A frequency reconfigurable RFID tag antenna

Abstract

The present invention discloses a frequency-reconfigurable RFID tag antenna, which relates to the technical field of frequency antenna design. The antenna comprises an antenna layer, a dielectric layer, an air layer, and a metal layer. The dielectric layer is disposed below the antenna layer, the air layer is disposed below the dielectric layer, and the metal layer is disposed below the air layer. The antenna layer comprises a patch dipole upper arm, a patch dipole lower arm, and a microchip. One end of the microchip is connected to the patch dipole upper arm, and the other end of the microchip is connected to the patch dipole lower arm. The patch dipole upper arm comprises a first inverted L-shaped microstrip line, one end of which is electrically connected to the microchip. This frequency-reconfigurable RFID tag antenna switches between three different frequency bands, resolving the problem of frequency incompatibility that occurs with traditional RFID tag antennas across countries. The antenna has the advantages of frequency reconfigurability, strong anti-interference capabilities, and compact size.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency antenna design, in particular to a frequency reconfigurable RFID tag antenna. Background Art

[0002] RFID tag antennas contain a microchip that stores the tag's information. RFID tag antennas dominate diverse applications, including logistics, product management, and vehicle management. RFID can communicate in standard frequency bands, such as low frequency (125-134 kHz), high frequency (13.56 MHz), ultrahigh frequency (UHF) (840-960 MHz), and microwave frequencies (2.45 or 5.8 GHz). The UHF band is used for vehicle management worldwide, with different countries using different frequency bands, such as 840-845 MHz (India), 920-925 MHz (China), and 950-955 MHz (Japan). When a vehicle crosses borders and then enters another country, it must adapt to the local frequency band to read the tag information. Currently, the main approach to addressing this issue is to design multi-band tag antennas.

[0003] Multi-band tag antennas are designed to operate efficiently across multiple frequencies by optimizing their structure, impedance matching, and multi-resonance characteristics, thereby achieving broad frequency compatibility and versatility. Multi-band tag antennas offer broad compatibility, meet diverse needs, save costs, and require no control signals. However, in a wide range of applications, multi-band antennas have drawbacks such as large size, complex design, and weak interference resistance. Summary of the Invention

[0004] To overcome the problems of large size, complex design, and weak anti-interference ability of multi-band RFID tag antennas, the present invention provides a frequency reconfigurable RFID tag antenna, comprising an antenna layer, a dielectric layer, an air layer, and a metal layer, wherein the dielectric layer is disposed below the antenna layer, the air layer is disposed below the dielectric layer, and the metal layer is disposed below the air layer.

[0005] The antenna layer consists of a patch dipole upper arm, a patch dipole lower arm and a microchip. One end of the microchip is connected to the patch dipole upper arm, and the other end of the microchip is connected to the patch dipole lower arm.

[0006] Preferably, the patch dipole upper arm comprises:

[0007] a first inverted L-shaped microstrip line, one end of which is electrically connected to the microchip, the first inverted L-shaped microstrip line consisting of a long microstrip line and a short microstrip line, wherein the long microstrip line and the short microstrip line are perpendicular to each other, and the microchip is connected to one end of the long microstrip line;

[0008] A first U-shaped microstrip line, wherein the first U-shaped microstrip line is connected to an end of the first inverted L-shaped microstrip line away from the microchip, the first U-shaped microstrip line is composed of two long microstrip lines and a short microstrip line perpendicular to the long microstrip line, the first U-shaped microstrip line is symmetrical about its own symmetry axis, and the first U-shaped microstrip line is connected to one end of the short microstrip line of the first inverted L-shaped microstrip line.

[0009] Preferably, the patch dipole upper arm further includes:

[0010] a second U-shaped microstrip line, the second U-shaped microstrip line being connected to an end of the first U-shaped microstrip line away from the first inverted L-shaped microstrip line, the second U-shaped microstrip line being longer in length than the first U-shaped microstrip line;

[0011] a third U-shaped microstrip line, the third U-shaped microstrip line being connected to an end of the second U-shaped microstrip line away from the first U-shaped microstrip line, the third U-shaped microstrip line having a greater vertical length than the first U-shaped microstrip line, and the third U-shaped microstrip line having a greater vertical length than the second U-shaped microstrip line;

[0012] A fourth U-shaped microstrip line is connected to an end of the third U-shaped microstrip line away from the second U-shaped microstrip line, and the fourth U-shaped microstrip line and the second U-shaped microstrip line are bilaterally symmetrical about the symmetry axis of the third U-shaped microstrip line.

[0013] Preferably, the patch dipole upper arm further includes:

[0014] A U-shaped switch loaded microstrip line, wherein the U-shaped switch loaded microstrip line is connected to an end of a fourth U-shaped microstrip line away from the third U-shaped microstrip line, and the U-shaped switch loaded microstrip line is bilaterally symmetrical with the first U-shaped microstrip line about a symmetry axis of the third U-shaped microstrip line;

[0015] An inverted L-shaped switch-loaded microstrip line is connected to an end of the U-shaped switch-loaded microstrip line away from the fourth U-shaped microstrip line. The inverted L-shaped switch-loaded microstrip line and the first inverted L-shaped microstrip line are bilaterally symmetrical about the symmetry axis of the third U-shaped microstrip line.

[0016] Preferably, the U-shaped switch loading microstrip line comprises:

[0017] Switch tube structure one, the switch tube structure one is arranged on the short microstrip line below the U-shaped switch loading microstrip line, the switch tube structure one is composed of a diode in parallel with a capacitor, the anode of the switch tube structure one is connected to the left microstrip line, and the cathode is connected to the right microstrip line.

[0018] Preferably, the inverted L-shaped switch loading microstrip line includes:

[0019] The switch tube structure 2 is arranged on the short microstrip line on the upper left side of the inverted L-shaped switch loading microstrip line. The switch tube structure 2 is composed of a diode and a capacitor in parallel. The anode of the switch tube structure 2 is connected to the left microstrip line, and the cathode is connected to the right microstrip line.

[0020] Preferably, the widths of the plurality of microstrip lines are the same.

[0021] Preferably, the patch dipole lower arm comprises:

[0022] A first inverted L-shaped tapered microstrip line, wherein the first inverted L-shaped tapered microstrip line is composed of an L-shaped patch microstrip line with an inverted long side and eleven tapered patch columns with short sides becoming longer;

[0023] A second inverted L-shaped tapered microstrip line is bilaterally symmetrical to the first inverted L-shaped tapered microstrip line about a symmetry axis of the third U-shaped microstrip line.

[0024] Preferably, the microchip is a commercial microchip that stores the required information and operates within a wide international frequency range of 840-960 MHz.

[0025] Preferably, the dielectric layer is made of a dielectric material with a dielectric constant of 4.4, a height of 1.6 mm, and a loss tangent of 0.02. The air layer is 5.4 mm high. The metal layer is made of a metal with good conductive properties and is pressed onto the bottom of the dielectric layer.

[0026] The present invention provides a frequency reconfigurable RFID tag antenna. It has the following beneficial effects:

[0027] This frequency-reconfigurable RFID tag antenna combines an RFID tag antenna with an RFPIN diode. The diode's switching performance enables the antenna to switch frequencies within the UHF band, allowing the tag to be used in different countries based on the assigned RFID communication frequencies. The reconfigurable tag antenna offers advantages such as frequency reconfigurability, strong anti-interference capabilities, and compact size, effectively resolving the issues of large size, complex design, and weak anti-interference capabilities often encountered in multi-band antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A top view of the present invention;

[0029] Figure 2 It is a front view of the present invention;

[0030] Figure 3 This is a dimensional diagram of the present invention.

[0031] In the figure: 1. Upper arm of the patch dipole; 2. Lower arm of the patch dipole; 3. Microchip; 4. Switch tube structure 1; 5. Switch tube structure 2; 6. First inverted L-shaped gradient microstrip line; 7. Second inverted L-shaped gradient microstrip line; 8. Antenna layer; 9. Dielectric layer; 10. Air layer; 11. Metal layer; 12. First inverted L-shaped microstrip line; 13. First U-shaped microstrip line; 14. Second U-shaped microstrip line; 15. Third U-shaped microstrip line; 16. Fourth U-shaped microstrip line; 17. U-shaped switch loaded microstrip line; 18. Inverted L-shaped switch loaded microstrip line. DETAILED DESCRIPTION

[0032] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described to better illustrate the principles of the invention and its practical application, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for specific applications.

[0033] like Figure 1-Figure 3 As shown, the present invention provides a technical solution: including an antenna layer 8, a dielectric layer 9, an air layer 10 and a metal layer 11, the dielectric layer 9 is arranged below the antenna layer 8, the air layer 10 is arranged below the dielectric layer 9, and the metal layer 11 is arranged below the air layer 10, the dielectric layer 9 includes a dielectric substrate of an insulating material, the air layer 10 includes air, and the metal layer 11 includes a metal plate, which is equal to the size of the dielectric substrate of the dielectric layer 9;

[0034] The antenna layer 8 is composed of a patch dipole upper arm 1 , a patch dipole lower arm 2 and a microchip 3 . One end of the microchip 3 is connected to the patch dipole upper arm 1 , and the other end of the microchip 3 is connected to the patch dipole lower arm 2 .

[0035] The upper arm 1 of the patch dipole includes:

[0036] a first inverted L-shaped microstrip line 12, one end of which is electrically connected to the microchip 3; the first inverted L-shaped microstrip line 12 is composed of a long microstrip line and a short microstrip line, wherein the long microstrip line and the short microstrip line are perpendicular to each other; and the microchip 3 is connected to one end of the long microstrip line;

[0037] a first U-shaped microstrip line 13, the first U-shaped microstrip line 13 being connected to an end of the first inverted L-shaped microstrip line 12 away from the microchip 3, the first U-shaped microstrip line 13 being composed of two long microstrip lines and a short microstrip line perpendicular to the long microstrip lines, the first U-shaped microstrip line 13 being symmetrical about its own axis of symmetry, and the first U-shaped microstrip line 13 being connected to one end of the short microstrip line of the first inverted L-shaped microstrip line 12;

[0038] A second U-shaped microstrip line 14, the second U-shaped microstrip line 14 is connected to the end of the first U-shaped microstrip line 13 away from the first inverted L-shaped microstrip line 12, and the second U-shaped microstrip line 14 is longer than the first U-shaped microstrip line 13;

[0039] a third U-shaped microstrip line 15, the third U-shaped microstrip line 15 being connected to an end of the second U-shaped microstrip line 14 away from the first U-shaped microstrip line 13, the third U-shaped microstrip line 15 being longer from top to bottom than the first U-shaped microstrip line 13, and the third U-shaped microstrip line 15 being longer from top to bottom than the second U-shaped microstrip line 14;

[0040] a fourth U-shaped microstrip line 16, the fourth U-shaped microstrip line 16 being connected to an end of the third U-shaped microstrip line 15 away from the second U-shaped microstrip line 14, and the fourth U-shaped microstrip line 16 and the second U-shaped microstrip line 14 being bilaterally symmetrical about the axis of symmetry of the third U-shaped microstrip line 15;

[0041] A U-shaped switch loaded microstrip line 17 is connected to an end of the fourth U-shaped microstrip line 16 away from the third U-shaped microstrip line 15 , and the U-shaped switch loaded microstrip line 17 and the first U-shaped microstrip line 13 are bilaterally symmetrical about the symmetry axis of the third U-shaped microstrip line 15 ;

[0042] The inverted L-shaped switch loaded microstrip line 18 is connected to the end of the U-shaped switch loaded microstrip line 17 away from the fourth U-shaped microstrip line 16 . The inverted L-shaped switch loaded microstrip line 18 and the first inverted L-shaped microstrip line 12 are symmetrical about the symmetry axis of the third U-shaped microstrip line 15 .

[0043] The U-shaped switch loaded microstrip line 17 comprises:

[0044] Switch tube structure 14 is arranged on the short microstrip line below the U-shaped switch loading microstrip line 17. Switch tube structure 14 is composed of a diode in parallel with a capacitor. The anode of switch tube structure 14 is connected to the left microstrip line, and the cathode is connected to the right microstrip line.

[0045] The inverted L-shaped switch loaded microstrip line 18 comprises:

[0046] The switch tube structure 2 5 is arranged on the short microstrip line on the upper left side of the inverted L-shaped switch loading microstrip line 18. The switch tube structure 2 5 is composed of a diode and a capacitor in parallel. The anode of the switch tube structure 2 5 is connected to the left microstrip line, and the cathode is connected to the right microstrip line.

[0047] The widths of the multiple microstrip lines are the same.

[0048] The lower arm 2 of the patch dipole includes:

[0049] A first inverted L-shaped tapered microstrip line 6 is composed of an L-shaped patch microstrip line with an inverted long side and eleven tapered patch pillars that gradually increase in length from short to long. The patch pillars extend away from the axis of symmetry of the third U-shaped microstrip line 15. Except for the first and eleventh patch pillars, the remaining patch pillars are paired in pairs, with lengths increasing by equal amounts. The left side of the eleventh patch pillar overlaps with one side of the first inverted L-shaped tapered microstrip line 6.

[0050] The second inverted L-shaped tapered microstrip line 7 is bilaterally symmetrical to the first inverted L-shaped tapered microstrip line 6 about the symmetry axis of the third U-shaped microstrip line 15 .

[0051] The microchip 3 provides excitation from the input port to the tag antenna. The microchip 3 uses a commercial microchip 3 to store the required information and operates within the wide international frequency range of 840-960 MHz.

[0052] The dielectric layer 9 is made of dielectric material with a dielectric constant of 4.4, a height of 1.6 mm, and a loss tangent of 0.02. The air layer 10 is 5.4 mm high. The metal layer 11 is made of metal with good conductive properties and is pressed onto the bottom of the dielectric layer 9 .

[0053] Working principle: The patch information and bias voltage energy are emitted by the microchip 3, flow into one end of the first inverted L-shaped microstrip line 12, flow and radiate along the upper arm 1 of the patch dipole, pass through the first U-shaped microstrip line 13, the second U-shaped microstrip line 14, the third U-shaped microstrip line 15, and the fourth U-shaped microstrip line 16 to reach the U-shaped switch loading microstrip line 17. At this time, there are three situations:

[0054] If the bias voltage emitted by microchip 3 is greater than the sum of the forward voltages of the two diodes, switch structure 1 4 is in the on state, and energy flows through U-shaped switch-loaded microstrip line 17 to inverted L-shaped switch-loaded microstrip line 18. Switch structure 2 5 is also turned on, and energy flows to the end of inverted L-shaped switch-loaded microstrip line 18. At this point, the radiation current path is the longest, corresponding to the lowest desired resonant frequency fL.

[0055] 2. If the bias voltage emitted by microchip 3 is less than the forward voltage of a single diode, switch structure 1 (4) is in the off state, and energy flow is cut off at switch structure 1 (4) along the long microstrip line to the left of inverted U-shaped switch loading microstrip line 17. At this point, no energy flows along the long microstrip line to the right of U-shaped switch loading microstrip line 17 and along inverted L-shaped switch loading microstrip line 18, corresponding to the desired highest resonant frequency fH.

[0056] 3. If the bias voltage emitted by microchip 3 is greater than the forward turn-on voltage of a single diode and less than the sum of the forward turn-on voltages of two diodes, switch tube structure 1 4 is in the on state, and energy flows through the U-shaped switch-loaded microstrip line 17 and reaches switch tube structure 2 5, where it is cut off. At this point, only the inverted L-shaped switch-loaded microstrip line 18 has no energy flowing, corresponding to the desired highest resonant frequency fM. This allows the antenna resonant frequency to be controlled by varying the bias voltage emitted by the microchip. The gradient patch columns on the left and right sides of the lower arm 2 of the patch dipole can slow down the drastic change in impedance at the antenna port and reduce the required antenna size.

[0057] The width of the microstrip lines at all locations in the upper arm 1 of the patch dipole is equal to W1.

[0058] The vertical extension length of the first U-shaped microstrip line 13 is equal to that of the U-shaped switch-loaded microstrip line 17. The vertical extension length of the second U-shaped microstrip line 14 is equal to that of the fourth U-shaped microstrip line 16. The vertical extension length L1 of the first U-shaped microstrip line 13, the vertical extension length L2 of the second U-shaped microstrip line 14, the vertical extension length L3 of the third U-shaped microstrip line 15, the vertical extension length L4 of the inverted L-shaped switch-loaded microstrip line, the vertical extension length L0 of the first inverted L-shaped microstrip line 12, the microstrip line width W1, the antenna length L, and the width W satisfy the following relationship:

[0059]

[0060] is the characteristic impedance, usually 50 ohms. h is the equivalent thickness of the dielectric layer and the air layer. It is a number between the dielectric constants of the dielectric layer 9 and the air layer 10.

[0061]

[0062]

[0063]

[0064] in, 、 、 are the center frequencies of the lowest, middle, and highest frequency bands you wish to reconstruct, and c is the speed of light in a vacuum. You can assign specific values ​​based on your needs.

[0065] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without making creative efforts should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention shall be implemented in accordance with conventional means in the field unless otherwise specified or limited.

Claims

1. A frequency reconfigurable RFID tag antenna, characterized by: The invention comprises an antenna layer (8), a dielectric layer (9), an air layer (10), and a metal layer (11), wherein the dielectric layer (9) is arranged below the antenna layer (8), the air layer (10) is arranged below the dielectric layer (9), and the metal layer (11) is arranged below the air layer (10); The antenna layer (8) is composed of a patch dipole upper arm (1), a patch dipole lower arm (2) and a microchip (3), one end of the microchip (3) is connected to the patch dipole upper arm (1), and the other end of the microchip (3) is connected to the patch dipole lower arm (2); The patch dipole upper arm (1) comprises: An inverted L-shaped switch loaded microstrip line (18), wherein the inverted L-shaped switch loaded microstrip line (18) comprises a second switch tube structure (5), wherein the second switch tube structure (5) is composed of a diode connected in parallel with a capacitor; The patch dipole upper arm (1) further comprises: a first inverted L-shaped microstrip line (12), one end of the first inverted L-shaped microstrip line (12) being electrically connected to the microchip (3), the first inverted L-shaped microstrip line (12) being composed of a long microstrip line and a short microstrip line, the long microstrip line and the short microstrip line being perpendicular to each other, and the microchip (3) being connected to one end of the long microstrip line; A first U-shaped microstrip line (13) is connected to one end of the first inverted L-shaped microstrip line (12) away from the microchip (3), the first U-shaped microstrip line (13) is composed of two long microstrip lines and a short microstrip line perpendicular to the long microstrip lines, the first U-shaped microstrip line (13) is symmetrical about its own symmetry axis, and the first U-shaped microstrip line (13) is connected to one end of the short microstrip line of the first inverted L-shaped microstrip line (12).

2. The frequency reconfigurable RFID tag antenna according to claim 1, wherein: The patch dipole upper arm (1) further comprises: a second U-shaped microstrip line (14), the second U-shaped microstrip line (14) being connected to an end of the first U-shaped microstrip line (13) away from the first inverted L-shaped microstrip line (12), the second U-shaped microstrip line (14) having a greater upper and lower length than the first U-shaped microstrip line (13); a third U-shaped microstrip line (15), the third U-shaped microstrip line (15) being connected to an end of the second U-shaped microstrip line (14) away from the first U-shaped microstrip line (13), the third U-shaped microstrip line (15) having a greater upper and lower length than the first U-shaped microstrip line (13), and the third U-shaped microstrip line (15) having a greater upper and lower length than the second U-shaped microstrip line (14); A fourth U-shaped microstrip line (16) is connected to an end of the third U-shaped microstrip line (15) away from the second U-shaped microstrip line (14), and the fourth U-shaped microstrip line (16) and the second U-shaped microstrip line (14) are bilaterally symmetrical about the symmetry axis of the third U-shaped microstrip line (15).

3. The frequency reconfigurable RFID tag antenna according to claim 2, wherein: The patch dipole upper arm (1) further comprises: A U-shaped switch loaded microstrip line (17), the U-shaped switch loaded microstrip line (17) being connected to an end of a fourth U-shaped microstrip line (16) away from the third U-shaped microstrip line (15), the U-shaped switch loaded microstrip line (17) being bilaterally symmetrical with the first U-shaped microstrip line (13) about an axis of symmetry of the third U-shaped microstrip line (15); The inverted L-shaped switch-loaded microstrip line (18) is connected to an end of the U-shaped switch-loaded microstrip line (17) away from the fourth U-shaped microstrip line (16), and the inverted L-shaped switch-loaded microstrip line (18) and the first inverted L-shaped microstrip line (12) are bilaterally symmetrical about the symmetry axis of the third U-shaped microstrip line (15).

4. The frequency reconfigurable RFID tag antenna according to claim 3, wherein: The U-shaped switch loaded microstrip line (17) comprises: A switch tube structure (4) is provided on a short microstrip line below the U-shaped switch loading microstrip line (17), the switch tube structure (4) is composed of a diode connected in parallel with a capacitor, the anode of the switch tube structure (4) is connected to the left microstrip line, and the cathode is connected to the right microstrip line.

5. The frequency reconfigurable RFID tag antenna according to claim 4, characterized in that: The switch tube structure 2 (5) is arranged on a short microstrip line on the upper left side of the inverted L-shaped switch loading microstrip line (18), and the anode of the switch tube structure 2 (5) is connected to the left microstrip line, and the cathode is connected to the right microstrip line.

6. The frequency reconfigurable RFID tag antenna according to claim 5, characterized in that: The widths of the plurality of microstrip lines are the same.

7. The frequency reconfigurable RFID tag antenna according to claim 6, wherein: The patch dipole lower arm (2) comprises: A first inverted L-shaped tapered microstrip line (6), the first inverted L-shaped tapered microstrip line (6) consisting of an L-shaped patch microstrip line with an inverted long side and eleven tapered patch columns with short sides becoming longer; A second inverted L-shaped gradient microstrip line (7), wherein the second inverted L-shaped gradient microstrip line (7) and the first inverted L-shaped gradient microstrip line (6) are bilaterally symmetrical about the symmetry axis of the third U-shaped microstrip line (15).

8. The frequency reconfigurable RFID tag antenna according to claim 1, wherein: The microchip (3) uses a commercial microchip (3) to store the required information and operates within a wide international frequency range of 840-960 MHz.

9. The frequency reconfigurable RFID tag antenna according to claim 1, wherein: The dielectric layer (9) is made of a dielectric material with a dielectric constant of 4.4, a height of 1.6 mm, and a loss tangent of 0.

02. The air layer (10) has a height of 5.4 mm. The metal layer (11) is made of a metal with good conductive properties and is pressed and attached to the bottom of the dielectric layer (9).

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