A miniaturized dual-band circularly polarized antenna

Abstract

The application provides a miniaturized dual-band circularly polarized antenna, comprising a dielectric substrate and a cover layer, the cover layer is located on the top of the dielectric substrate, a radiation surface is printed on the top of the dielectric substrate, a ground plane is printed on the bottom of the dielectric substrate, the radiation surface and the ground plane are connected and communicated through a short-circuit probe and a coaxial feed center probe, a cross-shaped rectangular slot group and an L-shaped rectangular slot group are arranged on the radiation surface, the radiation surface is a center-symmetrical structure, and a T-shaped ground plane rectangular slot group is arranged on the ground plane. The miniaturized dual-band circularly polarized antenna provided by the application has the advantages of simple structure, small size, low profile, low coupling, circular polarization, dual-band and the like.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a miniaturized dual-band circularly polarized antenna. Background Technology

[0002] In the clinical and medical research fields, implantable medical systems have enabled 31 highly precise treatment and diagnostic methods. Implantable medical systems are extremely useful in a variety of applications, such as capsule endoscopy, glucose monitoring implants, pacemakers, and intracranial pressure monitoring.

[0003] With the rapid development of wireless communication and electronic technology, more and more microsystems are being applied to mobile medical devices. Implantable antennas play an important role in mobile medical devices. To obtain satisfactory antenna dimensions, slots are cut into the radiating patch. On the other hand, human tissue is a complex electromagnetic environment, which reduces the antenna's operating bandwidth. To achieve a wider bandwidth, methods such as split-ring resonators, inner and outer rings on the substrate, defective grounding structures, and serpentine shapes on the radiating patch are employed. Although the impedance bandwidth is improved, the position of the linearly polarized antenna changes with human movement, thus affecting the antenna's efficiency. Circular polarization can effectively solve this problem. To improve the axial ratio of the circularly polarized antenna, the position of the coaxial feed is adjusted, and short pins are added to cover a reasonable bandwidth range. In addition, circular polarization can also be achieved by introducing a pair of perturbation elements. Introducing annular slots and short pins on the microstrip antenna, as well as introducing double-opening short pins inside the annular radiator, can improve circular polarization performance. We propose a compact structure to increase the axial ratio bandwidth of an implantable antenna operating in the Industrial, Scientific, and Medical (ISM) band for human health monitoring microsystems.

[0004] There is significant potential for research into multi-band implantable antennas in IMDS, as only a limited number of works have been reported to date. The paper "A miniaturized triple-band implantable antenna 624 system for bio-telemetry applications" presents a dual-band implantable antenna for bio-telemetry applications, operating in the ISM band (902-928MHz and 2400-2483.5MHz) and the mid-band (1824-1980MHz). The antenna is compact, measuring only 21mm³, achieved using various miniaturization techniques, such as through-holes connecting the radiating sheet to the ground; however, this makes design and fabrication quite complex. The paper "Scalp-implantable antenna systems 627 for intracranial pressure monitoring" describes the development of a dual-band antenna with an ISM band of 902-928MHz and 2400-2483.5MHz, also with a volume of 24mm³. This antenna has acceptable bandwidth and gain, but lacks frequency bands for wireless power transmission or power saving, which are essential for the operation of many wireless IMDS. A flower-shaped dual-band implantable antenna for skin implantation and endoscopic applications is reported in the paper "A miniaturized novel-shape dual-band antenna 630 for implantable applications"; however, it offers low gain at 2.45 GHz and has a complex structure. A dual-band antenna operating in 402-405 MHz and 2400-2480 MHz with a volume of 642.62 mm³ is proposed in the paper "A novel differentially fed 633 compact dual-band implantable antenna for biotelemetry applications". Besides its large size, this antenna does not support any frequency bands for wireless power transmission. Therefore, designing a miniaturized dual-band circularly polarized antenna is essential. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized dual-band circularly polarized antenna with a simple structure and advantages such as small size, low profile, low coupling, circular polarization, and dual-band operation.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A miniaturized dual-band circularly polarized antenna includes: a dielectric substrate and a cover layer, wherein the cover layer is located on top of the dielectric substrate;

[0008] The top of the dielectric substrate is printed with a radiating surface, and the bottom of the dielectric substrate is printed with a ground plane. The radiating surface and the ground plane are connected by a short-circuit probe and a coaxial feed point center probe.

[0009] The radiating surface is provided with cross-shaped rectangular groove groups and L-shaped rectangular groove groups, and the radiating surface has a centrally symmetrical structure. The ground plane is provided with T-shaped ground plane rectangular groove groups.

[0010] Optionally, the cross-shaped rectangular groove group includes a cross-shaped rectangular groove, and the L-shaped rectangular groove group includes a first L-shaped rectangular groove, a second L-shaped rectangular groove, a third L-shaped rectangular groove, and a rectangular groove. The cross-shaped rectangular groove is provided at the center of the radiating surface. The first L-shaped rectangular groove is provided on the upper left side of the radiating surface, and the rectangular groove is provided on the lower side of the first L-shaped rectangular groove. The first L-shaped rectangular groove is connected to the cross-shaped rectangular groove. The second L-shaped rectangular groove and the third L-shaped rectangular groove are provided on the lower left side of the radiating surface. The second L-shaped rectangular groove is located to the right of the third L-shaped rectangular groove. The second L-shaped rectangular groove, the third L-shaped rectangular groove, and the cross-shaped rectangular groove are not connected to each other. The second L-shaped rectangular groove and the third L-shaped rectangular groove are respectively connected to the lower edge and the left edge of the radiating surface. The right side of the radiating surface is symmetrical to the left side of the radiating surface.

[0011] Optionally, the T-shaped ground plane rectangular groove group includes a first T-shaped ground plane rectangular groove and a second T-shaped ground plane rectangular groove. The first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove are asymmetrical T-shaped grooves, and the first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove have different structures. The first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove are provided on the ground plane, and the first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove are not connected to each other. The first T-shaped ground plane rectangular groove is connected to the upper edge of the ground plane, and the second T-shaped ground plane rectangular groove is connected to the lower edge of the wide side of the ground plane.

[0012] Optionally, a short-circuit via solder joint is provided at the upper left corner of the radiating surface, and a coaxial feed point solder joint is provided on the rectangular branch on the lower right side of the radiating surface. The short-circuit via solder joint and the coaxial feed point solder joint are respectively connected to a short-circuit probe and a coaxial feed point center probe. A ground plane short-circuit via solder joint and a ground plane coaxial feed point grounding port are provided on the ground plane corresponding to the short-circuit via solder joint and the coaxial feed point solder joint. The short-circuit probe and the coaxial feed point center probe are connected to the ground plane short-circuit via solder joint and the ground plane coaxial feed point grounding port.

[0013] Optionally, an anti-matching stub is provided between the coaxial feed point center probe and the coaxial feed point solder joint of the radiating surface.

[0014] Optionally, the dielectric substrate and the capping layer are made of Rogers 3010 material with a relative permittivity of 10.2, the radiating surface and the ground plane are both made of copper, and the coaxial feed point center probe and the short-circuit probe are both metal cylinders.

[0015] According to specific embodiments provided by the present invention, the following technical effects are disclosed: The miniaturized dual-band circularly polarized antenna provided by the present invention introduces a short-circuit probe and uses a probe-feed method. Miniaturization is achieved by etching an L-shaped groove on the radiating surface, with a short leg between the radiating surface and the ground. In particular, etching two asymmetric T-shaped rectangular grooves on the ground plane achieves a wider impedance and axial ratio bandwidth. The bent structure helps to extend the effective current path, and the main frequency can be controlled by adjusting the length and position of the two asymmetric T-shaped rectangular grooves etched on the ground plane. The present invention has a small size, with a volume of only 17.78 mm³, and has advantages such as wide bandwidth (0.877 GHz-1.041 GHz, 1.879 GHz-2.929 GHz), circular polarization, and dual-band operation in the biological telemetry frequency band. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the radiation surface structure according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the ground plane structure according to an embodiment of the present invention;

[0019] Figure 3 This is a cross-sectional structural diagram of an embodiment of the present invention;

[0020] Figure 4 This is a curve diagram of S11 in an embodiment of the present invention;

[0021] Figure 5 This is a 3dB axial ratio curve of the antenna at 0.915GHz in an embodiment of the present invention;

[0022] Figure 6 This is a 3dB axial ratio curve of the antenna at 2.45GHz in an embodiment of the present invention;

[0023] Figure 7 This is a diagram showing the ground plane current amplitude distribution of the antenna at a center frequency of 0.915 GHz in an embodiment of the present invention.

[0024] Figure 8 This is a diagram showing the amplitude distribution of the radiating surface current of the antenna at a center frequency of 0.915 GHz in an embodiment of the present invention.

[0025] Figure 9 This is a radiation pattern of the antenna in skin tissue at a frequency of 0.915 GHz in an embodiment of the present invention;

[0026] Figure 10 This is a radiation pattern of the antenna in skin tissue at a frequency of 2.45 GHz in an embodiment of the present invention.

[0027] Reference numerals: 1. Cover layer; 2. Dielectric substrate; 3. Radiation surface; 4. Coaxial feed point solder joint on the radiation surface; 5. Short-circuit via solder joint on the radiation surface; 6. Short-circuit via solder joint on the ground plane; 7. Ground plane coaxial feed point grounding port; 8. Ground plane; 9. Short-circuit probe; 10. Center probe of the coaxial feed point; 11. Cross-shaped rectangular slot; 12. First L-shaped rectangular slot; 13. Rectangular slot; 14. Second L-shaped rectangular slot; 15. Third L-shaped rectangular slot; 16. First T-shaped ground plane rectangular slot; 17. Second T-shaped ground plane rectangular slot. Detailed Implementation

[0028] The purpose of this invention is to provide a miniaturized dual-band circularly polarized antenna with a simple structure and advantages such as small size, low profile, low coupling, circular polarization, and dual-band operation.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown, the miniaturized dual-band circularly polarized antenna provided in this embodiment of the invention includes: a dielectric substrate 2 and a cover layer 1, wherein the cover layer 1 is located on top of the dielectric substrate 2;

[0031] The top of the dielectric substrate 2 is printed with a radiating surface 3, and the bottom of the dielectric substrate 2 is printed with a ground plane 8. The radiating surface 3 and the ground plane 8 are connected by a short-circuit probe 9 and a coaxial feed point center probe 10.

[0032] The radiating surface 3 is provided with a cross-shaped rectangular groove group and an L-shaped rectangular groove group. The radiating surface 3 has a centrally symmetrical structure. The ground plane 8 is provided with a T-shaped ground plane rectangular groove group.

[0033] like Figure 2As shown, the cross-shaped rectangular groove group includes a cross-shaped rectangular groove 11, and the L-shaped rectangular groove group includes a first L-shaped rectangular groove 12, a second L-shaped rectangular groove 14, a third L-shaped rectangular groove 15, and a rectangular groove 13. The cross-shaped rectangular groove 11 is located at the center of the radiating surface 3. The first L-shaped rectangular groove 12 is located on the upper left side of the radiating surface 3, and the rectangular groove 13 is located below the first L-shaped rectangular groove 12. The first L-shaped rectangular groove 12 is connected to the cross-shaped rectangular groove 11. The second L-shaped rectangular groove 14 and the third L-shaped rectangular groove 15 are located on the lower left side of the radiating surface 3. The second L-shaped rectangular groove 14 is located to the right of the third L-shaped rectangular groove 15, and the second L-shaped rectangular groove 14, the third L-shaped rectangular groove 15, and the cross-shaped rectangular groove 11 are not connected to each other. The second L-shaped rectangular groove 14 and the third L-shaped rectangular groove 15 are connected to the lower edge and the left edge of the radiating surface 3, respectively. The right side of the radiating surface 3 is symmetrical to the left side of the radiating surface 3.

[0034] like Figure 3 As shown, the T-shaped ground plane rectangular groove group includes a first T-shaped ground plane rectangular groove 16 and a second T-shaped ground plane rectangular groove 17. The first T-shaped ground plane rectangular groove 16 and the second T-shaped ground plane rectangular groove 17 are asymmetrical T-shaped grooves, and the first T-shaped ground plane rectangular groove 16 and the second T-shaped ground plane rectangular groove 17 have different structures. The first T-shaped ground plane rectangular groove 16 and the second T-shaped ground plane rectangular groove 17 are provided on the ground plane 8, and the first T-shaped ground plane rectangular groove 16 and the second T-shaped ground plane rectangular groove 17 are not connected to each other. The first T-shaped ground plane rectangular groove 16 is connected to the upper edge of the ground plane 8, and the second T-shaped ground plane rectangular groove 17 is connected to the lower edge of the wide side of the ground plane 8.

[0035] like Figure 1 and Figure 2 The dimensions of the cross-shaped rectangular trench group, the L-shaped rectangular trench group, and the T-shaped ground plane rectangular trench group are described as follows:

[0036] Figure 1 and Figure 2 Most of the lengths and widths are marked, as shown in Table 1.

[0037] Table 1 Dimensional Parameters

[0038]

[0039]

[0040] Additionally, it should be noted that, taking the left side of the radiating surface 3 as an example, the first L-shaped rectangular groove 12, the second L-shaped rectangular groove 14, and the third L-shaped rectangular groove 15 are all inverted L-shaped designs. The difference is that the short end of the first L-shaped rectangular groove 12 points downward and the long end points to the right, while the short end of the second L-shaped rectangular groove 14 and the third L-shaped rectangular groove 15 points to the left and the long end points downward. The long end of the first L-shaped rectangular groove 12 has a length of L2 and a width of W9, the short end has a length of W1-W2 and a width of L5. The rectangular groove 13 has a width of W2 and a length of L11. The second L-shaped rectangular groove 14 has a width of L4, a short end length of L8, and a wide end length of W8. The third L-shaped rectangular groove 15 has a width of L1, a short end length of L9, and a wide end length of W7.

[0041] The dimensions of the ground plane 8 are shown in Table 1 and... Figure 2 As shown.

[0042] The upper left corner of the radiating surface 3 is provided with a short-circuit via solder joint 5, and the lower right side of the radiating surface 3 is provided with a coaxial feed point solder joint 4. The short-circuit via solder joint 5 and the coaxial feed point solder joint 4 are respectively connected to the short-circuit probe 9 and the coaxial feed point center probe 10. On the ground plane 8, corresponding to the short-circuit via solder joint 5 and the coaxial feed point solder joint 4, a ground plane short-circuit via solder joint 6 and a ground plane coaxial feed point grounding port 7 are provided. The short-circuit probe 9 and the coaxial feed point center probe 10 are connected to the ground plane short-circuit via solder joint 6 and the ground plane coaxial feed point grounding port 7.

[0043] An impedance matching stub is provided at the coaxial feed point center probe 10 and the coaxial feed point solder joint 4 of the radiating surface. The width of the impedance matching stub is 0.5 mm, which is used to adjust the position of the coaxial feed port along the Y-axis to improve impedance matching.

[0044] The dielectric substrate 2 and the capping layer 1 are made of Rogers 3010 material with a relative permittivity of 10.2. The radiating surface 3 and the ground plane 8 are both made of copper. The coaxial feed center probe 10 and the short-circuit probe 9 are both metal cylinders. The dimensions of the short-circuit via solder joint 5 and the coaxial feed solder joint 4 on the radiating surface, the short-circuit via solder joint 6 on the ground plane, and the ground plane coaxial feed grounding port 7 are shown in Table 1. Figure 1 , Figure 2 As shown.

[0045] Figure 4 This is the return loss curve of the antenna in skin tissue at a frequency of 0.915 GHz in this embodiment. Figure 4It can be seen that the antenna has a return loss of less than -10dB in the 0.880-1.046GHz and 1.884-2.960GHz frequency bands, and fully covers the 915MHz and 2.45GHz frequency bands, with the 2.45GHz frequency band having a wider bandwidth.

[0046] Figure 5 and Figure 6 The return loss curve and axial ratio curve of the antenna in skin tissue at a frequency of 0.915 GHz in this embodiment are shown below. Figure 4 It can be seen that the antenna's return loss is less than -10dB in the 0.880-1.046GHz and 1.884-2.960GHz frequency bands, achieving biological telemetry frequency bands. Meanwhile, from... Figure 5 and Figure 6 It can be seen that the antenna has an axial ratio of less than 3dB in the 0.710-1.334GHz and 2.161-2.465GHz frequency bands, and the circular polarization bandwidth is relatively wide, realizing dual circular polarization of biological telemetry in two frequency bands.

[0047] Figure 7 This is a diagram showing the electric field distribution of the radiating surface of the antenna in this embodiment at a center frequency of 0.915 GHz. Figure 7 As can be seen, at 0.915 GHz, the maximum electric field of the antenna occurs at the edge of one side with matching branches, and the electric field distribution on the ground plane 7 below the excitation patch is greater than that on the other side of the excitation patch.

[0048] Figure 8 This is a diagram showing the electric field distribution of the antenna in this embodiment at 0.915 GHz on the ground plane. Figure 8 It can be seen that the electric field is stronger on the side closer to the coaxial probe feed, while the electric field is weaker in the lower left part of the ground plane.

[0049] Figure 9 This is the radiation pattern of the antenna in skin tissue at a frequency of 0.915 GHz in this embodiment. The blue line in the figure represents the radiation direction of the antenna in the E-plane, where the E-plane refers to the plane electric field that passes through the antenna's maximum radiation direction and is parallel to the electric field vector. The red line in the figure represents the radiation direction of the antenna in the H-plane, where the H-plane refers to the plane that passes through the antenna's maximum radiation direction and is parallel to the magnetic field vector. It can be seen from the figure that the maximum radiation gain of the antenna in this embodiment is -35.8 dB.

[0050] Figure 10This is the radiation pattern of the antenna in skin tissue at a frequency of 2.45 GHz in this embodiment. The blue line in the figure represents the radiation direction of the antenna in the E-plane, where the E-plane refers to the plane electric field that passes through the antenna's maximum radiation direction and is parallel to the electric field vector. The red line in the figure represents the radiation direction of the antenna in the H-plane, where the H-plane refers to the plane that passes through the antenna's maximum radiation direction and is parallel to the magnetic field vector. It can be seen from the figure that the maximum radiation gain of the antenna in this embodiment is -18.51 dB.

[0051] The miniaturized dual-band circularly polarized antenna provided by this invention introduces a short-circuit probe and uses probe feeding. Miniaturization is achieved by etching an L-shaped slot on the radiating surface, with a short leg between the radiating surface and the ground. In particular, etching two asymmetric T-shaped rectangular slots on the ground plane achieves a wider impedance and axial ratio bandwidth. The bent structure helps to extend the effective current path, and the dominant frequency can be controlled by adjusting the length and position of the two asymmetric T-shaped rectangular slots etched on the ground plane. This invention has a small size, with a volume of only 17.78 mm². 3 It has advantages such as wide bandwidth (0.877GHz-1.041GHz, 1.879GHz-2.929GHz), circular polarization, and dual frequency bands in the biological telemetry frequency band.

[0052] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A miniaturized dual-band circularly polarized antenna, characterized in that, include: A dielectric substrate and a cover layer, wherein the cover layer is located on top of the dielectric substrate; The top of the dielectric substrate is printed with a radiating surface, and the bottom of the dielectric substrate is printed with a ground plane. The radiating surface and the ground plane are connected by a short-circuit probe and a coaxial feed point center probe. The radiating surface is provided with cross-shaped rectangular groove groups and L-shaped rectangular groove groups, the radiating surface has a centrally symmetrical structure, and the ground plane is provided with T-shaped ground plane rectangular groove groups; The cross-shaped rectangular groove group includes a cross-shaped rectangular groove, and the L-shaped rectangular groove group includes a first L-shaped rectangular groove, a second L-shaped rectangular groove, a third L-shaped rectangular groove, and a rectangular groove. The cross-shaped rectangular groove is located at the center of the radiating surface. The first L-shaped rectangular groove is located on the upper left side of the radiating surface, and the rectangular groove is located below the first L-shaped rectangular groove. The first L-shaped rectangular groove is connected to the cross-shaped rectangular groove. The second L-shaped rectangular groove and the third L-shaped rectangular groove are located on the lower left side of the radiating surface. The second L-shaped rectangular groove is located to the right of the third L-shaped rectangular groove, and the second L-shaped rectangular groove, the third L-shaped rectangular groove, and the cross-shaped rectangular groove are not connected to each other. The second L-shaped rectangular groove and the third L-shaped rectangular groove are connected to the lower edge and the left edge of the radiating surface, respectively. The right side of the radiating surface is symmetrical to the left side of the radiating surface.

2. The miniaturized dual-band circularly polarized antenna according to claim 1, characterized in that, The T-shaped ground plane rectangular groove group includes a first T-shaped ground plane rectangular groove and a second T-shaped ground plane rectangular groove. The first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove are asymmetrical T-shaped grooves, and the first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove have different structures. The first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove are arranged on the ground plane, and the first T-shaped ground plane rectangular groove and the second T-shaped ground plane rectangular groove are not connected to each other. The first T-shaped ground plane rectangular groove is connected to the upper edge of the ground plane, and the second T-shaped ground plane rectangular groove is connected to the lower edge of the wide side of the ground plane.

3. The miniaturized dual-band circularly polarized antenna according to claim 2, characterized in that, A short-circuit via solder joint is provided at the upper left corner of the radiating surface, and a coaxial feed point solder joint is provided on the rectangular branch on the lower right side of the radiating surface. The short-circuit via solder joint and the coaxial feed point solder joint are respectively connected to a short-circuit probe and a coaxial feed point center probe. A ground plane short-circuit via solder joint and a ground plane coaxial feed point grounding port are provided on the ground plane corresponding to the short-circuit via solder joint and the coaxial feed point solder joint. The short-circuit probe and the coaxial feed point center probe are connected to the ground plane short-circuit via solder joint and the ground plane coaxial feed point grounding port.

4. The miniaturized dual-band circularly polarized antenna according to claim 3, characterized in that, An anti-matching branch is provided between the coaxial feed point center probe and the coaxial feed point solder joint of the radiating surface.

5. The miniaturized dual-band circularly polarized antenna according to claim 1, characterized in that, The dielectric substrate and the capping layer are made of Rogers 3010 material with a relative permittivity of 10.

2. The radiating surface and the ground plane are both made of copper. The coaxial feed point center probe and the short-circuit probe are both metal cylinders.

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