CN114665259A - Ultra-wideband tag antenna suitable for metal liquid cross-coupling environment - Google Patents
Ultra-wideband tag antenna suitable for metal liquid cross-coupling environment Download PDFInfo
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- CN114665259A CN114665259A CN202210396470.9A CN202210396470A CN114665259A CN 114665259 A CN114665259 A CN 114665259A CN 202210396470 A CN202210396470 A CN 202210396470A CN 114665259 A CN114665259 A CN 114665259A
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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
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention relates to an ultra-wideband tag antenna suitable for a metal liquid cross-coupling environment, and belongs to the technical field of radio frequency identification electronic tags. The tag comprises an antenna conductor structure and a tag chip; the antenna conductor structure is a symmetrical dipole-like structure consisting of a bent double-L-shaped arm, a double-T matching network and a central spiral dipole; 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 connecting feed, a left arm inner feed, and a right arm inner feed. In a free environment, the-3 dB bandwidth is 550MHz-1300MHz, the ultrahigh frequency band of 840-960MHz is covered, and the input impedance of 11-j143 omega is provided at 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 working in an ultrahigh frequency band and suitable for metal, liquid and mutual coupling environments.
Background
Compared with the traditional bar code technology, the Radio Frequency Identification (RFID) system has the advantages of long identification distance, high reading speed, no need of 'visualization' condition in the identification process, manual participation and the like, has the greatest advantage that the RFID label has a repeated read-write function, has strong data containing capacity of a chip, and can overcome the defects of 'visualization', short distance and the like in the traditional identification technology. However, in the process of rapid development of the RFID technology, while showing many advantages, the disadvantages are not negligible, and these disadvantages hinder the development of the technology, which is a huge obstacle for wide popularization of the technology at present, because of complexity of electromagnetic wave communication, mutual influence between tags, influence of external environment such as metal, liquid, etc. on the tags themselves, and serious reduction of error-free reliability of tag data, solving these problems is a key for the next development of the technology.
In practical use of RFID tags, multiple tags are often used simultaneously, and their application environments are either metal, liquid or other, and when the tags are close to these media, the nonlinear interference of these media and the coupling effect between the mutual coupling distribution tags simultaneously act on the RFID system, resulting in significant changes in system performance. In recent years, many studies have been made on the application of tags in different environments, such as the application of tags in metal, the application of tags in liquid, and the application of tags in a multi-tag environment, and most of the previous studies have been made under the influence of a single environment, but few studies have been made on tags generally applicable to metal, liquid, and mutually coupled environments.
Secondly, in the free environment, the definition range of each country to the ultra high frequency band is different, and each country has its own frequency allocation. For example, the UHF bands in China are 840-845MHz and 920-925MHz, in Europe, 866-869MHz, in North America and south America, 902-928MHz, and in Japan, 950-956 MHz. The currently researched tag mainly takes 915MHz as a central frequency band, the main frequency coverage range is 902-928MHz in North America and south America, and the 840-960MHz ultrahigh frequency band cannot be covered globally. In view of the above, there is a need for a novel tag antenna suitable for use in metal, liquid and mutual coupling environments.
Disclosure of Invention
The invention provides an ultra-wideband tag antenna suitable for a metal liquid cross-coupling environment, aiming at solving the problem of antenna applicability and enabling the antenna to be normally suitable for various working environments.
An ultra-wideband tag antenna suitable for a metal liquid mutual coupling environment comprises an antenna conductor structure and a tag chip 11; the antenna conductor structure is a symmetrical dipole-like structure consisting of a bent double-L-shaped arm, a double-T matching network and a central spiral dipole;
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 label chip 11 is connected between the other end of the first lower feeder 2 and the other end of the second lower feeder 4 to form two closed rings;
the bent double L-shaped arm comprises a feeder line first connecting feeder line 5, a left arm external feeder line 7 and a right arm external feeder line 10; two ends of the first connecting feeder 5 are respectively connected with one end of the left arm external feeder 7 and one end of the right arm external feeder 10, and the left arm external feeder 7 and the right arm external feeder 10 symmetrically form a door-shaped structure; an open L-shaped groove is formed in the left arm outer feeder 7, and an open L-shaped groove is formed in the right arm outer feeder 10; the L-shaped groove enables the left arm external feeder line 7 and the right arm external feeder line 10 to form two long feeder lines with different thicknesses respectively, and the length of an open line is increased; the open end of the L-shaped groove of the left arm external feeder line 7 corresponds to the open end of the L-shaped groove of the right arm external feeder line 10;
the central spiral dipole comprises a second connecting feeder 6, a left arm inner feeder 8 and a right arm inner feeder 9; the left arm inner feed line 8 and the right arm inner feed line 9 have the same structure and opposite directions; the left arm inner feeder line 8 comprises a square feeder line, one side edge of the square feeder line is connected with an L-shaped feeder line, and the other corresponding side edge of the square feeder line is connected with a short feeder line; the right arm inner feeder 9 comprises a square feeder, one side edge of the square feeder is connected with an L-shaped feeder, and the other corresponding side edge of the square feeder is connected with a short feeder; two ends of the second connecting feeder 6 are respectively connected with an L-shaped feeder of the left arm inner feeder 8 and an L-shaped feeder of the right arm inner feeder 9;
the first connecting feeder 5 and the second connecting feeder 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;
when the ultra-wideband tag antenna is in a free environment, the-3 dB bandwidth is 550MHz-1300MHz, the ultra-high frequency band of 840 and 960MHz is covered, and the ultra-high frequency band has input impedance of 11-j143 omega when the working frequency is 915 MHz; the return loss at 915MHz was-47.3 dB.
The further technical scheme is as follows:
the chip 11 is a radio frequency identification chip with a model of Monza 4.
The antenna conductor structure is made of copper and is 0.2mm thick.
Compared with the prior art, the invention has the beneficial technical effects in the following aspects:
(1) the-3 dB bandwidth of the ultra-wideband tag antenna is 550MHz-1300MHz in a free environment, the ultra-high frequency band of 840-960MHz in the world is well covered, and the return loss at 915MHz is-47.3 dB.
(2) According to the invention, a circulating current is formed on the surface of the ultra-wideband tag antenna by utilizing the self-center spiral dipole annular structure, the environmental adaptability of the ultra-wideband tag antenna is improved, and the influence of metal on the performance of the ultra-wideband tag antenna is reduced; the bent double L-shaped arms are utilized, the length of a feeder line of the ultra-wideband tag antenna is increased 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 square-shaped closed rings in the double T matching network and adjusting the sizes of the upper square-shaped and the lower square-shaped, the impedance of the ultra-wide band tag antenna can be conveniently adjusted under the condition of not changing the size of the antenna, the impedance of the central frequency band of the ultra-wide band tag antenna is stabilized, and the bandwidth of the antenna is increased, so that the influence of different environments on the frequency deviation of the tag is weakened, and the applicability of the ultra-wide band tag antenna under different environments is improved; therefore, the ultra-wideband tag antenna has an ultra-wideband, and the applicability of the ultra-wideband tag antenna in a mutual coupling condition and a liquid environment is improved.
(3) Tests show that the ultra-wideband tag antenna has the transmission coefficients of the tag at the central frequency point of more than 0.8 in a metal environment, a liquid environment and a tag mutual coupling environment, and the transmission coefficient of the central frequency point is basically 1 in a free environment.
Drawings
FIG. 1 is a schematic view of the structure of the present invention.
Fig. 2 is a top view structural diagram of fig. 1.
Fig. 3 is a labeled diagram of the length and width dimensions of the radiation patch of the ultra-wideband tag antenna of the present invention.
FIG. 4 is a diagram of the power reflection function of the UWB tag antenna under free environment (S)11）。
Fig. 5 is a graph of impedance of the ultra-wideband tag antenna according to the present invention, in which a solid line represents resistance and a dotted line represents reactance.
Fig. 6 is a plan view of an EH of an uwb tagged antenna of the present invention.
Fig. 7 is a three-dimensional directional gain diagram of an ultra-wideband tag antenna of the present invention.
Fig. 8 is a simulation model of the ultra-wideband tag antenna according to 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 an uwb tagged antenna of the present invention in a cross-coupled environment.
Fig. 11 is a return loss plot for an uwb tagged antenna of the present invention in a variety of operating environments.
Fig. 12 is an impedance plot of an uwb tagged antenna of the present invention in various operating environment environments.
Fig. 13 is a graph of power transfer coefficients of the same type of dipole tag Alien-9640 in various operating environments.
Fig. 14 is a graph of power transmission coefficients for an ultra-wide band tag antenna of the present invention in various operating environments.
Number in fig. 1 and 2: the feed line structure comprises a first upper feed line 1, a first lower feed line 2, a second upper feed line 3, a second lower feed line 4, a first connecting feed line 5, a second connecting feed line 6, a left arm outer feed line 7, a left arm inner feed line 8, a right arm inner feed line 9, a right arm outer feed line 10, a chip 11 and an L-shaped groove 12.
Detailed Description
The present invention will be described in further detail 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 the antenna conductor structure is a symmetrical dipole-like. The antenna conductor structure is made of copper and has a thickness of 0.2 mm. The chip 11 is a radio frequency identification chip with a model number of Monza 4.
Referring to fig. 2, the dual T matching network includes 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; the other end of the first lower feed line 2 and the other end of the second lower feed line 4 are connected with a label chip 11 to form two closed rings.
Referring to fig. 2, the bent double L-shaped arm includes a feeder first connection feeder 5, a left arm external feeder 7, and a right arm external feeder 10. Two ends of the first connecting feeder 5 are respectively connected with one end of the left arm external feeder 7 and one end of the right arm external feeder 10, and the left arm external feeder 7 and the right arm external feeder 10 are symmetrically formed into a door-shaped structure. An open L-shaped groove 12 is formed in the left arm external feeder 7, and an open L-shaped groove 12 is formed in the right arm external feeder 10; the L-shaped groove 12 enables the left arm external feeder line 7 and the right arm external feeder line 10 to form two long feeder lines with different thicknesses respectively, and the length of an open line is increased; the open end of the L-shaped groove of the left arm external feed line 7 corresponds to the open end of the L-shaped groove of the right arm external feed line 10.
Referring to fig. 2, the center helical dipole includes a second connecting feed 6, a left arm inner feed 8, and a right arm inner feed 9. The left arm inner feed line 8 and the right arm inner feed line 9 are identical in structure and opposite in direction. The left arm inner feeder line 8 comprises a square feeder line, one side edge of the square feeder line is connected with an L-shaped feeder line, and the other corresponding side edge of the square feeder line is connected with a short feeder line; the right arm inner feeder 9 comprises a square feeder, one side edge of the square feeder is connected with an L-shaped feeder, and the other corresponding side edge of the square feeder is connected with a short feeder; two ends of the second connecting feeder 6 are respectively connected with an L-shaped feeder of the left arm inner feeder 8 and an L-shaped feeder of the right arm inner feeder 9.
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 3 are connected to a first connection feeder 5 and a second connection feeder 6, respectively.
Referring to fig. 3, the overall dimension of the ultra-wideband tag antenna is L1W 1 is 76mm 29mm, and the other dimensions in the feed line are as follows. In the double-T matching network, the upper lengths W5=16mm, the lower lengths W6=5mm, and the widths W3=1.2mm of the first upper feeder 1 and the second upper feeder 3, and the total lengths L4=22mm of the first lower feeder 2 and the second lower feeder 4; in the double-folded L-shaped arm, the length of the first connecting feed line L1=76mm, and the sizes of the left arm external feed line 7 and the right arm external feed line 10 are W1=29mm, W2=19mm, W4=5.2mm, L2=15.4mm, L8=6mm, and L9=2.4 mm; in the central spiral structure, the length of the second connecting feed line 6 is L6=56mm, and the sizes of the left arm inner feed line 8 and the right arm inner feed line 9 are W7=10mm, W8=4mm, L3=14mm, L5=11.6mm, and L7=3.2 mm.
The electromagnetic transient simulation software HFSS is used for testing the working performance of the ultra-wideband tag antenna under free, metal, liquid and mutual coupling environments respectively. The environment parameter setting will be described in detail below.
When the ultra-wideband tag antenna works in a free environment, namely the ultra-wideband tag antenna is independently positioned in a free space, wherein the free space is a space in which a uniform medium with the relative dielectric constant and the relative magnetic permeability of 1 exists, and no other interference source exists in the space. In the experiment, by defining the radiation boundary condition, the radiation boundary can absorb the electromagnetic wave of the whole radio frequency identification system, the radiation boundary can be regarded as extending to the infinite distance of the space essentially, and after the radiation boundary condition is set in the HFSS, software can automatically simulate the radiation field of the ultra-wideband tag antenna in the free space. The impedance and the resonant frequency of the antenna are adjusted by adjusting the bent double L-shaped arm, the double T-shaped matching network and the spiral dipole structure, the return loss curve of the ultra-wideband tag antenna in a free environment is shown in fig. 4, as can be seen from fig. 4, the resonant frequency of the antenna is 915MHz, the return loss of the antenna is-47.3 dB at the frequency, and the-3 dB bandwidth of the antenna is 550MHz-1300MHz, so that the ultra-wideband antenna has the ultra-wideband characteristic. 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, and the dotted line is the imaginary part of the antenna impedance, it can be seen from fig. 5 that the impedance of the antenna at 915MHz is 10.7+ j141.8 Ω, and 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 an EH plane radiation simulation diagram of the ultra-wideband tag antenna of the present invention in a free environment, where an outer line is a simulated radiation diagram of the principal radiation direction theta (θ) =0 on the E-plane when the outer line is 915MHz, and an inner line is a simulated radiation diagram of the principal radiation direction theta (θ) =90 on the H-plane when the inner line is 915 MHz; fig. 7 is a three-dimensional directional gain diagram of the ultra-wideband tag antenna according to the present invention in a free environment and at a working frequency of 915 MHz. As can be seen from fig. 6 and 7, the maximum gain achieved by the antenna at the 915MHz operating frequency is 0.88dBi, which meets the design requirement.
When the ultra-wideband tag antenna works in a metal environment, namely metal interference exists in the space near the ultra-wideband tag antenna. When a metal medium exists in the working environment of the ultra-wideband tag antenna, electromagnetic waves can be reflected by the metal surface, so that the working performance of the ultra-wideband tag antenna is influenced. As shown in fig. 8, a metal sheet is disposed at a position 40mm away from the ultra-wideband tag antenna, the analog ultra-wideband tag antenna is in a metal environment, and the size of the metal sheet is 100mm × 40 mm. Referring to fig. 11, a return loss simulation diagram of the ultra-wideband tag antenna of the present invention in a metal, liquid, and mutual coupling environment, wherein a dotted 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 operates in a metal environment, the resonant frequency band of the tag slightly shifts from 915MHz to a high frequency, and the return loss at the resonant frequency increases from-47.3 dB in a free environment to-35 dB or so. Referring to fig. 12, an impedance change diagram of the ultra-wideband tag antenna in a metal, liquid, and mutually coupled environment, where 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 are greatly increased, and although the impedance of the ultra-wideband tag antenna in the metal environment changes obviously, a high impedance matching degree with the chip can be maintained near 915 MHz. In a whole, the return loss of the ultra-wideband tag antenna working in a metal environment is still within a normal range, the bandwidth of the ultra-wideband tag antenna is basically unchanged, and a high impedance matching degree can be kept 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 space near the ultra-wideband tag antenna, and when a liquid medium exists in the working environment of the ultra-wideband tag antenna, the liquid surface can absorb electromagnetic waves, so that the working performance of the ultra-wideband tag antenna is influenced. As shown in fig. 9, rectangular liquid is disposed at a distance of 40mm from the ultra-wideband tag antenna, the analog ultra-wideband tag antenna is in a liquid environment, and the size of the liquid is 100mm × 40mm × 5 mm. Referring to fig. 11, a return loss simulation diagram of the ultra-wideband tag antenna of the present invention in a metal, liquid, and mutual coupling environment, wherein a dotted line is a return loss curve of the ultra-wideband tag antenna in a liquid environment. As can be seen from fig. 11, when the ultra-wideband tag antenna operates in a liquid environment, the resonant frequency band of the tag shifts from 915MHz to a low frequency to around 850MHz, and the return loss at the resonant frequency drops from-47.3 dB in a free environment to-27.5 dB. Referring to fig. 12, an impedance change diagram of the ultra-wideband tag antenna in a metal, liquid, and mutual coupling environment, where 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 impedance of the tag antenna are reduced and the peak value is shifted with the frequency under the liquid environment, but the impedance matching with the tag chip Monza4 can be kept better at the central frequency. In a whole, the return loss of the ultra-wideband tag antenna working in a liquid environment is better than that of the ultra-wideband tag antenna working in a free environment, the-10 dB working bandwidth of the ultra-wideband tag antenna is basically unchanged, and the impedance matching degree with a 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, namely mutual coupling interference exists in the space near the ultra-wideband tag antenna, the vector sum of coupling energy among the array antenna units is changed along with a scanning angle due to the mutual coupling interference, and larger power reflection can be generated in a specific frequency and direction. As shown in fig. 10, the analog tag antenna is in a mutual coupling environment by using two ultra-wideband first antennas and two ultra-wideband second antennas of the same type, wherein the distance between the two antennas is 40 mm. Referring to fig. 11, a return loss simulation diagram of the ultra-wideband tag antenna of the present invention in a metal, liquid, and mutual coupling environment, where a solid line is a return loss curve of the ultra-wideband tag antenna in the mutual coupling environment. It can be seen from fig. 11 that when the ultra-wideband tag antenna operates in a mutual coupling environment, the resonant frequency of the ultra-wideband tag antenna tag may shift to 950MHz, but it can maintain the return loss below-40 dB in the 870MHz-970MHz frequency band, and the return loss at the resonant frequency may be reduced from-47.3 dB in a free environment to about-57 dB. Referring to fig. 12, an impedance change diagram of the ultra-wideband tag antenna in a metal, liquid, and mutual coupling environment, where a solid line is an impedance change curve of the ultra-wideband tag antenna in the mutual coupling environment. The real part and the imaginary part of the impedance of the tag antenna under the mutual coupling environment can be close to the real part and the imaginary part of the tag chip in a wider frequency band. Overall, the echo 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 with a 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 a folded dipole tag Alien-9640 of the same type is carried out. As is obvious from the experimental results shown in fig. 13 and fig. 14, when two dipole tags are in a liquid environment, the central frequency band shifts to a low frequency, the transmission coefficient is reduced, the matching degree between the antenna and the chip is reduced, the transmission coefficient of the Alien-9640 tag is lower than 0.7 as a whole, and the ultra-wideband tag antenna of the present invention can maintain a transmission coefficient of about 0.8 near the central frequency band. In a metal and tag mutual coupling environment, the Alien-9640 tag can generate frequency deviation and transmission coefficient reduction, which are similar to the situation 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 to be more than 0.9 or 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 wide band, and the tag performance is better than that in a free environment.
It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the scope of the present invention.
Claims (3)
1. An ultra wide band tag antenna suitable for metal liquid cross coupling environment, its characterized in that: comprises an antenna conductor structure and a tag chip (11); the antenna conductor structure is a symmetrical dipole-like structure consisting of a bent double-L-shaped arm, a double-T matching network and a central spiral dipole;
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 (4) is fixedly connected with the middle part of the second upper feeder (3) to form a T-shaped structure; a label 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 rings;
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 (5) are respectively connected with one end of the left arm external feeder (7) and one end of the right arm external feeder (10), and the left arm external feeder (7) and the right arm external feeder (10) symmetrically form a door-shaped structure; an open L-shaped groove is formed in the left arm outer feeder (7), and an open L-shaped groove is formed in the right arm outer feeder (10); the L-shaped groove enables the left arm external feeder line (7) and the right arm external feeder line (10) to form two long feeder lines with different thicknesses, and the length of an open line is increased; the open end of the L-shaped groove of the left arm external feeder line (7) corresponds to the open end of the L-shaped groove of the right arm external feeder line (10);
the central spiral dipole comprises a second connecting feeder (6), a left arm inner feeder (8) and a right arm inner feeder (9); the left arm inner feeder (8) and the right arm inner feeder (9) are identical in structure and opposite in direction; the left arm inner feeder (8) comprises a square feeder, one side edge of the square feeder is connected with the L-shaped feeder, and the other corresponding side edge of the square feeder is connected with the short feeder; the right arm inner feeder (9) comprises a square feeder, one side edge of the square feeder is connected with the L-shaped feeder, and the other corresponding side edge of the square feeder is connected with the short feeder; two ends of the second connecting feeder (6) are respectively connected with an L-shaped feeder of the left arm inner feeder (8) and an L-shaped feeder of the right arm inner feeder (9);
the first connecting feeder (5) and the second connecting feeder (6) are parallel; two ends of the first upper feeder (1) are respectively connected with a first connecting feeder (5) and a second connecting feeder (6); two ends of the second upper feeder (3) are respectively connected with a first connecting feeder (5) and a second connecting feeder (6);
when the ultra-wideband tag antenna is in a free environment, the-3 dB bandwidth is 550MHz-1300MHz, the ultra-high frequency band of 840 and 960MHz is covered, and the ultra-high frequency band has input impedance of 11-j143 omega when the working frequency is 915 MHz; the return loss at 915MHz was-47.3 dB.
2. The ultra-wideband tag antenna suitable for use in a metal-liquid mutual coupling environment, as recited in claim 1, wherein: the chip (11) is a radio frequency identification chip with the model of Monza 4.
3. The ultra-wideband tag antenna suitable for use in a metal-liquid mutual coupling environment, as recited in claim 1, wherein: the antenna conductor structure is made of copper and is 0.2mm thick.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210396470.9A CN114665259B (en) | 2022-04-15 | 2022-04-15 | Ultra-wideband tag antenna suitable for metal-liquid mutual coupling environment |
Applications Claiming Priority (1)
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| CN114665259B (en) | 2023-04-25 |
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