CN114665259B - Ultra-wideband tag antenna suitable for metal-liquid mutual coupling environment - Google Patents
Ultra-wideband tag antenna suitable for metal-liquid mutual coupling environment Download PDFInfo
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- CN114665259B CN114665259B CN202210396470.9A CN202210396470A CN114665259B CN 114665259 B CN114665259 B CN 114665259B CN 202210396470 A CN202210396470 A CN 202210396470A CN 114665259 B CN114665259 B CN 114665259B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
- H01Q1/2225—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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Abstract
The invention relates to an ultra-wideband tag antenna suitable for a metal-liquid mutual coupling environment, and belongs to the technical field of radio frequency identification electronic tags. Comprises an antenna conductor structure and a tag chip; the antenna conductor structure is a plane structure formed by a bent double-L-shaped arm, a double-T matching network and a central spiral dipole, and is a symmetrical dipole-like structure; the double-T matching network comprises a first upper feeder line, a first lower feeder line, a second upper feeder line and a second lower feeder line; the bent double-L-shaped arm comprises a feeder line first connecting feeder line, a left arm outer feeder line and a right arm outer feeder line; the center helical dipole includes a second connection feed line, a left-arm inner feed line, and a right-arm inner feed line. The invention has the bandwidth of-3 dB of 550MHz-1300MHz in free environment, realizes the coverage of 840-960MHz ultra-high frequency band, and has the input impedance of 11-j143 omega in the working frequency of 915 MHz; the return loss at 915MHz was-47.3 dB.
Description
Technical Field
The invention belongs to the technical field of radio frequency identification, and particularly relates to a tag antenna which works in an ultra-high frequency band and is suitable for metal, liquid and mutual coupling environments.
Background
Compared with the traditional bar code technology, the Radio Frequency Identification (RFID) system based on the electromagnetic wave backscattering principle has the advantages of long identification distance, high reading speed, no requirement of 'visualization' condition in the identification process, manual participation and the like, and the greatest advantage is that the RFID tag has a repeated reading and writing function, the chip has strong data accommodating capability, and the defects of 'visualization', short distance and the like in the traditional identification technology can be overcome. However, in the rapid development process of the RFID technology, while showing numerous advantages, the disadvantages of the RFID technology are not negligible, and prevent the development of the technology, so that the RFID technology is a huge obstacle to the wide popularization of the technology at present, due to the complexity of electromagnetic wave communication and the mutual influence between tags, the influence of external environment such as metal, liquid and the like on the tags themselves seriously reduces the reliability of tag data, and the problem is solved, which is the key of the development of the technology next.
In the practical use of RFID tags, multiple tags are often used simultaneously, and when the tags are in proximity to such media, the nonlinear interference of such media and the coupling effect between the cross-coupled distributed tags act on the RFID system at the same time, resulting in significant changes in system performance. In recent years, the application of labels in different environments, such as the application of labels in metals, the application of labels in liquids and the application of labels in multi-label environments, has been studied quite often, starting from the influence of a single environment, and has been studied less often for labels commonly applied in metal, liquid and cross-coupling environments.
Secondly, in the free environment, the definition range of each country for the ultra-high frequency band is different, and each country has own frequency allocation. For example, the ultra-high frequency bands of China are 840-845MHz, 920-925MHz, european 866-869MHz, north America and south America 902-928MHz, and Japanese 950-956MHz. The currently studied tag mainly takes 915MHz as a central frequency band, the main frequency coverage area is 902-928MHz in North America and south America, and the ultra-high frequency band of 840-960MHz in the world cannot be covered. In view of this, there is a need for a new tag antenna suitable for use in metal, liquid, and mutual coupling environments.
Disclosure of Invention
In order to solve the problem of antenna applicability, the antenna can be normally applicable to various working environments, and the invention provides an ultra-wideband tag antenna applicable to a metal-liquid mutual coupling environment.
An ultra-wideband tag antenna suitable for use in a metal-liquid mutual coupling environment comprises an antenna conductor structure and a tag chip 11; the antenna conductor structure is a plane structure formed by a bent double-L-shaped arm, a double-T matching network and a central spiral dipole, and is a symmetrical dipole-like structure;
the double-T matching network comprises a first upper feeder 1, a first lower feeder 2, a second upper feeder 3 and a second lower feeder 4; one end of the first lower feeder line 2 is fixedly connected with the middle part of the first upper feeder line 1 to form a T-shaped structure; one end of the second lower feeder line 4 is fixedly connected with the middle part of the second upper feeder line 3 to form a T-shaped structure; a tag chip 11 is connected between the other end of the first lower feeder line 2 and the other end of the second lower feeder line 4 to form two closed loops;
the bent double-L-shaped arm comprises a feeder line first connecting feeder line 5, a left arm outer feeder line 7 and a right arm outer feeder line 10; two ends of the first connecting feeder line 5 are respectively connected with one end of the left arm outer feeder line 7 and one end of the right arm outer feeder line 10, and the left arm outer feeder line 7 and the right arm outer feeder line 10 symmetrically form a door-shaped structure; the left arm outer feeder 7 is provided with an open L-shaped groove, and the right arm outer feeder 10 is provided with an open L-shaped groove; the L-shaped groove enables the left arm outer feeder 7 and the right arm outer feeder 10 to respectively form two long feeders with different thicknesses, so that the length of an opening line is increased; the opening end of the L-shaped groove of the left arm outer feeder 7 corresponds to the opening end of the L-shaped groove of the right arm outer feeder 10;
the center helical dipole comprises a second connecting feeder line 6, a left-arm inner feeder line 8 and a right-arm inner feeder line 9; the left-arm inner feeder line 8 and the right-arm inner feeder line 9 have the same structure and opposite directions; the left-arm inner feeder line 8 comprises a notch-shaped feeder line, one side edge of the notch-shaped feeder line is connected with an L-shaped feeder line, and the other corresponding side edge of the notch-shaped feeder line is connected with a short feeder line; the right-arm inner feeder 9 comprises a notch-shaped feeder, one side edge of the notch-shaped feeder is connected with an L-shaped feeder, and the other corresponding side edge of the notch-shaped feeder is connected with a short feeder; the two ends of the second connecting feeder line 6 are respectively connected with an L-shaped feeder line of the left-arm inner feeder line 8 and an L-shaped feeder line of the right-arm inner feeder line 9;
the first connecting feeder line 5 and the second connecting feeder line 6 are parallel; two ends of the first upper feeder line 1 are respectively connected with a first connecting feeder line 5 and a second connecting feeder line 6; two ends of the second upper feeder line 3 are respectively connected with a first connecting feeder line 5 and a second connecting feeder line 6;
the ultra-wideband tag antenna has a bandwidth of 550-1300 MHz in a 3dB when in a free environment, realizes the coverage of 840-960MHz ultra-high frequency band, and has an input impedance of 11-j143 omega when the working frequency is 915 MHz; the return loss at 915MHz was-47.3 dB.
The technical scheme is as follows:
the chip 11 is a radio frequency identification chip, and the model is Monza4.
The antenna conductor is made of copper, and the thickness of the antenna conductor is 0.2mm.
Compared with the prior art, the invention has the following beneficial technical effects:
(1) The ultra-wideband tag antenna of the invention has the bandwidth of 550-1300 MHz at-3 dB in free environment, well covers the ultra-high frequency band of 840-960MHz of the world, and has the return loss of-47.3 dB at 915 MHz.
(2) The invention forms circulation on the surface of the ultra-wideband tag antenna by utilizing the self-central spiral dipole ring structure, increases the environmental adaptability of the ultra-wideband tag antenna, and reduces the influence of metal on the performance of the ultra-wideband tag antenna; the length of the feeder line of the ultra-wideband tag antenna is increased by utilizing the bent double L-shaped arms under the condition that the size of the antenna is not increased, and the adjustment range of the impedance of the ultra-wideband tag antenna is increased; by utilizing the structure of two similar-mouth-shaped closed rings in the double-T matching network, the impedance of the ultra-wideband tag antenna can be conveniently adjusted under the condition of not changing the size of the antenna by adjusting the sizes of the upper and lower mouth-shaped closed rings, the impedance at the central frequency band of the ultra-wideband tag antenna is stabilized, the bandwidth of the antenna is increased, the influence of different environments on tag frequency offset is reduced, and the applicability of the ultra-wideband tag antenna in different environments is improved; therefore, the ultra-wideband tag antenna has ultra-wideband, and the applicability of the ultra-wideband tag antenna in the mutual coupling condition and the liquid environment is improved.
(3) Tests show that the transmission coefficient of the tag at the center frequency point is larger than 0.8 in a metal environment, a liquid environment and a tag mutual coupling environment, and the transmission coefficient of the center frequency point is basically 1 in a free environment.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention.
Fig. 2 is a top view of the structure of fig. 1.
Fig. 3 is a diagram illustrating the length and width dimensions of a radiating patch of an ultra-wideband tag antenna of the present invention.
FIG. 4 is a graph of the power reflection function of the ultra-wideband tag antenna of the present invention in a free environment (S 11 ）。
Fig. 5 is a graph of impedance of an ultra-wideband tag antenna of the present invention, where the solid line represents resistance and the dashed line represents reactance.
Fig. 6 is an EH plan view of an ultra-wideband tag antenna of the present invention.
Fig. 7 is a three-dimensional directional gain pattern of the ultra-wideband tag antenna of the present invention.
Fig. 8 is a simulation model of the ultra-wideband tag antenna of the present invention in a metal environment.
Fig. 9 is a simulation model of the ultra-wideband tag antenna of the present invention in a liquid environment.
Fig. 10 is a simulation model of the ultra-wideband tag antenna of the present invention in a cross-coupling environment.
Fig. 11 is a graph of return loss of an ultra-wideband tag antenna of the present invention in various operating environments.
Fig. 12 is an impedance diagram of an ultra-wideband tag antenna of the present invention in various operating environment environments.
Fig. 13 is a graph of power transfer coefficients for the same type of dipole tag Alien-9640 in various operating environments.
Fig. 14 is a graph of power transfer coefficients of an ultra wideband tag antenna of the present invention in various operating environments.
Serial numbers in fig. 1 and 2: a first upper feeder 1, a first lower feeder 2, a second upper feeder 3, a second lower feeder 4, a first connecting feeder 5, a second connecting feeder 6, a left-arm outer feeder 7, a left-arm inner feeder 8, a right-arm inner feeder 9, a right-arm outer feeder 10, a chip 11, and an L-shaped slot 12.
Detailed Description
The invention is described in further detail below by way of examples with reference to the accompanying drawings.
Referring to fig. 1, an ultra-wideband tag antenna suitable for use in a metal-liquid mutual coupling environment includes an antenna conductor structure and a tag chip 11. The antenna conductor structure is a plane structure and comprises a bent double-L-shaped arm, a double-T matching network and a central spiral dipole, and is a symmetrical dipole-like structure. The antenna conductor is made of copper and has a thickness of 0.2mm. The chip 11 is a radio frequency identification chip, and the model is Monza4.
Referring to fig. 2, the dual T matching network includes a first upper feed line 1, a first lower feed line 2, a second upper feed line 3, and a second lower feed line 4. One end of the first lower feeder line 2 is fixedly connected with the middle part of the first upper feeder line 1 to form a T-shaped structure; one end of the second lower feeder line 4 is fixedly connected with the middle part of the second upper feeder line 3 to form a T-shaped structure; a tag chip 11 is connected between the other end of the first lower feed line 2 and the other end of the second lower feed line 4 to form two closed loops.
Referring to fig. 2, the bent double L-shaped arm includes a feeder first connection feeder 5, a left arm outer feeder 7, and a right arm outer feeder 10. The two ends of the first connecting feeder 5 are respectively connected with one end of the left arm outer feeder 7 and one end of the right arm outer feeder 10, and the left arm outer feeder 7 and the right arm outer feeder 10 symmetrically form a gate-shaped structure. The left arm outer feeder 7 is provided with an open L-shaped groove 12, and the right arm outer feeder 10 is provided with an open L-shaped groove 12; the L-shaped groove 12 enables the left arm outer feeder 7 and the right arm outer feeder 10 to respectively form two long feeders with different thicknesses, so that the length of an opening line is increased; the open end of the L-shaped slot of the left arm outer feed line 7 corresponds to the open end of the L-shaped slot of the right arm outer feed line 10.
Referring to fig. 2, the center helical dipole includes a second connection feed line 6, a left-arm inner feed line 8, and a right-arm inner feed line 9. The left-arm inner feeder line 8 and the right-arm inner feeder line 9 have the same structure and opposite directions. The left-arm inner feeder line 8 comprises a notch-shaped feeder line, one side edge of the notch-shaped feeder line is connected with an L-shaped feeder line, and the other corresponding side edge of the notch-shaped feeder line is connected with a short feeder line; the right-arm inner feeder 9 comprises a notch-shaped feeder, one side edge of the notch-shaped feeder is connected with an L-shaped feeder, and the other corresponding side edge of the notch-shaped feeder is connected with a short feeder; both ends of the second connection feeder 6 are connected to the L-shaped feeder of the left-arm inner feeder 8 and the L-shaped feeder of the right-arm inner feeder 9, respectively.
Referring to fig. 2, the first connection feed line 5 and the second connection feed line 6 are parallel. Two ends of the first upper feeder line 1 are respectively connected with a first connecting feeder line 5 and a second connecting feeder line 6; both ends of the second upper feeder line 3 are connected to the first connection feeder line 5 and the second connection feeder line 6, respectively.
Referring to fig. 3, the overall dimension of the ultra-wideband tag antenna is L1 x W1 is 76mm x 29mm, and the other dimensions in the feed line are as follows. In the double-T matching network, the upper length W5=16 mm, the lower length W6=5 mm and the width W3=1.2 mm of the first upper feeder line 1 and the second upper feeder line 3, and the total length L4=22 mm of the first lower feeder line 2 and the second lower feeder line 4; in the double-folded L-shaped arm, the length of the first connecting feeder line L1=76 mm, and the sizes of the left arm outer feeder line 7 and the right arm outer feeder line 10 are W1=29 mm, W2=19 mm, W4=5.2 mm, L2=15.4 mm, L8=6 mm and L9=2.4 mm; in the center spiral structure, the length of the second connecting feeder line 6 is l6=56 mm, and the sizes of the left-arm inner feeder line 8 and the right-arm inner feeder line 9 are w7=10 mm, w8=4 mm, l3=14 mm, l5=11.6 mm and l7=3.2 mm.
The working performance of the ultra-wideband tag antenna of the invention in free, metal, liquid and mutual coupling environments is tested by using electromagnetic transient simulation software HFSS. The environment parameter setting will be described in detail below.
When the ultra-wideband tag antenna of the invention works in a free environment, namely the ultra-wideband tag antenna is solely located in a free space, wherein the free space refers to a space where uniform media with relative dielectric constants and relative magnetic conductivities of 1 exist, and other interference sources are not located in the space. In the experiment, by defining the radiation boundary condition, the radiation boundary can absorb electromagnetic waves of the whole radio frequency identification system, the radiation boundary can be essentially regarded as extending to the space infinity, and after the radiation boundary condition is set in the HFSS, the software can automatically simulate the radiation field of the ultra-wideband tag antenna in the free space. The impedance and resonance frequency of the antenna are adjusted by adjusting the bent double L-shaped arms, the double T-shaped matching network and the spiral dipole structure, the return loss curve of the ultra-wideband tag antenna in the free environment is shown in figure 4, and as can be seen from figure 4, the resonance frequency of the antenna is 915MHz, the return loss at the frequency is-47.3 dB, the bandwidth of-3 dB of the antenna is 550MHz-1300MHz, and the ultra-wideband tag antenna has ultra-wideband characteristics. The impedance curve of the ultra-wideband tag antenna in the free environment is shown in fig. 5, wherein the solid line is the real part of the antenna impedance, the broken line is the imaginary part of the antenna impedance, and as can be seen from fig. 5, the impedance of the antenna at 915MHz is 10.7+j141.8Ω, the impedance is perfectly matched with the tag chip Monza4, and the antenna impedance is in a stable state at the whole central frequency band. Fig. 6 is a simulated EH plane radiation diagram of the ultra-wideband tag antenna of the present invention in a free environment, wherein the E-plane main radiation direction theta (θ) =0 simulated radiation diagram when the external line is 915MHz, and the H-plane main radiation direction theta (θ) =90 simulated radiation diagram when the internal line is 915 MHz; fig. 7 is a three-dimensional gain diagram of the ultra-wideband tag antenna of the present invention in free environment at an operating frequency of 915 MHz. As can be seen from fig. 6 and 7, the maximum gain achieved by the antenna at 915MHz operating frequency is 0.88dBi, which meets the design requirements.
When the ultra-wideband tag antenna of the invention works in a metal environment, namely, metal interference exists in the adjacent space of the ultra-wideband tag antenna. When the working environment of the ultra-wideband tag antenna is provided with a metal medium, the metal surface can reflect electromagnetic waves, so that the working performance of the ultra-wideband tag antenna is affected. As shown in fig. 8, a metal sheet is disposed at a position 40mm away from the ultra-wideband tag antenna, and the ultra-wideband tag antenna is simulated to be in a metal environment, and the size of the metal sheet is 100mm by 40mm. Referring to fig. 11, a return loss simulation diagram of an ultra-wideband tag antenna of the present invention in a metal, liquid, and cross-coupling environment, wherein a dashed line is a return loss curve of the ultra-wideband tag antenna in the metal environment. As can be seen from fig. 11, when the ultra-wideband tag antenna is operated in a metal environment, the tag resonant frequency band is slightly shifted from 915MHz to high frequency, and the return loss at the resonant frequency is increased from-47.3 dB to around-35 dB in a free environment. Referring to fig. 12, an impedance change diagram of an ultra-wideband tag antenna in a metal, liquid, and mutual coupling environment is shown, wherein a dotted line is an impedance change curve of the ultra-wideband tag antenna in the metal environment. It can be seen that near 950MHz, the real part and the imaginary part of the tag impedance in the metal environment can be greatly raised, and although the impedance of the ultra-wideband tag antenna in the metal environment is obviously changed, the impedance matching degree with the chip can be kept high near the center frequency 915 MHz. In the whole, the return loss of the ultra-wideband tag antenna working in the metal environment is still in the normal range, the ultra-wideband bandwidth is basically unchanged, and the ultra-wideband tag antenna can keep higher impedance matching degree with a chip, so that the adaptability of the ultra-wideband tag antenna in the metal environment can be seen.
When the ultra-wideband tag antenna works in a liquid environment, namely, liquid interference exists in the vicinity of the ultra-wideband tag antenna, and when a liquid medium exists in the working environment of the ultra-wideband tag antenna, electromagnetic waves can be absorbed on the surface of the liquid, so that the working performance of the ultra-wideband tag antenna is affected. As shown in fig. 9, a rectangular liquid is disposed at a position 40mm away from the ultra-wideband tag antenna, and the ultra-wideband tag antenna is simulated to be in a liquid environment, and the liquid size is 100mm by 40mm by 5mm. Referring to fig. 11, a return loss simulation diagram of an ultra-wideband tag antenna of the present invention in a metal, liquid, and cross-coupling environment, wherein the dotted line is the return loss curve of the ultra-wideband tag antenna in the liquid environment. As can be seen from fig. 11, when the ultra-wideband tag antenna is operated in a liquid environment, the tag resonant frequency range is shifted from 915MHz to a low frequency to around 850MHz, and the return loss at the resonant frequency is reduced from-47.3 dB to around-27.5 dB in a free environment. Referring to fig. 12, an impedance change diagram of an ultra-wideband tag antenna in a metal, liquid, and mutual coupling environment is shown, wherein a dotted line is an impedance change curve of the ultra-wideband tag antenna in the liquid environment. It can be seen that the imaginary part and the real part of the tag antenna impedance are reduced and the peak value is shifted with frequency in a liquid environment, but the impedance matching with the tag chip Monza4 can be kept better at the center frequency. In the whole, the return loss of the ultra-wideband tag antenna working in the liquid environment is better than that of the ultra-wideband tag antenna working in the free environment, the-10 dB working bandwidth of the ultra-wideband tag antenna is basically unchanged, and the impedance matching degree with the chip is higher, so that the adaptability of the ultra-wideband tag antenna in the liquid environment can be seen.
When the ultra-wideband tag antenna works in a mutual coupling environment, that is, mutual coupling interference exists in the adjacent space of the ultra-wideband tag antenna, the vector sum of coupling energy among array antenna units changes along with a scanning angle, and larger power reflection can be generated in specific frequency and direction. As shown in fig. 10, the tag antenna is simulated in a mutual coupling environment by using two ultra-wideband first antennas and second antennas of the same type, wherein the distance between the two antennas is 40mm. Referring to fig. 11, a return loss simulation diagram of an ultra-wideband tag antenna of the present invention in a metal, liquid, and cross-coupling environment, where the solid line is the return loss curve of the ultra-wideband tag antenna in the cross-coupling environment. As can be seen from fig. 11, when the ultra-wideband tag antenna operates in a mutual coupling environment, the resonant frequency of the ultra-wideband tag antenna tag shifts to 950MHz toward high frequency, but the return loss below-40 dB can be maintained in the 870MHz-970MHz frequency band, and the return loss at the resonant frequency can be reduced from-47.3 dB to about-57 dB in a free environment. Referring to fig. 12, an impedance change diagram of an ultra-wideband tag antenna in a metal, liquid, and mutual coupling environment is shown, wherein a solid line is an impedance change curve of the ultra-wideband tag antenna in the mutual coupling environment. It can be seen that the real part and the imaginary part of the impedance of the tag antenna can be close to the real part and the imaginary part of the tag chip in a wider frequency band under the mutual coupling environment. In the whole, the return loss of the ultra-wideband tag antenna working in the mutual coupling environment is better than that in the free environment, the-10 dB working bandwidth of the ultra-wideband tag antenna is basically unchanged, and the impedance matching degree of the chip is higher than that in the free environment, so that the adaptability of the ultra-wideband tag antenna in the mutual coupling environment can be seen.
In order to highlight the adaptability of the ultra-wideband tag antenna in various environments, a performance comparison experiment of the ultra-wideband tag antenna and the folded dipole tag Alien-9640 of the same type is performed. As shown in the experimental results shown in fig. 13 and 14, it is obvious that when two dipole tags are in a liquid environment, the center frequency band shifts to a low frequency and the transmission coefficient is reduced, the matching degree of the antenna and the chip is reduced, the transmission coefficient of the Alien-9640 tag is wholly lower than 0.7, and the ultra-wideband tag antenna can maintain the transmission coefficient of about 0.8 near the center frequency band. In a metal-to-tag mutual coupling environment, the Alien-9640 tag may experience frequency offset and transmission coefficient drop, similar to that in a liquid environment. When the ultra-wideband tag antenna is in a metal environment, the central frequency band can shift to high frequency, but the transmission coefficient near the central frequency band can be maintained above 0.9 and even close to 1, and when the ultra-wideband tag antenna is in a mutual coupling environment, the power transmission coefficient of the ultra-wideband tag antenna can be close to 1 in a very wide band, and the tag performance is better than that in a free environment.
It will be readily appreciated by those skilled in the art that the foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (3)
1. An ultra-wideband tag antenna suitable for use in a metal-liquid mutual coupling environment, characterized in that: comprises an antenna conductor structure and a tag chip (11); the antenna conductor structure is a plane structure formed by a bent double-L-shaped arm, a double-T matching network and a central spiral dipole, and is a symmetrical dipole-like structure;
the double-T matching network comprises a first upper feeder line (1), a first lower feeder line (2), a second upper feeder line (3) and a second lower feeder line (4); one end of the first lower feeder line (2) is fixedly connected with the middle part of the first upper feeder line (1) to form a T-shaped structure; one end of the second lower feeder line (4) is fixedly connected with the middle part of the second upper feeder line (3) to form a T-shaped structure; a tag chip (11) is connected between the other end of the first lower feeder line (2) and the other end of the second lower feeder line (4);
the bent double-L-shaped arm comprises a feeder line first connecting feeder line (5), a left arm outer feeder line (7) and a right arm outer feeder line (10); two ends of the first connecting feeder line (5) are respectively connected with one end of the left arm outer feeder line (7) and one end of the right arm outer feeder line (10), and the left arm outer feeder line (7) and the right arm outer feeder line (10) are symmetrical to form a door-shaped structure; an open L-shaped groove is formed in the left arm outer feeder line (7), and an open L-shaped groove is formed in the right arm outer feeder line (10); the L-shaped groove enables the left arm outer feeder line (7) and the right arm outer feeder line (10) to respectively form two long feeder lines with different thicknesses, so that the length of an open line is increased; the opening end of the L-shaped groove of the left arm outer feeder line (7) corresponds to the opening end of the L-shaped groove of the right arm outer feeder line (10);
the center spiral dipole comprises a second connecting feeder line (6), a left arm inner feeder line (8) and a right arm inner feeder line (9); the left-arm inner feeder line (8) and the right-arm inner feeder line (9) are identical in structure and opposite in direction; the left-arm inner feeder (8) comprises a notch-shaped feeder, one side edge of the notch-shaped feeder is connected with an L-shaped feeder, and the other corresponding side edge of the notch-shaped feeder is connected with a short feeder; the right-arm inner feeder (9) comprises a notch-shaped feeder, one side edge of the notch-shaped feeder is connected with an L-shaped feeder, and the other corresponding side edge of the notch-shaped feeder is connected with a short feeder; two ends of the second connecting feeder line (6) are respectively connected with an L-shaped feeder line of the left arm inner feeder line (8) and an L-shaped feeder line of the right arm inner feeder line (9);
the first connecting feeder line (5) and the second connecting feeder line (6) are parallel; two ends of the first upper feeder line (1) are respectively connected with a first connecting feeder line (5) and a second connecting feeder line (6); two ends of the second upper feeder line (3) are respectively connected with a first connecting feeder line (5) and a second connecting feeder line (6);
the ultra-wideband tag antenna has a bandwidth of 550-1300 MHz in a 3dB when in a free environment, realizes the coverage of 840-960MHz ultra-high frequency band, and has an input impedance of 11-j143 omega when the working frequency is 915 MHz; the return loss at 915MHz was-47.3 dB.
2. An ultra-wideband tag antenna adapted for use in a metal-liquid mutual coupling environment as defined in claim 1, wherein: the chip (11) is a radio frequency identification chip, and the model is Monza4.
3. An ultra-wideband tag antenna adapted for use in a metal-liquid mutual coupling environment as defined in claim 1, wherein: the antenna conductor is made of copper, and the thickness of the antenna conductor is 0.2mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| KR100812061B1 (en) * | 2006-10-11 | 2008-03-07 | 엘지이노텍 주식회사 | Rfid antenna, rfid tag and rfid system |
| CN201117797Y (en) * | 2007-06-13 | 2008-09-17 | 华南理工大学 | Coplanar waveguide feeding radio frequency identification tag antenna |
| JP5337834B2 (en) * | 2011-03-31 | 2013-11-06 | 富士フイルム株式会社 | RFID tag and RFID communication system |
| CN202585712U (en) * | 2012-06-11 | 2012-12-05 | 杭州电子科技大学 | RFID (Radio Frequency Identification) tag antenna |
| CN104347945A (en) * | 2013-08-08 | 2015-02-11 | 国家电网公司 | Broadband UHF (Ultra High Frequency) RFID (Radio Frequency Identification Device) electronic tag antenna and electronic tag |
| CN106602284A (en) * | 2016-11-30 | 2017-04-26 | 南京邮电大学 | Small-scale metal-resistant broadband tag antenna |
| CN207441958U (en) * | 2017-09-22 | 2018-06-01 | 北京邮电大学 | A UHF radio frequency identification anti-metal tag antenna |
| CN112701449A (en) * | 2020-12-28 | 2021-04-23 | 成都科灵智能光电科技有限公司 | Ultrahigh frequency high-gain double dipole tag antenna with low profile |
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| CN101355195A (en) * | 2008-08-29 | 2009-01-28 | 浙江大学 | UHF RF dual-frequency-recognizing metal-resistance label antenna |
| CN112151935A (en) * | 2019-06-27 | 2020-12-29 | 亘冠智能技术（杭州）有限公司 | Liquid insensitive ultrahigh frequency RFID flexible tag antenna |
| CN112164861A (en) * | 2020-08-24 | 2021-01-01 | 南京航空航天大学 | Miniaturized foldable ultrahigh-frequency anti-metal anti-liquid tag antenna |
| CN112038750A (en) * | 2020-09-04 | 2020-12-04 | 合肥工业大学 | Anti-metal tag antenna applied to UHF frequency band |
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