Antenna structure

Abstract

The present invention provides an antenna structure, comprising a plurality of radiating parts and a plurality of extending parts. The radiating parts are separated from each other and arranged in a circle. The extending part is connected to the radiating parts and extends toward the center of the circle. The first gap between the two top ends of two adjacent radiating parts is equal to the second gap between the two bottom ends of two adjacent extending parts. The antenna structure of the present invention can provide a uniformly distributed close-range magnetic field and has a high induction sensitivity and induction accuracy.

Description

Technical Field

[0001] The invention relates to an antenna structure, and in particular to an antenna structure used in short-distance wireless communication. Background Art

[0002] Radio Frequency Identification (RFID) technology uses an RFID reader with an antenna to generate an electromagnetic field or transmit electromagnetic waves to an RFID tag. After receiving or sensing the electromagnetic wave, the RFID tag can generate a response electromagnetic field or electromagnetic wave for the RFID reader to identify. Wireless identification through RFID technology has been widely used in automated production equipment, warehouse management, electronic toll collection and other purposes.

[0003] Antenna is an important component of RFID reader, and the design of antenna greatly affects the efficiency of wireless identification. Existing antennas are divided into far field antennas and near field antennas according to the transmission distance. Far field antennas are used to transmit or receive far field electromagnetic waves, so they focus more on the size of gain; while near field antennas are mostly used in RFID readers, which use electromagnetic coupling to read the memory data of the object to be tested. Therefore, near field antennas pay more attention to the electromagnetic field strength. Summary of the invention

[0004] The present invention is directed to an antenna structure which can provide a uniformly distributed short-range magnetic field and has high sensing sensitivity and sensing accuracy.

[0005] According to an embodiment of the present invention, the antenna structure includes a plurality of radiating portions and a plurality of extending portions. The radiating portions are separated from each other and arranged in a circle. The extending portions are connected to the radiating portions and extend toward the center of the circle. A first gap between two top ends of two adjacent radiating portions is equal to a second gap between two bottom ends of two adjacent extending portions.

[0006] In the antenna structure according to the embodiment of the present invention, the range of the first gap is between 0.5 mm and 4 mm.

[0007] In the antenna structure according to the embodiment of the present invention, the radiation portion and the extension portion are integrally formed.

[0008] In the antenna structure according to the embodiment of the present invention, each of the above-mentioned radiating portions has a first arc-shaped edge and a second arc-shaped edge opposite to each other. The length of the first arc-shaped edge is greater than the length of the second arc-shaped edge. The extension portion connects two opposite sides of the second arc-shaped edge respectively.

[0009] In the antenna structure according to the embodiment of the present invention, the shortest distance from the first arc-shaped edge to the second arc-shaped edge is between 34 mm and 40 mm.

[0010] In the antenna structure according to the embodiment of the present invention, each of the above-mentioned radiating portions is in a sector shape.

[0011] In the antenna structure according to the embodiment of the present invention, the angle between the extension direction of the two adjacent first gaps and the center of the circle is 90 degrees.

[0012] In the antenna structure according to the embodiment of the present invention, one of the radiating parts has an opening to divide the radiating part into a first radiating part and a second radiating part. The diameter of the opening is equal to the first gap.

[0013] In the antenna structure according to the embodiment of the present invention, each of the extension portions includes a first extension portion and a second extension portion, and the first extension portion is vertically connected to the second extension portion.

[0014] In the antenna structure according to the embodiment of the present invention, the length of the first extension portion is between 29 mm and 32 mm.

[0015] In the antenna structure according to the embodiment of the present invention, the length of the second extension portion is between 8 mm and 15 mm.

[0016] In the antenna structure according to the embodiment of the present invention, each of the extension portions is L-shaped.

[0017] In the antenna structure according to the embodiment of the present invention, the L-shaped extensions of each of the extensions are separated by a second gap and are back-to-back in a left-right inverted structure.

[0018] In the antenna structure according to the embodiment of the present invention, the thickness of each radiating portion and the thickness of each extending portion are between 0.018 mm and 0.07 mm.

[0019] In the antenna structure according to the embodiment of the present invention, the first radiating portion and the second radiating portion are connected by a transmission line as a feeding line.

[0020] In the antenna structure according to the embodiment of the present invention, the transmission line is a SAM connector, an N-type connector or a TNC connector.

[0021] In the antenna structure according to the embodiment of the present invention, the antenna structure further includes a carrier, and the radiation portion and the extension portion are disposed on the carrier.

[0022] In the antenna structure according to the embodiment of the present invention, the shape of the carrier includes square or circle.

[0023] In the antenna structure according to the embodiment of the present invention, the side length or diameter of the carrier is between 160 mm and 180 mm.

[0024] In the antenna structure according to the embodiment of the present invention, the thickness of the carrier is between 1.5 mm and 2.5 mm.

[0025] In the antenna structure according to the embodiment of the present invention, the material of the carrier includes paper material, ceramic, epoxy resin glass fiber board, polyimide, polyester, polyurethane, polycarbonate, polyethylene or polypropylene.

[0026] In the antenna structure according to the embodiment of the present invention, the material of the radiation portion and the material of the extension portion include copper, silver or conductive ink.

[0027] Based on the above, in the design of the antenna structure of the present invention, the radiating parts of the antenna structure are separated from each other and arranged in a circle, which can achieve the effect of mutual resonance and generate a close-range magnetic field above the antenna structure. In addition, the extension part of the antenna structure is connected to the radiating part and extends toward the center of the circle, so that the magnetic field is evenly distributed. In short, the antenna structure of the present invention can provide a uniformly distributed close-range magnetic field and has a higher sensing sensitivity and sensing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic top view of an antenna structure according to an embodiment of the present invention;

[0029] Figure 2 yes Figure 1 The frequency and impedance value curve of HFSS computer simulation antenna structure test;

[0030] Figure 3 yes Figure 1 The frequency and loss value curve of the HFSS computer simulation antenna structure test.

[0031] Description of Reference Numerals

[0032] 10: transmission line;

[0033] 100: antenna structure;

[0034] 110a, 110b, 110c, 110d: radiation parts;

[0035] 112: first arc-shaped edge;

[0036] 114: second arc-shaped edge;

[0037] 113: Open your mouth;

[0038] 115: first radiation part;

[0039] 117: second radiation part;

[0040] 120: extension;

[0041] 122: first extension portion;

[0042] 124: second extension portion;

[0043] 130: carrier;

[0044] A: Angle;

[0045] C: center of circle;

[0046] D: caliber;

[0047] L: shortest distance;

[0048] L1, L2: length;

[0049] G1: first gap;

[0050] G2: second gap;

[0051] T: side length. DETAILED DESCRIPTION

[0052] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, like element reference numerals are used in the drawings and the description to refer to the same or like parts.

[0053] Figure 1 is a top view schematic diagram of an antenna structure according to an embodiment of the present invention. Figure 1 In the present embodiment, the antenna structure 100 includes a plurality of radiating portions (four radiating portions 110a, 110b, 110c, 110d are schematically shown) and a plurality of extending portions (eight extending portions 120 are schematically shown). The radiating portions 110a, 110b, 110c, 110d are separated from each other and arranged in a circle. The extending portion 120 connects the radiating portions 110a, 110b, 110c, 110d and extends toward the center C of the circle. The first gap G1 between the two top ends of two adjacent radiating portions 110a, 110b is equal to the second gap G2 between the two bottom ends of two adjacent extending portions 120. Preferably, the range of the first gap G1 is, for example, between 0.5 mm and 4 mm.

[0054] Specifically, in this embodiment, each radiating portion (such as radiating portion 110a) has a first arcuate edge 112 and a second arcuate edge 114 opposite to each other. The length of the first arcuate edge 112 is greater than the length of the second arcuate edge 114, wherein the first arcuate edge 112 and the second arcuate edge 114 are arranged in a co-centric manner. Preferably, the shortest distance L from the first arcuate edge 112 to the second arcuate edge 114 is, for example, between 34 mm and 40 mm. Figure 1 As shown, the shape of each radiation portion 110a, 110b, 110c, 110d of this embodiment is, for example, a sector, and the outer diameter (i.e., the distance from the first arc edge 112 to the center C) and the inner diameter (i.e., the distance from the second arc edge 114 to the center C) of each sector are the same.

[0055] Furthermore, the radiation portion 110c of this embodiment has an opening 113 to divide the radiation portion 110c into a first radiation portion 115 and a second radiation portion 117 for connection to a feeding circuit. Preferably, the diameter D of the opening 113 is equal to the first gap G1, that is, the diameter D of the opening 113 ranges from 0.5 mm to 4 mm, for example. Figure 1 As shown, the transmission line 10 can be connected to the first radiation portion 115 and the second radiation portion 117 , wherein the transmission line 10 can be a SAM connector, an N-type connector or a TNC connector, which is not limited herein.

[0056] In particular, in this embodiment, the first gap G1 between two adjacent radiating portions 110a, 110b, 110c, 110d can be used as a gap for the radiating portions 110a, 110b, 110c, 110d to couple with each other, so as to achieve a mutual resonance effect and generate a close-range magnetic field above the antenna structure 100. Here, the angle A between the extension direction of the two adjacent first gaps G1 and the center C is, for example, 90 degrees, which means that the angles between the gaps of the four sectors (i.e., the radiating portions 110a, 110b, 110c, 110d) and the center are each 90 degrees.

[0057] Please refer to Figure 1, the extensions 120 of this embodiment are respectively connected to the opposite sides of the second arc-shaped edge 114, that is, each of the radiation portions 110a, 110b, 110c, 110d is connected to two extensions 120. Each extension portion 120 includes a first extension portion 122 and a second extension portion 124, wherein the first extension portion 122 is vertically connected to the second extension portion 124. That is, the shape of each extension portion 120 is, for example, L-shaped, and the L-shaped portions of each extension portion are separated by a second gap G2, and are back-to-back in a left-right inverted structure. Preferably, the length L1 of the first extension portion 122 is between 29 mm and 32 mm, and the length L2 of the second extension portion 124 is between 8 mm and 15 mm. The L-shaped extension portion 120 is located inside the circle formed by the radiation portions 110a, 110b, 110c, 110d, so that the overall antenna structure 100 can have an ideal impedance adjustment and a uniform magnetic field distribution.

[0058] In this embodiment, the radiation parts 110a, 110b, 110c, 110d and the extension part 120 are preferably integrally formed, wherein the radiation parts 110a, 110b, 110c, 110d and the extension part 120 are formed, for example, by etching or printing. The material of the radiation parts 110a, 110b, 110c, 110d and the material of the extension part 120 are, for example, copper, silver or conductive ink, but not limited thereto. The thickness of each radiation part 110a, 110b, 110c, 110d and the thickness of each extension part 120 are, for example, between 0.018 mm and 0.07 mm.

[0059] In addition, please refer to Figure 1 The antenna structure 100 of the present embodiment further includes a carrier 130, wherein the radiation portions 110a, 110b, 110c, 110d and the extension portion 120 are disposed on the carrier 130. The material of the carrier 130 is, for example, paper material, ceramic, epoxy resin glass fiber board, polyimide (PI), polyester (PET), polyurethane (PU), polycarbonate (PC), polyethylene (PE) or polypropylene (PP), but is not limited thereto. Here, the shape of the carrier 130 is, for example, a square, and preferably, the side length T of the carrier 130 is, for example, between 160 mm and 180 mm. Of course, in other embodiments not shown, the shape of the carrier may also be circular, and the diameter of the carrier is, for example, between 160 mm and 180 mm. In addition, the thickness of the carrier 130 is, for example, between 1.5 mm and 2.5 mm, which means that the antenna structure 100 of the present embodiment has the advantage of a small volume. When fixing, holes may be drilled on the carrier 130 and the carrier 130 may be fixed to the device using related parts, or an adhesive layer may be applied to the back side of the carrier 130 (ie, the side opposite to the antenna) to fix the carrier to the device, which is not limited here.

[0060] In short, the present embodiment uses four fan-shaped radiating parts 110a, 110b, 110c, and 110d as antenna conductors, and the first gap G1 between each fan-shaped part can be used as a gap for mutual coupling, so as to achieve the effect of mutual resonance and generate a close-range magnetic field above the antenna structure 100. In addition, the extension part 120 of the antenna structure 100 connects the radiating parts 110a, 110b, 110c, and 110d and extends toward the center C of the circle, so that the magnetic field is evenly distributed. Therefore, the antenna structure 100 of the present embodiment can provide a uniformly distributed close-range magnetic field, and has a higher sensing sensitivity and sensing accuracy.

[0061] In terms of application, the antenna structure 100 of this embodiment has a receiving range of less than 30 cm and can be used in unmanned stores or vending machines. If the goods are placed on the shelf, each product can have its own near-field antenna; if they are not placed on the shelf, the goods can be placed on it for checkout, but the size or number of goods increases the number of antennas. Furthermore, the antenna structure 100 of this embodiment can be used in smart shelves, with near-field sensing reading, so that customers or employees can take away the goods on the shelf by swiping their identification cards on the sensing device, and the back-end big data can be used to deduct money and compile the details of this transaction.

[0062] Figure 2 yes Figure 1 The frequency and impedance curve of the HFSS computer simulation antenna structure test. Theoretically, in the 902MHz to 928MHz frequency band, the impedance approaches 50±10Ω, which is the ideal value. Figure 2 In the impedance test of the HFSS computer simulated antenna structure, three frequencies (labeled as 1, 2, and 3) in the frequency band of 902MHz to 928MHz were taken out, and their corresponding impedance values ​​were measured as shown in Table 1. From the test results, it can be seen that the impedance values ​​are close to 50±10Ω, which is in line with the ideal value range.

[0063] Table 1

[0064] HFSS computer simulation antenna structure test Frequency (GHz) Impedance(Ω) Mark 1 0.90 41.26 Mark 2 0.91 42.41 Mark 3 0.92 43.68

[0065] Figure 3 yes Figure 1The frequency and loss value curve of the HFSS computer simulation antenna structure test. Theoretically, in the 902MHz to 928MHz frequency band, the loss value (i.e., signal feedback loss value) should be lower than -12dB to be the ideal value, which means that the lower the loss value, the more completely the energy sent by the reader to the antenna can be transmitted. In the HFSS computer simulation antenna structure loss test, three frequencies (labeled as 4, 5, and 6) in the 902MHz to 928MHz frequency band were taken out, and their corresponding loss values ​​(i.e., signal feedback loss values) were measured as shown in Table 2. From the test results, it can be seen that the loss values ​​are all lower than -12dB, which is in line with the ideal value range.

[0066] Table 2

[0067] HFSS computer simulation antenna structure test Frequency (GHz) Loss value(dB) Mark 4 0.90 -20.09 Mark 5 0.91 -21.67 Mark 6 0.92 -23.36

[0068] On the other hand, the actual antenna structure was tested with a network instrument. Three frequencies (labeled as 7, 8, and 9) in the frequency band of 902MHz to 928MHz were taken out. The test results are shown in Table 3. It can be seen from the test results that the corresponding impedance values ​​are close to 50±10Ω, and the corresponding loss values ​​are lower than -12dB, so they are all within the ideal value range.

[0069] Table 3

[0070] Network instrument physical test Frequency (GHz) Impedance(Ω) Loss value(dB) Mark 7 0.902 56.971 -17.089 Mark 8 0.915 57.108 -19.957 Mark 9 0.928 55.228 -20.443

[0071] In general, the ideal standard for antenna matching is that the impedance value is close to 50±10Ω and the loss value is lower than -12dB, which means that the magnetic field distribution is uniform at a close distance of the antenna structure and has a high sensing sensitivity and sensing accuracy. Please also refer to Figure 2 , Figure 3 As shown in Table 4 below, the impedance values ​​of the antenna structure simulated by HFSS computer and the actual antenna test by the physical instrument are close to 50±10Ω, and the loss values ​​are lower than -12dB, which are both within the ideal standard range, indicating that the magnetic field distribution of this antenna structure is uniform at a short distance, and it has a high sensing sensitivity and sensing accuracy.

[0072] Table 4

[0073]

[0074] In summary, in the design of the antenna structure of the present invention, the radiating parts of the antenna structure are separated from each other and arranged in a circle, which can achieve the effect of mutual resonance and generate a close-range magnetic field above the antenna structure. In addition, the extension part of the antenna structure is connected to the radiating part and extends toward the center of the circle, so that the magnetic field is evenly distributed. In short, the antenna structure of the present invention can provide a uniformly distributed close-range magnetic field and has a higher sensing sensitivity and sensing accuracy.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An antenna structure, characterized in that: include: A plurality of radiating parts are separated from each other and arranged in a circle; as well as A plurality of extension portions are connected to the plurality of radiation portions and extend toward the center of the circle, wherein a first gap between two top ends of two adjacent plurality of radiation portions is equal to a second gap between two bottom ends of two adjacent plurality of extension portions, and each of the plurality of extension portions includes a first extension portion and a second extension portion, wherein the first extension portion is vertically connected to the second extension portion.

2. The antenna structure according to claim 1, characterized in that: The first gap ranges from 0.5 mm to 4 mm.

3. The antenna structure according to claim 1, characterized in that: The plurality of radiation portions and the plurality of extension portions are integrally formed.

4. The antenna structure according to claim 1, characterized in that: Each of the plurality of radiation portions has a first arc edge and a second arc edge opposite to each other, the length of the first arc edge is greater than the length of the second arc edge, and the plurality of extension portions are respectively connected to two opposite sides of the second arc edge.

5. The antenna structure according to claim 4, characterized in that: The shortest distance from the first arc-shaped edge to the second arc-shaped edge is between 34 mm and 40 mm.

6. The antenna structure according to claim 1 or 4, characterized in that: Each of the plurality of radiation portions is in a fan shape.

7. The antenna structure according to claim 1, characterized in that: The included angle between the extension direction of two adjacent first gaps and the center of the circle is 90 degrees.

8. The antenna structure according to claim 1, characterized in that: One of the plurality of radiation portions has an opening to divide the radiation portion into a first radiation portion and a second radiation portion, and a diameter of the opening is equal to the first gap.

9. The antenna structure according to claim 8, characterized in that: The first radiating portion and the second radiating portion are connected by a transmission line as a feeding line.

10. The antenna structure according to claim 9, characterized in that: The transmission line is a SAM connector, an N-type connector or a TNC connector.

11. The antenna structure according to claim 1, characterized in that: The length of the first extension portion is between 29 mm and 32 mm.

12. The antenna structure according to claim 11, characterized in that: The length of the second extension portion is between 8 mm and 15 mm.

13. The antenna structure according to claim 12, characterized in that: Each of the plurality of extensions is L-shaped.

14. The antenna structure according to claim 13, characterized in that: The L-shaped portions of each of the plurality of extension portions are separated by the second gap and are back-to-back and inverted in a left-right structure.

15. The antenna structure according to claim 1, characterized in that: A thickness of each of the plurality of radiation portions and a thickness of each of the plurality of extension portions are between 0.018 mm and 0.07 mm.

16. The antenna structure according to claim 1, characterized in that: Also includes: A carrier, the plurality of radiation portions and the plurality of extension portions are configured on the carrier.

17. The antenna structure according to claim 16, characterized in that: The shape of the carrier includes square or circle.

18. The antenna structure according to claim 17, characterized in that: The side length or diameter of the carrier is between 160 mm and 180 mm.

19. The antenna structure according to claim 16, characterized in that: The thickness of the carrier is between 1.5 mm and 2.5 mm.

20. The antenna structure according to claim 16, characterized in that: The material of the carrier includes paper material, ceramic, epoxy resin glass fiber board, polyimide, polyester, polyurethane, polycarbonate, polyethylene or polypropylene.

21. The antenna structure according to claim 1, characterized in that: The material of the plurality of radiation parts and the material of the plurality of extension parts include copper, silver or conductive ink.

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