A low-profile ultra-high frequency high-gain dual-dipole tag antenna

Abstract

The present invention provides a low-profile ultra-high frequency high-gain double dipole tag antenna, which uses a single-layer rectangular FR4 dielectric plane dielectric plate to form an antenna. Metal dipole antennas are respectively designed on the upper surface of the plane dielectric plate, and the middle part thereof is in an open arc shape. A wireless radio frequency identification chip antenna interface is designed in the middle part of the upper surface of the plane dielectric plate, which is connected to a ring coil. The metal dipole antennas on the bottom layer and the top layer are coupled through a single-open metal circular ring coupling structure, a double-open metal circular ring coupling structure and a single-open metal ring coupling feeding ring in the middle of the plane dielectric plate, so as to achieve good matching and large bandwidth with a 915MHz ultra-high frequency wireless radio frequency identification chip. At the same time, by adjusting the current path, the radiation electric fields on the two metal dipole antenna arms on the bottom layer of the plane dielectric plate and the two metal dipole antenna arms on the bottom layer of the top layer are constructed, so that the high gain of the tag antenna is achieved with an extremely low profile and length, and the bandwidth can be as wide as 550MHz.

Description

Technical Field

[0001] The invention relates to the technical field of wireless radio frequency identification, and in particular to a low-profile ultra-high frequency high-gain double dipole tag antenna. Background Art

[0002] Radio Frequency Identification (RFID) is a type of automatic identification technology that uses radio frequency to conduct non-contact two-way data communication and read and write recording media (electronic tags or radio frequency cards) to achieve the purpose of identifying targets and exchanging data. It is considered to be one of the information technologies with the greatest development potential in the 21st century.

[0003] Radio frequency identification technology uses radio waves for non-contact rapid information exchange and storage technology, combines wireless communication with data access technology, and then connects to the database system to achieve non-contact two-way communication, thereby achieving the purpose of identification and being used for data exchange, connecting an extremely complex system.

[0004] As a key technology for data interaction in the Internet of Things, radio frequency identification technology RFID is currently widely used for marking and identifying objects. The current development directions of RFID mainly include long-distance data identification communication, identification communication in complex environments, and passive and active sensor identification communication.

[0005] In the RFID system, the antenna that acts as the electromagnetic wave transmitter and receiver plays a pivotal role. For the tags placed on the objects for marking and identification, the tag antenna usually needs to be impedance matched with the RFID chip. However, the impedance of the RFID chip is usually not the standard 50 ohms, which increases the difficulty of antenna matching design. Most of the tag antennas currently used are dipole meander line antennas. However, with the advent of the Internet of Things era and the continuous deepening of RFID applications, there is an urgent need for tag antennas with high gain, good stability and easy expansion design. Metal dipole antennas are favored as the simplest antennas. The gain of a single metal dipole antenna is about 2.14dB, which is difficult to meet people's needs. Adding a reflector behind the antenna can increase the antenna gain, but the reflector needs to be a quarter wavelength away from the antenna. For RFID antennas working at ultra-high frequencies, the thickness will reach 10cm or more. In recent years, academic research on electromagnetic bandgap structures can increase antenna gain and reduce the distance between the reflector and the antenna, but its structure and manufacturing process are relatively complex. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a low-profile UHF high-gain dual dipole tag antenna to solve the high gain, low profile and impedance adjustment problems of RFID tag antennas in the UHF band in the prior art.

[0007] To achieve the above-mentioned purpose and other related purposes, the present invention provides a low-profile ultra-high frequency high-gain dual dipole tag antenna, comprising: a planar dielectric plate, and a single-open metal annular coupling structure, a single-open metal annular coupling feeding ring and a double-open metal annular coupling structure located on the upper surface of the planar dielectric plate;

[0008] The single-open metal annular coupling feeding ring is embedded in the single-open metal circular coupling structure, and there is a first distance between the two, and the distance value of the first distance can be adjusted;

[0009] The double-opening metal annular coupling structure is embedded in the single-opening metal annular coupling structure, and there is a second distance between the two, and the distance value of the second distance can be adjusted;

[0010] Two sets of mutually parallel metal dipole antennas are also arranged on the upper surface of the planar dielectric plate, one set of metal dipole antennas is connected to the single-opening metal circular ring coupling structure, and the other set of metal dipole antennas is connected to the double-opening metal circular ring coupling structure.

[0011] Optionally, each set of metal dipole antennas includes two metal dipole antenna arms;

[0012] The single-opening metal annular coupling structure has a first opening, and two sides of the first opening are respectively connected to a metal dipole antenna arm;

[0013] The double-opening metal circular ring coupling structure has a second opening and a third opening, two parallel metal strips extend from both sides of the second opening, and each metal strip is respectively connected to a metal dipole antenna arm; the opening direction of the third opening is close to or overlaps the opening direction of the first opening, or the opening direction of the third opening is close to or overlaps the opening direction of the single-opening metal ring coupling feeding ring.

[0014] Optionally, the single-open metal annular coupling feeding ring, the single-open metal annular coupling structure, and two metal dipole antenna arms connected to the single-open metal annular coupling structure together form a layer structure on the upper surface of the planar dielectric plate, which is recorded as a top layer structure;

[0015] The double-opening metal circular ring coupling structure and the two metal dipole antenna arms connected to the double-opening metal circular ring coupling structure form a layer of structure on the upper surface of the planar dielectric plate, which is recorded as the bottom layer structure; and the top layer structure is located on the bottom layer structure.

[0016] Optionally, the single-opening metal annular coupling feed ring has a fourth opening, two parallel square metal strips are connected to the opening of the fourth opening, and the two parallel square metal strips cooperate with the single-opening metal annular coupling feed ring to form a wireless radio frequency identification chip welding port.

[0017] Optionally, the distance value of the first spacing is smaller than the distance value of the second spacing; the first spacing is 0.5 mm, and the second spacing is 0.65 mm.

[0018] Optionally, the planar dielectric plate is FR4; the planar dielectric plate has a dielectric constant of 4.4, a thickness of 1 mm, a length of 196 mm, and a width of 28.25 mm.

[0019] Optionally, the inner radius of the single-opening metal circular ring coupling structure is 8.5 mm, and the outer radius is 10.5 mm; the inner radius of the double-opening metal circular ring coupling structure is 4.92 mm, and the outer radius is 5.85 mm.

[0020] Optionally, the inner radius of the single-open metal ring-shaped coupling feeding ring is 6.5 mm, and the outer radius is 8 mm.

[0021] Optionally, the opening width of the single-opening metal ring-shaped coupling feeding ring is 1.6 mm; the opening width of the double-opening metal ring-shaped coupling structure is 4 mm; and the opening width of the single-opening metal ring-shaped coupling structure is 4 mm.

[0022] Optionally, the metal dipole antenna is formed by a metal copper sheet; any one of the metal dipole antenna arms connected to the single-opening metal circular ring coupling structure is 95.5 mm long and 2 mm wide; any one of the metal dipole antenna arms connected to the double-opening metal circular ring coupling structure is 95 mm long and 2.25 mm wide.

[0023] As described above, the present invention provides a low-profile ultra-high frequency high-gain dual-dipole tag antenna, which has the following beneficial effects: the present invention adopts a circular nested co-feeding method to increase the bandwidth and make its working performance more stable; the antenna in the present invention is composed of two metal dipole antennas, which can achieve high gain under low profile conditions; the impedance of the circular feeding structure in the present invention is easy to adjust, so that it is easy to match with radio frequency identification chips of various impedances. The present invention can increase the inductive reactance by increasing the width of the coupling feed ring or the circular feeding structure; and can increase the capacitive reactance by increasing the spacing between the coupling feed ring and the circular feeding structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of an antenna body of the present invention;

[0025] Figure 2 It is a schematic diagram of a double-open metal circular ring coupling structure;

[0026] Figure 3 It is a schematic diagram of a single-open metal circular ring coupling structure and a single-open ring feeding ring;

[0027] Figure 4 It is the S parameter simulation diagram in the present invention;

[0028] Figure 5 It is a schematic diagram of the radiation direction of the H surface in the present invention;

[0029] Figure 6 It is a schematic diagram of the E-plane radiation direction in the present invention. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0032] See also Figures 1 to 6As shown, the present invention provides a low-profile ultra-high frequency high-gain dual dipole tag antenna, including a planar dielectric plate, the planar dielectric plate is FR4; the dielectric constant of the planar dielectric plate is 4.4, the thickness is 1mm, the length is 196mm, and the width is 28.25mm.

[0033] It also includes a single-open metal circular ring coupling structure, a single-open metal circular ring coupling feeding ring, a double-open metal circular ring coupling structure and a metal dipole antenna arm located on the upper surface of the planar dielectric plate; the single-open metal circular ring coupling feeding ring is embedded in the single-open metal circular ring coupling structure, and there is a first spacing between the two; the double-open metal circular ring coupling structure is embedded in the single-open metal circular ring coupling structure, and there is a second spacing between the two; wherein the distance value of the first spacing can be adjusted, and the distance value of the second spacing can be adjusted; two groups of metal dipole antennas are also provided on the upper surface of the planar dielectric plate, and the two groups of metal dipole antennas are parallel to each other; one group of metal dipole antennas is connected to the single-open metal circular ring coupling structure, and the other group of metal dipole antennas is connected to the double-open metal circular ring coupling structure.

[0034] Each group of metal dipole antennas includes two metal dipole antenna arms; the single-opening metal circular ring coupling structure has a first opening, and the two sides of the first opening are respectively connected to a metal dipole antenna arm. The double-opening metal circular ring coupling structure has a second opening and a third opening, and two parallel metal strips extend from the two sides of the second opening, and each metal strip is respectively connected to a metal dipole antenna arm; the opening direction of the third opening is close to or overlaps the opening direction of the first opening, or the opening direction of the third opening is close to or overlaps the opening direction of the single-opening metal circular ring coupling feeding ring. The parallel metal strips extending from the central lower opening of the double-opening metal circular ring coupling structure are 1.5mm wide and 7.42mm long.

[0035] In the embodiments of the present application, Figures 1 to 3 As shown, the single-open metal ring coupling feed ring, the single-open metal ring coupling structure, and the two metal dipole antenna arms connected to the single-open metal ring coupling structure together form a layer structure on the upper surface of the planar dielectric plate, which is recorded as the top structure, and the corresponding metal dipole antenna is recorded as the dielectric plate top metal dipole antenna. The double-open metal ring coupling structure and the two metal dipole antenna arms connected to the double-open metal ring coupling structure form a layer structure on the upper surface of the planar dielectric plate, which is recorded as the bottom structure, and the corresponding metal dipole antenna is recorded as the dielectric plate bottom metal dipole antenna.

[0036] A wireless radio frequency identification chip antenna interface is designed in the middle of the upper surface of the planar dielectric plate, which is connected to an open ring coil. The upper and lower layers of metal dipole antennas are coupled with the single open ring coil through the single open metal circular ring coupling structure and the double open circular ring structure in the middle, achieving good matching and large bandwidth with the 915MHz ultra-high frequency wireless radio frequency identification chip. At the same time, the three continuously nested coupling structures adjust the current path so that the radiation electric fields on the two metal dipole antenna arms on the bottom layer and the two metal dipole antenna arms on the top layer on the upper surface of the planar dielectric plate are constructive, so that the high gain of the tag antenna is achieved with an extremely low profile and length, and the bandwidth can be as wide as 550MHz, perfectly covering the entire ultra-high frequency band (860MHz-960MHz). As an example, two parallel square metal strips are connected to the opening of the single open metal ring coupling feed ring, and the two parallel square metal strips cooperate with the single open metal ring coupling feed ring to form a wireless radio frequency identification chip welding port.

[0037] In the embodiment of the present application, the distance between the first spacing and the second spacing can be adjusted. As an example, the first spacing is 0.5 mm and the second spacing is 0.65 mm.

[0038] In the present invention, the opening direction of the single-open coupling feed ring or the single-open metal annular coupling structure is the upper end. The planar dielectric plate in the present invention is FR4 material, whose dielectric constant is 4.4, thickness is 1mm, length is 196mm, and width is 28.25mm. The inner circle radius of the single-open coupling feed ring is 6.5mm, the outer circle radius is 8mm, and the central upper end opening width of the single-open coupling feed ring is 1.6mm. Two parallel square metal strips with a length of 8mm and a width of 0.7mm are longitudinally connected at the opening, which is the chip welding port. The upper metal dipole antenna of the dielectric plate is composed of two identical metal copper sheets extending left and right. The length of a single metal copper sheet is 95.5mm and the width is 2mm. The upper metal dipole antenna of the dielectric plate is connected to the single-open metal annular coupling structure at the opening. The inner circle radius of the single-open metal annular coupling structure is 8.5mm, the outer circle radius is 10.5mm, the opening direction of the single-open metal annular coupling structure is the central upper part of the ring, and the opening width is 4mm. The single-open coupling feed ring is embedded in the single-open annular coupling feed structure, and the spacing between them is 0.5mm. The lower metal dipole antenna of the dielectric plate is composed of two identical metal copper sheets extending left and right. The length of a single metal copper sheet is 95mm and the width is 2.25mm. The lower metal dipole antenna of the dielectric plate is connected to the parallel metal strips extending from the central lower opening of the double-opening metal circular coupling structure. The parallel metal strips extending from the central lower opening of the double-opening metal circular coupling structure are 1.5mm wide and 7.42mm long. The central opening of the double-opening metal circular coupling structure is 4mm wide, the inner circle radius of the double-opening metal circular coupling structure is 4.92mm, and the outer circle radius is 5.85mm. The double-opening metal circular coupling structure is embedded in the single-opening annular coupling feed structure, and the spacing between them is 0.65mm. The double-open metal circular ring coupling structure, the embedding distance between the single-open metal circular ring coupling feeding ring and the single-open metal circular ring coupling structure, the embedding shape and the thickness of the ring structure can be adjusted, so as to adjust the impedance matching with the radio frequency chip and adjust the current path so that the currents of the two metal dipole antenna arms in the same group can flow in the same direction, thereby improving the gain of the antenna in the present invention.

[0039] The antenna of the present invention has good broadband performance and high gain. Figures 4 to 6 The figure shows the S parameter simulation diagram of the antenna of the present invention and the schematic diagram of the radiation direction of the E plane and the H plane. The antenna impedance of the present invention is easy to adjust. By increasing the width of the coupling feed ring or the annular feed structure, the inductive reactance can be increased; by increasing the spacing between the coupling feed ring and the annular feed structure, the capacitive reactance can be increased.

[0040] In summary, the present invention adopts a circular nested co-feeding method to increase the bandwidth and make its working performance more stable; the antenna in the present invention is composed of two metal dipole antennas, which can achieve high gain in the case of low profile; the impedance of the circular feeding structure in the present invention is easy to adjust, so that it is easy to match with radio frequency identification chips of various impedances, and realize long-distance wireless radio frequency identification. In the present invention, a single-layer rectangular FR4 dielectric plane dielectric plate is used to form an antenna. The upper surface of the plane dielectric plate is respectively designed with metal dipole antennas, and the middle part is an open arc shape. A wireless radio frequency identification chip antenna interface is designed in the middle of the upper surface of the plane dielectric plate, which is connected to a ring coil, that is, a single open metal ring coupling feeding ring. The metal dipole antenna on the bottom layer and the metal dipole antenna on the top layer are coupled with the single open metal ring coupling feeding ring through the single open metal ring coupling structure and the double open metal ring coupling structure in the middle of the plane dielectric plate, which can achieve good matching and large bandwidth with the 915MHz ultra-high frequency wireless radio frequency identification chip. At the same time, by adjusting the current path, the radiation electric fields on the two metal dipole antenna arms at the bottom layer of the planar dielectric board and the two metal dipole antenna arms at the bottom layer of the top layer are constructive, so that the high gain of the tag antenna is achieved with an extremely low profile and length, and the bandwidth can be as wide as 550MHz.

[0041] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A low-profile ultra-high frequency high-gain dual-dipole tag antenna, characterized in that: It includes a planar dielectric plate, and a single-opening metal annular coupling structure, a single-opening metal annular coupling feeding ring and a double-opening metal annular coupling structure located on the upper surface of the planar dielectric plate; The single-open metal annular coupling feeding ring is embedded in the single-open metal circular coupling structure, and there is a first distance between the two, and the distance value of the first distance can be adjusted; The double-opening metal annular coupling structure is embedded in the single-opening metal annular coupling structure, and there is a second distance between the two, and the distance value of the second distance can be adjusted; Two sets of mutually parallel metal dipole antennas are also provided on the upper surface of the planar dielectric plate, wherein one set of metal dipole antennas is connected to the single-opening metal circular ring coupling structure, and the other set of metal dipole antennas is connected to the double-opening metal circular ring coupling structure; Wherein, each set of metal dipole antennas includes two metal dipole antenna arms; The single-opening metal annular coupling structure has a first opening, and two sides of the first opening are respectively connected to a metal dipole antenna arm; The double-opening metal annular coupling structure has a second opening and a third opening, two parallel metal strips extend from both sides of the second opening, and each metal strip is respectively connected to a metal dipole antenna arm; the opening direction of the third opening is close to or overlaps the opening direction of the first opening, or the opening direction of the third opening is close to or overlaps the opening direction of the single-opening metal annular coupling feeding ring; The single-opening metal annular coupling feed ring has a fourth opening, and two parallel square metal strips are connected to the opening of the fourth opening, and the two parallel square metal strips cooperate with the single-opening metal annular coupling feed ring to form a wireless radio frequency identification chip welding port; The single-open metal annular coupling feeding ring, the single-open metal annular coupling structure, and two metal dipole antenna arms connected to the single-open metal annular coupling structure together form a layer of structure on the upper surface of the planar dielectric plate, which is recorded as a top layer structure; The double-opening metal circular ring coupling structure and the two metal dipole antenna arms connected to the double-opening metal circular ring coupling structure form a layer of structure on the upper surface of the planar dielectric plate, which is recorded as the bottom layer structure; and the top layer structure is located on the bottom layer structure.

2. The low-profile ultra-high frequency high-gain dual dipole tag antenna according to claim 1, characterized in that: The distance value of the first spacing is smaller than the distance value of the second spacing; the first spacing is 0.5 mm, and the second spacing is 0.65 mm.

3. The low-profile ultra-high frequency high-gain dual dipole tag antenna according to claim 1, characterized in that: The planar dielectric plate is FR4; the planar dielectric plate has a dielectric constant of 4.4, a thickness of 1 mm, a length of 196 mm, and a width of 28.25 mm.

4. The low-profile ultra-high frequency high-gain dual dipole tag antenna according to claim 1, characterized in that: The inner radius of the single-opening metal circular ring coupling structure is 8.5 mm, and the outer radius is 10.5 mm; the inner radius of the double-opening metal circular ring coupling structure is 4.92 mm, and the outer radius is 5.85 mm.

5. The low-profile ultra-high frequency high-gain dual-dipole tag antenna according to claim 1, characterized in that: The inner radius of the single-open metal annular coupling feeding ring is 6.5 mm, and the outer radius is 8 mm.

6. The low-profile ultra-high frequency high-gain dual dipole tag antenna according to claim 1, characterized in that: The opening width of the single-opening metal ring coupling feeding ring is 1.6 mm; the opening width of the double-opening metal ring coupling structure is 4 mm; and the opening width of the single-opening metal ring coupling structure is 4 mm.

7. The low-profile ultra-high frequency high-gain dual-dipole tag antenna according to claim 1, characterized in that: The metal dipole antenna is formed of a metal copper sheet; any one of the metal dipole antenna arms connected to the single-opening metal circular coupling structure is 95.5 mm long and 2 mm wide; Any one of the metal dipole antenna arms connected to the double-open metal circular coupling structure is 95 mm long and 2.25 mm wide.

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