A co-boresight dual-frequency dual-circularly polarized array antenna

Abstract

The application discloses a co-bore dual-frequency dual-circularly polarized array antenna, which comprises dual-polarized array antenna components arranged uniformly along the horizontal direction, an equal-amplitude in-phase power division feeding network component below the array antenna, a grid array component covering the dual-polarized array antenna, and a circularly polarized grid array component covering the grid array component. The grid array component is used for suppressing the antenna directional diagram grating lobe of the dual-frequency band. In the power division network component, the transition structure of the microstrip line to the ridge waveguide realizes the continuous impedance matching of the microstrip quasi TEM mode and the main mode of the ridge waveguide, and realizes the low-loss electromagnetic energy transition of the dual-frequency band. The circularly polarized grid array can convert the dual-polarized electromagnetic wave of the working frequency band into left-handed circularly polarized wave and right-handed circularly polarized wave respectively. According to the application, the co-bore dual-frequency dual-circularly polarized array antenna can realize the function of radiating dual-circularly polarized electromagnetic wave at two working frequency bands with a lower antenna profile.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, and specifically relates to a common-aperture dual-frequency dual-circular polarization antenna array. Background Technology

[0002] With the rapid iteration of low-Earth orbit high-throughput satellite communication, airborne / vehicle-mounted mobile communication, and spaceborne active phased array terminal technologies, Ka-band satellite communication (K-band and Ka-band frequency full-duplex communication) has become an urgent requirement for next-generation broadband satellite communication. Ka-band satellite communication offers stable signal coverage, large bandwidth, and high transmission rates. Furthermore, through dual circular polarization, it significantly improves the communication capacity of satellite communication links, making it widely adaptable to various core application scenarios such as spaceborne payloads, mobile satellite communication terminals, and ground-based high-throughput receiving stations.

[0003] Currently, the mainstream K / Ka dual-band dual-circular polarization antenna technologies in the industry mainly include four types: reflector-nested feed antennas, planar co-aperture microstrip array antennas, transmission / reflection array antennas, and waveguide slot array antennas. Among them, the reflector-nested feed antenna technology is the most mature. It achieves dual-band dual-circular polarization radiation by using a nested structure of an inner Ka-band circular waveguide and an outer K-band coaxial horn, combined with an internal polarizer. It has the characteristics of high polarization purity and good engineering stability, and has been commercially deployed on a large scale in traditional terrestrial fixed satellite communication terminals. However, this solution has a large cross-sectional size and low integration, which cannot meet the assembly requirements of vehicle-mounted, airborne, and spaceborne equipment for thinner and flat-panel designs.

[0004] Planar co-aperture microstrip array antennas, with their advantages of low profile and easy integration, employ layered patch stacking or staggered element array structures, combined with sequential rotating array technology to broaden the circular polarization bandwidth, effectively improving aperture utilization. However, limited by the near-octave high frequency ratio characteristics of the K / Ka band, existing planar array structures cannot simultaneously achieve impedance bandwidth and axial ratio bandwidth for both bands, resulting in a bandwidth adaptability imbalance.

[0005] Transmittance / reflection array antennas offer advantages such as low profile, high gain, and low cost, eliminating the need for complex active feed networks and making them suitable for lightweight civilian mobile communication terminals. However, these antennas have weak normal radiation capability, making it difficult to achieve flexible multi-beam control and limiting their application scenarios. Waveguide slot array antennas offer high radiation efficiency, large power capacity, and excellent cross-polarization performance, making them suitable for high-power spaceborne transmission scenarios. However, they suffer from drawbacks such as large profile thickness, complex manufacturing processes, and relatively high overall weight, resulting in lower mass production costs and poor equipment integration.

[0006] In summary, existing K / Ka band dual circularly polarized antenna technologies generally suffer from core technical bottlenecks such as poor bandwidth matching at high frequency ratios, insufficient dual-port isolation, and difficulty in balancing integration and performance. Furthermore, current mainstream common-aperture arrays mostly employ large-scale array configurations, relying on a large number of elements to achieve gain targets. This results in large overall array size, high element redundancy, and complex feeding networks, increasing both the overall weight and power consumption of the antenna. It also easily exacerbates inter-band and inter-element coupling interference, leading to high debugging difficulty and mass production costs. Consequently, these technologies are ill-suited for miniaturized, lightweight, and low-power applications such as micro satellite communication terminals, portable airborne terminals, and small spaceborne payloads. Therefore, there is an urgent need to develop a common-aperture K / Ka band dual circularly polarized antenna that balances dual-band broadband characteristics, high port isolation, and stable circular polarization characteristics to address the numerous shortcomings of existing technologies and meet the application requirements of next-generation miniaturized satellite communication terminals. Summary of the Invention

[0007] Purpose of the invention: In view of the above-mentioned prior art, a common aperture dual-frequency dual-circular polarization array antenna is proposed to suppress grating lobes, ensure the isolation between the two polarization ports, and take into account the reception and transmission of dual-circular polarization waves in two frequency bands under the condition of limited physical space.

[0008] Technical solution: A common-aperture dual-frequency dual-circular polarization array antenna, comprising: a dual-polarization array antenna assembly uniformly arranged in the horizontal direction, an equal-amplitude and in-phase power divider network assembly below the dual-polarization array antenna assembly, a grid array assembly covering the dual-polarization array antenna assembly, and a circularly polarized grid array assembly covering the grid array assembly; the circularly polarized grid array assembly is used to convert the dual-linear polarized waves radiated by the antenna into left-circularly polarized waves and right-circularly polarized waves respectively; the grid array is used to suppress grating lobes in the radiation pattern of the antenna in the operating frequency band; the dual-polarization array antenna assembly is used to radiate dual-linear polarized waves with good polarization isolation; and the power divider network assembly is used to provide equal-amplitude and in-phase power distribution for the dual-polarization array antenna.

[0009] Preferably, the dual-polarized array antenna assembly is composed of several dual-polarized antenna units with two pairs of orthogonal metal ridges built in, arranged evenly along the horizontal direction. The metal ridges inside the unit form two sets of orthogonal independent radiation channels to achieve dual-band dual-line polarized radiation. The spatial isolation structure between the metal ridges weakens the electromagnetic coupling between polarizations, improves the isolation of the dual-polarized ports, and at the same time completes the impedance matching of the dual-band high frequency ratio.

[0010] Preferably, the grid array assembly is composed of a dielectric substrate and periodic metal grid units attached to the surface of the substrate, which cover the array aperture as a whole; in view of the array unit spacing constraints, the periodic metal grid cancels and suppresses high-frequency spatial harmonics, eliminates grating lobes in the antenna radiation pattern, and improves the purity of the array radiation pattern.

[0011] Preferably, the circular polarization gate array assembly is composed of multiple layers of stacked polarization gates, with each gate layer having polarization gate units arranged uniformly along the horizontal direction; the metal pattern of the polarization gate unit is optimized for dual-band wavelength coordination, possessing dual-band anisotropic electromagnetic control characteristics; at the same time, it converts the orthogonal bilinear polarized waves of the two frequency bands into left-handed and right-handed circularly polarized waves; the polarization phase difference of the normal radiation remains stable over a wide bandwidth, exhibiting excellent axial ratio performance.

[0012] Preferably, the equal-amplitude, in-phase power divider network component adopts a two-layer architecture, with the two layers isolated by a metal ground plane between the two dielectric substrates. Each layer corresponds to a set of orthogonal polarization independent feeds, and the metal isolation layer significantly improves polarization port isolation. The power divider network consists of four integrated cascaded parts: a subarray microstrip line power divider network, an inter-subarray ridge waveguide power divider network, a microstrip line to ridge waveguide transition structure, and a ridge waveguide to rectangular waveguide output transition at the end. The microstrip line to ridge waveguide transition structure incorporates a multi-level gradient matching structure. One end of the metal ridge of the multi-level gradient matching structure is directly attached to the microstrip conductor, and the other end is embedded inside the ridge waveguide cavity. Through the multi-level variable width and thickness metal ridge, continuous impedance matching between the microstrip quasi-TEM mode and the ridge waveguide master mode is achieved, realizing low-loss electromagnetic energy transition in both frequency bands. The equal-amplitude, in-phase power divider network component combines the low-loss characteristics of the ridge waveguide feed network with the compact characteristics of the microstrip line feed network, realizing dual-polarization feeding for all antenna elements within a limited space.

[0013] Beneficial effects: 1. The antenna unit and the equal amplitude and phase feeding network of the present invention are compactly integrated, without independent heavy feed source and large waveguide cavity, which greatly reduces the size and weight of the antenna, and is suitable for the lightweight assembly requirements of miniature satellite payloads, portable mobile communication, and small ground satellite communication terminals, solving the pain points of poor integration and large overall size of traditional antennas.

[0014] 2. This invention employs a multi-stage gradient microstrip line to ridge waveguide transition structure, relying on multi-stage metal ridges to achieve continuous impedance matching, significantly reducing dual-band transmission line conversion loss. At the same time, the shielding structure of the metal ridge waveguide can suppress inter-polarization crosstalk, solving the industry problems of standing wave degradation, narrow bandwidth, and high loss that exist in traditional stepped transitions.

[0015] 3. The multilayer composite polarization gate array of the present invention can passively and synchronously complete the conversion of dual-band dual-linear polarized waves to dual-circular polarized waves without the need for additional active phase compensation devices; both frequency bands can achieve wide axial ratio bandwidth, and the polarization purity is better than that of traditional sequential rotating patch arrays.

[0016] 4. This invention adopts a microstrip plus ridge waveguide composite integrated feeding network, which takes into account the advantages of PCB planar integration and ridge waveguide low loss and high power capacity; the double-layer metal isolation architecture realizes polarization and high isolation of high and low frequency ports, suppresses array mutual coupling, and provides equal amplitude and in-phase feeding for the entire array, resulting in no beam distortion and stable gain.

[0017] 5. The colored pen grid array assembly of the present invention suppresses the radiation grating lobes of dual-band antennas, which can reduce the number of array elements and reduce processing and debugging costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the array antenna of the present invention;

[0019] Figure 2 This is a diagram of a 2×2 common aperture K / Ka band dual circularly polarized array antenna according to an embodiment of the present invention;

[0020] Figure 3 This is a diagram of the antenna radiating element according to an embodiment of the present invention;

[0021] Figure 4 This is a periodic metal pattern used in the polarization gate of the present invention;

[0022] Figure 5 This is a diagram of the metal pattern of the grid layer and its metal patch pattern according to the present invention;

[0023] Figure 6 This is a diagram of the microstrip line to ridge waveguide transition structure according to an embodiment of the present invention;

[0024] Figure 7 The normal radiation pattern of the antenna with a central operating frequency of 19.45 GHz in the embodiment of the invention;

[0025] Figure 8 The image shows the normal radiation pattern of the antenna with a center operating frequency of 29.5 GHz in the embodiment of the invention. Detailed Implementation

[0026] The invention will now be further explained with reference to the accompanying drawings.

[0027] To illustrate the structure and performance of the antenna of the present invention, a common-aperture dual-frequency dual-circularly polarized array antenna with a center operating frequency of 19.45 GHz and 29.5 GHz is used for illustration. The operating frequency band of this embodiment should not be construed as a limitation of the present invention.

[0028] like Figure 1As shown, the array antenna architecture of this invention adopts a four-layer vertically stacked architecture. From top to bottom, a polarization grating layer, a grid layer, a horizontally arrayed dual-polarization antenna element layer, and a bottom integrated feed network are arranged sequentially. The four layers are coaxially stacked and assembled with the same aperture. The polarization grating layer and the grid layer completely cover the radiation aperture of all antenna elements below. The bottom feed network independently provides equal amplitude and in-phase feed links for each group of antenna elements. The four-layered modular structure works independently and collaboratively, and simultaneously realizes the four core functions of polarization conversion, grating lobe suppression, dual-frequency radiation, and equal amplitude feeding within a compact vertical profile. No additional horizontal assembly space is required, which greatly improves the antenna aperture utilization and the overall integration.

[0029] like Figure 2 As shown, this embodiment provides an 8×8 common aperture K / Ka band dual circularly polarized array antenna, which, from top to bottom, includes a circularly polarized grating array assembly 100, a grating array assembly 200, a dual-polarized array antenna assembly 300, and an equal amplitude and in-phase power divider network assembly 400. The whole adopts a stacked common aperture integrated assembly structure, with a total height of about 30mm. The size of a single antenna radiating element is 18mm×18mm, and the total size is 144mm×144mm. It belongs to the Ka band common aperture satellite communication antenna for transmission and reception.

[0030] The dual-polarized array antenna assembly 300 is composed of multiple sets of dual-polarized antenna elements arranged at equal intervals along the horizontal direction. Figure 3 A schematic diagram of the dual-polarized antenna radiating element of an embodiment is provided, in which metal ridges 301, 302, 303, and 304 are arranged internally and fixed to a substrate. Metal ridges 304 and 301 form one group, and metal ridges 302 and 303 form another group, arranged orthogonally within the element. Feed slots are formed on one side of metal ridges 304 and 303, used to connect microstrip line feed structures in orthogonal polarization directions. The two groups of orthogonal metal ridges excite two sets of orthogonal dual-polarized radiation modes, and the spatial isolation structure between the metal ridges blocks electromagnetic coupling between the two polarization channels. The outer periphery of the dual-polarized antenna radiating element is a metal shell of a horn antenna, covering the exterior of each metal ridge structure. By optimizing the geometry of the metal ridges, the resonant impedances of both the K-band and Ka-band are matched simultaneously, ensuring good standing wave ratios in both bands.

[0031] The circularly polarized gate array assembly 100 is composed of three layers of dielectric substrates printed with metal patterns, which convert bilinearly polarized waves into circularly polarized waves. Figure 4 The metal pattern of the circular polarized gate array assembly 100 of the embodiment is given, wherein each gate layer is arranged with polarized gate units uniformly arranged in a horizontal direction, and the metal pattern of the polarized gate units is a bent microstrip line.

[0032] The grid array assembly is composed of two dielectric substrates with metal patterns attached to their surfaces stacked together. Figure 5 An embodiment of the metal pattern 201 of the grid array is given, that is, the grid array assembly 200 is composed of a number of grid units uniformly arranged in the horizontal direction, and each grid unit is also provided with a 2×2 metal patch 202. The grid array assembly 200 can suppress the grid lobes of the antenna radiation pattern.

[0033] The equal-amplitude and in-phase power divider network component 400 is the underlying integrated feed network. This component adopts a two-layer structure, isolated by a metal ground plane. Each layer independently feeds two sets of orthogonal metal ridges in each dual-polarized antenna radiating element, achieving equal-amplitude and in-phase power distribution. Each layer consists of a microstrip line feed network component within the subarray, a ridge waveguide power divider network used between subarrays, a transition structure component from microstrip line to ridge waveguide, and a transition structure from ridge waveguide to rectangular waveguide exit.

[0034] Figure 6 The microstrip line to ridge waveguide transition structure used in the embodiment is given, which employs a complex metal ridge structure 402. This complex metal ridge structure 402 differs from the ridge waveguide of the ridge waveguide power divider network used between subarrays; it is an independent metal ridge component within the microstrip line to ridge waveguide transition structure. Specifically, the conductor of the microstrip line 401 at the output end of the microstrip line feed network component is directly bonded to the bottom front surface of the complex metal ridge structure 402, and the rear end of the complex metal ridge structure 402 extends into the cavity of the rear ridge waveguide. The overall outline of the complex metal ridge structure 402 is a three-dimensional stepped geometric configuration that gradually transitions from the narrow, thin cross-sectional profile of the microstrip conductor to the wide, thick ridge cross-section of the rear ridge waveguide cavity.

[0035] Specifically, the complex metal ridge structure 402 adopts a multi-stage, variable-width, variable-thickness gradient structure. Along the transmission direction from the microstrip line 401 to the rear-end ridge waveguide, the complex metal ridge structure 402 is divided into three segments. The first segment is a cuboid structure with the same width as the microstrip line 401, and its bottom surface is flush with the conductive strip of the microstrip line 401. The width of the second segment gradually increases to the width of the third segment, and the bottom of the second segment has a downward-protruding rectangular tooth structure on its plane. The overall thickness of the second segment at the location of the rectangular tooth is the same as the thickness of the first segment. The third segment has a constant width, but its thickness decreases in a stepped manner along the length direction. This transition structure, through the complex metal ridge structure 402, achieves a low-loss electromagnetic energy transition from the microstrip line 401 to the rear-end ridge waveguide cavity, ensuring low-loss power distribution within a limited space.

[0036] In this embodiment, both the circularly polarized gate array assembly 100 and the grid array assembly 200 can be processed using PCB technology. The ridge waveguide and the transition metal ridge are integrally milled and assembled in a modular, layered manner.

[0037] This embodiment uses Ansys HFSS 2022 R1 software to perform periodic boundary simulation on the antenna element. Figure 7 The radiation pattern of the embodiment at a center operating frequency of 19.45 GHz was plotted. Figure 8 The radiation pattern of the embodiment at a center operating frequency of 29.5 GHz is plotted. This array antenna features high gain and high efficiency.

[0038] In the description of this invention, the frequency bands of the embodiments are only for illustrative purposes and do not limit the operating frequency band of the method in this invention. By appropriately enlarging or reducing the size of the antenna element, grid element and circularly polarized grid element, the antenna can operate in frequency bands such as microwave, millimeter wave and terahertz.

[0039] The number of antenna elements and operating frequency described herein are for the purpose of simplifying the description of the invention. Applications, modifications and variations of the invention will be readily apparent to those skilled in the art.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A common-aperture dual-frequency dual-circularly polarized array antenna, characterized in that, include: A dual-polarized array antenna assembly is uniformly arranged horizontally. Below the dual-polarized array antenna assembly is an equal-amplitude, in-phase power divider network assembly. Above the dual-polarized array antenna assembly is a grid array assembly, and above the grid array assembly is a circularly polarized grid array assembly. The power divider network assembly provides equal-amplitude, in-phase power distribution to the dual-polarized array antenna assembly to achieve antenna feeding in two operating frequency bands. The grid array assembly suppresses grating lobes in the antenna radiation patterns of the two operating frequency bands. The circularly polarized grid array assembly converts a dual-linearly polarized wave into a dual-circularly polarized wave.

2. The common-aperture dual-frequency dual-circular polarization array antenna according to claim 1, characterized in that, The dual-polarized array antenna assembly is composed of several dual-polarized antenna elements arranged uniformly in the horizontal direction; each dual-polarized antenna element has four metal ridges inside, with two metal ridges forming a group and arranged orthogonally. One metal ridge in each group is connected to a microstrip line feed structure. The two groups of metal ridges are used to excite two groups of orthogonal dual-polarized radiation modes respectively. The spatial isolation structure between the metal ridge structures is used to block the electromagnetic coupling of the two polarization channels.

3. The common-aperture dual-frequency dual-circular polarization array antenna according to claim 2, characterized in that, The equal amplitude and in phase power divider network component adopts a double-layer structure, with the two layers isolated by a metal ground plane. Each layer is independently fed by two sets of orthogonal metal ridges in each dual-polarized antenna radiating element. Each layer consists of a microstrip line power divider network within the subarray, a ridge waveguide power divider network used between subarrays, a transition structure from microstrip line to ridge waveguide, and a transition structure from ridge waveguide to rectangular waveguide outlet.

4. The common-aperture dual-frequency dual-circular polarization array antenna according to claim 3, characterized in that, The transition structure of the microstrip line to ridge waveguide is used to realize the low-loss transition of electromagnetic waves from microstrip line feeding to ridge waveguide feeding. The transition structure of the microstrip line to ridge waveguide adopts a complex metal ridge structure, which is a three-dimensional stepped geometric configuration that gradually transitions from a narrow and thin cross section to a wide and thick ridge cross section along the length direction.

5. The common-aperture dual-frequency dual-circular polarization array antenna according to claim 4, characterized in that, The complex metal ridge structure is divided into three segments along its length. The first segment is a cuboid structure with a width consistent with the width of the connected microstrip line. The bottom surface of the first segment is in close contact with the conductor of the microstrip line. The width of the second segment gradually increases to the width of the third segment. The bottom of the second segment has a rectangular tooth structure with downward protrusions on its plane. The thickness of the second segment at the position of the rectangular tooth is consistent with the thickness of the first segment. The third segment has a constant width but a stepped structure with a progressively decreasing thickness along its length. The tail of the third segment extends into the cavity of the rear ridge waveguide.

6. The common-aperture dual-frequency dual-circular polarization array antenna according to claim 1, characterized in that, The grid array assembly is formed by stacking several layers of dielectric substrates with metal patterns attached to their surfaces. Each layer of metal pattern includes grid units arranged periodically in the horizontal direction, and each grid unit is further provided with 2×2 metal patches.

7. The common-aperture dual-frequency dual-circular polarization array antenna according to claim 1, characterized in that, The circular polarized gate array assembly is composed of multiple layers of stacked polarized gates, with each layer having polarized gate units arranged uniformly along the horizontal direction. By co-optimizing the metal pattern of the polarized gate units for dual-band wavelengths, it possesses dual-frequency anisotropic electromagnetic control characteristics.

Images