一种倒相多环耦合近场RFID天线阵列

Abstract

本实用新型涉及天线技术领域，尤其是涉及一种倒相多环耦合近场RFID天线阵列，包括作为天线背面结构的金属反射面，金属反射面上设置有N个天线阵列单元，在金属反射面的左侧位置上设置有信号馈入点，信号馈入点连接有进行一分N信号功率等分的N个分配枝节，N个分配枝节分别连接于N个天线阵列单元，使信号馈入点通过N个分配枝节将输入信号的功率平均分配给N个天线阵列单元；每个天线阵列单元具有上路径传输线、下路径传输线以及多个电容；上路径传输线和下路径传输线均由直线段与弯折段交替连接构成；本实用新型提供的倒相多环耦合近场RFID天线阵列，有效克服了常规近场RFID天线因尺寸限制导致识别范围有限、信号易丢失的技术局限。

Claims

1. A phase-inverting multi-ring coupled near-field RFID antenna array, characterized in that, The antenna includes a metal reflector (10) as the back structure of the antenna, on which N antenna array elements (20) are arranged. A signal feed point (30) is arranged on the left side of the metal reflector (10). The signal feed point (30) is connected to N distribution branches (31) that divide the signal power into N equal parts. The N distribution branches (31) are respectively connected to the N antenna array elements (20), so that the signal feed point (30) distributes the power of the input signal equally to the N antenna array elements (20) through the N distribution branches (31). Each antenna array element (20) has an upper path transmission line (40), a lower path transmission line (50), and multiple capacitors (C); the upper path transmission line (40) and the lower path transmission line (50) are both composed of alternating straight and bent segments, and multiple closed loops (60) are formed through capacitor (C) coupling and path bending, wherein: The upper path transmission line (40) has a coupling bend inverted segment (41) at the starting end. The coupling bend inverted segment (41) is used to make the upper path transmission signal and the lower path transmission signal form a 180-degree phase difference. The upper path transmission line (40) extends in sequence along the signal transmission direction with multiple upper branch segments (42). Each upper branch segment (42) has a first upward bend segment (421), a first straight segment (422) and a first downward bend segment (423) connected in sequence. The coupling bend inverted segment (41) serves as the first upward bend segment (421) of the first upper branch segment (42). The first downward bend segment (423) of the previous upper branch segment (42) and the first upward bend segment (421) of the next upper branch segment (42) are connected by a capacitor (C). The lower path transmission line (50) extends sequentially along the signal transmission direction through multiple lower branch segments (51). Each lower branch segment (51) has a second upward bending segment (511), a second straight segment (512), and a second downward bending segment (513) connected sequentially. The second upward bending segment (511) of the upper lower branch segment (51) and the second downward bending segment (513) of the lower lower branch segment (51) are connected by a capacitor (C). In the upper path transmission line (40), the capacitor (C) bridging the adjacent upper branch segment (42) forms a spatial coupling with the middle position of the second straight segment (512) of the lower branch segment (51) corresponding to the lower path transmission line (50); in the lower path transmission line (50), the capacitor (C) bridging the adjacent lower branch segment (51) forms a spatial coupling with the middle position of the first straight segment (422) of the upper branch segment (42) corresponding to the upper path transmission line (40). Through this spatial coupling relationship, multiple closed loops (60) are formed between the upper path transmission line (40) and the lower path transmission line (50). The signal in the loop flows in a closed loop based on the coupling between the capacitor (C) and the straight segment, thereby generating near-field radiation, and the radiation range covers the area where the loop is located.

2. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, The metal reflector (10) is an integral structure that covers the back of the antenna and is used to ensure that the antenna signal radiates only in the direction of the line surface.

3. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, The distribution branch (31) that divides the power of the N signal equally follows the power equal division matching principle. Its signal input impedance is 50Ω, and the impedance of each signal line is 50Ω×N. The width of the input line and the width of the signal line after division are matched with the corresponding impedance values.

4. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, The total length of the coupling bend antiphase segment (41) is a multiple of 1 / 2 of the wavelength of a specific frequency, so that the upper path transmission signal lags behind the lower path transmission signal by 180 degrees, forming an antiphase, which is conducive to the flow of coupled signals in the subsequent loop to form a radiation loop.

5. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, The first lower branch segment (51) of the lower path transmission line (50) has a total length of 1 / 2 wavelength of a specific frequency. Its second downward bending segment (513), second straight segment (512) and second upward bending segment (511) form a semi-open loop. The second upward bending segment (511) forms a spatial coupling with the center point of the first straight segment (422) of the first upper branch segment (42) of the upper path transmission line (40), forming the first closed loop (60) and realizing the first near-field radiation.

6. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, In the upper path transmission line (40) and the lower path transmission line (50), the total length of the upper branch segment (42) and the lower branch segment (51) corresponding to each closed loop (60) is one wavelength of a specific frequency. Taking one wavelength of a specific frequency as the cycle unit, a spatial coupling point is formed at the intersection center point of the upper path transmission line (40) and the lower path transmission line (50), forming a closed loop (60) to generate near-field radiation.

7. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, The antenna array is made using a single PCB fabrication process. The signal feed point (30) is directly connected to the signal line. It can connect the signal path with the PCB of the whole circuit of the device using the antenna, or it can be connected to the product through a cable.

8. The inverted phase multi-loop coupled near field RFID antenna array of claim 1, wherein, N is 3, and the 3 distribution branches (31) are connected to the 3 antenna array units (20) respectively.

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