RFID near-field antenna

Abstract

The utility model discloses a radio frequency identification (RFID) near field antenna, which comprises an upper antenna layer, a substrate material layer, a metal connecting layer, a lower antenna layer and a chip, the upper antenna layer and the lower antenna layer are conductively connected through the metal connecting layer to form a continuous annular circuit structure, the antenna layer is annular, and the chip is arranged on the substrate material layer. The side end of the upper antenna layer is connected with a first parallel metal block through a first connecting line, the side end of the lower antenna layer is connected with a second parallel metal block through a second connecting line, the first parallel metal block and the second parallel metal block are vertically opposite and are separated through a substrate material layer, and a classic parallel plate capacitor structure is formed. Through the above mode, the antenna impedance is convenient to adjust, the antenna can be rapidly adapted to various RFID chips by adjusting the area of the antenna loop and the area of the parallel plate capacitor, the impedance matching problem of the antenna and the chip under the condition of small size is solved, and the reading distance of the small-size near-field antenna is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to antenna engineering technical field especially relates to a kind of RFID near-field antennas. BACKGROUND

[0002] RFID antenna design requires that the antenna impedance and chip impedance are conjugate matched, so that the best antenna radiation efficiency can be achieved.The chip impedance of the common RFID chip M730 is 9.85-j166, and the chip as a whole is a capacitive element.It is necessary to design the antenna into a loop circuit to form an inductive device to meet the requirement of conjugate matching.The larger the area of the antenna loop is, the greater the reactance is.For example, the loop antenna with a diameter of 10mm generates a reactance of about 100Ohm, which is less than the impedance matching requirement of 166Ohm.For a conventional RFID tag, it is only necessary to increase the area of the loop antenna to achieve the matching of the imaginary part of impedance.But for a near-field antenna with a size less than 10*10mm, it is impossible to achieve the conjugate matching between the antenna and the chip.

[0003] The existing RFID near-field antenna is mostly a single-layer loop antenna, which provides the reactance of the antenna through a single closed loop.The single-layer loop antenna cannot achieve the conjugate matching with the RFID chip in the case of small size (less than 10*10mm), and the antenna radiation efficiency is low.

[0004] Based on the above defects and disadvantages, it is necessary to improve the existing technology and design a RFID near-field antenna. CONTENT OF UTILITY MODEL

[0005] The utility model mainly solves the technical problem of providing a RFID near-field antenna, which is convenient to adjust the antenna impedance, and can quickly adapt to various RFID chips by adjusting the area of the antenna loop and the parallel plate capacitor, solves the impedance matching problem between the antenna and the chip in the case of small size, and improves the reading distance of the small-size near-field antenna.

[0006] To solve the above technical problems, the utility model adopts one technical scheme, which provides an RFID near field antenna, the RFID near field antenna includes upper antenna layer, base material layer, metal connecting layer, lower antenna layer and chip, the upper antenna layer and the lower antenna layer are conductively connected through the metal connecting layer and form a continuous annular circuit structure, the inductance of the antenna is changed by adjusting the area of the upper antenna layer and the lower antenna layer, the size of the imaginary part of the antenna impedance is adjusted, the antenna layer is annular, the first parallel metal block is connected to the side end of the upper antenna layer through the first connecting line, the second parallel metal block is connected to the side end of the lower antenna layer through the second connecting line, the first parallel metal block and the second parallel metal block are vertically opposite and are separated by the base material layer in the middle, form a classic parallel plate capacitor structure, the reactance of the near field antenna is increased by adjusting the facing area S of the first parallel metal block and the second parallel metal block, adjusting the capacitance C of the parallel plate capacitor, realizing the impedance matching with the chip.

[0007] Preferably, a chip binding opening is formed at the upper edge of the upper antenna layer, and the chip binding opening is connected with the chip through conductive medium at both ends.

[0008] Preferably, the lower edge of the lower antenna layer is disconnected, and the first connecting point and the second connecting point are arranged at both ends of the fracture.

[0009] Preferably, the material of the upper antenna layer and the lower antenna layer is conductive material such as aluminum, copper, conductive silver paste or graphene.

[0010] Preferably, the material of the base material layer is insulating material such as PET film, PI film, paper or RF4.

[0011] Compared with the prior art, the utility model has the beneficial effects that:

[0012] The upper antenna layer and the lower antenna layer are double-layer line structures, the first parallel metal block and the second parallel metal block are vertically opposite and are separated by the base material layer in the middle, forming a classic parallel plate capacitor structure; the reactance of the small-size near field antenna is increased through the parallel plate capacitor in parallel, realizing the impedance matching between the antenna and the chip, enhancing the radiation efficiency of the antenna and improving the reading distance of the antenna. BRIEF DESCRIPTION OF DRAWINGS

[0013] Fig. 1 It is an expanded structure diagram of the RFID near field antenna.

[0014] Fig. 2 It is a top view of the upper antenna layer of the RFID near field antenna.

[0015] Fig. 3 It is a top view of a lower antenna layer of an RFID near field antenna.

[0016] Wherein, 1, the upper antenna layer, 101, the chip binding opening, 102, the first connecting point, 103, the second connecting point, 104, the first parallel metal block, 105, the first connecting line, 2, the substrate material layer, 3, the metal connecting layer, 4, the lower antenna layer, 402, the third connecting point, 403, the fourth connecting point, 404, the second parallel metal block, 405, the second connecting line, 5, the chip. DETAILED DESCRIPTION

[0017] The preferred embodiments of the utility model are described in detail below with reference to the drawings, so that the advantages and characteristics of the utility model can be more easily understood by those skilled in the art, and the protection scope of the utility model can be more clearly and explicitly defined.

[0018] Please refer to Figs. 1 to 3 The utility model embodiment includes:

[0019] An RFID near field antenna, which comprises an upper antenna layer 1, a substrate material layer 2, a metal connecting layer 3, a lower antenna layer 4 and a chip 5.

[0020] The upper antenna layer 1 and the lower antenna layer 4 are conductively connected through the metal connecting layer 3 to form a continuous annular circuit structure, the inductance of the antenna is changed by adjusting the area of the upper antenna layer 1 and the lower antenna layer 4, the size of the imaginary part of the antenna impedance is adjusted, maximum impedance matching is realized, and the upper antenna layer 1 and the lower antenna layer 4 are both located on the substrate material layer 2.

[0021] The upper antenna layer 1 is annular, a chip binding opening 101 is formed at the upper edge of the upper antenna layer 1, the chip binding opening 101 is connected with the chip 5 at both ends through a conductive medium, and the lower edge of the upper antenna layer 1 is disconnected, and the first connecting point 102 and the second connecting point 103 are arranged at both ends of the disconnected part.

[0022] The lower antenna layer 4 is annular, the lower edge of the lower antenna layer 4 is disconnected, the third connecting point 402 and the fourth connecting point 403 are arranged at both ends of the disconnected part, the third connecting point 402 is vertically opposite to the first connecting point 102, the fourth connecting point 403 is vertically opposite to the second connecting point 103, and the two pairs of connecting points are electrically connected through the metal connecting layer 3.

[0023] The upper antenna layer 1 side end is connected with a first parallel metal block 104 through a first connecting line 105, the first parallel metal block 104 is located in the upper antenna layer 1, the lower antenna layer 4 side end is connected with a second parallel metal block 404 through a second connecting line 405, the second parallel metal block 404 is located in the lower antenna layer 4, the first parallel metal block 104 and the second parallel metal block 404 are vertically opposite and separated by the base material layer 2, forming a classic parallel plate capacitor structure, according to the formula of the parallel plate capacitor: Wherein C is the capacitance of the parallel plate capacitor, ∈ is the dielectric constant of the base material layer 2, d is the thickness of the base material layer 2, and S is the opposite area of the first parallel metal block 104 and the second parallel metal block 404, in the case that the dielectric constant ∈ and the thickness d of the base material layer 2 are constant, the capacitance C of the parallel plate capacitor can be adjusted conveniently and quickly by adjusting the opposite area S of the first parallel metal block 104 and the second parallel metal block 404, the reactance of the near-field antenna is increased, and impedance matching with the chip is realized.

[0024] The materials of the upper and lower antenna layers are conductive materials such as aluminum, copper, conductive silver paste or graphene.

[0025] The material of the base material layer 2 is an insulating material such as a PET film, a PI film, paper or RF4.

[0026] The RFID near-field antenna is convenient to adjust the antenna impedance, can quickly adapt to various RFID chips by adjusting the areas of the antenna loop and the parallel plate capacitor, solves the impedance matching problem of the antenna and the chip under small size, and improves the reading distance of the small-size near-field antenna.

[0027] The above only describes the embodiments of the utility model, and does not limit the patent range of the utility model, and any equivalent structure or equivalent process conversion according to the contents of the utility model specification and drawings, or direct or indirect application in other related technical fields, are all included in the patent protection range of the utility model.

Claims

1. An RFID near-field antenna, characterized in that: The invention comprises an upper antenna layer (1), a base material layer (2), a metal connection layer (3), a lower antenna layer (4) and a chip (5); the upper antenna layer (1) and the lower antenna layer (4) are conductively connected via the metal connection layer (3) to form a continuous ring circuit structure; the inductance of the antenna is changed and the imaginary part of the antenna impedance is adjusted by adjusting the area of ​​the upper antenna layer (1) and the lower antenna layer (4); the antenna layer is ring-shaped; the side end of the upper antenna layer (1) is connected to a first parallel metal block ( 104), the side end of the lower antenna layer (4) is connected to the second parallel metal block (404) through a second connecting line (405), the first parallel metal block (104) and the second parallel metal block (404) are vertically opposite and separated by a base material layer (2) in the middle, forming a classic parallel plate capacitor structure, by adjusting the area S of the first parallel metal block (104) and the second parallel metal block (404), adjusting the capacitance C of the parallel plate capacitor, increasing the reactance of the near-field antenna, and achieving impedance matching with the chip.

2. The RFID near-field antenna according to claim 1, wherein: A chip binding opening (101) is provided at the upper edge of the upper antenna layer (1), and chips (5) are connected at both ends of the chip binding opening (101) via a conductive medium. The upper antenna layer (1) is disconnected at the lower edge, and a first connection point (102) and a second connection point (103) are provided at both ends of the disconnection.

3. The RFID near-field antenna according to claim 2, wherein: The lower antenna layer (4) is disconnected at its lower edge, with a third connection point (402) and a fourth connection point (403) provided at both ends of the disconnection; the third connection point (402) is vertically opposite to the first connection point (102), and the fourth connection point (403) is vertically opposite to the second connection point (103); the two pairs of connection points are electrically connected via the metal connection layer (3).

4. The RFID near-field antenna according to claim 1, wherein: The upper antenna layer (1) and the lower antenna layer (4) are made of conductive materials such as aluminum, copper, conductive silver paste or graphene.

5. The RFID near-field antenna according to claim 1, wherein: The base material layer (2) is made of PET film, PI film, paper or RF4 insulating material.

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