100 is not larger than a distance D2 between the gap 150 and the one end 100A of the RFID tag component 100.

In addition, the RFID tag component 100 further includes a first through hole 170A (which is arranged in the substrate 110 at the one end 100A of the RFID tag component 100) and a second through hole 170B (which is arranged in the substrate 110 at the other end 100B of the RFID tag component 100). The through hole structures may be manufactured by the mechanical processing, and then a conductive material (such as copper) is coated on the inner surfaces of the through hole structures to enable conduction between different objects electrically connected to the conductive material, thereby forming the through holes. The first through hole 170A connects the one end 130A of the middle layer 130 to the one end 120A of the bottom layer 120. The second through hole 170B connects the other end 140B of the top layer 140 to the other end 120B of the bottom layer 120.

In the embodiment shown in FIG. 1a and FIG. 1b, the bottom layer 120 serves as a ground layer of the RFID tag component 100. There is a spacing of H1 between the bottom layer 120 and the middle layer 130 (for example, through the first through hole 170A). The spacing between the middle layer 130 and the top layer 140 is H2. There is a spacing of H1+H2 between the bottom layer 120 and the top layer 140 (for example, through the second through hole 170B). This three-dimensional structure of the RFID tag component 100 may effectively reduce the area of the tag component in the limited space, and by making the top layer 140 and the middle layer 130 closely coupled in a disconnected manner instead of a short-circuit connection, the working impedance bandwidth of the RFID tag component 100 is improved and the adjustability is provided.

The center frequency may be adjusted by changing various design variables of the RFID tag component 100, such as the spacing H1 between the bottom layer 120 and the middle layer 130, the spacing H2 between the middle layer 130 and the top layer 140, a position of the other end 130B of the middle layer 130, a length T1 of the top layer 140, a position of the chip 160 on the top layer 140 (here, indicated by a distance off1 between the chip 160 and the other end 140B of the top layer 140), and so on. In the assembly state, it is difficult to adjust the spacing H1 between the bottom layer 120 and the middle layer 130, the spacing H2 between the middle layer 130 and the top layer 140, and the position of the other end 130B of the middle layer 130. In the case that the distance D1 between the other end 130B of the middle layer 130 and the one end 100A of the RFID tag component 100 exceeds the distance D2 between the gap 150 and the one end 100A of the RFID tag component 100, even very subtle changes in other variables may greatly affect the center frequency of the RFID tag component 100. Therefore, this embodiment predetermines the distance D1 between the other end 130B of the middle layer 130 and the one end 100A of the RFID tag component 100 to not exceed the distance D2 between the gap 150 and the one end 100A of the RFID tag component 100. In FIG. 1a, the other end 130B of the middle layer 130 is basically aligned with a side of the gap 150 closer to the one end 100A of the RFID tag component 100. Furthermore, the spacing H1 and the spacing H2 are predetermined, and the center frequency and the impedance matching of the RFID tag component 100 are fine-tuned by fine-tuning the position off1 of the chip 160 and the length T1 of the top layer 140.

In addition, a width W1 of the RFID tag component 100 is designed to be very narrow compared to its length. Therefore, the equivalent capacitance formed by the close coupling between the top layer 140 and the middle layer 130 which is realized through the bottom layer 120 and the connected through holes 170A and 170B on both sides may relatively easily achieve the complex impedance matching of the chip 160 of the RFID tag component. And by having the RFID tag component 100 itself with a ground plane, the RFID tag component 100 may be attached to a metal surface or inserted into a metal environment and various dielectric materials.

FIG. 2a and FIG. 2b show a side view and an exploded view of an RFID tag component 200 according to another embodiment of the present disclosure. The RFID tag component 200 includes one end 200A and other end 200B along a length direction (the x-axis). The RFID tag component 200 includes a substrate 210, a bottom layer 220, a middle layer 230, and a top layer 240. The substrate 210 may be made of a dielectric material. The bottom layer 220, the middle layer 230, and the top layer 240 may be made of a conductive material (for example, copper) and fabricated into a very thin sheet. The bottom layer 220 is located at a bottom of the substrate 210 and extends along the x-axis direction. One end 220A of the bottom layer 220 is close to the one end 200A of the RFID tag component 200. Other end 220B of the bottom layer 220 is close to the other end 200B of the RFID tag component 200. The middle layer 230 is located between a top and the bottom of the substrate 210. One end 230A of the middle layer 230 is close to the one end 200A of the RFID tag component 200. Other end 230B of the middle layer 230 is close to the other end 200B of the RFID tag component 200. The middle layer 230 includes a gap 250. The gap 250 is located at a middle position of the middle layer 230 in the x-axis direction. The chip 260 of the RFID tag component 200 is bonded to the middle layer 230 across the gap 250. The chip 260 may be covered with a protective layer. The top layer 240 is located on the top of the substrate 210. One end 240A of the top layer 240 is spaced apart from the one end 200A of the RFID tag component 200. Other end 240B of the top layer 240 is spaced apart from the other end 200B of the RFID tag component 200. The top layer 240 includes a mechanical hole 280 which at least partially overlaps the gap 250 of the middle layer 230 in the longitudinal direction (the y-axis in FIG. 2a). The chip 260 and an optional protective layer of the chip 260 may be accommodated in the mechanical hole 280. The mechanical hole 280 defines a cavity structure in the top layer 240, thereby conveniently arranging the chip 260 in the middle layer 230 and playing a role in avoiding and protecting the chip 260. Preferably, the top layer 240 is symmetrical with respect to a midline cl of the RFID tag component 200 in the x-axis direction. The top layer 240 and the middle layer 230 are at least partially overlapped in the longitudinal direction (the y-axis in FIG. 2a).

In addition, the RFID tag component 200 further includes a first through hole 270A (which is arranged at the one end 200A of the RFID tag component 200 in the substrate 210) and a second through hole 270B (which is arranged at the other end 200B of the RFID tag component 200 in the substrate 210). The first through hole 270A connects the one end 230A of the middle layer 230 to the one end 220A of the bottom layer 220. The second through hole 270B connects the other end 230B of the middle layer 230 to the other end 220B of the bottom layer 220.

In the embodiment shown in FIG. 2a and FIG. 2b, the bottom layer 220 serves as a ground layer of the RFID tag component 200. There is a spacing of H3 between the bottom layer 220 and the middle layer 230. There is a spacing of H4 between the middle layer 230 and the top layer 240. A length D1 of the top layer 240 along the x-axis direction may be used as a design variable. As the material of the attached object and the attached depth change, the RFID tag component 200 may be fine-tuned by adjusting the design variable D1. When the length D1 of the top layer 240 increases, the equivalent capacitance between the top layer 240 and the middle layer 230 increases, thereby reducing the center frequency of the RFID tag component 200. Conversely, when the length D1 decreases, the equivalent capacitance decreases, thereby increasing the center frequency of the RFID tag component 200. This sheet-like structure of the top layer 240 may easily improve the deviation/offset caused by the changes in the surrounding environment outside the RFID tag component 200 and the changes in the arrangement environment. In addition, it may also reduce the protrusion of the top of the RFID tag component 200, reduce the friction during the arrangement process, and improve the convenience. The structure shown in this embodiment may be used as a technical solution that may efficiently and conveniently implement the impedance matching of the chip in the UHF frequency band through the conventional PCB manufacturing processes.

FIG. 3a and FIG. 3b show the impedance characteristics of the RFID tag component 100 according to one embodiment and the RFID tag component 200 according to another embodiment of the present disclosure when various parameters are set based on the 920 MHz center frequency band of the UHF frequency band. As shown in FIG. 3a and FIG. 3b, the imaginary component of the input impedance of the RFID tag component 100 is a relatively low 0.23+j137.57Ω (f₀=920 MHz), and the imaginary component of the input impedance of the RFID tag component 200 is set to a relatively high 7.48+j212.47Ω (f₀=920 MHz). The most critical design variable of the RFID tag components 100/200 of the present disclosure is the distance between the through holes arranged on both sides of the RFID tag component (the distance between the through hole 170A and the through hole 170B, the distance between the through hole 270A and the through hole 270B, hereinafter referred to as the “through hole spacing”) and the spacing between each layer in the multi-layer RFID tag component (the spacing H1 and the spacing H2 in the RFID tag component 100, and the spacing H3 and the spacing H4 in the RFID tag component 200, hereafter referred to as the “spacing between layers”). The through hole spacing is the most important design variable for adjusting the inductance component of the RFID tag component. The spacing between layers is the most important design variable for adjusting the capacitance of the RFID tag component. However, the thickness of the RFID tag component, the thickness of each layer, and the length of each layer through the through hole, which serve as these design variables, may not be significantly changed after the manufacturing process of the RFID tag component is determined; only other means may be used for fine-tuning.

The RFID tag component 100 in FIG. 1a and FIG. 1b may adjust the electrical parameters of the RFID tag component 100 by adjusting the length T1 of the top layer 140 and the bonding position off1 of the chip 160. The RFID tag component 200 in FIG. 2a and FIG. 2b may achieve fine-tuning of the center frequency of the RFID tag component 200 by adjusting the length D1 of the top layer 240. FIG. 3c schematically shows the process of fine-tuning the center frequency of the RFID tag component 200 by adjusting the length D1 of the top layer 240. This fine-tuning of the design variables of the RFID tag component provides the convenient means to easily fine-tune the changes and the tolerances in the materials of various attached objects. As an embodiment, the input impedances of the RFID tag component 100 and the RFID tag component 200 of the present disclosure are formed to be 0.23+j137.57Ω and 7.48+j212.47Ω respectively based on 920 MHz. It may be seen that the imaginary input impedance which needs to be redesigned as the chip changes may be adjusted by adjusting the distributed area, thus improving the usability of the RFID tag component.

Generally, the RFID tag component itself attached onto the metal surface includes a ground plane. When the ground plane is connected to the metal surface in a short-circuit manner, the attached metal surface itself serves as the common ground plane of the RFID tag component. Therefore, when the area of the attached metal object is large, the radiation gain and the spatial radiation pattern of the RFID tag component may also be greatly affected as the attached position changes. There are significant differences in the radiation gain patterns between the front side and the back side of the RFID tag component attached onto the metal object. In order to improve the aesthetics and reduce the risk of the damage to the RFID tag component in practical applications, the RFID tag component is generally embedded in a groove on the metal surface. As the depth of the groove increases, the radiation efficiency of the tag component decreases, and the spatial radiation gain decreases, which in turn affects its identification distance.

FIG. 4a shows a schematic diagram of the RFID tag component 100 attached onto a planar tool 400 according to the first embodiment of the present disclosure. Moreover, the RFID tag component 100 includes a protruding chip, which may be covered by a protective layer. The tool 400 is made of narrow and long metal. The planar surface 401 of the tool 400 is not provided with any cavity or groove for accommodating the RFID tag component 100.

FIG. 4b