Circularly polarized spherical phased-array antenna for Ka-band operation

Abstract

The invention belongs to the technical field of millimeter wave phased-array antennas, and particularly discloses a circularly polarized spherical phased-array antenna for Ka-band operation, which comprises a hemispherical antenna base and a plurality of radiation units, the plurality of radiation units are arranged on the hemispherical surface of the hemispherical antenna base in an array form; the circularly polarized spherical phased-array antenna is configured in a frequency range from 27GHz to 29GHz, so that + / -90-degree beam scanning of any azimuth tangent plane is realized. The scanning angle limitation of a planar array is broken through, and + / -90-degree continuous scanning of any tangent plane is realized; meanwhile, the array element spacing and the arrangement density are optimized in combination with the short wavelength characteristic of the Ka wave band, the mutual coupling effect of the high frequency band is reduced, and the problem that the actual use effect is poor due to the fact that the large-angle scanning radiation capacity of an existing Ka wave band planar phased array antenna is limited and the polarization purity is reduced is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of millimeter wave phased array antennas, and particularly relates to a circularly polarized spherical phased array antenna for Ka-band operation. BACKGROUND

[0002] At present, for the wide-angle scanning requirement of the millimeter wave frequency band, the wide-angle scanning phased array antennas disclosed in the related art are mainly implemented based on a planar array layout. For example, one scheme realizes the wide-angle scanning and circular polarization characteristics in the millimeter wave frequency band by designing a circular microstrip patch radiating element, a rotationally symmetric coupling slot and a metal through-hole isolation structure, and using a multi-layer PCB mixed pressure process; another scheme adopts a non-uniform golden spiral arranged dipole array layer, combines an electromagnetic isolation layer and an intelligent beam forming algorithm, and optimizes the beam directivity and gain stability during large-angle scanning.

[0003] Although the above schemes reflect the wide-angle scanning capability in their respective application scenarios, their cores are all dependent on a planar array layout. Limited by the physical characteristics of the planar structure, when the array elements are scanned at an angle other than the normal direction, the mutual coupling between the elements is enhanced, the wave path difference is increased, and the beam tilting effect is caused, which leads to a limited scanning angle range (usually difficult to break through ±60° to ±70°), and problems such as sharp gain drop and polarization purity deterioration are easily caused when the scanning angle is close to the maximum scanning angle. The two-dimensional layout characteristics of the planar array make it impossible to realize full-space coverage in three-dimensional space, and it is difficult to meet the application requirement of continuous scanning in the ±90° range of any cross section.

[0004] The existing millimeter wave phased array antenna technology scheme usually relies on a planar array layout, and although it has certain effect in wide-angle scanning, the scanning range is often difficult to break through ±60° to ±70°. When working at a large angle, the mutual coupling between the array elements is enhanced, the wave path difference is increased, which easily leads to gain drop and polarization purity reduction, and it is difficult to realize full-space coverage in three-dimensional space. In addition, in the millimeter wave frequency band, the related spherical phased array technology is almost in a blank state, especially in the Ka band, there is no mature implementation scheme. SUMMARY

[0005] The application aims to solve the problem of poor actual use effect caused by the limited large-angle scanning radiation capability and reduced polarization purity of the existing Ka-band planar phased array antenna, and proposes a circularly polarized spherical phased array antenna for Ka-band operation.

[0006] The technical scheme of the application is as follows: a circularly polarized spherical phased array antenna for Ka-band operation, comprising a hemispherical antenna base and a plurality of radiating elements; the plurality of radiating elements are arranged in an array form on the hemispherical surface of the hemispherical antenna base; the circularly polarized spherical phased array antenna is configured in a frequency range of 27GHz to 29GHz, and realizes beam scanning in the ±90° range of any azimuth cross section.

[0007] Preferably, the hemispherical antenna base is obtained by additive manufacturing from a resin material having a dielectric constant less than 5.

[0008] Preferably, each radiation unit is a circularly polarized magnetic electric dipole antenna for ensuring impedance matching characteristics and circularly polarized radiation characteristics in the operating frequency range.

[0009] Preferably, the circularly polarized magnetic electric dipole antenna comprises a substrate material, a metallized via, a microstrip antenna bottom plate, and a radiation metal patch structure arranged on the substrate material, the radiation metal patch structure comprising two pairs of metal patch pairs, the two pairs of metal patch pairs exciting modes with equal amplitudes and orthogonal phases to realize circularly polarized radiation, and the two pairs of metal patch pairs being short-circuited to the microstrip antenna bottom plate through the metallized via.

[0010] Preferably, the substrate material is a Rogers 4350B board material with a dielectric constant of 3.66 and a loss tangent angle of 0.004, and a thickness of 1.524 mm.

[0011] Preferably, in the two pairs of metal patch pairs, the first pair of metal patch pairs is composed of a first rectangular metal patch and a second rectangular metal patch loaded with a Γ-shaped structure at the tail, and the second pair of metal patch pairs is composed of a first regular rectangular metal patch and a second regular rectangular metal patch; wherein the first pair of metal patch pairs and the second pair of metal patch pairs are arranged vertically to form a pair of electric dipoles.

[0012] Preferably, the metallized via comprises a first via, a second via, a third via and a fourth via, the inner edges of the first rectangular metal patch, the second rectangular metal patch, the first regular rectangular metal patch and the second regular rectangular metal patch are respectively short-circuited to the microstrip antenna bottom plate through the first via, the second via, the third via and the fourth via to form a pair of magnetic dipoles.

[0013] Preferably, the thicknesses of the first rectangular metal patch, the second rectangular metal patch, the first regular rectangular metal patch and the second regular rectangular metal patch are 0.035 mm; and the diameters of the first via, the second via, the third via and the fourth via are 8 mil.

[0014] Preferably, the circularly polarized spherical phased array antenna further comprises an ssmp connector, a coaxial inner core of the ssmp connector passing through the substrate material and being connected to the metal strip on the top layer of the substrate material to jointly excite the magnetic electric dipole.

[0015] The beneficial effects of the present application are: 1. The present application adopts a hemispherical array layout, so that the antenna can maintain stable gain performance when scanning at a wide angle, significantly improving the gain attenuation problem of a planar array at a large scanning angle.

[0016] 2. The application realizes high polarization purity and stable beam pointing characteristics in the full scanning range through the synergistic design of circularly polarized radiating elements and three-dimensional array.

[0017] 3. The application takes into account the processing and integration requirements of high frequency bands in structural design, realizes high element density and compact arrangement, and provides a simple and stable solution for Ka-band applications.

[0018] 4. The Ka-band circularly polarized spherical phased array antenna proposed in the application breaks through the scanning angle limitation of planar arrays and realizes continuous scanning of ±90° on any cross section. At the same time, the element spacing and arrangement density are optimized in combination with the short wavelength characteristics of Ka-band to reduce the mutual coupling effect of high frequency bands. Further, through the design of circularly polarized elements, the consistency of polarization direction under three-dimensional array is ensured, and the polarization purity and gain stability are improved, thereby providing a solution that can balance full airspace coverage and high performance for millimeter wave wide-angle scanning applications. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Fig. 1 shows a perspective view of a circularly polarized spherical phased array antenna for Ka-band operation.

[0020] Figure 2 Fig. 2 shows a side view of a circularly polarized spherical phased array antenna for Ka-band operation.

[0021] Figure 3 Fig. 3 shows a top view of a circularly polarized spherical phased array antenna for Ka-band operation.

[0022] Figure 4 Fig. 4 shows a structure diagram of a radiating element.

[0023] Figure 5 Fig. 5 shows a side view of a radiating element.

[0024] Figure 6 Fig. 6 shows a top view of a radiating element.

[0025] Figure 7 Fig. 7 shows a reflection coefficient frequency curve of a radiating element.

[0026] Figure 8 Fig. 8 shows a normal gain frequency curve of a radiating element.

[0027] Figure 9 Fig. 9 shows a normal axial ratio frequency curve of a radiating element.

[0028] Figure 10 Fig. 10 shows the scanning beam pattern of a spherical phased array antenna in the cross section.

[0029] Figure 11 The spherical phased array antenna is shown in a cross-sectional view.

[0030] BRIEF DESCRIPTION OF DRAWINGS: 1a - first rectangular metal patch, 1b - second rectangular metal patch, 2a - first regular rectangular metal patch, 2b - second regular rectangular metal patch, 3a - first via, 3b - second via, 4a - third via, 4b - fourth via, 5 - substrate material, 6 - ssmp connector, 6a - coaxial inner core of ssmp connector, 7 - metal strip. DETAILED DESCRIPTION

[0031] Exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments illustrated and described herein are merely exemplary and are not intended to limit the scope of the present application, as defined by the appended claims, and their equivalents.

[0032] Example 1: As shown in Figure 1 , a circularly polarized spherical phased array antenna for Ka-band operation, a hemispherical antenna base and a plurality of radiating elements; the plurality of radiating elements are arranged in an array form on the hemispherical surface of the hemispherical antenna base; the circularly polarized spherical phased array antenna is configured in a frequency range of 27 GHz to 29 GHz, realizing beam scanning of ±90° in any azimuthal cross-section.

[0033] In this embodiment, as shown in Figure 2 and Figure 3 , a circularly polarized spherical phased array antenna for Ka-band operation, the hemispherical radius is 27.12 mm, the main body is mainly composed of an antenna base and 73 antenna radiating elements. The antenna base is made of universal resin material of future 8600 Pro, and is processed by LCD laser cladding deposition forming process, mainly playing a supporting and fixing role. The radiating element selects a magneto-electric dipole antenna based on PCB process, which can ensure good impedance matching characteristics and circularly polarized radiation characteristics in the working frequency range.

[0034] The hemispherical antenna base is obtained by additive manufacturing from a resin material with a dielectric constant less than 5.

[0035] The antenna radiating element is as shown in Figure 4 , Figure 5 and Figure 6As shown, a magnetic electric dipole structure based on PCB process is selected. Each radiation unit is a circularly polarized magnetic electric dipole antenna, which is used to ensure the impedance matching characteristics and circularly polarized radiation characteristics in the working frequency range. The circularly polarized magnetic electric dipole antenna includes a substrate material 5, a metalized via, a microstrip antenna bottom plate, and a radiation metal patch structure arranged on the substrate material 5, the radiation metal patch structure including two pairs of metal patch pairs, the two pairs of metal patch pairs exciting modes with equal amplitude and orthogonal phase to realize circularly polarized radiation; the two pairs of metal patch pairs are short-circuited to the microstrip antenna bottom plate through the metalized via.

[0036] The substrate material 5 is a Rogers 4350B board material with a dielectric constant of 3.66, a loss tangent angle of 0.004, and a magnetic permeability of 1, and the board material has a thickness of 1.524 mm.

[0037] In the two pairs of metal patch pairs, the first pair of metal patch pairs is composed of a first rectangular metal patch 1a and a second rectangular metal patch 1b loaded with a Γ-shaped structure at the tail, and the second pair of metal patch pairs is composed of a first regular rectangular metal patch 2a and a second regular rectangular metal patch 2b; wherein the first pair of metal patch pairs and the second pair of metal patch pairs are arranged vertically to form a pair of electric dipoles. By reasonably designing the shapes of the first rectangular metal patch 1a, the second rectangular metal patch 1b, the first regular rectangular metal patch 2a, and the second regular rectangular metal patch 2b, the current path can be effectively changed to realize the circularly polarized radiation characteristics.

[0038] The metalized via includes a first via 3a, a second via 3b, a third via 4a, and a fourth via 4b, the inner edges of the first rectangular metal patch 1a, the second rectangular metal patch 1b, the first regular rectangular metal patch 2a, and the second regular rectangular metal patch 2b are short-circuited to the microstrip antenna bottom plate through the first via 3a, the second via 3b, the third via 4a, and the fourth via 4b, respectively, to form a pair of magnetic dipoles.

[0039] The thicknesses of the first rectangular metal patch 1a, the second rectangular metal patch 1b, the first regular rectangular metal patch 2a, and the second regular rectangular metal patch 2b are 0.035 mm; the diameters of the first via 3a, the second via 3b, the third via 4a, and the fourth via 4b are 8 mil.

[0040] If the input impedance of the antenna and the impedance of the feed line are not matched, signal reflection will occur, which will affect the actual performance of the antenna. The reflection coefficient is expressed as:

[0041] wherein, is the input impedance of the antenna, The transmission line characteristic impedance is 50 ohms. In the embodiment of the application, a 50 ohm ssmp connector 6 is used as an excitation end, the coaxial inner core 6a of the ssmp connector has a diameter of 0.3 mm and an outer conductor inner diameter of 1 mm, the coaxial inner core extends outward from the insulator by 2 mm, that is, penetrates through the substrate material 5, and is connected with the metal strip 7 on the top layer of the substrate material 5 to jointly excite the magnetoelectric dipole, so that a relatively low reflection coefficient of the antenna can be ensured in a wide frequency band.

[0042] In the embodiment, as shown in Figure 7 , Figure 8 and Figure 9 , they are respectively the frequency curve of the reflection coefficient of the antenna radiation unit, the frequency curve of the normal gain, and the frequency curve of the normal axial ratio. The design of the application can ensure that the radiation unit has a reflection coefficient less than -15 dB, a radiation gain greater than 5 dBi, and a normal axial ratio less than 3 dB in the frequency range of 27-29 GHz, that is, in a wide frequency band, the characteristics of good impedance matching, high radiation efficiency, low axial ratio circularly polarized radiation, and the like can be simultaneously met, and the antenna gain basically presents a linear change with the frequency.

[0043] In the embodiment, as shown in Figure 10 and Figure 11 , they are respectively the scanning beam pattern of the spherical phased array antenna in and cut planes, and the scanning angles are respectively -90°, 0°, and 90°. The design can ensure that the spherical phased array antenna realizes a high-gain scanning beam in the range of ±90° in any cut plane, the main lobe is clear without grating lobes, and the side lobe is kept at a relatively low level. The side lobe level can be further reduced through weighting processing of the excitation of the radiation unit.

[0044] In the embodiment, double feed can be used instead of single coaxial feed to realize double circular polarization excitation. A larger radius hemispherical base can be selected to arrange a larger number of radiation units to realize higher antenna gain and stronger communication capability. Meanwhile, a person skilled in the art can upgrade or replace the medium substrate, the radiation body material, and the process precision, and optimize the radiation patch shape to realize a larger bandwidth on the premise of maintaining the overall performance.

[0045] The antenna designed in the application is a circularly polarized spherical phased array antenna for Ka-band operation, and 73 radiation units are uniformly arranged on a hemispherical array surface. Through optimization of the positions and distances of the array elements, the requirements of beam side lobe suppression and array element mutual coupling control are met in the structure, so that the scanning range of ±90° in any cut plane can be reached while the excellent gain and polarization purity are maintained.

[0046] The implementation of wide-angle scanning and circular polarization characteristics depends on the cooperative design of the hemispherical structure and the circularly polarized radiation unit. The three-dimensional distribution of the radiation unit on the array surface effectively avoids the gain attenuation problem of the planar array at large angle scanning, and the circular polarization design ensures the consistency of the polarization direction at different scanning angles, improving the transmission stability of the system in satellite communication and millimeter wave long-distance link.

[0047] The array element layout and structure design combine the Ka-band short wavelength characteristics, and by reasonably controlling the element spacing and arrangement density, the high-frequency mutual coupling effect is suppressed while maintaining three-dimensional full-space coverage. In addition, the hemispherical structure can balance the full-azimuth scanning capability and gain stability without increasing the structural complexity, filling the gap of millimeter wave phased array antenna technology.

[0048] Compared with the traditional millimeter wave phased array antenna design scheme, the present application has higher performance advantages and application value. The hemispherical layout of the present application realizes high gain stability under wide-angle scanning, and the circular polarization design ensures high polarization purity and signal reliability under full-azimuth coverage. The structure is compact and easy to integrate, and is suitable for satellite communication, unmanned aerial vehicle link, 5G / 6G millimeter wave backhaul, intelligent transportation and high-speed mobile platform and other scenes.

[0049] Those skilled in the art will realize that the embodiments described herein are for the purpose of helping the reader to understand the principles of the present application, and should be understood as not limiting the scope of protection of the present application to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations according to the technical inspiration disclosed in the present application without departing from the essence of the present application, and these modifications and combinations are still within the scope of protection of the present application.

Claims

1. A circularly polarized spherical phased array antenna for Ka-band operation, characterized in that, It includes a hemispherical antenna base and multiple radiating elements; the multiple radiating elements are arranged in an array on the hemispherical surface of the hemispherical antenna base; the circularly polarized spherical phased array antenna is configured in the frequency range of 27GHz to 29GHz to achieve beam scanning of ±90° in any azimuth section.

2. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 1, characterized in that, The hemispherical antenna base is made of resin material with a dielectric constant of less than 5 through additive manufacturing.

3. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 1, characterized in that, Each radiating element is a circularly polarized magnetoelectric dipole antenna, used to ensure impedance matching characteristics and circularly polarized radiation characteristics within the operating frequency range.

4. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 1, characterized in that, The circularly polarized magnetoelectric dipole antenna includes a substrate material (5), metallized vias, a microstrip antenna base plate, and a radiating metal patch structure disposed on the substrate material (5). The radiating metal patch structure includes two pairs of metal patches. The two pairs of metal patches excite modes with equal amplitude and orthogonal phase to achieve circularly polarized radiation. The two pairs of metal patches are short-circuited to the microstrip antenna base plate through the metallized vias.

5. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 4, characterized in that, The substrate material (5) is Rogers 4350B plate with a dielectric constant of 3.66, a loss tangent of 0.004, and a thickness of 1.524 mm.

6. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 4, characterized in that, In the two pairs of metal patches, the first pair of metal patches consists of a first rectangular metal patch (1a) and a second rectangular metal patch (1b) with a Γ-shaped structure loaded at the tail, and the second pair of metal patches consists of a first regular rectangular metal patch (2a) and a second regular rectangular metal patch (2b); wherein the first pair of metal patches and the second pair of metal patches are arranged perpendicularly to form a pair of electric dipoles.

7. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 6, characterized in that, The metallized vias include a first via (3a), a second via (3b), a third via (4a), and a fourth via (4b). The inner edges of the first rectangular metal patch (1a), the second rectangular metal patch (1b), the first regular rectangular metal patch (2a), and the second regular rectangular metal patch (2b) are shorted to the microstrip antenna substrate through the first via (3a), the second via (3b), the third via (4a), and the fourth via (4b), respectively, forming a pair of magnetic dipoles.

8. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 7, characterized in that, The thickness of the first rectangular metal patch (1a), the second rectangular metal patch (1b), the first regular rectangular metal patch (2a), and the second regular rectangular metal patch (2b) is 0.035mm; the diameter of the first via (3a), the second via (3b), the third via (4a), and the fourth via (4b) is 8mil.

9. The circularly polarized spherical phased array antenna for Ka-band operation according to claim 4, characterized in that, The circularly polarized spherical phased array antenna also includes an SSMP connector (6). The coaxial inner core (6a) of the SSMP connector (6) passes through the substrate material (5) and is connected to the metal strip (7) on the top layer of the substrate material (5) to jointly excite the magnetoelectric dipole.

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