Miniaturized and co-calibrated dual-band circularly polarized patch antenna

Abstract

The application relates to the technical field of antennas, in particular to a small-sized and co-aperture dual-frequency circularly-polarized patch antenna. The antenna comprises a ground plate, a main radiation patch, a plurality of parasitic monopoles, a plurality of capacitive coupling branches and a feeding assembly. The ground plate is located at the lowermost layer of the antenna structure, the main radiation patch is arranged above the ground plate, the plurality of capacitive coupling branches are arranged at the edge region of the main radiation patch, the plurality of parasitic monopoles are distributed at the periphery of the main radiation patch, a circumferential gap is left between the edge of the main radiation patch and the parasitic monopoles, and the main radiation patch inputs a radio frequency signal through the feeding assembly. The antenna structure is compact, light in weight and low in profile, two working frequency bands are independent of each other, the radiation direction is stable, the circular polarization characteristic is excellent, and the antenna has the advantages of simplified structure, low manufacturing cost and the like.

Description

Technical Field

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

[0002] With the rapid development of satellite navigation and wireless communication technologies, especially in emerging application scenarios such as portable terminals, UAV platforms, wearable devices, and IoT nodes, extremely stringent requirements have been placed on the size, weight, and integration of antennas. Miniaturization and lightweighting of antennas have become core design trends. However, modern communication systems require antennas to meet more than just compact structures; they must also ensure multi-system compatibility, wideband coverage, and high-precision circular polarization performance. For example, dual-band GNSS receivers need to simultaneously cover L1, L2, and L5 frequency bands to compensate for ionospheric delay errors and achieve centimeter-level high-precision positioning. Therefore, how to achieve dual-band coexistence within a limited volume has become a crucial issue in antenna design.

[0003] In existing technologies, miniaturization based on high dielectric constant materials is a traditional and commonly used approach. By using a substrate with a high dielectric constant (such as a ceramic substrate), the same electrical length can be achieved within a smaller geometric dimension, thereby significantly reducing the antenna size. However, this approach has a series of inherent drawbacks: high dielectric constant materials are typically dense and heavy, which contradicts the need for lightweight design; the high dielectric constant causes electromagnetic energy to be strongly concentrated inside the dielectric, resulting in a significant decrease in radiation efficiency; increased dielectric loss reduces the antenna gain and circular polarization quality; and the complex and costly manufacturing process limits its application in low-cost terminal devices.

[0004] To overcome the limitations of high-dielectric-material solutions while maintaining dual-frequency characteristics, the industry has proposed two main technical approaches: (1) Multi-layer stacked structure scheme.

[0005] By stacking multiple radiating elements vertically, each corresponding to a different frequency band, dual-band coexistence can be achieved to some extent. However, the multi-layer structure inevitably increases the thickness and weight of the antenna, which goes against the trend of thinner and lighter terminal devices. At the same time, the parasitic coupling effect between the multiple layers is extremely difficult to control, and performance optimization of one frequency band often leads to performance degradation of another frequency band, making the design and debugging process complex and time-consuming.

[0006] (2) Single-layer coplanar dual-frequency scheme.

[0007] Such schemes attempt to achieve two resonant modes on a single dielectric substrate to maintain low profile characteristics. However, due to limited effective space, the electromagnetic coupling between the two operating modes is extremely strong, causing the impedance characteristics and polarization states between frequency bands to be mutually constrained, making it difficult to obtain ideal matching and circular polarization performance at both frequency points simultaneously.

[0008] Therefore, achieving dual-frequency independent resonance, common-aperture radiation, and stable circular polarization in a single-layer low-profile structure without relying on high dielectric constant materials has become a key scientific and engineering problem that urgently needs to be solved in the field of antenna design. Summary of the Invention

[0009] This invention provides a miniaturized and common-aperture dual-frequency circularly polarized patch antenna, aiming to solve the pain points of existing antenna miniaturization designs. It proposes a miniaturized common-aperture dual-frequency circularly polarized patch antenna based on the cooperative mechanism of capacitive coupling stubs and parasitic monopoles, achieving a new balance and breakthrough in terms of lightweight, dual-frequency independence and radiation performance.

[0010] This invention provides a miniaturized and common-aperture dual-band circularly polarized patch antenna, comprising a ground plane, a main radiating patch, multiple parasitic monopoles, multiple capacitive coupling stubs, and a feeding assembly. The ground plane is located at the bottom layer of the antenna structure, the main radiating patch is disposed above the ground plane, the multiple capacitive coupling stubs are arranged in the edge region of the main radiating patch, the multiple parasitic monopoles are distributed around the periphery of the main radiating patch, and a circumferential gap is left between the edge of the main radiating patch and the parasitic monopoles. The main radiating patch receives radio frequency signals through the feeding assembly.

[0011] As a further improvement of the present invention, each of the capacitive coupling stubs includes a capacitive element and a connecting wire, wherein the capacitive element is loaded between the main radiating patch and the ground plane via the connecting wire.

[0012] As a further improvement of the present invention, one end of the connecting line is connected to the edge of the main radiating patch, and the other end is connected to the ground plane, with a capacitive element connected in series on the connecting line; Alternatively, one end of the connecting wire can be connected to the main radiating patch, and the other end can be electrically connected to the ground plane through a capacitive element; Alternatively, one end of the connecting wire can be connected to the grounding plate, and the other end can be electrically connected to the main radiating patch through a capacitive element.

[0013] As a further improvement of the present invention, each of the capacitive coupling stubs includes a capacitive metal sheet and a connecting metal strip; one end of the connecting metal strip is electrically connected to the main radiating patch, and the other end is connected to the capacitive metal sheet, forming a gap between the capacitive metal sheet and the ground plane; and / or one end of the connecting metal strip is connected to the ground plane, and the other end is connected to the capacitive metal sheet, forming a gap between the capacitive metal sheet and the main radiating patch.

[0014] As a further improvement of the present invention, the parasitic monopole has a folded structure, which includes a vertical connecting section, a horizontal extending section, a vertical section, and a horizontal end section. The vertical connecting section, the horizontal extending section, the vertical section, and the horizontal end section are connected in sequence. The vertical connecting section is connected to the ground plane, and the horizontal end section is open.

[0015] As a further improvement of the present invention, the capacitive coupling stub is located in the vertical space between the main radiating patch and the ground plane, and the main radiating patch and each capacitive coupling stub respectively form projections on the ground plane, and the projections of the capacitive coupling stubs are adjacent to, closely attached to or partially overlapped with the projection edges of the main radiating patch.

[0016] As a further improvement of the present invention, the parasitic monopoles are arranged symmetrically and evenly around the main radiating patch, and the parasitic monopoles are located outside the projection area of ​​the main radiating patch on the ground plane and are spaced apart from the main radiating patch.

[0017] As a further improvement of the present invention, the minimum width of the circumferential gap between the edge of the main radiating patch and each parasitic monopole does not exceed λ / 30, where λ is the free space wavelength corresponding to the antenna operating frequency.

[0018] As a further improvement of the present invention, the power supply assembly includes at least one power supply line, one end of which is connected to the main radiating patch and the other end is connected to an external radio frequency port, and the main radiating patch receives radio frequency signals through the power supply line.

[0019] As a further improvement of the present invention, the power supply assembly includes at least one power supply line, one end of which is connected to the main radiating patch and the other end is connected to an external radio frequency port, and the main radiating patch receives radio frequency signals through the power supply line.

[0020] As a further improvement of the present invention, a dielectric substrate and / or a support structure are provided between the main radiating patch and the ground plane. The dielectric substrate is one or a combination of two of the following: air dielectric and low dielectric constant material. The support structure includes, but is not limited to, support columns and support legs.

[0021] As a further improvement of the present invention, the shape of the main radiating patch includes, but is not limited to, annular, circular, square, elliptical, triangular or polygonal structures; And / or the main radiating patch includes, but is not limited to, having one or more combinations of slotted or slit structures.

[0022] The beneficial effects of this invention are: it achieves a good balance and unity between miniaturization, dual-band performance, common-aperture integration, and circular polarization quality. The antenna has a compact structure, light weight, and low profile; the two operating frequency bands are independent and do not interfere with each other; the radiation direction is stable; and the circular polarization characteristics are excellent. It also possesses advantages such as simplified structure, low manufacturing cost, and mass production capability. It fundamentally solves the coupling interference and complex debugging problems of traditional miniaturized dual-band antennas, providing an efficient and engineerable new technical path for high-performance, lightweight dual-band circularly polarized antennas. Attached Figure Description

[0023] Figure 1 This is a first three-dimensional structural diagram of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 1 of the present invention; Figure 2 This is a top view of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in the xy plane according to Embodiment 1 of the present invention. Figure 3 This is a first three-dimensional structural diagram of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 2 of the present invention; Figure 4 This is a top view of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in the xy plane of Embodiment 2 of the present invention. Figure 5 This is a first three-dimensional structural diagram of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 3 of the present invention; Figure 6 This is a top view of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in the xy plane of Embodiment 3 of the present invention. Figure 7 This is a reflection coefficient curve from the simulation of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 1 of the present invention; Figure 8 This is a planar radiation diagram at 1.23 GHz in the simulation of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 1 of the present invention. Figure 9 This is a planar radiation diagram at 1.57 GHz in the simulation of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 1 of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] The present invention discloses a miniaturized and common-aperture dual-band circularly polarized patch antenna, comprising a ground plane 100, a main radiating patch 102, multiple parasitic monopoles, multiple capacitive coupling stubs, and a feeding assembly. The ground plane 100 is located at the bottom layer of the antenna structure, the main radiating patch 102 is disposed above the ground plane 100, multiple capacitive coupling stubs are arranged in the edge region of the main radiating patch 102, multiple parasitic monopoles are distributed around the periphery of the main radiating patch 102, and a circumferential gap is left between the edge of the main radiating patch 102 and the parasitic monopoles. The main radiating patch 102 receives radio frequency signals through the feeding assembly.

[0026] The following examples illustrate various structural variations of this miniaturized and common-aperture dual-frequency circularly polarized patch antenna.

[0027] Example 1:

[0028] like Figure 1 and Figure 2 As shown, Figure 1 This is a three-dimensional structural diagram of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna provided in Embodiment 1 of the present invention. Figure 2 This is a top view of the antenna in the xy plane. The miniaturized and common-aperture dual-band circularly polarized patch antenna of this embodiment includes a ground plane 100, a dielectric substrate 101, a main radiating patch 102, a set of parasitic monopoles (first parasitic monopole 103, second parasitic monopole 104, and third parasitic monopole 105) and a set of capacitive coupling stubs (including a first capacitive element 106a and a first connecting line 107a, a second capacitive element 106b and a second connecting line 107b, and a third capacitive element 106c and a third connecting line 107c).

[0029] Ground plane 100 is located at the bottom of the antenna structure and provides electrical grounding and mechanical support. Dielectric substrate 101 is disposed above ground plane 100 and supports main radiating patch 102, capacitive coupling stubs, and parasitic monopole structures. Main radiating patch 102 is suspended above dielectric substrate 101. Dielectric substrate 101 and / or support structure are provided between main radiating patch 102 and ground plane 100. Dielectric substrate is one or a combination of air dielectric and low dielectric constant material. Dielectric substrate 101 does not require high dielectric constant dielectric material. For example, air dielectric or other low dielectric constant materials can be used to reduce the weight of the antenna structure and improve radiation efficiency, thereby achieving lightweight design. Support structure includes, but is not limited to, support columns and support legs.

[0030] The main radiating patch 102 is a circular conductor, and a set of capacitive coupling stubs are arranged in its edge region to excite and control the resonant mode and radiation characteristics of the first operating frequency band. Each capacitive coupling stub consists of a capacitive element and a connecting line, corresponding to the first capacitive element 106a and the first connecting line 107a, the second capacitive element 106b and the second connecting line 107b, and the third capacitive element 106c and the third connecting line 107c, respectively.

[0031] like Figure 1 and Figure 2 As shown, the first capacitive element 106a is loaded between the main radiating patch 102 and the ground plane 100 via the first connecting line 107a. Specifically, one end of the first connecting line 107a is connected to the edge of the main radiating patch 102, and the other end is connected to the ground plane 100, with the first capacitive element 106a connected in series on this connecting line. Alternatively, one end of the first connecting line 107a is connected to the main radiating patch 102, and the other end is electrically connected to the ground plane 100 via the first capacitive element 106a; or, one end of the first connecting line 107a is connected to the ground plane 100, and the other end is electrically connected to the main radiating patch 102 via the first capacitive element 106a. The structure and connection method of the second capacitive element 106b and the second connecting line 107b, and the third capacitive element 106c and the third connecting line 107c are the same as described above, together forming a set of capacitive coupling branches.

[0032] A set of capacitive coupling stubs is uniformly arranged along the edge of the main radiating patch 102, located at the edge of the patch's projection area on the ground plane 100. In this structure, the capacitive coupling stubs are located in the vertical space between the main radiating patch 102 and the ground plane 100. When the main radiating patch 102 and each capacitive coupling stub project onto the ground plane 100, the projection of the capacitive coupling stub is in close contact with the projection edge of the main radiating patch 102. This arrangement aims to fully utilize the electric field lines between the main radiating patch 102 and the ground plane 100, and adjust the equivalent impedance characteristics of the main radiating patch 102 through electromagnetic coupling, thereby changing the resonant frequency to achieve miniaturization. Each capacitive coupling stub is arranged along the vertical direction between the main radiating patch 102 and the ground plane 100, generating a current distributed in the vertical direction, parallel to the electric field lines of the main radiating patch 102, thus forming a strong electric field coupling effect. This coupling effect is mainly dominated by capacitive elements. Since the physical size of the capacitive element is relatively small compared to the size and operating wavelength of the main radiating patch 102, the electric field formed is concentrated near the capacitive element, exhibiting a localized characteristic of electric field distribution.

[0033] In this embodiment, three capacitive coupling stubs are evenly distributed along the circumference of the patch, with a spatial angle of approximately 120°. This structure can form two sets of mutually orthogonal electric field vector components on the main radiating patch, thereby exciting stable circularly polarized radiation. It should be noted that the use of three sets of capacitive stubs is only a preferred example. In other embodiments, the number of capacitive stubs can be flexibly adjusted according to factors such as operating frequency, miniaturization degree, and structural symmetry. For example, four, six, or eight sets of stubs can be used, evenly distributed along the circumference of the main radiating patch, all of which can achieve the dual-frequency coupling mechanism and circular polarization performance of this invention.

[0034] The connecting lines 107a, 107b, and 107c can be implemented using metal wires, metal sheets, or other conductive structures, or they can be conductive films, conductive coatings, or other composite material structures with conductive properties, to adapt to different manufacturing processes and antenna shape requirements, thereby improving process compatibility and structural feasibility while maintaining stable electrical performance.

[0035] Capacitive elements possess a capacitive component and can be lumped elements, such as chip capacitors, variable capacitors, electrolytic capacitors, ceramic capacitors, and film capacitors, or distributed elements, such as parallel conductors (two or more conductors arranged in parallel, generating an electric field between them to form capacitance, with the capacitance value adjusted by changing the conductor spacing and length), transmission line structures (such as microstrip lines or coaxial cables), capacitive plates (two parallel metal plates separated by a dielectric layer or air gap to form a capacitor), and planar capacitive structures (metal patterns printed on a PCB, such as finger-like or interlaced structures, with the geometry adjusted to optimize capacitance characteristics). These forms can be flexibly combined according to design requirements to optimize antenna performance. Furthermore, capacitive elements can consist of a single capacitor element or multiple elements connected together. To obtain a specific capacitance, a combination of multiple elements can be used instead of a single capacitor element; for example, a capacitive element can be replaced by a combination of a capacitor element and an inductive element. Inductive elements possess an inductive component and can be lumped elements, such as chip inductors and chip resistors, or distributed elements, such as wires and coils. Similarly, an inductor can be composed of a single inductor or multiple inductors connected together.

[0036] In addition, a set of parasitic monopoles, including a first parasitic monopole 103, a second parasitic monopole 104, and a third parasitic monopole 105, are disposed around the main radiating patch 102. The parasitic monopoles are folded monopole structures, with one end of each monopole electrically connected to the ground plane 100 and the other end open. This structure mainly consists of four parts: the first part is a vertical connecting section, used to determine the height of the monopole; the second part is a horizontal extension section, the physical length of which determines the fundamental resonant length of the monopole; the third part is a vertical section bent downwards from the end of the horizontal extension section, used to adjust the current distribution and equivalent electrical length; the fourth part is a horizontal end section, laid on the upper surface of the dielectric substrate 101, forming a gap with the ground plane 100, thereby generating an equivalent capacitance at the end, realizing the miniaturization of the parasitic monopole. Thus, its resonant frequency is jointly determined by the equivalent electrical length of the monopole and the equivalent capacitance at the end, achieving a balance between compact structure and frequency control.

[0037] Three parasitic monopoles are symmetrically arranged around the main radiating patch 102, evenly distributed around its periphery, forming the core resonant unit for the second operating frequency band. A circumferential gap is maintained between the edge of the main radiating patch 102 and each parasitic monopole; this gap is used to adjust the electromagnetic coupling strength, thereby affecting the antenna's impedance matching and resonance characteristics. The parasitic monopoles are located outside the projection area of ​​the main radiating patch onto the ground plane, maintaining an appropriate distance to achieve effective coupling using the magnetic field component of the main radiating patch 102. Preferably, to ensure energy transmission efficiency, the minimum width of this gap does not exceed λ / 30, where λ is the free-space wavelength corresponding to the antenna's operating frequency.

[0038] In terms of electromagnetic properties, parasitic monopoles can simultaneously excite current components in both the transverse and vertical directions, resulting in a relatively dispersed field distribution that is not confined to the local space between the main radiating patch and the ground plane. This dispersed electromagnetic field distribution complements the concentrated electric field distribution of the capacitive coupling stub, naturally isolating the two in terms of spatial and electromagnetic properties. By adjusting the structural parameters of the parasitic monopoles and the capacitance value of the capacitive stubs respectively, independent tuning and non-interference between the two operating frequency bands can be achieved, ensuring the efficient coexistence of dual-frequency characteristics in a common-aperture structure.

[0039] Furthermore, to avoid the shielding effect of parasitic monopoles on the inner capacitive coupling stubs, this invention limits the total length of the horizontal extension of the parasitic monopoles to no more than 70% of the perimeter of the main radiating patch 102. This configuration can effectively reduce the electromagnetic shielding effect between structures, thereby balancing the high-performance characteristics of the first and second operating frequency bands.

[0040] In this embodiment, three parasitic monopoles are uniformly distributed circumferentially along the main radiating patch 102 at an angle of approximately 120°. This allows for the formation of an electric field distribution with two orthogonal vector components in the far field, achieving stable circularly polarized radiation characteristics. In other embodiments, four parasitic monopoles can be symmetrically arranged at 90° intervals to further improve polarization purity and pattern symmetry.

[0041] Furthermore, such as Figure 1 and Figure 2 As shown, the feed assembly of the miniaturized and common-aperture dual-band circularly polarized patch antenna includes a single feed line. One end of the feed line is connected to the main radiating patch 102, and the other end is connected to an external radio frequency port. The main radiating patch 102 receives radio frequency signals through the feed line.

[0042] The feeding assembly also includes a first feed line 108 and a second feed line 109. Both can be probe-fed or coaxially fed, with one end connected to the main radiating patch 102 and the other end connected to an external RF port. The first feed line 108 is arranged along the x-axis, and the second feed line 109 is arranged along the y-axis, and the two are orthogonal to each other. When RF signals of equal amplitude and 90° phase difference are input to the two feed lines respectively, a rotating electromagnetic field can be excited on the main radiating patch 102 to form a stable circular polarization mode. This rotating electromagnetic field further drives the peripheral parasitic monopole resonance through spatial coupling, thereby realizing dual-frequency circular polarization radiation characteristics. In other embodiments, the feeding structure can be extended to a two-feed differential configuration or a four-feed differential configuration to achieve higher polarization purity and pattern symmetry. The two-feed differential configuration uses two feed lines to input the RF signal; the first feed line 108 and the second feed line 109 are examples of a two-feed differential configuration. The four-feed differential configuration uses four feed lines to input the RF signal, for example, two first feed lines 108 are arranged in the x-axis direction, and two second feed lines 109 are arranged in the y-axis direction. Other types of feeding methods, such as probe feeding, coupling feeding, microstrip feeding, or slot feeding, can also be used to adapt to different application scenarios and manufacturing process requirements.

[0043] Furthermore, the geometric configuration of the main radiating patch 102 is not limited to the circular structure shown in the attached figure. To meet the diverse requirements for antenna size, frequency response, and integration in different application scenarios, the main radiating patch 102 can be flexibly selected in various geometric shapes according to design goals, including but not limited to ring, square, elliptical, triangular, or polygonal structures. It can also adopt irregular designs with optimized features, such as truncated, curved, or chamfered configurations, to improve current distribution, enhance radiation pattern symmetry, and improve circular polarization performance.

[0044] Furthermore, to achieve lower operating frequencies and higher bandwidth without significantly increasing antenna size, the present invention can also introduce miniaturized structures on the surface of the main radiating patch 102. For example, the surface current path can be extended by etching slots or gaps of specific shapes (such as U-shaped slots, L-shaped slots, spiral slots, etc.), thereby reducing the resonant frequency and improving impedance matching characteristics. As long as the formed resonant mode can maintain stable electromagnetic coupling with the peripheral parasitic monopole, the integrity of the dual-frequency circular polarization performance can be maintained.

[0045] In summary, the main radiating patch 102 design of this invention possesses high structural scalability and engineering feasibility. By flexibly adjusting the patch geometry, feeding method, and miniaturized structural parameters, efficient, broadband, and radiation-stable circular polarization characteristics can be achieved under limited size conditions. Preferably, the main radiating patch 102 adopts a symmetrical structural layout to obtain better circular polarization purity and radiation direction stability.

[0046] Example 2:

[0047] like Figure 3 and Figure 4 As shown, Figure 3 This is a three-dimensional structural diagram of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 2 of the present invention. Figure 4 This is a top view of the antenna. This embodiment illustrates another preferred implementation of the invention, whose core technical concept is consistent with that of Embodiment 1, aiming to achieve common-aperture circularly polarized radiation characteristics across two frequency bands. Compared to Embodiment 1, the main difference in this embodiment lies in the number and arrangement of parasitic monopoles.

[0048] In this embodiment, the number of parasitic monopoles is increased from three to four groups, namely, the first parasitic monopole 201, the second parasitic monopole 202, the third parasitic monopole 203, and the fourth parasitic monopole 204. The four parasitic monopoles also adopt a folded structure design and are symmetrically arranged at 90° intervals along the circumference of the main radiating patch 102, with the main radiating patch as the center. Their basic structural form is consistent with the parasitic monopole in Embodiment 1, both including a vertical connecting section, a horizontal extension section, a downward bending section, and a horizontal end section to ensure a compact structure and achieve miniaturized resonance.

[0049] Within the operating frequency band of the parasitic monopoles, the rotating electromagnetic field generated by the biorthogonal feeding on the main radiating patch 102 excites the four peripheral parasitic monopoles through spatial coupling. Since the four parasitic monopoles are spatially orthogonally distributed at 90°, they form a pair of orthogonal resonant units with a 90° phase difference. When these resonant units are superimposed in far-field radiation, they can synthesize a high-purity circularly polarized wave, achieving excellent radiation pattern symmetry and polarization stability.

[0050] Compared with Example 1, this example introduces four parasitic monopole structures, which not only further improves the radiation gain and polarization purity of the antenna, but also effectively improves the symmetry and stability of the far-field radiation pattern, thereby verifying the universality and scalability of the technical solution of the present invention.

[0051] The number of parasitic monopoles and the number of coupled branches can be configured according to structural characteristics or requirements. The number of parasitic monopoles is 3 or 4, and the number of coupled branches is 3 or more.

[0052] Example 3:

[0053] like Figure 5 and Figure 6 As shown, Figure 5 This is a three-dimensional structural diagram of the miniaturized and common-aperture dual-frequency circularly polarized patch antenna in Embodiment 3 of the present invention. Figure 6 This is a top view of the antenna in the xy plane. This embodiment illustrates another preferred implementation of the invention, whose overall structure is similar to that of Embodiment 2, but with further optimization in the construction of the capacitive coupling stub, to verify the versatility and flexibility of the technical solution of the invention.

[0054] The antenna in this embodiment includes a main radiating patch 302, a set of parasitic monopoles (first parasitic monopole 305, second parasitic monopole 306, third parasitic monopole 307, and fourth parasitic monopole 308), a set of capacitive coupling stubs (including a first capacitive metal sheet 309a and a first connecting metal strip 309b, a second capacitive metal sheet 310a and a second connecting metal strip 310b, a third capacitive metal sheet 311a and a third connecting metal strip 311b, and a fourth capacitive metal sheet 312a and a fourth connecting metal strip 312b), a ground plane 300, a first feed line 303, and a second feed line 304.

[0055] The main difference from the aforementioned embodiments is that the main radiating patch 302 in this embodiment adopts a square structure. A parasitic monopole is arranged at each of the four edges of the main radiating patch 302, and the four parasitic monopoles are symmetrically distributed at 90° intervals along the circumference with the patch center as the axis of symmetry. A certain coupling gap is left between each parasitic monopole and the side of the main radiating patch 302. This gap is used to adjust the electromagnetic coupling strength and affect the resonant characteristics of the second operating frequency band. Preferably, the horizontal extension length of each parasitic monopole parallel to the side of the patch does not exceed 70% of the patch's side length to avoid excessive disturbance to the patch's radiation field. The geometry and working principle of the parasitic monopoles are consistent with the structures in Embodiments 1 and 2.

[0056] like Figure 5 and Figure 6As shown, one end of the first connecting metal strip 309b is connected to the middle of one side of the main radiating patch 302 and is conductive to the edge of the patch, while the other end is connected to the first capacitive metal sheet 309a. A gap is formed between the first capacitive metal sheet 309a and the ground plane 300, which constitutes a capacitive load and forms a strong electric field distribution in the vertical direction. This electric field is mainly concentrated in the region of the first capacitive metal sheet 309a, thereby realizing the concentrated resonant mode of the first operating frequency band. Similarly, the second capacitive metal sheet 310a and the second connecting metal strip 310b, the third capacitive metal sheet 311a and the third connecting metal strip 311b, and the fourth capacitive metal sheet 312a and the fourth connecting metal strip 312b constitute another set of three sets of capacitive coupling branches, which are symmetrically arranged along the four sides of the main radiating patch 302.

[0057] All capacitive coupling stubs are located at the edge of the projection area of ​​the main radiating patch 302 on the ground plane 300. In this structure, the capacitive coupling stubs are located in the vertical space between the main radiating patch 102 and the ground plane 100. When the main radiating patch 102 and each capacitive coupling stub project onto the ground plane 100, the projection of the capacitive coupling stub is in close contact with the projection edge of the main radiating patch 102. The aim is to fully utilize the vertical electric field lines between the main radiating patch and the ground plane, and adjust the equivalent impedance characteristics of the patch through electromagnetic coupling, thereby changing the resonant frequency to achieve miniaturization. The connecting metal strip and the capacitive metal sheet together form a current and electric field distribution in the vertical direction, parallel to the electric field lines of the main radiating patch, thus generating a stable electric field coupling effect. Since the size of the capacitive metal sheet is much smaller than the antenna operating wavelength, the electric field exhibits a concentrated distribution characteristic, limited only to the area around the capacitive metal sheet.

[0058] In another embodiment, one end of the first connecting metal strip 309b can also be connected to the ground plane 300, and the other end can be connected to the first capacitive metal sheet 309a. A gap is formed between the first capacitive metal sheet 309a and the main radiating patch 302, thereby achieving the same capacitive loading effect and further improving the flexibility and feasibility of the structural design. Since the first connecting metal strip 309b is not directly connected to the main radiating patch 302 in this structure, and the first capacitive metal sheet 309a is in a horizontal state, there will be some overlapping or interleaved shadows on the overall capacitive coupling branch projection. That is, in this structure, the capacitive coupling branches are located in the vertical space between the main radiating patch 102 and the ground plane 100. When the main radiating patch 102 and each capacitive coupling branch form projections on the ground plane 100, the projection of the capacitive coupling branch is adjacent to or partially overlaps with the projection edge of the main radiating patch 102.

[0059] In summary, the miniaturized and common-aperture dual-band circularly polarized patch antenna provided in this embodiment achieves an efficient coupling mechanism for dual-band common-aperture radiation by optimizing the construction and layout of capacitive coupling stubs. The fundamental technical feature of this invention lies in simultaneously realizing the resonant function of two independent frequency bands within a single-layer structure. The capacitive coupling stubs and parasitic monopoles respectively form concentrated and distributed electric field distributions, maintaining electromagnetic isolation and independent adjustability during coupling with the patch, thereby ensuring the independent operation of the first and second operating frequency bands. This structural design significantly simplifies the antenna debugging process, improves the controllability and consistency of dual-band performance, and fundamentally solves the problem of severe inter-frequency coupling interference in traditional single-layer multi-band antennas, providing a reliable engineering foundation for achieving independent dual-band optimization and high-performance circular polarization characteristics.

[0060] like Figure 7 , Figure 8 and Figure 9 The figures shown are simulation performance results of the miniaturized dual-frequency circularly polarized patch antenna in Embodiment 1 of the present invention, which are used to verify the effectiveness and technical advantages of the structural design of the present invention.

[0061] like Figure 7 As shown, curve 501 represents the reflection coefficient (S) of the antenna in Embodiment 1 of the present invention. 11 The simulation results show that the antenna forms two clear and independent resonant points at 1.22 GHz and 1.57 GHz, with corresponding reflection coefficients better than -10 dB, indicating that the antenna achieves good impedance matching performance in both operating frequency bands. This result is highly consistent with the design objectives, fully verifying the feasibility and accuracy of the proposed "capacitive coupling stub + parasitic monopole" dual-resonant coupling mechanism.

[0062] Figure 8 and Figure 9 The normalized planar radiation characteristics of the antenna at the first operating frequency of 1.23 GHz and the second operating frequency of 1.57 GHz are shown respectively.

[0063] exist Figure 8 At the 1.23 GHz frequency point shown, curves 601 and 602 correspond to the radiation patterns in the xz plane (φ = 0°) and yz plane (φ = 90°), respectively. The results show that the antenna exhibits stable normal radiation characteristics in both orthogonal planes, with the main lobe direction concentrated in the zenith direction (θ = 0°), and a wide beamwidth with good pattern symmetry. This indicates that the present invention can generate a high-purity circularly polarized beam with stable radiation direction and good coverage capability in the low-frequency operating range.

[0064] exist Figure 9At the 1.57 GHz frequency point shown, curves 701 and 702 correspond to the radiation patterns in the xz and yz planes, respectively. It can be seen that the antenna maintains good normal radiation characteristics in the high-frequency operating band, with a concentrated main lobe direction and the two plane radiation patterns basically overlapping, exhibiting excellent symmetry. This indicates that the antenna can maintain stable circularly polarized radiation performance even in the second operating frequency band. Compared with the low-frequency results, the antenna beam is slightly narrower in the high-frequency band, and the radiation gain is further improved, verifying its efficient radiation characteristics in both frequency bands.

[0065] In summary, the simulation results fully demonstrate that the miniaturized and common-aperture dual-band circularly polarized patch antenna proposed in this invention can simultaneously achieve efficient circularly polarized radiation in two independent operating frequency bands within a single-layer low-profile structure. This design exhibits excellent performance in impedance matching, radiation pattern symmetry, and circular polarization stability, verifying the innovative advantages and engineering feasibility of this invention in dual-band common-aperture, miniaturized integration, and high-performance circular polarization.

[0066] The miniaturized and common-aperture dual-band circularly polarized patch antenna provided by this invention achieves independent dual-band resonance, common-aperture radiation, and high-quality circular polarization performance while maintaining a low profile and lightweight design. Compared with existing technologies, this invention has significant advantages in structural design, functional integration, and engineering feasibility. (1) In terms of structural innovation, this invention proposes a novel concept of "cooperative design of capacitive coupling stubs and parasitic monopoles," achieving spatial and electromagnetic separation of the two resonant mechanisms in a single-layer structure. The capacitive coupling stubs form a concentrated electric field distribution between the patch and the ground plane, used to generate the resonant mode of the first operating frequency band; the parasitic monopoles generate a dispersed electric field distribution around the patch, dominating the resonant characteristics of the second operating frequency band. The two are spatially partitioned and complement each other in terms of electric field distribution, thereby achieving independent tuning of dual frequencies and common-aperture integration. This design effectively avoids the problems of heavy and complex parasitic coupling in traditional multi-layer stacked antenna structures, and also overcomes the technical bottleneck of strong coupling of resonant modes and difficulty in simultaneous optimization in single-layer dual-frequency design.

[0067] (2) Regarding functional integration and common-aperture characteristics, the two sets of resonant units in this invention share the same patch to achieve radiation and energy coupling, constructing a single-layer dual-frequency common-aperture highly integrated structure. This scheme ensures that the two operating frequency bands do not interfere with each other in terms of electromagnetic distribution, while maintaining excellent circular polarization characteristics and stable radiation patterns at their respective frequency points. Compared with the prior art, this invention can achieve dual-frequency coexistence and high-purity circular polarization radiation in a smaller space, and is particularly suitable for satellite navigation, UAV communication, and other scenarios with high requirements for beam directionality and polarization consistency.

[0068] (3) In terms of engineering feasibility and design scalability, this invention adopts a single-layer dielectric substrate structure, which is fully compatible with standard PCB (printed circuit board) manufacturing processes, avoiding the complex lamination, alignment, and soldering processes in multi-layer antenna structures. This results in simpler manufacturing, lower cost, and higher consistency. Simultaneously, this invention has excellent scalability: the number of capacitive components can be flexibly configured according to operating frequency requirements (e.g., three, four, six, or eight groups), and the geometry of the patch can be selected according to the application environment (e.g., circular, square, elliptical, or other irregular structures). Furthermore, the low-frequency and high-frequency operating points can be controlled separately by adjusting the capacitive load or parasitic arm size, thereby achieving independent tuning and rapid design migration for the two frequency bands. This feature significantly improves the design flexibility and engineering practicality of this invention.

[0069] In summary, this invention achieves a good balance and unity between miniaturization, dual-band performance, common-aperture integration, and circular polarization quality. The antenna is compact, lightweight, and has a low profile. The two operating frequency bands are independent and do not interfere with each other, exhibiting stable radiation direction and excellent circular polarization characteristics. It also boasts advantages such as simplified structure, low manufacturing cost, and mass production capability. It fundamentally solves the coupling interference and complex debugging problems inherent in traditional miniaturized dual-band antennas, providing an efficient and engineerable new technological path for high-performance, lightweight dual-band circularly polarized antennas.

[0070] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A miniaturized and common-aperture dual-frequency circularly polarized patch antenna, characterized in that, The antenna includes a ground plane, a main radiating patch, multiple parasitic monopoles, multiple capacitive coupling stubs, and a feeding assembly. The ground plane is located at the bottom layer of the antenna structure, the main radiating patch is disposed above the ground plane, the multiple capacitive coupling stubs are arranged in the edge region of the main radiating patch, and the multiple parasitic monopoles are distributed around the periphery of the main radiating patch. A circumferential gap is left between the edge of the main radiating patch and the parasitic monopoles. One end of each parasitic monopole is electrically connected to the ground plane, and the other end is open. The power supply component inputs a radio frequency signal and causes the capacitive coupling stub to resonate in the first operating frequency band between the main radiating patch and the ground plane, while the parasitic monopole resonates in the second operating frequency band around the main radiating patch. The parasitic monopole has a folded structure, which includes a horizontal end section located at the open end. A gap is formed between the horizontal end section and the ground plane to generate an equivalent capacitance at the end.

2. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to claim 1, characterized in that, Each of the capacitive coupling stubs includes a capacitive element and a connecting wire, the capacitive element being loaded between the main radiating patch and the ground plane via the connecting wire.

3. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to claim 2, characterized in that, One end of the connecting line is connected to the edge of the main radiating patch, and the other end is connected to the ground plane. The capacitive element is connected in series on the connecting line. Alternatively, one end of the connecting wire can be connected to the main radiating patch, and the other end can be electrically connected to the ground plane through a capacitive element; Alternatively, one end of the connecting wire can be connected to the grounding plate, and the other end can be electrically connected to the main radiating patch through a capacitive element.

4. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to claim 1, characterized in that, Each of the capacitive coupling stubs includes a capacitive metal sheet and a connecting metal strip; One end of the connecting metal strip is electrically connected to the main radiating patch, and the other end is connected to a capacitive metal sheet, with a gap formed between the capacitive metal sheet and the ground plane; And / or one end of the connecting metal strip is connected to the ground plane, and the other end is connected to the capacitive metal sheet, with a gap formed between the capacitive metal sheet and the main radiating patch.

5. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to claim 1, characterized in that, The parasitic monopole's folded structure includes a vertical connecting section, a horizontal extending section, a vertical section, and a horizontal end section. The vertical connecting section, the horizontal extending section, the vertical section, and the horizontal end section are connected sequentially. The vertical connecting section is connected to the ground plane, and the horizontal end section is open-circuited.

6. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, The capacitive coupling stubs are located in the vertical space between the main radiating patch and the ground plane. The main radiating patch and each capacitive coupling stub form projections on the ground plane, and the projections of the capacitive coupling stubs are adjacent to, close to, or partially overlap with the projection edges of the main radiating patch.

7. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, The parasitic monopoles are arranged symmetrically and evenly around the main radiating patch. The parasitic monopoles are located outside the projection area of ​​the main radiating patch onto the ground plane and are spaced apart from the main radiating patch.

8. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, The minimum width of the circumferential gap between the edge of the main radiating patch and each parasitic monopole does not exceed λ / 30, where λ is the free space wavelength corresponding to the second operating frequency of the antenna.

9. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, The power supply assembly includes at least one power supply line, one end of which is connected to the main radiating patch and the other end is connected to an external radio frequency port. The main radiating patch receives radio frequency signals through the power supply line.

10. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, The power supply assembly also includes one or more combinations of two-feed differential mode, four-feed differential mode, probe feeding, coupling feeding, microstrip feeding, and slot feeding. The main radiating patch receives radio frequency signals with equal amplitude and 90° phase difference through the power supply assembly.

11. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, A dielectric substrate and / or a support structure are provided between the main radiating patch and the ground plane. The dielectric substrate is one or a combination of two of the following: air dielectric and low dielectric constant material. The support structure is a support column or a support leg.

12. The miniaturized and common-aperture dual-frequency circularly polarized patch antenna according to any one of claims 1 to 5, characterized in that, The main radiating patch can be ring-shaped, circular, square, elliptical, triangular, or polygonal. And / or the main radiating patch is one or more combinations of having a slotted or slit structure.

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