Circularly polarized reader antenna applied to combination of far and near fields in UHF (Ultra High Frequency) band

Abstract

The invention discloses a circularly polarized reader antenna applied to combination of far and near fields in a UHF (Ultra High Frequency) band, which comprises a metal ground, a radiation unit, a feed unit and an intermediate dielectric substrate, and is characterized in that the radiation unit comprises a far-field radiation unit and a near-field radiation unit, the far-field radiation unit is a radiation patch printed on the upper surface of the upper layer of the intermediate dielectric substrate, and the near-field radiation unit is a near-field radiation patch printed on the upper surface of the lower layer of the intermediate dielectric substrate; two ends are connected with a near-field radiation unit applied to a near field; the feed unit adopts a coaxial feed mode, and the radiation unit is connected with the metal ground through a coaxial line; the metal ground is located on the lower layer of the middle dielectric substrate and slightly larger than the far-field radiation unit in size. According to the invention, the far and near field radiation units are combined to greatly improve the reading effect of the reader on the label and reduce the plating leakage rate; the near-field radiation unit is directly connected to the two sides of the far-field radiation unit, so that the space is saved, the size of the antenna is reduced, the feed network of the antenna is simplified, and the energy loss caused by feed is reduced; and the whole plate is of a single-layer plate structure, and is low in profile, light in weight and convenient to install.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communication, and in particular relates to a circularly polarized reader antenna applied to a UHF frequency band far-field and near-field combination. Background Art

[0002] As an essential part of the RFID system, the reader antenna is mainly responsible for sending and receiving RF signals.

[0003] Although a single far-field radiating unit has good gain, in 2D 2 / λ (D is the maximum physical aperture of the antenna, λ is the working wavelength) has excellent reading performance, but when the antenna surface is close to the tag or even close to it, there is a situation where the tag is missed. Therefore, it is necessary to design an antenna that combines far and near fields. Traditional far and near field radiators feed the far field radiator and the near field radiator separately. Although some antennas design the two on the same substrate, the use of a power divider for feeding increases the energy loss by about 3dB. Summary of the invention

[0004] The main purpose of the present invention is to solve the defects and shortcomings existing in the above-mentioned prior art, and to provide a circularly polarized reader antenna for combining near and far fields in the UHF frequency band, in which the near-field radiating unit is directly connected to the radiating surface of the far-field radiating unit through a branch, which not only ensures the integrity of the tag reading, but also simplifies the feeding method of the antenna and reduces energy loss.

[0005] The present invention is implemented by the following technical solution: a circularly polarized reader antenna for combining near and far fields in the UHF frequency band, comprising a metal ground, a radiation unit, a feeding unit and an intermediate dielectric substrate,

[0006] The radiation unit includes a far-field radiation unit and a near-field radiation unit. The far-field radiation unit is a radiation patch printed on the upper surface of the upper layer of the intermediate dielectric substrate, and the two ends are connected to the near-field radiation unit applied to the near field.

[0007] The feeding unit adopts a coaxial feeding method, and the radiation unit is connected to the metal ground through a coaxial line;

[0008] The metal ground is located at the lower layer of the intermediate dielectric substrate and has a size slightly larger than the far-field radiation unit.

[0009] Preferably, the substrate of the radiation unit adopts a PCB substrate, which ensures the miniaturization of the antenna while ensuring low cost.

[0010] Preferably, the far-field radiation unit is designed to be circularly polarized to achieve a better reading effect.

[0011] Preferably, both ends of the far-field radiation unit are connected to near-field radiation unit branches, adopting a traveling wave antenna structure.

[0012] Preferably, the near-field radiation unit is a centrosymmetric structure to ensure the circular polarization characteristics of the far-field radiation unit.

[0013] Preferably, the feeding network of the antenna unit adopts a coaxial feeding network, and the feeding point is located on the far-field radiating unit, thereby ensuring the far-field performance of the far-field radiating unit and reducing energy loss.

[0014] Preferably, the metal ground of the antenna is located at the lower layer of the intermediate dielectric substrate, and its size is slightly larger than that of the far-field radiation unit to ensure the main radiation direction of the far-field radiation unit.

[0015] Preferably, the size of the metal ground of the antenna should be smaller than the size of the inner periphery of the near-field radiation unit to avoid affecting the performance of the near-field radiation unit.

[0016] The beneficial effects of adopting the above technical solution are:

[0017] Combining the far-field and near-field radiation units can greatly improve the reader's reading effect on the tag, reduce the leakage rate, and reduce the problem of incomplete tag reading due to the close distance of the far-field antenna without adding additional antennas; directly connecting the near-field radiation unit on both sides of the far-field radiation unit saves space, reduces the antenna size, simplifies the antenna feeding network, and reduces the energy loss caused by feeding; the antenna is a single-layer board structure as a whole, with compact structure, low profile, lightweight, easy installation and excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the implementation cases of the present invention, the drawings required in the description of the embodiments are briefly introduced below. As a part of the present invention, the schematic embodiments of the present invention and their description are used to explain the present invention, but do not constitute improper limitations on the present invention.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the top-level structure of the present invention;

[0021] Figure 3 It is a schematic diagram of the underlying structure of the present invention;

[0022] Among them: 1. Near-field radiation unit; 2. Far-field radiation unit; 3. Feed unit; 4. Metal ground; 5. Intermediate dielectric substrate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] like Figure 1-3 As shown, a circularly polarized reader antenna for combining near and far fields in the UHF band includes a metal ground 4, a radiation unit, a feeding unit 3 and an intermediate dielectric substrate 5.

[0025] The radiation unit includes a far-field radiation unit 2 and a near-field radiation unit 1. The far-field radiation unit 2 is a radiation patch printed on the upper surface of the upper layer of the intermediate dielectric substrate 5, and the two ends are connected to the near-field radiation unit 1 applied to the near field.

[0026] The feeding unit 3 adopts a coaxial feeding method, and the radiation unit is connected to the metal ground 4 through a coaxial line;

[0027] The metal ground 4 is located at the lower layer of the intermediate dielectric substrate 5 , and is slightly larger than the far-field radiation unit 2 .

[0028] The substrate of the radiation unit adopts a PCB substrate, which ensures the miniaturization of the antenna while ensuring low cost.

[0029] The far-field radiation unit 2 is designed to be circularly polarized to achieve a better reading effect.

[0030] The far-field radiation unit 2 has near-field radiation unit branches connected to both ends, and adopts a traveling wave antenna structure.

[0031] The near-field radiation unit 1 is a centrosymmetric structure to ensure the circular polarization characteristics of the far-field radiation unit 2 .

[0032] The feeding network of the antenna adopts a coaxial feeding network, and the feeding point is located on the far-field radiation unit 2, which ensures the far-field performance of the far-field radiation unit and reduces energy loss.

[0033] The metal ground 4 of the antenna is located at the lower layer of the intermediate dielectric substrate 5 , and its size is slightly larger than that of the far-field radiation unit 2 to ensure the main radiation direction of the far-field radiation unit 2 .

[0034] The size of the metal ground 4 of the antenna should be smaller than the size of the inner periphery of the near-field radiation unit 1 to avoid affecting the performance of the near-field radiation unit 1 .

[0035] 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, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. Therefore, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A circularly polarized reader antenna for UHF band combined near and far fields, characterized by: It includes metal ground, radiation unit, feeding unit and intermediate dielectric substrate. The radiation unit includes a far-field radiation unit and a near-field radiation unit. The far-field radiation unit is a radiation patch printed on the upper surface of the upper layer of the intermediate dielectric substrate, and the two ends are connected to the near-field radiation unit applied to the near field. The feeding unit adopts a coaxial feeding method, and the radiation unit is connected to the metal ground through a coaxial line; The metal ground is located at the lower layer of the intermediate dielectric substrate and has a size slightly larger than the far-field radiation unit.

2. The circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The substrate of the radiation unit adopts a PCB substrate, which ensures the miniaturization of the antenna while ensuring low cost.

3. A circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The far-field radiation unit is designed to be circularly polarized to achieve a better reading effect.

4. The circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The two ends of the far-field radiation unit are connected to near-field radiation unit branches, and a traveling wave antenna structure is adopted.

5. A circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The near-field radiation unit is a centrosymmetric structure to ensure the circular polarization characteristics of the far-field radiation unit.

6. A circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The feeding network of the antenna adopts a coaxial feeding network, and the feeding point is located on the far-field radiating unit, which ensures the far-field performance of the far-field radiating unit and reduces energy loss.

7. A circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The metal ground of the antenna is located at the lower layer of the intermediate dielectric substrate, and its size is slightly larger than that of the far-field radiation unit to ensure the main radiation direction of the far-field radiation unit.

8. A circularly polarized reader antenna for combining near and far fields in the UHF band according to claim 1, characterized in that: The size of the metal ground of the antenna should be smaller than the size of the inner periphery of the near-field radiation unit to avoid affecting the performance of the near-field radiation unit.

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