CN109149092B - Compact single-feed broadband circularly polarized RFID reader antenna - Google Patents
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- CN109149092B CN109149092B CN201810840531.XA CN201810840531A CN109149092B CN 109149092 B CN109149092 B CN 109149092B CN 201810840531 A CN201810840531 A CN 201810840531A CN 109149092 B CN109149092 B CN 109149092B
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- 230000005855 radiation Effects 0.000 claims abstract description 80
- 239000002184 metal Substances 0.000 claims abstract description 66
- 230000003071 parasitic effect Effects 0.000 claims abstract description 59
- 239000000758 substrate Substances 0.000 claims abstract description 40
- 239000000523 sample Substances 0.000 claims description 10
- 239000004677 Nylon Substances 0.000 claims description 7
- 229920001778 nylon Polymers 0.000 claims description 7
- 230000008878 coupling Effects 0.000 claims description 4
- 238000010168 coupling process Methods 0.000 claims description 4
- 238000005859 coupling reaction Methods 0.000 claims description 4
- 230000005284 excitation Effects 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000010287 polarization Effects 0.000 description 19
- 230000001965 increasing effect Effects 0.000 description 7
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- 238000004088 simulation Methods 0.000 description 3
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- 230000007547 defect Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
- H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
- H01Q1/2216—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in interrogator/reader equipment
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/48—Earthing means; Earth screens; Counterpoises
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
Abstract
The invention discloses a compact single-feed broadband circularly polarized RFID reader antenna, which comprises a first layer of main radiation structure, a second layer of parasitic radiation structure and a grounding layer structure; the first layer of main radiation structure comprises a first medium substrate, a modified half E-shaped metal patch is etched on the upper surface of the first medium substrate, and an elliptical groove and a chamfer are etched on the half E-shaped patch; the second layer of parasitic radiation structure comprises a second dielectric substrate, and a parasitic metal patch with two corners cut off to the same size is etched above the second dielectric substrate; the ground layer structure includes four vertical metal plates and a ground plate. The modified half E-shaped metal patch is used as a main radiation structure, circular polarized radiation can be generated, the antenna has wider impedance bandwidth, the four vertical metal plates are beneficial to reducing the overall size of the antenna, the parasitic radiation structure can further enhance the circular polarized bandwidth and the impedance bandwidth of the antenna, and compared with other antennas, the antenna has the characteristic of small size and is suitable for smaller space environments.
Description
Technical Field
The invention belongs to the technical field of circularly polarized antennas, and relates to a compact single-feed broadband circularly polarized RFID reader antenna.
Background
With the rapid rise and development of the internet of things industry in recent years, radio Frequency Identification (RFID) technology is applied to many fields, such as wireless cashing systems, object tracking, and car security. Antennas have long been a hotspot in research as an important component of RFID systems. For close range RFID systems, high frequency near field RFID systems, such as 13.56MHz RFID systems of less than 10cm, are often employed, which tends to integrate the RFID reader with the antenna. For RFID systems that require remote operation, RFID systems that operate in the UHF band or the microwave band are employed. The frequency band of the current remote work is the UHF frequency band RFID system, the antenna and the reader-writer are usually in a separated structure, and the reader-writer and the antenna are connected together through an impedance matching coaxial cable. RFID systems face new challenges in the design of reader antennas due to the variety of structures, installation and use environments, and the development of reader products toward miniaturization and even microminiaturization. The placement direction of the RFID tag is arbitrary in practical applications, and the tag antenna is usually linearly polarized, and a circularly polarized reader antenna is required to ensure the reliability of communication between the reader and the tag. In addition, in most practical situations, there is a higher demand for reader antennas, such as a wider impedance bandwidth, an axial ratio bandwidth, a high antenna gain, and a directional stable symmetrical pattern. Circular polarized microstrip antennas are often designed as RFID reader antennas because of their compact structure, low profile, and ease of integration.
At present, researchers at home and abroad conduct many researches on circularly polarized RFID patch antennas, but the antenna volume of a single-fed RFID circularly polarized reader is relatively large in the existing literature, mainly because a mode of laminating a radiation patch or loading matching branches is adopted to enhance the bandwidth. The small-size single-feed circularly polarized RFID antenna has a relatively narrow working bandwidth, so that the application range of the RFID system is reduced. If the reader antenna has a relatively wide circular polarization bandwidth under the condition of small size, the antenna needs to introduce an additional power divider or coupler, i.e. a double-feed or multi-feed mode is adopted. This increases the complexity of the antenna system and also increases the loss of the antenna, reducing the radiation efficiency and gain of the antenna.
Therefore, there is an urgent need to design an RFID reader antenna that is compact, adopts a single feed method, and has a certain circular polarization bandwidth, so as to meet current commercial and industrial needs.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art and provide a compact single-feed broadband circularly polarized RFID reader antenna which has larger impedance, circular polarization bandwidth and higher circular polarization antenna gain under the condition of smaller maintenance size and compact structure.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention relates to a compact single-feed broadband circularly polarized RFID reader antenna, which comprises three layers, wherein the three layers are a first layer of main radiation structure, a second layer of parasitic radiation structure and a ground layer structure respectively; the main radiation structure comprises a first medium substrate, a modified half E-shaped metal patch is etched on the upper surface of the first medium substrate, an elliptical groove is etched in the center of the half E-shaped metal patch, a chamfer is arranged at one corner, and a section of branch is added into the half E-shaped metal patch, so that the patch antenna formed by the half E-shaped metal patch generates circularly polarized radiation; the second layer of parasitic radiation structure comprises a second dielectric substrate, and a parasitic metal patch with two angles with the same size cut off is etched above the second dielectric substrate; the grounding layer structure comprises four vertical metal plates and a grounding plate, wherein the four vertical metal plates are rotationally symmetrical and are arranged on the periphery of the grounding plate, and the vertical metal plates are connected with the grounding plate to form a metal cavity with four gaps; the bottom of the grounding plate is provided with a feed port, and an SMA radio frequency connector and an SMA feed probe are arranged at the feed port; an antenna ground is arranged below the second layer of parasitic radiation structure, the SMA radio frequency connector and the antenna ground are welded together, and an SMA feed probe directly feeds the modified half E-shaped metal patch through the second layer of parasitic radiation structure; and a circular groove is etched on the square metal patch of the second layer of parasitic radiation structure, and is used for cutting off the contact between the SMA feed probe and the parasitic metal patch, and excitation of the second layer of parasitic radiation structure is generated through mutual coupling between the parasitic metal patch and the modified half E-shaped metal patch.
As a preferable technical scheme, the first medium substrate is a square substrate, and the side length of the substrate is 140mm. As a preferable technical scheme, the long side of the modified half E-shaped metal patch is 125mm, and the wide side is 110mm;
the long axis of the elliptical groove is 27mm, and the short axis is 18.9mm;
the length of the chamfer is 27mm.
As a preferable technical scheme, the parasitic metal patch is a corner-missing square patch.
As a preferable technical scheme, the unfilled corner square patch is 122mm in length and 30mm in chamfer length.
As a preferable technical scheme, the antenna grounding plate is square in shape and has a side length of 150mm.
As a preferable technical scheme, the height of the first layer of main radiation structure is 1mm;
the height of the second layer parasitic radiation structure is 1mm;
the distance between the first layer of main radiation structure and the second layer of parasitic radiation structure is 8mm;
the distance between the second layer of parasitic radiation structure and the ground is 15mm.
As the preferable technical scheme, the novel high-power LED lamp further comprises a nylon column used for fixing the first layer of main radiation structure, the second layer of parasitic radiation structure and the grounding layer structure, and the nylon column is installed around each layer of structure.
As a preferable technical scheme, the first dielectric substrate is an FR4 dielectric substrate with a dielectric constant of 4.4 and a thickness of 1mm.
As a preferable technical scheme, the second dielectric substrate is an FR4 dielectric substrate with a dielectric constant of 4.4 and a thickness of 1mm.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the compact single-feed broadband circularly polarized RFID reader antenna takes the modified half E-shaped patch as a main radiation patch, can generate circularly polarized radiation, has wider impedance bandwidth, has the characteristic of small patch size compared with other patch antennas, and is suitable for a smaller space environment.
2. The compact single-feed broadband circularly polarized RFID reader antenna adopts the combination of the grounding plate and the modified half E-shaped metal patch by loading the rotary vertical metal plate around, thereby effectively reducing the working frequency of the original modified half E-shaped patch antenna, and effectively reducing the physical size of the antenna. Therefore, the invention can enable the antenna to work in the RFID frequency band of the corresponding low frequency band without increasing the size of the antenna, thereby meeting the requirement of more RFID systems.
3. In the compact single-feed broadband circularly polarized RFID reader antenna, in improving the circular polarization radiation performance, an elliptical groove and a chamfer are loaded on a modified half E-shaped metal patch, so that the current disturbance on the half E-shaped metal patch is changed, and the amplitude and the phase of orthogonal current in space are adjusted, so that the circular polarization radiation purity and the impedance bandwidth are improved.
4. In order to further widen the circular polarization bandwidth of the antenna, the near-field parasitic radiation patch is arranged below the main radiation patch, so that another new circular polarization mode is excited, and the impedance bandwidth and the circular polarization bandwidth of the antenna are increased under the condition that the height of the antenna is not increased.
5. The antenna has the characteristics of wide working bandwidth, compact structure, low profile, low manufacturing material cost and fewer processing and assembly procedures, and has strong practical value.
Drawings
FIG. 1 is a schematic diagram of the perspective structure of a compact single feed broadband circularly polarized RFID reader antenna of the present invention;
FIG. 2 is a top view of the compact single feed wideband circularly polarized RFID reader antenna of FIG. 1;
FIG. 3 is a side view of the compact single feed wideband circularly polarized RFID reader antenna of FIG. 1;
FIG. 4 is a schematic diagram of a second layer parasitic radiating structure of the compact single feed wideband circularly polarized RFID reader antenna of FIG. 1;
fig. 5 is a single-feed circularly polarized patch antenna 1 without a near-field parasitic patch loaded;
FIG. 6 (a) is a graph of simulated reflection coefficients for the compact single feed circularly polarized patch antenna (antenna II) of FIG. 1 compared to a circularly polarized patch antenna (antenna I) without parasitic patches loaded;
FIG. 6 (b) is a graph of the reflection coefficient for the simulation and testing of the compact single feed circularly polarized patch antenna (antenna II) of FIG. 1;
FIG. 7 (a) is a graph of simulated axial ratio coefficients for the compact single feed circularly polarized patch antenna (antenna II) of FIG. 1 compared to a circularly polarized patch antenna (antenna I) without parasitic patches loaded;
FIG. 7 (b) is an axial ratio plot of the simulation and testing of the compact single feed circularly polarized patch antenna (antenna II) of FIG. 1;
FIG. 8 is a graph of gain for simulation and testing of the compact single feed wideband circularly polarized RFID reader antenna II of FIG. 1;
FIGS. 9 (a) and 9 (b) are simulated and tested radiation patterns of the compact single feed wideband circularly polarized RFID reader antenna of FIG. 1 at different planes of 920 MHz;
fig. 10 (a) and 10 (b) are simulated and tested radiation patterns of the compact single feed wideband circularly polarized RFID reader antenna of fig. 1 at different planes of 875 MHZ.
Reference numerals illustrate: 1. a first dielectric substrate; 2. a second dielectric substrate; 3. a primary radiating patch; 4. a near field parasitic radiation patch; 5. a vertical metal plate; 6. a ground plate; 7. a feeding point; 8. a nylon column; 9. branch knots; 10. an elliptical groove; 11. a first chamfer; 12. the SMA feed probe 13, the SMA radio frequency connector 14 and the second chamfer; 15. a circular groove.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.
Examples
The invention provides a compact single-feed broadband circularly polarized RFID reader antenna for increasing the impedance bandwidth and the circularly polarized bandwidth thereof. The compact single-feed broadband circularly polarized RFID reader patch antenna comprises three layers, wherein the three layers are a first layer of main radiation structure, a second layer of parasitic radiation structure and a ground layer structure respectively; the main radiation structure comprises a first dielectric substrate, and a modified half E-shaped metal patch (configured as a main radiation patch in the embodiment) is etched on the upper surface of the first dielectric substrate; the second layer parasitic radiation structure comprises a second dielectric substrate, and a square parasitic metal patch (configured as a near-field parasitic radiation patch in the embodiment) with two corners cut off by the same size is etched above the second dielectric substrate; the grounding layer structure comprises four vertical metal plates and a grounding plate; the main radiation patch and the near-field parasitic radiation patch are both positioned above the grounding plate, and the vertical metal plate is rotationally symmetrical and is arranged around the grounding plate. The invention realizes circular polarization radiation by using the modified half E-shaped metal patch as the main radiation patch of the antenna. Four vertical metal plates are arranged around the main radiation patch and around the grounding plate, so that the horizontal size of the antenna is effectively reduced. In order to enhance the impedance bandwidth and the circular polarization bandwidth of the antenna, the invention provides a method for loading the near field parasitic patch, the technology does not increase the height of the antenna, the bandwidth work broadening is realized, the near field parasitic radiation patch is added below the main radiator, thereby exciting another circular polarization mode, broadening the circular polarization bandwidth of the antenna, and enhancing the impedance bandwidth.
Fig. 1 is a schematic perspective view of a single-fed wideband circularly polarized RFID patch antenna in accordance with a preferred embodiment of the present invention, which includes a main radiating patch 3, a near-field parasitic radiating patch 4, a ground plate 6, and 4 vertical metal plates 5. The primary radiating patch is arranged on top of the first dielectric substrate 1. The near field parasitic radiation patch is arranged on the second medium substrate 2; the materials of the first dielectric substrate and the second dielectric substrate can be FR4 epoxy resin or other corresponding dielectric materials with dielectric constants of 4.4. The height of the vertical metal plate 5 is consistent with the height of the main radiation patch, so that the height of the antenna is not increased; the feed port 7 is located at the lower left of the main radiating patch 3.
Fig. 2 and 3 are top and side views of the single feed circularly polarized RFID patch antenna, with the primary radiating patch being in the shape of a modified half E-patch. When the half E-shaped patch antenna is not provided with the branches 9, the radio frequency current on the patch only flows in the x-axis direction. When the branch 9 is added, the radio frequency current in the Y-axis direction of the antenna is excited. By adjusting the current amplitude and phase in both directions, the antenna can be made to produce circularly polarized radiation. In order not to increase the lateral dimensions of the antenna, four identical vertical metal plates 5 need to be introduced, and are arranged rotationally symmetrically around the ground plate; the four vertical metal plates 5 are all connected with the grounding plate 6 to form a metal cavity with four notches. In this embodiment, the four vertical metal plates 5 can effectively reduce the working frequency of the patch, so that the antenna can work in the corresponding RFID frequency band without increasing the transverse dimension of the antenna, and the length of the metal plates is 75mm and the width is 25mm. Meanwhile, the metal cavity can play a role in inhibiting radiation around the antenna, so that the antenna radiates in one direction, and the front-to-back ratio of the radiation pattern of the antenna is effectively improved by the four loaded metal plates. In order to increase the circular polarization purity of the antenna, a current disturbance unit needs to be added on the half E-shaped patch with the branches 9, and only because the vertical metal plate 5 is loaded, the half E-shaped patch antenna with the branches 9 and the metal plate generate strong coupling, so that the impedance bandwidth is narrowed, and the radiation axis ratio of the antenna is larger than 3dB. The half E-shaped patch with the stem 9 becomes a modified half E-shaped patch. Therefore, adding a current perturbation unit to the modified half E patch can increase the impedance bandwidth and the axial ratio bandwidth of the antenna. The modified semi-E-shaped patch is etched with an elliptical groove 10 and a first chamfer 11, and the impedance bandwidth and the axial ratio bandwidth of the original antenna can be improved by adjusting the sizes of the elliptical groove and the first chamfer. The improved antenna impedance bandwidth is 11.6%, and the circular polarization bandwidth is 5.6%, which is used as the single-feed circular polarization RFID reader antenna I in the example.
In order to further improve the impedance bandwidth and the axial ratio bandwidth, the invention provides a method for widening the bandwidth of an antenna under the condition of not increasing the original height of the antenna. A second dielectric substrate 2 was mounted 8mm below the first dielectric substrate 1, with an added intermediate layer structure as shown in fig. 4. The top surface of the second dielectric substrate is provided with two near field parasitic radiation patches 4 with the same size chamfer. The height between the second layer of medium substrate and the ground is 15mm. The near field parasitic radiation patch 4 excites the outgoing frequency current in a coupled manner to produce a pair of orthogonal degenerate modes having a resonant frequency similar to that of the improved half-E patch. The circular polarization modes of the two patches are made to be close to each other by adjusting the elliptical groove 10, the first chamfer 11 and the second chamfer 14, so that the impedance bandwidth and the circular polarization bandwidth are expanded. An SMA radio frequency connector 13 and an SMA feed probe 12 are arranged at the feed port 7; an antenna ground is arranged below the second layer of parasitic radiation structure, the SMA radio frequency connector and the antenna ground are welded together, and an SMA feed probe directly feeds the modified half E-shaped metal patch through the second layer of parasitic radiation structure; and a circular groove is etched on the square metal patch of the second layer of parasitic radiation structure, and is used for cutting off the contact between the SMA feed probe and the parasitic metal patch, and excitation of the second layer of parasitic radiation structure is generated through mutual coupling between the parasitic metal patch and the modified half E-shaped metal patch.
Wherein, as shown in fig. 5, the antenna I is a single-feed circularly polarized RFID reader patch antenna without a near field parasitic patch, and the antenna II is a single-feed wideband circularly polarized RFID reader patch antenna provided by the preferred embodiment of the present invention. From the results of fig. 6 (a), 6 (b), 7 (a), and 7 (b), it can be seen that the addition of the near field parasitic radiation patch does not increase the height of the antenna, and widens the impedance bandwidth and the axial ratio bandwidth of the patch antenna of the single-feed circularly polarized RFID reader. The test impedance bandwidth of the improved single-feed circularly polarized antenna can reach 14.2% (833-960 MHz), and the 3dB axial ratio bandwidth can reach 9.0% (846-926 MHz).
Fig. 8 is a graph of simulated and tested gain for the single-feed wideband circularly polarized RFID reader antenna II of the invention shown in fig. 1, where it can be seen that the gain is relatively stable within the axial ratio bandwidth, and the highest tested gain reaches 7.6dBic.
Furthermore, the single-feed broadband circularly polarized antenna needs 4 nylon posts 8 to be assembled and installed, and the 4 nylon posts 8 are installed around the two-layer structure and the ground layer to play a role of a fixed structure. The radiation patterns of the x-Z plane and the y-Z plane of the single-feed broadband circularly polarized RFID reader antenna in this embodiment at 870MHz are shown in fig. 9 (a) and fig. 9 (b), and it can be seen that the radiation patterns of the antenna are in a directional radiation manner, radiate along the positive Z direction, and have smaller back lobes. The radiation patterns of the RFID reader antenna in the x-z plane and the y-z plane of 920MHz in FIG. 10 (a) and FIG. 10 (b) are more stable, the co-polarized gain ratio is greater than 15dB, and the front-to-back ratio of the antenna radiation pattern is greater than 14dB within the 3dB axial ratio bandwidth.
The compact single-feed broadband circularly polarized RFID reader antenna designed by the invention can be used for determining the size of the main radiation patch according to the frequency band required by a designer, and if the size is larger, the frequency can be reduced by adopting sequentially rotating metal plates, so that the effect of reducing the size is achieved. By adding parasitic radiating patches below the selected primary radiating patches, the shape of the patches need not be the same as the primary radiating patches, but rather the operating frequency of the primary radiating patches is close to the operating mode of the parasitic patches. The distance between the two patches and the size of the current perturbation unit of each patch are then adjusted to optimize the operating impedance bandwidth and circular polarization bandwidth of the antenna. Besides the single-feed antennas, the bandwidth expansion technical scheme of the invention can be applied to double-feed even multi-feed circularly polarized patch antennas.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (10)
1. The compact single-feed broadband circularly polarized RFID reader antenna is characterized by comprising a three-layer structure, wherein the three-layer structure is a first layer main radiation structure, a second layer parasitic radiation structure and a ground layer structure respectively; the main radiation structure comprises a first medium substrate, a modified half E-shaped metal patch is etched on the upper surface of the first medium substrate, an elliptical groove is etched in the center of the half E-shaped metal patch, a chamfer is arranged at one corner, and a section of branch is added into the half E-shaped metal patch, so that the patch antenna formed by the half E-shaped metal patch generates circularly polarized radiation; the second layer of parasitic radiation structure comprises a second dielectric substrate, and a parasitic metal patch with two angles with the same size cut off is etched above the second dielectric substrate; the grounding layer structure comprises four vertical metal plates and a grounding plate, wherein the four vertical metal plates are rotationally symmetrical and are arranged on the periphery of the grounding plate, and the vertical metal plates are connected with the grounding plate to form a metal cavity with four gaps; the height of the vertical metal plate is the same as that of the first layer of main radiation structure; the bottom of the grounding plate is provided with a feed port, and an SMA radio frequency connector and an SMA feed probe are arranged at the feed port; an antenna ground is arranged below the second layer of parasitic radiation structure, the SMA radio frequency connector and the antenna ground are welded together, and an SMA feed probe directly feeds the modified half E-shaped metal patch through the second layer of parasitic radiation structure; and a circular groove is etched on the square metal patch of the second layer of parasitic radiation structure, and is used for cutting off the contact between the SMA feed probe and the parasitic metal patch, and excitation of the second layer of parasitic radiation structure is generated through mutual coupling between the parasitic metal patch and the modified half E-shaped metal patch.
2. The compact, single feed, wideband circularly polarized RFID reader antenna of claim 1, wherein the first dielectric substrate is a square substrate with a substrate side length of 140mm.
3. The compact single feed wideband circularly polarized RFID reader antenna of claim 1, wherein the modified half E-shaped metal patch has a long side of 125mm and a wide side of 110mm;
the long axis of the elliptical groove is 27mm, and the short axis is 18.9mm;
the length of the chamfer is 27mm.
4. The compact, single feed, wideband circularly polarized RFID reader antenna of claim 1, wherein the parasitic metal patch is a corner-missing square patch.
5. The compact, single feed, wideband circularly polarized RFID reader antenna of claim 4, wherein the unfilled corner square patch has a length of 122mm and a cut-out length of 30mm.
6. The compact, single feed, wideband circularly polarized RFID reader antenna of claim 1, wherein the antenna ground plate is square in shape with a side length of 150mm.
7. The compact single feed wideband circularly polarized RFID reader antenna as in claim 1, wherein,
the height of the first layer of main radiation structure is 1mm;
the height of the second layer parasitic radiation structure is 1mm;
the distance between the first layer of main radiation structure and the second layer of parasitic radiation structure is 8mm;
the distance between the second layer of parasitic radiation structure and the ground is 15mm.
8. The compact, single feed, wideband circularly polarized RFID reader antenna of claim 1, further comprising nylon posts for securing the first layer of main radiating structure, the second layer of parasitic radiating structure, and the ground layer structure, the nylon posts being mounted around each layer of structure.
9. The compact single feed wideband circularly polarized RFID reader antenna of claim 1, wherein the first dielectric substrate is an FR4 dielectric substrate having a dielectric constant of 4.4 and a thickness of 1mm.
10. The compact single feed wideband circularly polarized RFID reader antenna of claim 1, wherein the second dielectric substrate is an FR4 dielectric substrate having a dielectric constant of 4.4 and a thickness of 1mm.
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| CN201810840531.XA CN109149092B (en) | 2018-07-27 | 2018-07-27 | Compact single-feed broadband circularly polarized RFID reader antenna |
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| CN201810840531.XA CN109149092B (en) | 2018-07-27 | 2018-07-27 | Compact single-feed broadband circularly polarized RFID reader antenna |
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| CN112310609A (en) * | 2020-11-25 | 2021-02-02 | 福州大学 | Low-profile wide-beam circularly polarized reader antenna applied to RFID |
| CN113036459A (en) * | 2021-03-08 | 2021-06-25 | 安徽大学 | Millimeter wave low-profile broadband circularly polarized slot-fed dipole array antenna |
| CN117832829A (en) * | 2024-02-28 | 2024-04-05 | 长光卫星技术股份有限公司 | S-band double-layer microwave bandwidth beam antenna based on metal cavity |
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| CN208723085U (en) * | 2018-07-27 | 2019-04-09 | 华南师范大学 | Compact list presents broadband circle polarized RFID reader antenna |
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| US10211535B2 (en) * | 2015-07-20 | 2019-02-19 | The Regents Of The University Of California | Low-profile circularly-polarized single-probe broadband antenna |
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| CN105896091A (en) * | 2016-06-07 | 2016-08-24 | 桂林电子科技大学 | Miniaturized broadband high-gain circular polarized microstrip antenna |
| CN107895846A (en) * | 2017-10-30 | 2018-04-10 | 华南理工大学 | One kind has wide band circularly-polarized patch antenna |
| CN208723085U (en) * | 2018-07-27 | 2019-04-09 | 华南师范大学 | Compact list presents broadband circle polarized RFID reader antenna |
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