Near-field antenna for self-service cashier desk

Abstract

The utility model relates to a near-field antenna for a self-service cashier desk. The near-field antenna comprises an upper circuit board and a lower circuit board, the eight oscillator groups of the upper circuit board are arranged into a rectangular array with two rows and four columns, and the distance between the rows and the distance between the columns are D; each oscillator group comprises four microstrip lines which are distributed in an annular array by taking a point M1 as a center; the lower circuit board is fixed below the upper circuit board, and a feed circuit is arranged on the lower circuit board; the feed circuit is provided with an input connecting end and eight feed units; the eight feed units are in one-to-one correspondence with the eight oscillator groups, the feed units are located below the oscillator groups between the corresponding feed units and the oscillator groups, the four output connecting ends of the feed units are in one-to-one correspondence with the four microstrip lines of the oscillator groups, and the corresponding output connecting ends are connected and conducted with the feed connecting ends of the microstrip lines. The directional antenna has the characteristics of simple structure, reasonable design, small lobe width in use, strong directivity, low loss rate and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of RFID application technology, especially a near field antenna for self-service checkout counter. BACKGROUND

[0002] The self-service checkout counter is a device that combines RFID technology and automation operation, which provides a fast and convenient checkout method, improves the shopping experience of customers, and improves the operation efficiency of retailers. The near field antenna is an important component of the self-service checkout counter, which needs to provide efficient and accurate RFID tag reading capability for the self-service checkout counter system. At present, the lobe width of the near field antenna on the market is large when used, which will lead to insufficient directivity of the near field antenna, so that such near field antenna is prone to misreading when applied to the self-service checkout counter. Based on the existing deficiencies of the near field antenna, it is urgent to design a near field antenna special for self-service checkout counter to meet the use needs of users. SUMMARY

[0003] The utility model aims at providing a kind of near field antenna for self-service checkout counter, which has the advantages of simple structure, reasonable design, small lobe width when used, strong directivity and low loss rate.

[0004] The technical scheme of the utility model is realized as follows: a kind of near field antenna for self-service checkout counter, in particular, including upper circuit board, lower circuit board and coaxial cable;Wherein:

[0005] The upper circuit board and the lower circuit board are both rectangular plates, and 8 vibrator groups are arranged on the top surface of the upper circuit board;8 vibrator groups are arranged into a rectangular array with 2 rows and 4 columns, and the direction of the rows is parallel to the length direction of the upper circuit board;In the rectangular array formed by the arrangement of 8 vibrator groups: the spacing between rows and the spacing between columns are both D, and the size range of D is 100±5mm;

[0006] Each vibrator group includes a point M1 and 4 microstrip lines, and the 4 microstrip lines are arranged in a ring array with the point M1 as the center;Each microstrip line is a spiral line arranged on the upper circuit board in a copper-clad manner, and each microstrip line includes 6 straight line segments;The 6 straight line segments are respectively F1, F2, F3, F4, F5 and F6;The range of the line width W of each of F1, F2, F3, F4, F5 and F6 is 3±0.1mm;

[0007] The range of the length L1 of F1 is 15±0.2mm;The length direction of F1 is parallel to two side edges of the upper circuit board, and the vertical spacing D1 between F1 and the point M1 has a size range of 5±0.2mm;

[0008] The line length L2 of F2 is 27±0.2mm; the vertical distance D2 between F2 and point M1 is 12.5±0.2mm; one end of F2 is connected to one end of F1 in vertical direction, and the side of F2 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4±0.1mm to the side of F1 close to point M1, and the side of F2 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5±0.1mm to the side of F1 far from point M1;

[0009] The line length L3 of F3 is 41±0.2mm; F3 is opposite to F1, and point M1 is between F3 and F1, one end of F3 is connected to the other end of F2 in vertical direction, and the side of F3 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4±0.1mm to the side of F2 close to point M1, and the side of F3 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5±0.1mm to the side of F2 far from point M1;

[0010] The line length L4 of F4 is 54±0.2mm; F4 is opposite to F2, one end of F4 is connected to the other end of F3 in vertical direction, and the side of F4 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4±0.1mm to the side of F3 close to point M1, and the side of F4 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5±0.1mm to the side of F3 far from point M1;

[0011] The line length L5 of F5 is 67±0.2mm; F5 is on the side of F1 away from F3, one end of F5 is connected to the other end of F4 in vertical direction, and the side of F5 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4±0.1mm to the side of F4 close to point M1, and the side of F5 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5±0.1mm to the side of F4 far from point M1;

[0012] The line length L6 of F6 is 70±0.2mm; F6 is on the side of F2 away from F4, one end of F6 is connected to the other end of F5 in vertical direction, and the side of F6 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4±0.1mm to the side of F5 close to point M1, and the side of F6 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5±0.1mm to the side of F5 far from point M1; the other end of F6 is connected with a feeding connection end;

[0013] The lower circuit board is fixed below the upper circuit board, and a feeding circuit is arranged on the lower circuit board; the feeding circuit is provided with an input connection end and eight feeding units, each of which includes a point M2 and four output connection ends; the four output connection ends of each feeding unit are a first connection end, a second connection end, a third connection end and a fourth connection end arranged around the point M2 in turn, and the signal phases output by the first connection end, the second connection end, the third connection end and the fourth connection end are 0°, 90°, 180° and 270° respectively; the eight feeding units correspond to the eight vibrator groups one by one, and between each corresponding feeding unit and vibrator group: the feeding unit is below the vibrator group, and the four output connection ends of the feeding unit correspond to the four microstrip lines of the vibrator group one by one, and the corresponding output connection end and the feeding connection end of the microstrip line are connected and conducted.

[0014] The inner conductor of the coaxial cable is electrically connected with the input connection end of the feeding circuit, and the outer conductor of the coaxial cable is connected with the ground.

[0015] The present scheme is provided with eight vibrator groups arranged in a rectangular array, each microstrip line of each vibrator group is a spiral line, and the four microstrip lines of the vibrator group are arranged in a ring array with the point M1 as the center to form a mutually nested structure. After a specific size limitation is performed on the microstrip lines of the vibrator group and the distance between each adjacent two vibrator groups is set, the lobe width of the present scheme can reach Hor: 40°, Ver: 64° when used under the premise of meeting the required gain of the self-service checkout counter. The smaller lobe width makes the present scheme have strong directivity, so that it is not easy to appear misreading when applied to the self-service checkout counter. In addition, the design of the chamfer with a specific size between each adjacent two straight line segments on the microstrip line of each vibrator group also makes the present scheme have a low loss rate when used. In addition, the following electrical indicators can be obtained when the present scheme is used: frequency range: 902-928MHz, gain: -6dBi, polarization mode: circular polarization, voltage standing wave ratio ≤1.8, front-to-back ratio ≥14, impedance: 50Ω, maximum input power: 100W.

[0016] Further, a reflecting surface is formed on the bottom surface of the lower circuit board in a copper-clad manner, and the orthographic projection of each vibrator group on the bottom surface of the lower circuit board is in the reflecting surface.

[0017] Further, each feeding unit includes a connection circuit, a first power divider, a second power divider, a first output segment, a second output segment, a third output segment and a fourth output segment formed on the top surface of the lower circuit board in a copper-clad manner.

[0018] The connecting circuit is provided with an input section, a first branch section and a second branch section; one end of each of the first branch section and the second branch section is connected in conduction with one end of the input section, the line width of the second branch section is the same as the line width of the first branch section, and the line length of the second branch section is longer than the line length of the first branch section;

[0019] The first power divider and the second power divider are of the same structure, the input end of the first power divider is connected in conduction with the other end of the first branch section, and the input end of the second power divider is connected in conduction with the other end of the second branch section;

[0020] The first output section is the same as the third output section; the line width of the second output section is the same as the line width of the first output section, the line length of the second output section is longer than the line length of the first output section, the second output section is the same as the fourth output section; the two output ends of the first power divider correspond to the first output section and the second output section respectively, one end of each of the first output section and the second output section is connected in conduction with the output end of the first power divider, the other end of the first output section is connected in conduction with the first connecting end, and the other end of the second output section is connected in conduction with the second connecting end; the two output ends of the second power divider correspond to the third output section and the fourth output section respectively, one end of each of the third output section and the fourth output section is connected in conduction with the output end of the second power divider, the other end of the third output section is connected in conduction with the third connecting end, and the other end of the fourth output section is connected in conduction with the fourth connecting end;

[0021] The other end of the input section of the connecting circuit of each feeding unit is connected in conduction with the input connecting end.

[0022] Further, the feeding circuit further comprises an input circuit and four groups of connecting line groups, the input circuit is arranged on the top surface of the lower circuit board in a copper-clad manner, the input circuit is connected in conduction with the input connecting end, and the input circuit is provided with four conduction branches;

[0023] The four groups of connecting line groups are arranged in a rectangular array; each connecting line group comprises a first connecting section, a second connecting section and a third connecting section, the length direction of each of the first connecting section, the second connecting section and the third connecting section is parallel to the length direction of the lower circuit board, the first connecting section and the third connecting section are arranged on the top surface of the lower circuit board in a copper-clad manner, the second connecting section is arranged on the bottom surface of the lower circuit board in a copper-clad manner, and one end of each of the first connecting section and the third connecting section is connected in conduction with the second connecting section through the metallized hole provided on the lower circuit board;

[0024] The four conduction branches of the input circuit correspond to the four groups of connecting line groups respectively, and the corresponding conduction branch is connected in conduction with the third connecting section of the connecting line group;

[0025] The eight feeding units are respectively referred to as a first feeding unit, a second feeding unit, a third feeding unit, a fourth feeding unit, a fifth feeding unit, a sixth feeding unit, a seventh feeding unit and an eighth feeding unit; the first feeding unit, the second feeding unit, the third feeding unit and the fourth feeding unit are arranged in a row in sequence along the length direction of the lower circuit board; the fifth feeding unit, the sixth feeding unit, the seventh feeding unit and the eighth feeding unit are arranged in another row in sequence along the length direction of the lower circuit board.

[0026] The four groups of connecting lines are respectively referred to as a first group of connecting lines, a second group of connecting lines, a third group of connecting lines and a fourth group of connecting lines; the first group of connecting lines and the second group of connecting lines are arranged in a row in sequence along the length direction of the lower circuit board; the third group of connecting lines and the fourth group of connecting lines are arranged in another row in sequence along the length direction of the lower circuit board.

[0027] The other end of the first connecting segment of the first group of connecting lines is connected in conduction with the input segment of the first feeding unit; the other end of the third connecting segment of the first group of connecting lines is connected in conduction with the input segment of the second feeding unit; and the second branch segment of the first feeding unit passes through the gap between the first connecting segment and the third connecting segment of the first group of connecting lines.

[0028] The other end of the first connecting segment of the second group of connecting lines is connected in conduction with the input segment of the third feeding unit; the other end of the third connecting segment of the second group of connecting lines is connected in conduction with the input segment of the fourth feeding unit; and the second branch segment of the third feeding unit passes through the gap between the first connecting segment and the third connecting segment of the second group of connecting lines.

[0029] The other end of the first connecting segment of the third group of connecting lines is connected in conduction with the input segment of the fifth feeding unit; the other end of the third connecting segment of the third group of connecting lines is connected in conduction with the input segment of the sixth feeding unit; and the second branch segment of the fifth feeding unit passes through the gap between the first connecting segment and the third connecting segment of the third group of connecting lines.

[0030] The other end of the first connecting segment of the fourth group of connecting lines is connected in conduction with the input segment of the seventh feeding unit; the other end of the third connecting segment of the fourth group of connecting lines is connected in conduction with the input segment of the eighth feeding unit; and the second branch segment of the seventh feeding unit passes through the gap between the first connecting segment and the third connecting segment of the fourth group of connecting lines.

[0031] Further, the upper circuit board and the lower circuit board are both FR-4 boards with a dielectric coefficient in the range of 4.2-4.7.

[0032] Further, the size range of the length A1 of each of the upper circuit board and the lower circuit board is 400±5mm, the size range of the width A2 of each of the upper circuit board and the lower circuit board is 200±5mm, and the size range of the thickness T1 of each of the upper circuit board and the lower circuit board is 1±0.1mm; the size range of the spacing D3 between the upper circuit board and the lower circuit board is 8±0.2mm.

[0033] Further, mounting holes are formed at four corners of the lower circuit board, and notches for exposing the mounting holes are formed at four corners of the upper circuit board.

[0034] Further, each of the corresponding output connecting end and the feed connecting end of the microstrip line is connected through metal column welding.

[0035] Further, four EVA cotton pads are clamped between the upper circuit board and the lower circuit board, and the four EVA cotton pads are arranged along four sides of the upper circuit board respectively.

[0036] The utility model discloses the beneficial effects of having simple structure, reasonable in design, the advantages such as small lobe width, strong directivity and low loss rate when using. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is the three-dimensional structure schematic diagram of example.

[0038] Figure 2 It is the dismounting structure schematic diagram of example.

[0039] Figure 3 It is the main view structure schematic diagram of the upper circuit board of example.

[0040] Figure 4 It is the structure schematic diagram of the vibrator group of example.

[0041] Figure 5 It is the structure schematic diagram of the microstrip line of the vibrator group in unchamfered state of example.

[0042] Figure 6 It is the main view structure schematic diagram of the lower circuit board of example.

[0043] Figure 7 It is the rear view structure schematic diagram of the lower circuit board of example.

[0044] Figure 8 It is the structure schematic diagram of the feed unit of example.

[0045] Figure 9 It is the horizontal plane radiation pattern when using of example.

[0046] Figure 10 It is the vertical plane radiation pattern when using of example.

[0047] Explanation of reference numerals: 1 - upper circuit board; 11 - notch; 2 - lower circuit board; 21 - reflecting surface; 22 - mounting hole; 3 - coaxial cable; 4 - vibrator group; 41 - microstrip line; 42 - feed connection end; 5 - feed circuit; 51 - input connection end; 61 - first feed unit; 62 - second feed unit; 63 - third feed unit; 64 - fourth feed unit; 65 - fifth feed unit; 66 - sixth feed unit; 67 - seventh feed unit; 68 - eighth feed unit; 71 - first connection end; 72 - second connection end; 73 - third connection end; 74 - fourth connection end; 75 - connection circuit; 751 - input section; 752 - first branch section; 753 - second branch section; 76 - first power divider; 77 - second power divider; 78 - first output section; 79 - second output section; 710 - third output section; 720 - fourth output section; 8 - input circuit; 81 - conducting branch; 91 - first connection line group; 92 - second connection line group; 93 - third connection line group; 94 - fourth connection line group; 95 - first connection section; 96 - second connection section; 97 - third connection section; 10 - EVA cotton pad. DETAILED DESCRIPTION

[0048] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 8 The self-service checkout counter near-field antenna of the embodiment comprises an upper circuit board 1, a lower circuit board 2 and a coaxial cable 3; wherein:

[0049] The upper circuit board 1 and the lower circuit board 2 are both rectangular plates, and eight vibrator groups 4 are arranged on the top surface of the upper circuit board 1; the eight vibrator groups 4 are arranged in a rectangular array with two rows and four columns, and the direction of the rows is parallel to the length direction of the upper circuit board 1; in the rectangular array formed by the arrangement of the eight vibrator groups 4, the spacing between the rows and the spacing between the columns are both D, and D is 100 mm;

[0050] Each vibrator group 4 comprises a point M1 and four microstrip lines 41, and the four microstrip lines 41 are arranged in a ring array with the point M1 as the center; each microstrip line 41 is a spiral line arranged on the upper circuit board 1 in a copper-clad manner, and each microstrip line 41 comprises six straight line sections; the six straight line sections are respectively F1, F2, F3, F4, F5 and F6; the line width W of each of F1, F2, F3, F4, F5 and F6 is 3 mm;

[0051] The line length L1 of F1 is 15mm; the length direction of F1 is parallel to two sides of the upper circuit board 1, and the vertical distance D1 between F1 and point M1 is 5mm;

[0052] The line length L2 of F2 is 27mm; the vertical distance D2 between F2 and point M1 is 12.5mm; one end of F2 is connected to one end of F1 in perpendicular, and the side of F2 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4mm from the side of F1 close to point M1, and the side of F2 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5mm from the side of F1 far from point M1;

[0053] The line length L3 of F3 is 41mm; F3 is opposite to F1, and point M1 is between F3 and F1, one end of F3 is connected to the other end of F2 in perpendicular, and the side of F3 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4mm from the side of F2 close to point M1, and the side of F3 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5mm from the side of F2 far from point M1;

[0054] The line length L4 of F4 is 54mm; F4 is opposite to F2, one end of F4 is connected to the other end of F3 in perpendicular, and the side of F4 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4mm from the side of F3 close to point M1, and the side of F4 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5mm from the side of F3 far from point M1;

[0055] The line length L5 of F5 is 67mm; F5 is on the side of F1 away from F3, one end of F5 is connected to the other end of F4 in perpendicular, and the side of F5 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4mm from the side of F4 close to point M1, and the side of F5 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5mm from the side of F4 far from point M1;

[0056] The line length L6 of F6 is 70mm; F6 is on the side of F2 away from F4, one end of F6 is connected to the other end of F5 in perpendicular, and the side of F6 close to point M1 is formed with a chamfer with an angle of 45° and a distance of 4mm from the side of F5 close to point M1, and the side of F6 far from point M1 is formed with a chamfer with an angle of 45° and a distance of 5.5mm from the side of F5 far from point M1; the other end of F6 is connected with a feeding connection end 42;

[0057] The lower circuit board 2 is fixed below the upper circuit board 1, and a feeding circuit 5 is arranged on the lower circuit board 2; the feeding circuit 5 is provided with an input connecting end 51 and eight feeding units, each of which comprises a point M2 and four output connecting ends; the four output connecting ends of each feeding unit are a first connecting end 71, a second connecting end 72, a third connecting end 73 and a fourth connecting end 74 arranged in turn around the point M2, and the signal phases output by the first connecting end 71, the second connecting end 72, the third connecting end 73 and the fourth connecting end 74 are 0°, 90°, 180° and 270° respectively; the eight feeding units correspond to the eight vibrator groups 4 one by one, and between each corresponding feeding unit and the vibrator group 4: the feeding unit is below the vibrator group 4, and the four output connecting ends of the feeding unit correspond to the four microstrip lines 41 of the vibrator group 4 one by one, and the corresponding output connecting end is connected in conduction with the feeding connecting end 42 of the microstrip line 41;

[0058] The inner conductor of the coaxial cable 3 is electrically connected with the input connecting end 51 of the feeding circuit 5, and the outer conductor of the coaxial cable 3 is connected with the ground. Such a design can meet the required gain of the self-service checkout counter when in use, and the small lobe width makes the self-service checkout counter near-field antenna have strong directivity, so that it is not easy to appear misreading when applied to the self-service checkout counter. In addition, the design of the chamfer of a certain size between each adjacent two straight line segments on the microstrip line 41 of each vibrator group 4 also makes the self-service checkout counter near-field antenna have a low loss rate when in use.

[0059] In order to further optimize the self-service checkout counter near-field antenna and enhance the radiation intensity of the self-service checkout counter near-field antenna in the specified direction, as shown in Figure 7 A reflecting surface 21 is formed on the bottom surface of the lower circuit board 2 in a copper-clad manner, and the orthographic projection of each vibrator group 4 on the bottom surface of the lower circuit board 2 is in the reflecting surface 21.

[0060] In order to make the structure of the feeding unit more reasonable, as shown in Figure 6 、 Figure 8 Each feeding unit comprises a connecting circuit 75, a first power divider 76, a second power divider 77, a first output segment 78, a second output segment 79, a third output segment 710 and a fourth output segment 720 formed on the top surface of the lower circuit board 2 in a copper-clad manner;

[0061] The connecting circuit 75 is provided with an input segment 751, a first branch segment 752 and a second branch segment 753; one end of each of the first branch segment 752 and the second branch segment 753 is connected in conduction with one end of the input segment 751, the line width of the second branch segment 753 is the same as that of the first branch segment 752, and the line length of the second branch segment 753 is longer than that of the first branch segment 752;

[0062] The first power divider 76 and the second power divider 77 have the same structure. The input terminal of the first power divider 76 is connected to the other end of the first branch segment 752, and the input terminal of the second power divider 77 is connected to the other end of the second branch segment 753.

[0063] The first output segment 78 is the same as the third output segment 710; the line width of the second output segment 79 is the same as the line width of the first output segment 78, and the line length of the second output segment 79 is longer than the line length of the first output segment 78. The second output segment 79 is the same as the fourth output segment 720; the two output terminals of the first power divider 76 correspond one-to-one with the first output segment 78 and the second output segment 79, and one end of each of the first output segment 78 and the second output segment 79 is connected to the output terminal of the first power divider 76 for conduction. The other end of 8 is connected to the first connection terminal 71 and conduction is achieved; the other end of the second output segment 79 is connected to the second connection terminal 72 and conduction is achieved; the two output terminals of the second power divider 77 correspond one-to-one with the third output segment 710 and the fourth output segment 720; one end of each of the third output segment 710 and the fourth output segment 720 is connected to the output terminal of the second power divider 77 and conduction is achieved; the other end of the third output segment 710 is connected to the third connection terminal 73 and conduction is achieved; the other end of the fourth output segment 720 is connected to the fourth connection terminal 74 and conduction is achieved.

[0064] The other end of the input segment 751 of the connection circuit 75 of each power supply unit is connected to the input connection terminal 51 for conduction.

[0065] To make the layout design of power supply circuit 5 more reasonable, so that all 8 power supply units can supply power simultaneously, such as... Figure 6 , Figure 7 , Figure 8 As shown, the power supply circuit 5 also includes an input circuit 8 and four sets of connecting lines. The input circuit 8 is arranged on the top surface of the lower circuit board 2 in a copper-clad manner. The input circuit 8 is connected to the input connection terminal 51 and has four conducting branches 81.

[0066] The four sets of connecting lines are arranged in a rectangular array. Each connecting line set includes a first connecting segment 95, a second connecting segment 96, and a third connecting segment 97. The length direction of each of the first connecting segment 95, the second connecting segment 96, and the third connecting segment 97 is parallel to the length direction of the lower circuit board 2. The first connecting segment 95 and the third connecting segment 97 are respectively set on the top surface of the lower circuit board 2 with copper plating. The second connecting segment 96 is set on the bottom surface of the lower circuit board 2 with copper plating. One end of each of the first connecting segment 95 and the third connecting segment 97 is connected and connected to the second connecting segment 96 through a metallized hole provided on the lower circuit board 2.

[0067] The four conducting branches 81 of the input circuit 8 correspond one-to-one with the four sets of connecting lines, and the corresponding conducting branches 81 are connected to the third connecting segment 97 of the connecting line group.

[0068] The eight feeding units are respectively referred to as a first feeding unit 61, a second feeding unit 62, a third feeding unit 63, a fourth feeding unit 64, a fifth feeding unit 65, a sixth feeding unit 66, a seventh feeding unit 67 and an eighth feeding unit 68; the first feeding unit 61, the second feeding unit 62, the third feeding unit 63 and the fourth feeding unit 64 are arranged in a row in sequence, and the fifth feeding unit 65, the sixth feeding unit 66, the seventh feeding unit 67 and the eighth feeding unit 68 are arranged in another row in sequence;

[0069] The four groups of connecting lines are respectively referred to as a first connecting line group 91, a second connecting line group 92, a third connecting line group 93 and a fourth connecting line group 94; the first connecting line group 91 and the second connecting line group 92 are arranged in a row in sequence along the length direction of the lower circuit board 2, and the third connecting line group 93 and the fourth connecting line group 94 are arranged in another row in sequence along the length direction of the lower circuit board 2;

[0070] The other end of the first connecting segment 95 of the first connecting line group 91 is connected and conducted with the input segment 751 of the first feeding unit 61, the other end of the third connecting segment 97 of the first connecting line group 91 is connected and conducted with the input segment 751 of the second feeding unit 62, and the second branch segment 753 of the first feeding unit 61 passes through the gap between the first connecting segment 95 and the third connecting segment 97 of the first connecting line group 91;

[0071] The other end of the first connecting segment 95 of the second connecting line group 92 is connected and conducted with the input segment 751 of the third feeding unit 63, the other end of the third connecting segment 97 of the second connecting line group 92 is connected and conducted with the input segment 751 of the fourth feeding unit 64, and the second branch segment 753 of the third feeding unit 63 passes through the gap between the first connecting segment 95 and the third connecting segment 97 of the second connecting line group 92;

[0072] The other end of the first connecting segment 95 of the third connecting line group 93 is connected and conducted with the input segment 751 of the fifth feeding unit 65, the other end of the third connecting segment 97 of the third connecting line group 93 is connected and conducted with the input segment 751 of the sixth feeding unit 66, and the second branch segment 753 of the fifth feeding unit 65 passes through the gap between the first connecting segment 95 and the third connecting segment 97 of the third connecting line group 93;

[0073] The other end of the first connecting segment 95 of the fourth connecting line group 94 is connected and conducted with the input segment 751 of the seventh feeding unit 67, the other end of the third connecting segment 97 of the fourth connecting line group 94 is connected and conducted with the input segment 751 of the eighth feeding unit 68, and the second branch segment 753 of the seventh feeding unit 67 passes through the gap between the first connecting segment 95 and the third connecting segment 97 of the fourth connecting line group 94.

[0074] As shown in Figure 1 , Figure 2 , the upper circuit board 1 and the lower circuit board 2 are both FR-4 boards with a dielectric coefficient of 4.5. The FR-4 boards have stable electrical insulation performance and good flatness, which facilitates the copper cladding production on the surfaces of the upper circuit board 1 and the lower circuit board 2, and makes the near-field antenna for the self-service cash register easier to produce.

[0075] As shown in Figure 1 , Figure 3 , Figure 5 , the length A1 of each of the upper circuit board 1 and the lower circuit board 2 is 400 mm, the width A2 of each of the upper circuit board 1 and the lower circuit board 2 is 200 mm, and the thickness T1 of each of the upper circuit board 1 and the lower circuit board 2 is 1 mm; the spacing D3 between the upper circuit board 1 and the lower circuit board 2 is 8 mm. Such a design makes the structure of the near-field antenna for the self-service cash register more reasonable, and makes the near-field antenna for the self-service cash register reach the preset electrical indicators when in use.

[0076] In order to facilitate the installation of the near-field antenna for the self-service cash register, as shown in Figure 1 , Figure 2 , Figure 3 , Figure 5 , mounting holes 22 are formed at the four corners of the lower circuit board 2, and notches 11 for exposing the mounting holes 22 are formed at the four corners of the upper circuit board 1.

[0077] As shown in Figure 2 , each corresponding output connecting end and the feed connecting end 42 of the microstrip line 41 are connected through a metal column. In addition to connecting the output connecting end and the feed connecting end 42 of the microstrip line 41, the metal column also serves to fixedly connect the upper circuit board 1 and the lower circuit board 2, making it very convenient to assemble the upper circuit board 1 and the lower circuit board 2.

[0078] In order to further improve the structural strength of the near-field antenna for the self-service cash register, as shown in Figure 2 , four EVA cotton pads 10 are clamped between the upper circuit board 1 and the lower circuit board 2; the four EVA cotton pads 10 are respectively arranged along the four sides of the upper circuit board 1.

[0079] The near-field antenna for the self-service cash register has the following electrical indicators when in use: frequency range: 902-928 MHz, gain: -6dBi, beam width: Hor: 40°, Ver: 64°, polarization mode: circular polarization, voltage standing wave ratio ≤1.8, front-to-back ratio ≥14, impedance: 50 Ω, maximum input power: 100 W. The near-field antenna for the self-service cash register can obtain the horizontal plane radiation pattern as shown in Figure 9 and the vertical plane radiation pattern as shown in Figure 10The vertical plane radiation pattern is shown.

Claims

1. A near field antenna for a self-checkout, characterized by: It comprises an upper circuit board, a lower circuit board and a coaxial cable; wherein: The upper circuit board and the lower circuit board are both rectangular plates, and eight vibrator groups are arranged on the top surface of the upper circuit board; the eight vibrator groups are arranged in a rectangular array with two rows and four columns, and the direction of the rows is parallel to the length direction of the upper circuit board; in the rectangular array formed by the eight vibrator groups, the spacing between the rows and the spacing between the columns are both D, and the size range of D is 100±5mm; Each vibrator group comprises a point M1 and four microstrip lines, and the four microstrip lines are arranged in a ring array with the point M1 as the center; each microstrip line is a spiral line arranged on the upper circuit board in a copper-clad manner, and each microstrip line comprises six straight line segments; the six straight line segments are respectively F1, F2, F3, F4, F5 and F6; the line width W of each of F1, F2, F3, F4, F5 and F6 ranges from 3±0.1mm; The length L1 of F1 ranges from 15±0.2mm; the length direction of F1 is parallel to two side edges of the upper circuit board, and the vertical spacing D1 between F1 and the point M1 ranges from 5±0.2mm; The length L2 of F2 ranges from 27±0.2mm; the vertical spacing D2 between F2 and the point M1 ranges from 12.5±0.2mm; one end of F2 is connected to one end of F1 in a perpendicular manner, and an angle of 45° is formed between the side edge of F2 close to the point M1 and the side edge of F1 close to the point M1, and the distance ranges from 4±0.1mm; an angle of 45° is formed between the side edge of F2 away from the point M1 and the side edge of F1 away from the point M1, and the distance ranges from 5.5±0.1mm; The length L3 of F3 ranges from 41±0.2mm; F3 is opposite to F1, and the point M1 is between F3 and F1; one end of F3 is connected to the other end of F2 in a perpendicular manner, and an angle of 45° is formed between the side edge of F3 close to the point M1 and the side edge of F2 close to the point M1, and the distance ranges from 4±0.1mm; an angle of 45° is formed between the side edge of F3 away from the point M1 and the side edge of F2 away from the point M1, and the distance ranges from 5.5±0.1mm; The length L4 of F4 ranges from 54±0.2mm; F4 is opposite to F2, one end of F4 is connected to the other end of F3 in a perpendicular manner, and an angle of 45° is formed between the side edge of F4 close to the point M1 and the side edge of F3 close to the point M1, and the distance ranges from 4±0.1mm; an angle of 45° is formed between the side edge of F4 away from the point M1 and the side edge of F3 away from the point M1, and the distance ranges from 5.5±0.1mm; The length L5 of F5 ranges from 67±0.2mm; F5 is on the side of F1 away from F3, one end of F5 is connected to the other end of F4 in a perpendicular manner, and an angle of 45° is formed between the side edge of F5 close to the point M1 and the side edge of F4 close to the point M1, and the distance ranges from 4±0.1mm; an angle of 45° is formed between the side edge of F5 away from the point M1 and the side edge of F4 away from the point M1, and the distance ranges from 5.5±0.1mm. The line length L6 of F6 is 70±0.2mm; F6 is on the side of F2 away from F4, one end of F6 is connected in parallel with the other end of F5, and an angle of 45° and a distance of 4±0.1mm are formed between the side of F6 close to point M1 and the side of F5 close to point M1, and an angle of 45° and a distance of 5.5±0.1mm are formed between the side of F6 away from point M1 and the side of F5 away from point M1; the other end of F6 is connected with a feeding connection end; The lower circuit board is fixed below the upper circuit board, and a feeding circuit is arranged on the lower circuit board; the feeding circuit is provided with an input connection end and eight feeding units, each of which includes point M2 and four output connection ends; the four output connection ends of each feeding unit are a first connection end, a second connection end, a third connection end and a fourth connection end arranged in turn around the point M2 thereof, and the signal phases output by the first connection end, the second connection end, the third connection end and the fourth connection end are 0°, 90°, 180° and 270° respectively; the eight feeding units correspond to the eight vibrator groups one by one, and between each corresponding feeding unit and vibrator group: the feeding unit is below the vibrator group, and the four output connection ends of the feeding unit correspond to the four microstrip lines of the vibrator group one by one, and the corresponding output connection end is connected in parallel with the feeding connection end of the microstrip line; The inner conductor of the coaxial cable is electrically connected with the input connection end of the feeding circuit, and the outer conductor of the coaxial cable is connected with the ground.

2. The near field antenna for a self-checkout station of claim 1, wherein: A reflecting surface is formed on the bottom surface of the lower circuit board in a copper-clad manner, and the orthographic projection of each vibrator group on the bottom surface of the lower circuit board is in the reflecting surface.

3. The near field antenna for a self-checkout station of claim 1, wherein: Each feeding unit includes a connection circuit, a first power divider, a second power divider, a first output section, a second output section, a third output section and a fourth output section formed on the top surface of the lower circuit board in a copper-clad manner; The connection circuit is provided with an input section, a first branch section and a second branch section; one end of each of the first branch section and the second branch section is connected in parallel with one end of the input section, the line width of the second branch section is the same as that of the first branch section, and the line length of the second branch section is longer than that of the first branch section; The first power divider and the second power divider are the same in structure, the input end of the first power divider is connected in parallel with the other end of the first branch section, and the input end of the second power divider is connected in parallel with the other end of the second branch section; The first output section is the same as the third output section; the line width of the second output section is the same as the line width of the first output section, the line length of the second output section is longer than the line length of the first output section, and the second output section is the same as the fourth output section; the two output ends of the first power divider correspond to the first output section and the second output section one by one, one end of the first output section and the second output section is connected to the output end of the first power divider in conduction, the other end of the first output section is connected to the first connection end in conduction, and the other end of the second output section is connected to the second connection end in conduction; the two output ends of the second power divider correspond to the third output section and the fourth output section one by one, one end of the third output section and the fourth output section is connected to the output end of the second power divider in conduction, the other end of the third output section is connected to the third connection end in conduction, and the other end of the fourth output section is connected to the fourth connection end in conduction; The other end of the input section of the connection circuit of each feeding unit is connected to the input connection end in conduction.

4. The near field antenna for a self-checkout station of claim 3, wherein: The feeding circuit further comprises an input circuit and four groups of connection line groups, the input circuit is arranged on the top surface of the lower circuit board in a copper-clad manner, the input circuit is connected to the input connection end in conduction, and the input circuit is provided with four conduction branches; The four groups of connection line groups are arranged in a rectangular array; each connection line group comprises a first connection section, a second connection section and a third connection section, the length direction of each of the first connection section, the second connection section and the third connection section is parallel to the length direction of the lower circuit board, the first connection section and the third connection section are arranged on the top surface of the lower circuit board in a copper-clad manner, the second connection section is arranged on the bottom surface of the lower circuit board in a copper-clad manner, and one end of each of the first connection section and the third connection section is connected to the second connection section in conduction through the metalized hole provided on the lower circuit board; The four conduction branches of the input circuit correspond to the four groups of connection line groups one by one, and the corresponding conduction branch is connected to the third connection section of the connection line group in conduction; The eight feeding units are respectively referred to as a first feeding unit, a second feeding unit, a third feeding unit, a fourth feeding unit, a fifth feeding unit, a sixth feeding unit, a seventh feeding unit and an eighth feeding unit; the first feeding unit, the second feeding unit, the third feeding unit and the fourth feeding unit are arranged in a row in sequence, and the fifth feeding unit, the sixth feeding unit, the seventh feeding unit and the eighth feeding unit are arranged in another row in sequence; The four groups of connection line groups are respectively referred to as a first connection line group, a second connection line group, a third connection line group and a fourth connection line group; the first connection line group and the second connection line group are arranged in a row along the length direction of the lower circuit board in sequence, and the third connection line group and the fourth connection line group are arranged in another row along the length direction of the lower circuit board in sequence; The other end of the first connection section of the first connection line group is connected to the input section of the first feeding unit in conduction, the other end of the third connection section of the first connection line group is connected to the input section of the second feeding unit in conduction, and the second branch section of the first feeding unit passes through the gap between the first connection section and the third connection section of the first connection line group. The other end of the first connecting segment of the second connecting wire group is connected with the input segment of the third feeding unit, the other end of the third connecting segment of the second connecting wire group is connected with the input segment of the fourth feeding unit, and the second branch segment of the third feeding unit passes through the gap between the first connecting segment and the third connecting segment of the second connecting wire group; The other end of the first connecting segment of the third connecting wire group is connected with the input segment of the fifth feeding unit, the other end of the third connecting segment of the third connecting wire group is connected with the input segment of the sixth feeding unit, and the second branch segment of the fifth feeding unit passes through the gap between the first connecting segment and the third connecting segment of the third connecting wire group; The other end of the first connecting segment of the fourth connecting wire group is connected with the input segment of the seventh feeding unit, the other end of the third connecting segment of the fourth connecting wire group is connected with the input segment of the eighth feeding unit, and the second branch segment of the seventh feeding unit passes through the gap between the first connecting segment and the third connecting segment of the fourth connecting wire group.

5. The near field antenna for a self-checkout station of claim 1, wherein: The upper circuit board and the lower circuit board are both FR-4 boards with a dielectric coefficient in the range of 4.2-4.

7.

6. The near field antenna for a self-checkout station of claim 1, wherein: The length A1 of each of the upper circuit board and the lower circuit board is in the range of 400±5mm, the width A2 of each of the upper circuit board and the lower circuit board is in the range of 200±5mm, and the thickness T1 of each of the upper circuit board and the lower circuit board is in the range of 1±0.1mm; the distance D3 between the upper circuit board and the lower circuit board is in the range of 8±0.2mm.

7. The near field antenna for a self-checkout station of claim 1, wherein: Mounting holes are formed at the four corners of the lower circuit board, and notches for exposing the mounting holes are formed at the four corners of the upper circuit board.

8. The near field antenna for a self-checkout station of claim 1, wherein: Each corresponding output connecting end and the feeding connecting end of the microstrip line are connected through metal column welding.

9. The near field antenna for a self-checkout station of claim 1, wherein: Four EVA cotton pads are clamped between the upper circuit board and the lower circuit board, and the four EVA cotton pads are arranged along the four side edges of the upper circuit board respectively.

Images