, in this frequency range, REID is chosen 13.56MHz or the 6.78MHz centre carrier frequency as radio frequency transceiver conventionally, in this frequency range, all tag read distance are greater than the REID of 20 centimetres and all can be regarded as long apart from high-frequency radio frequency recognition technology, at present, the long air interface protocol apart from high-frequency radio frequency recognition technology that had in the world the standard definition such as ISO 15693, ISO 18000-3, IPX.
Length comprises reader and radio-frequency (RF) tag conventionally apart from high-frequency radio frequency recognition system, utilizes mode transferring energy and the data of inductance coupling high between reader and radio-frequency (RF) tag.In general, reader antenna and label antenna are coil form, and according to Faraday's electromagnetic induction law, the caused magnetic flux change of the curent change of one of them coil can form induced electromotive force on another coil.Based on this principle, between two slave antennas, carry out Energy Transfer and exchanges data.Whole length apart from radio frequency system in, reader antenna directly affects outward appearance and the performance of whole system.
For reaching best reading performance, coiling is grown up should possess high Q value, low-resistance characteristic apart from the cable of high frequency reader antenna.For reducing costs, most long coaxial cables that all adopt 75 ohm or 50 ohm apart from high frequency reader antenna.Because the skin depth of copper cash when the 13.56MHz only has 18 microns, therefore directly utilize the screen of coaxial cable as current path, can reach the resistance characteristic similar to single core Stranded cable of same diameter; Wherein, two kinds of modes can realize this type of reader antenna, are respectively short circuit type and open ended.The feed of short circuit type antenna is added in respectively the two ends of coaxial cable shielding layer disconnection mouth, simultaneously at disconnected opening part shunt capacitance, forms resonant tank with the inductance, and receiver voltage is drawn from the two ends that disconnect mouth, and two ends are short circuit with respect to direct current; The feed of open ended antenna is added in respectively coaxial cable shielding layer and disconnects one end of mouth and one end of coaxial cable inner core conductor disconnection mouth, distributed nature electric capacity between screen and interior core conductor forms resonant tank as a part and the coil inductance of total capacitance, receiver voltage is load resistance both end voltage, and two ends are open circuit with respect to direct current.Because the impact of the receiver voltage at the shunt capacitance two ends of the electric interfering field in space on short circuit type antenna, the impact of the receiver voltage at comparison open ended antenna load resistance two ends is much bigger, so generally use open ended antenna as the long antenna apart from high-frequency radio frequency recognition system.
But traditional open ended antenna structure has larger total distributed capacitance.This has limited the overall circumference of antenna, has also limited read range and the maximum read distance of antenna; Therefore, in the application of existing Meeting Signature or access control and attendance passage, the width of passage is generally no more than 1.2 meters, in the application such as intelligent book shop or intelligent commodity shelf, conventionally needs multiple antenna to cover a bookshelf or shelf, has greatly increased installation cost.
Summary of the invention
For above-mentioned technical problem, the object of the present invention is to provide a kind of Equated symmetrical type open-circuit coaxial antenna, its total distributed capacitance by coaxial cable resolves into the segmentation distributed capacitance of multiple series connection, reduce total distributed capacitance, improve the resonance frequency of coil, break through the girth restriction of coaxial cable open antenna, made the scope that described antenna cover is larger and reach the farther distance that reads; And the structure of antenna, with respect to reference to ground full symmetric, can fully suppress common mode disturbances, unbalanced feeder line structure is transitioned into the structure of the antenna of balance.
For achieving the above object, the present invention is achieved through the following technical solutions:
A kind of Equated symmetrical type open-circuit coaxial antenna, comprise receiving element and feed element, described receiving element is used for receiving field signal, wherein, described receiving element has reduced the total distributed capacitance that forms the coaxial coil of antenna, breaks through the girth restriction of coaxial cable open ended antenna; Described feed element is receiving element feed by uneven mode.
Especially, described coaxial coil is made up of coaxial cable, described coaxial cable comprise screen, interior core conductor and be arranged at screen and interior core conductor between insulating barrier.
Especially, the head and the tail of described coaxial cable connect, and described interior core conductor starts to be evenly provided with several nodes from one end of cable, and interior core conductor disconnects from Nodes.
Especially, described screen arranges node in the centre position of adjacent two nodes of interior core conductor, and screen disconnects from Nodes.
Especially, described interior core conductor gap, screen is connected, described screen gap, interior core conductor is connected.
Especially, described feed element comprises feeder line, and described feeder line is receiving element feed by uneven mode.
Especially, the Nodes of described interior core conductor all can be used as feed placement, and described feeder line comprises the screen of feeder line inner core and feeder line, and described feeder line inner core is connected with one end of interior core conductor gap, and the screen of described feeder line is connected with the screen of coaxial cable.
Especially, the structure of described antenna is with respect to reference to ground full symmetric.
Beneficial effect of the present invention, adopt technical scheme of the present invention by the coaxial cable structure of decile, the total distributed capacitance of coaxial cable is resolved into the segmentation distributed capacitance of multiple series connection, reduce total distributed capacitance, thereby improve the resonance frequency of coil, break through the girth restriction of coaxial cable open antenna, made the scope that described antenna cover is larger and reach the farther distance that reads; And the structure of antenna of the present invention is with respect to reference ground full symmetric, can fully suppress common mode disturbances, unbalanced feeder line structure is transitioned into the structure of the antenna of balance, be applied to long apart from high-frequency radio frequency recognition system, can effectively improve systematic function, reduce system cost.
Brief description of the drawings
According to drawings and embodiments the present invention is described in further detail below.
Fig. 1 is the schematic diagram of Equated symmetrical type open-circuit coaxial antenna of the present invention;
Fig. 2 is the schematic diagram of uneven mode feed in the present invention;
Fig. 3 is the structural representation of coaxial cable;
Fig. 4 is equivalent serial resonant circuit diagram illustraton of model of the present invention;
Fig. 5 is the schematic diagram of short circuit type coaxial antenna;
Fig. 6 is the schematic diagram of open ended coaxial antenna;
Fig. 7 is the transmission-line equivalent circuit schematic diagram of coaxial cable;
In figure: 101, interior core conductor; 102, insulating barrier; 103, screen; 104, plastic peel; 105, feeder line inner core; 106, the screen of feeder line.
Embodiment
The technology of the present invention principle: please refer to shown in Fig. 5, Fig. 5 is the schematic diagram of short circuit type coaxial antenna, interior core conductor 101 and the screen 103 of coaxial cable are only drawn, the feed of short circuit type antenna is added in respectively the two ends of coaxial cable shielding layer 103 disconnection mouths, simultaneously at disconnected opening part shunt capacitance, form resonant tank with the inductance, receiver voltage is drawn from the two ends that disconnect mouth, and two ends are short circuit with respect to direct current.
Fig. 6 is the schematic diagram of open ended coaxial antenna, interior core conductor 101 and the screen 103 of coaxial cable are only drawn, the feed of open ended antenna is added in respectively coaxial cable shielding layer 103 and disconnects one end of mouth and one end of coaxial cable inner core conductor 101 disconnection mouths, distributed nature electric capacity between screen 103 and interior core conductor 101 forms resonant tank as a part and the coil inductance of total capacitance, receiver voltage is load resistance both end voltage, and two ends are open circuit with respect to direct current.
Fig. 7 is the transmission-line equivalent circuit schematic diagram of coaxial cable, and it comprises distributed series resistance, inductance, and distributed shunt conductance, electric capacity.
In transmission-line equivalent circuit schematic diagram by coaxial cable, can find out, have distributed series inductance and shunt capacitance on coaxial cable, the series inductance of every meter of length can be by
estimation, wherein D is screen external diameter, d is inner core conductor diameter.μ
0and μ
rbe respectively the magnetic permeability of permeability of vacuum and insulating barrier.The shunt capacitance of every meter of length can be by
estimation, wherein ε
0and ε
rbe respectively dielectric constant in vacuum and the medium dielectric constant of insulating barrier.Every meter of length series inductance of most of coaxial cables is less than 0.5 microhenry, can ignore with respect to the inductance value that turns to coil with it.Conventionally, the distributed shunt capacitance of 50 ohm coaxial cable is about every meter of 96 pico farad; The distributed shunt capacitance of 75 ohm coaxial cable is about every meter of 64 pico farad.With the total capacitance of open ended coaxial antenna be the distributed shunt capacitance and the external shunt capacitance sum of mating in total cable length, therefore the minimum value of the total capacitance of this antenna can be considered as the distributed capacitor in total cable length, again because the one-turn coil that the coiled coaxial cable of regular length becomes to compare multi-turn coil inductance little, so the minimum value of the total inductance of this antenna such as can be regarded as at the inductance value of the annulus that the wire of the wire diameters such as girth is coiled into.The maximum resonance frequency that can further obtain thus open ended coaxial antenna is:
the individual pen open ended antenna that a for example pair is coiled into by the 2 meters long coaxial cables of 75 ohm, its minimum capacity is 128 pico farads, maximum resonance frequency is about 10.4MHz.This antenna cannot be supported the operating frequency of 13.56MHz, must reduce the length of cable, reduces electric capacity, could improve its resonance frequency.
In 13.56MHz frequency, adopt coaxial cable maximum can only make the open ended antenna of 0.4 meter long, 0.4 meter wide, the read range of high frequency antenna is no more than 1.5 times of its size conventionally, and above-mentioned like this antenna only can read in 0.6 meter long, the 0.6 meter label in wide scope.
The present invention is on the basis of open ended circuit, the separation structures such as coaxial cable employing, the total distributed capacitance of coaxial cable is resolved into the segmentation distributed capacitance of multiple series connection, total distributed formula electric capacity greatly reduces, and the scope of antenna read signal is no longer subject to the restriction of antenna circumference.
Below in conjunction with drawings and Examples, the invention will be further described.
In the present embodiment, a kind of Equated symmetrical type open-circuit coaxial antenna, it comprises receiving element and feed element, described receiving element is made up of coaxial cable; Described feed element is made up of feeder line, and described feeder line comprises the screen 106 of feeder line inner core 105 and feeder line.
As shown in figures 1 and 3, the schematic diagram that Fig. 1 is Equated symmetrical type open-circuit coaxial antenna of the present invention, has only drawn interior core conductor 101 and the screen 103 of coaxial cable, the structural representation that Fig. 3 is coaxial cable in figure; Described coaxial cable is the coaxial cable structure of decile, and it comprises screen 103, interior core conductor 101, is arranged at the insulating barrier 102 between screen 103 and interior core conductor 101 and is arranged at the outermost plastic peel 104 of coaxial cable; The head and the tail of described coaxial cable connect, in it, core conductor 101 starts interval suitably apart from being evenly provided with N node from one end of cable, be labeled as respectively the the 1st, 3,5 ..., a 2N-1 node, and interior core conductor disconnects from Nodes, and screen 103 is connection status.
Described screen 103 is provided with node in the centre position of adjacent two nodes of interior core conductor 101, and nodes is also N, be labeled as respectively the the 2nd, 4,6 ..., a 2N node, screen 103 is from Nodes disconnection, and interior core conductor 101 is connection status.
As shown in Figure 2, Fig. 2 is the schematic diagram of uneven mode feed in the present invention; Described interior core conductor 101 the the 1st, 3,5 ..., a 2N-1 Nodes all can be used as feed placement, described feeder line inner core 105 is connected with one end of interior core conductor gap, the screen 106 of described feeder line is connected with the screen 103 of coaxial cable; The structure of antenna of the present invention is with respect to reference ground full symmetric, not only can fully suppress common mode disturbances, and the structure of described antenna is transitioned into uneven feeder line structure the structure of the antenna of balance, do not need before feeder line enters the structure of antenna, to add Ba Lun as short circuit type antenna, just can complete conversion between Balanced or unbalanced and mate.
Ignore the impact of distributed resistance and distributed inductance, the Equated symmetrical type open-circuit coaxial antenna of uneven mode feed can equivalence become series resonant circuit model as shown in Figure 4, wherein C
m, n, m, n ∈ [1,2N] represents the total distributed capacitance of the coaxial cable between m and n node.L represents overall coil inductance.The total distributed formula electric capacity that can find out decile symmetrical expression coaxial coil only has coaxial coil before decile
be similar to and think that coil inductance is directly proportional to coil girth, the girth that reaches the symmetrical open-circuit coaxial antenna of the 2N decile of same resonance frequency is 2N times of the front open circuit of decile coaxial antenna, scope by antenna read signal is directly proportional to antenna circumference, so Equated symmetrical type open-circuit coaxial antenna have larger read range and a farther distance that reads.Except circle, Equated symmetrical type open-circuit coaxial antenna also can be coiled into the profiles such as square, triangle, only needs to ensure symmetrical with respect to ground reference planes; Coil can be individual pen, also can optionally be coiled into multi-turn.
The coaxial open antenna of described decile symmetrical expression adopts the coaxial cable structure of decile, the total distributed capacitance of coaxial cable is resolved into the segmentation distributed capacitance of multiple series connection, reduce total distributed capacitance, thereby improve the resonance frequency of coil, break through the girth restriction of coaxial cable open ended antenna, made the scope that described antenna cover is larger and reach the farther distance that reads; And the structure of antenna of the present invention is with respect to reference ground full symmetric, can fully suppress common mode disturbances, unbalanced feeder line structure is transitioned into the structure of the antenna of balance, be applied to long apart from high-frequency radio frequency recognition system, improve systematic function, reduce system cost.
Above are only preferred embodiment of the present invention and institute's application technology principle, any be familiar with those skilled in the art the present invention disclose technical scope in, the variation that can expect easily or replacement, all should be encompassed in protection scope of the present invention in.
Claims (4)
1. an Equated symmetrical type open-circuit coaxial antenna, comprise receiving element and feed element, described receiving element is used for receiving field signal, it is characterized in that, described receiving element has reduced the total distributed capacitance that forms the coaxial coil of antenna, breaks through the girth restriction of coaxial cable open ended antenna; Described feed element is used in uneven mode as receiving element feed; Described coaxial coil is made up of coaxial cable, described coaxial cable comprise screen, interior core conductor and be arranged at screen and interior core conductor between insulating barrier; The head and the tail of described coaxial cable connect, and described interior core conductor starts to be evenly provided with several nodes from one end of cable, and interior core conductor disconnects from Nodes; Described screen arranges node in the centre position of adjacent two nodes of interior core conductor, and screen disconnects from Nodes; Described interior core conductor gap, screen is connected, described screen gap, interior core conductor is connected.
2. Equated symmetrical type open-circuit coaxial antenna according to claim 1, is characterized in that, described feed element comprises feeder line, and described feeder line is receiving element feed by uneven mode.
3. Equated symmetrical type open-circuit coaxial antenna according to claim 2, it is characterized in that, the Nodes of described interior core conductor all can be used as feed placement, described feeder line comprises the screen of feeder line inner core and feeder line, described feeder line inner core is connected with one end of interior core conductor gap, and the screen of described feeder line is connected with the screen of coaxial cable.
4. according to the Equated symmetrical type open-circuit coaxial antenna one of claims 1 to 3 Suo Shu, it is characterized in that, the structure of described antenna is with respect to reference ground full symmetric.
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| CN201110347270.6A CN102509893B (en) | 2011-11-04 | 2011-11-04 | Equated symmetrical type open-circuit coaxial antenna |
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| CN201110347270.6A CN102509893B (en) | 2011-11-04 | 2011-11-04 | Equated symmetrical type open-circuit coaxial antenna |
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| CN103855459A (en) * | 2012-11-29 | 2014-06-11 | 细美事有限公司 | Plasma antenna and apparatus for generating plasma having the same |
| US10181656B2 (en) * | 2013-10-21 | 2019-01-15 | Commscope Technologies Llc | Antenna detection with non-volatile memory powered by DC over coaxial cable |
| CN105162477B (en) * | 2015-09-30 | 2018-06-12 | 北京交大思诺科技股份有限公司 | A kind of transponder for extending sphere of action |
| CA3017199A1 (en) * | 2016-03-09 | 2017-09-14 | Peerbridge Health, Inc. | System and method for monitoring conditions of a subject based on wireless sensor data |
| WO2018077679A1 (en) * | 2016-10-24 | 2018-05-03 | Koninklijke Philips N.V. | A balun for use in magnetic resonance imaging (mri) systems and an mri system that employs the balun |
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| DE19540880A1 (en) * | 1995-11-02 | 1997-05-07 | Willi Ollenik | Shortened closed loop antenna using coaxial trap principle |
| US6636040B1 (en) * | 1999-12-17 | 2003-10-21 | Fonar Corporation | MRI antenna |
| US6847210B1 (en) * | 1999-12-17 | 2005-01-25 | Fonar Corporation | MRI antenna |
| US7091919B2 (en) * | 2003-12-30 | 2006-08-15 | Spx Corporation | Apparatus and method to increase apparent resonant slot length in a slotted coaxial antenna |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19540880A1 (en) * | 1995-11-02 | 1997-05-07 | Willi Ollenik | Shortened closed loop antenna using coaxial trap principle |
| US6636040B1 (en) * | 1999-12-17 | 2003-10-21 | Fonar Corporation | MRI antenna |
| US6847210B1 (en) * | 1999-12-17 | 2005-01-25 | Fonar Corporation | MRI antenna |
| US7091919B2 (en) * | 2003-12-30 | 2006-08-15 | Spx Corporation | Apparatus and method to increase apparent resonant slot length in a slotted coaxial antenna |
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Effective date of registration: 20190411 Address after: 230061 North Village, Amber Villa, No. 6 Changjiang West Road, Shushan District, Hefei City, Anhui Province, 107 Patentee after: Wang Xinhua Address before: 214135 Block D, Cetacea, Building 1, Phase III, National Software Park, North Research Road, Linghu Avenue, New District, Wuxi City, Jiangsu Province (Bee Dance Technology) Co-patentee before: Wang Xinhua Patentee before: Yan Li |
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Effective date of registration: 20210106 Address after: Room 114-1, 1st floor, area a, building 34, No. 58, Baozhen South Road, Chongming District, Shanghai 202150 (Shanghai Baozhen economic community) Patentee after: SHANGHAI FENGZHIWU ELECTRONICS Co.,Ltd. Address before: 230061 North Village, Amber Villa, No. 6 Changjiang West Road, Shushan District, Hefei City, Anhui Province, 107 Patentee before: Wang Xinhua |
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