A three-frequency circular patch antenna operating in C-band
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- THE 54TH RESEARCH INSTITUTE OF CHINA ELECTRONICS TECHNOLOGY GROUP CORPORATION
- Filing Date
- 2026-04-13
- Publication Date
- 2026-07-21
AI Technical Summary
Existing tri-band circular patch antennas suffer from resonant mode coupling interference, high return loss, and structural incompatibility with the miniaturization requirements of portable devices in multi-band coverage.
By employing a design with a double-layer dielectric substrate, a composite circular patch, and metal pillar positioning, combined with a feed microstrip line and a metal ground plane for reflection, the patch structure and impedance matching are optimized to achieve stable linear polarization radiation and high gain.
It achieves stable linear polarization radiation across three frequency bands in the C-band, with a return loss of less than -10dB and stable gain fluctuations, making it suitable for miniaturized integration of 5G mid-band communication equipment.
Smart Images
Figure CN122051640B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microwave antenna technology, specifically a tri-band circular patch antenna operating in the C-band, suitable for scenarios such as 5G mid-band communication, high-speed data transmission terminals for the Internet of Things, portable communication devices, and miniaturized base stations. Background Technology
[0002] With the large-scale deployment of 5G communication in the mid-band, various communication devices are increasingly demanding higher requirements for antennas in terms of "precise multi-band coverage, high-gain output, and compact structure." Tri-band circular patch antennas, leveraging the resonant characteristics of their circular radiating structure, can achieve multi-band expansion within a limited space, becoming an important development direction for mid-band 5G antennas. However, existing antennas of this type have the following technical limitations: Existing tri-band circular patch antennas mostly achieve multi-band coverage through slotting a single patch, which is prone to resonant mode coupling interference, resulting in frequency band overlap and large gain fluctuations. Although some designs introduce parasitic structures to optimize frequency bands, improper impedance matching between the feed structure and the patch leads to excessive return loss in certain frequency bands. At the same time, traditional structures often use heavy dielectric substrates or complex support structures, which are difficult to meet the miniaturization and lightweight requirements of portable terminal devices. To address these shortcomings, there is an urgent need to optimize the composite circular patch structure, feed microstrip line design, and substrate parameter matching to achieve a tri-band circular patch antenna with "precise tri-band coverage, stable gain, and compact structure". Summary of the Invention
[0003] To achieve the above objectives, the present invention provides a tri-band circular patch antenna operating in the C-band, which can achieve impedance matching and stable linear polarization radiation in the three frequency bands of 4.27-4.45GHz, 5.474-5.677GHz, and 5.967-6.35GHz, meeting the core requirements of 5G mid-band communication for multi-band compatibility, high gain stability, and miniaturized integration.
[0004] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: A tri-band circular patch antenna operating in the C-band includes an upper dielectric substrate and a lower dielectric substrate; The upper surface of the upper dielectric substrate is provided with a composite circular patch, and the lower surface is provided with a matching patch; The upper surface of the lower dielectric substrate is provided with a metal ground plane, and the lower surface is provided with a feed microstrip line. The composite circular patch is connected to the matching patch via a first metal pillar, and the metal ground plane is connected to the feed microstrip line via a third metal pillar; the first metal pillar and the third metal pillar respectively penetrate the upper dielectric substrate and the lower dielectric substrate. An air layer is also provided between the upper dielectric substrate and the lower dielectric substrate; the lower surface of the upper dielectric substrate is connected to and supported by a metal floor on the upper surface of the lower dielectric substrate through a second metal pillar.
[0005] Furthermore, the composite circular patch includes a circular main patch and a parasitic patch; the circular main patch is located at the center of the upper dielectric substrate, and the parasitic patch is a rectangular strip connected to the circular main patch and serving as an extension of one of the diameters of the circular main patch.
[0006] Furthermore, the circular main patch has two mutually perpendicular patch slots; both patch slots are located on the same side of the diameter of the parasitic patch, and both form a 45° angle with the diameter.
[0007] Furthermore, the matching patch is a rectangular notched structure, the main body of which is a rectangle with triangles cut off at the four corners to form an octagon; The long side of the matching patch is perpendicular to the diameter of the circular main patch where the parasitic patch is located.
[0008] Furthermore, the projection of the matching patch onto the circular master patch is located on the other side of the diameter of the circular master patch where the parasitic patch is located.
[0009] Furthermore, the power-fed microstrip line includes strip line A and strip line B; strip line A extends from the center of the lower surface of the lower dielectric substrate to the edge and is flush with the edge of the lower dielectric substrate; strip line B is connected to one side of strip line A and is perpendicular to strip line A.
[0010] Furthermore, the metal floor has a floor groove; the floor groove is parallel to the strip line B.
[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention adopts a design scheme of "double-layer dielectric substrate + composite circular patch + metal pillar positioning". Through electromagnetic coordinated control of the patch and the feed layer and precise matching of parameters of each component, the performance target is achieved. The antenna achieves stable linear polarization radiation in three frequency bands: 4.27-4.45GHz, 5.474-5.677GHz, and 5.967-6.35GHz. There is no overlap in each frequency band and the return loss is less than -10dB, which is suitable for different mid-frequency communication scenarios. The maximum gain of the three frequency bands is 8.71dB, 9.99dB, and 10.81dB, respectively. The gain fluctuation is stable, ensuring the stability of signal transmission.
[0012] 2. The antenna of this invention adopts an integrated design with a double-layer dielectric substrate and metal pillar positioning. The overall size is optimized based on parameters, resulting in a compact structure and light weight. It can be directly integrated into 5G mid-band base station antenna arrays or miniaturized terminal devices, adapting to the miniaturization design requirements of 5G devices.
[0013] 3. The antenna adopts a metal ground plane reflection and directional radiation design, combined with impedance optimization of the matching patch and anti-interference design of the metal ground plane slot, which effectively reduces signal scattering loss and inter-band interference, improves energy utilization efficiency, and can maintain stable communication quality in complex electromagnetic environments, with outstanding anti-interference capability. Attached Figure Description
[0014] Figure 1 This is an overall structural diagram of an embodiment of the present invention.
[0015] Figure 2 This is a diagram of the feed layer structure according to an embodiment of the present invention; Figure 3 This is a structural diagram of the grooved floor layer according to an embodiment of the present invention; Figure 4 This is a structural diagram of the matching patch layer according to an embodiment of the present invention; Figure 5 This is a structural diagram of the composite circular patch layer according to an embodiment of the present invention; Figure 6 This is a side view of an embodiment of the present invention; Figure 7 This is a schematic diagram showing the relative positions of the matching patch and the composite circular patch in an embodiment of the present invention; Figure 8 This is the return loss S11 curve of the antenna; Figure 9 This is the radiation pattern of the antenna at 4 GHz; Figure 10 This is the radiation pattern of the antenna at 5.6 GHz; Figure 11 This is the radiation pattern of the antenna at 6 GHz.
[0016] In the diagram: 1. Strip A, 2. Strip B, 3. Third metal pillar, 4. Metal ground plane, 5. Ground plane slot, 6. Matching patch, 7. Second metal pillar, 8. Circular master patch, 9. Parasitic patch, 10. Patch slot, 11. First metal pillar, 12. Upper dielectric substrate, 13. Lower dielectric substrate, 89. Composite circular patch, 121. Feed microstrip line. Detailed Implementation
[0017] Reference Figures 1 to 7 The antenna in this embodiment adopts a stacked three-dimensional structure combining a double-layer dielectric substrate and an air layer to achieve miniaturization, lightweighting, and high-performance multi-band radiation. The overall structure, from top to bottom, includes a composite circular patch layer, a matching patch layer, an air layer, a slotted ground plane layer, and a feed layer. The layers are electrically interconnected and mechanically fixed by metal pillars with a specific layout.
[0018] The dielectric substrate is made of F4BM220 high-performance material with a dielectric constant of 2.2 and a loss tangent of 0.001. Both the upper dielectric substrate 12 and the lower dielectric substrate 13 are 0.6 mm thick, and are supported by a second metal pillar 7, maintaining a certain distance between them to form an air layer. The introduction of this air layer effectively reduces the overall weight of the antenna and helps adjust its impedance and bandwidth characteristics.
[0019] A composite circular patch 89, located at the top layer of the structure, is disposed on the upper surface of the upper dielectric substrate 12. This layer is the core radiator of the antenna, consisting of a circular main patch 8 located at the geometric center of the substrate and a rectangular strip parasitic patch 9 connected to it. The parasitic patch 9 extends one diameter of the circular main patch 8; its introduction is mainly used to extend and optimize the high-frequency response of the antenna. Two mutually perpendicular rectangular patch slots 10 are etched on the circular main patch 8. Both patch slots 10 are located on the same side of the diameter of the parasitic patch 9, and each forms a 45-degree angle with that diameter. The function of the patch slots 10 is to disturb the current path on the surface of the radiating patch, thereby effectively exciting multiple separate resonant modes, laying the physical foundation for achieving tri-band operation.
[0020] The matching patch layer is located on the lower surface of the upper dielectric substrate 12, and its main body is a shape-optimized matching patch 6. The matching patch 6 is designed as an octagonal structure formed by cutting off the four corner triangles of a rectangle. Its long side is perpendicular to the extension direction of the parasitic patch 9 above, and the matching patch 6 is located on the opposite side of the diameter of the parasitic patch 9 in its vertical projection. The matching patch 6 is electrically connected to the upper circular main patch 8 via a first metal pillar 11 that vertically penetrates the upper dielectric substrate 12. The main function of the matching patch layer is to introduce additional resonant modes, and simultaneously, as an impedance matching network, to finely adjust the impedance characteristics at the antenna input, ensuring efficient energy transmission from the feed port to the radiating patch and significantly reducing return loss.
[0021] A slotted ground plane layer is provided on the upper surface of the lower dielectric substrate 13. This layer is composed of a single metal ground plane 4, which serves as the reflective backplane of the antenna, shielding the rear end and enhancing forward radiation. A symmetrical rectangular ground plane slot 5 is formed on the metal ground plane 4, through which electromagnetic waves are radiated to the upper dielectric substrate. The metal ground plane 4 is connected upward to the lower surface of the upper dielectric substrate 12 via a second metal pillar 7, providing the main support; simultaneously, the metal ground plane 4 is connected downward to the feed system of the underlying layer via a third metal pillar 3.
[0022] The feed layer is disposed on the lower surface of the lower dielectric substrate 13, employing a microstrip line feeding method. The feed microstrip line 121 consists of two parts: line A1 and line B2. Line A1 starts from the central region of the lower surface of the lower dielectric substrate 13 and extends to the edge of the lower dielectric substrate 13; line B2 is perpendicularly connected to one side of line A1, forming a T-shaped structure. The width of this microstrip line is precisely calculated and set to 0.71 mm, achieving a characteristic impedance of 50 ohms in conjunction with the selected substrate parameters to minimize feed line loss. Notably, the orientation of the ground plane slot 5 is parallel to the feed stub line B2. This design helps optimize the current distribution on the ground plane, improves the impedance matching of the antenna, especially in the low-frequency band, and suppresses coupling interference between different frequency bands.
[0023] This embodiment also provides more specific structural data, in which the structural dimensions (the following data are in millimeters) are: a is 67.5; b is 37; c is 8.47; d is 1.72; e is 18; f is 0.71; g is 8.25; h is 5.3; i is 22; j is 6; k is 4.5; l is 3; and m is 0.6.
[0024] The antenna described in this invention achieves excellent performance in three independent frequency bands of the C-band through the precise and coordinated design of the above-mentioned multi-layer structure, especially the combined effect of the composite circular patch, matching patch, slotted ground plane and T-shaped feed line.
[0025] The specific operating frequency bands are: Band 1: 4.27-4.45 GHz; Band 2: 5.474-5.677 GHz; Band 3: 5.967-6.35 GHz. (Refer to...) Figures 8 to 11 The measured results show that the return loss S11 of the antenna in these three frequency bands is less than -10 dB, indicating good impedance matching in each frequency band and no overlap between the bands, resulting in high isolation. Meanwhile, the antenna exhibits stable directional radiation patterns at 4 GHz, 5.6 GHz, and 6 GHz, with maximum gains of 8.71 dB, 9.99 dB, and 10.81 dB respectively. The gain curves are smooth, fully meeting the key technical requirements of mid-band equipment in 5G mobile communication for multi-band compatibility, high-gain stable radiation, and compact integration.
[0026] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A tri-band circular patch antenna operating in the C-band, comprising an upper dielectric substrate (12) and a lower dielectric substrate (13), characterized in that, The upper surface of the upper dielectric substrate (12) is provided with a composite circular patch (89), and the lower surface is provided with a matching patch (6). The upper surface of the lower dielectric substrate (13) is provided with a metal ground plane (4), and the lower surface is provided with a feed microstrip line (121). The composite circular patch (89) is connected to the matching patch (6) through the first metal post (11), and the metal ground plane (4) is connected to the feed microstrip line (121) through the third metal post (3); the first metal post (11) and the third metal post (3) pass through the upper dielectric substrate (12) and the lower dielectric substrate (13) respectively. An air layer is also provided between the upper dielectric substrate (12) and the lower dielectric substrate (13); the lower surface of the upper dielectric substrate (12) is connected to and supported by the metal floor (4) on the upper surface of the lower dielectric substrate (13) through the second metal pillar (7).
2. A tri-band circular patch antenna operating in the C-band according to claim 1, characterized in that, The composite circular patch (89) includes a circular main patch (8) and a parasitic patch (9); the circular main patch (8) is located at the center of the upper dielectric substrate (12), and the parasitic patch (9) is a rectangular strip connected to the circular main patch (8) and serving as an extension of one of the diameters of the circular main patch (8).
3. A tri-band circular patch antenna operating in the C-band according to claim 2, characterized in that, The circular main patch (8) has two mutually perpendicular patch slots (10); both patch slots (10) are located on the same side of the diameter of the parasitic patch (9), and both form a 45° angle with the diameter.
4. A tri-band circular patch antenna operating in the C-band according to claim 3, characterized in that, The matching patch (6) is a rectangular cut-out structure, the main body of which is a rectangle with the four corners cut off to form an octagon; The long side of the matching patch (6) is perpendicular to the diameter of the circular main patch (8) where the parasitic patch (9) is located.
5. A tri-band circular patch antenna operating in the C-band according to claim 4, characterized in that, The projection of the matching patch (6) onto the circular main patch (8) is located on the other side of the diameter of the circular main patch (8) where the parasitic patch (9) is located.
6. A tri-band circular patch antenna operating in the C-band according to claim 1, characterized in that, The power-fed microstrip line (121) includes a strip line A (1) and a strip line B (2); the strip line A (1) extends from the center of the lower surface of the lower dielectric substrate (13) to the edge and is flush with the edge of the lower dielectric substrate (13); the strip line B (2) is located on one side of the strip line A (1) and is connected to the strip line A (1), and the strip line B is perpendicular to the strip line A (1).
7. A tri-band circular patch antenna operating in the C-band according to claim 6, characterized in that, The metal floor (4) is provided with floor grooves (5); the floor grooves (5) are parallel to the strip line B (2).