Millimeter-wave miniaturized circularly polarized reflectarray antenna

Abstract

The present invention discloses a millimeter-wave miniaturized circularly polarized reflectarray antenna, which relates to the technical field of antennas for communication. The antenna includes a plurality of antenna units, and the antenna unit includes a dielectric layer, a first metal layer is formed on the upper surface of the dielectric layer, and a second metal layer is formed on the lower surface of the dielectric layer, and the first metal layer and the second metal layer are interconnected through metallized through holes located in the dielectric plate; the first metal layer includes a cross-sector electric dipole structure, and the cross-sector electric dipole structure includes four circumferentially arranged sector electric dipole patches, and a fishbone-shaped patch structure is formed at the end of each of the electric dipole patches. The antenna has low loss, small size, and can achieve 360° full phase coverage.

Description

Technical Field

[0001] The present invention relates to the technical field of communication antennas, and in particular to a millimeter-wave miniaturized circularly polarized reflectarray antenna. Background Art

[0002] As a typical representative of the family of space-fed antennas, reflectarray antennas have received extensive research attention and extensive exploration in the past few decades. The fact that space-fed antennas no longer require the complex feeding network associated with phased arrays makes the design and implementation of reflectarrays easier and less time-consuming. In addition, the use of printed circuit board technology and the invention of microstrip phasing elements make the designed reflectarray antennas more cost-effective and easy to manufacture. Based on these advantages, reflectarray antennas have broad research value and application value.

[0003] Circularly polarized antennas can be used to achieve polarization diversity and prevent signal loss due to possible misalignment between two linearly polarized transmitting and receiving antennas. The methods of generating far-field circularly polarized radiation by reflectarray antennas can be divided into two categories. The first method uses variable-size units or units with variable-length delay lines to adjust the phase of the reflected circularly polarized wave. The other method is the unit rotation method, which is the most practical method for designing circularly polarized reflectarrays because of its relative simplicity. The development of micromachining technology has greatly reduced the size of various components in wireless communication systems, but the miniaturization of antenna size is still challenging. Common wireless communication standards such as Wi-Fi and WiMAX often have a frequency range between 700MHz and 6GHz, and the conventional antenna size is half a wavelength. Therefore, the size of antennas working in lower frequency bands in these communication standards will be relatively large. In addition, the miniaturization of antennas can effectively reduce the cost of raw materials for manufacturers. It can be seen that the research on miniaturized antennas is of great significance to the development of wireless communications.

[0004] At present, as microwave spectrum resources in the frequency band below 6 GHz are becoming increasingly scarce, millimeter wave spectrum resources in the range of 30 GHz to 300 GHz are attracting more and more attention worldwide. The rich spectrum resources contained in the millimeter wave band can not only effectively solve the problem of tight spectrum resources in the current wireless communication system, but also make ultra-high-speed wireless communication technology possible. For actual application scenarios, the design of millimeter wave array antennas with wideband characteristics, circular polarization characteristics and miniaturization characteristics is becoming a research difficulty that needs to be solved urgently. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to provide a millimeter-wave miniaturized circularly polarized reflectarray antenna with low loss, small size and the ability to achieve 360° full phase coverage.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a millimeter wave miniaturized circularly polarized reflectarray antenna, characterized in that: it includes a plurality of antenna units, the antenna unit unit includes a dielectric layer, a first metal layer is formed on the upper surface of the dielectric layer, and a second metal layer is formed on the lower surface of the dielectric layer, and the first metal layer and the second metal layer are interconnected through a metallized through hole located in the dielectric plate; the first metal layer includes a cross-sector electric dipole structure, the cross-sector electric dipole structure includes four circumferentially arranged sector electric dipole patches, and a fishbone-shaped patch structure is formed at the end of each of the electric dipole patches, and the fishbone-shaped patch structure includes a first metal strip and a plurality of second metal strips, one end of the first metal strip is connected to the inner end of the corresponding sector electric dipole patch, and the other end of the first metal strip is connected to the square patch at the center of the first metal layer, and the length of the second metal strip gradually decreases from the outside to the inside, and is vertically connected to the first metal strip.

[0007] Preferably, the cross-sector electric dipole structure is formed by an etching process.

[0008] A further technical solution is that the fan-shaped electric dipole patch is arranged in an asymmetrical cross.

[0009] A further technical solution is to etch opposite square grooves on the x-direction and y-direction arm lengths of the cross-sector electric dipole structure to construct a fishbone structure, thereby changing the current path on the surface of the electric dipole structure to achieve miniaturization.

[0010] A further technical solution is to add a square patch at the center of the cross-sector electric dipole structure to reduce the variation of mutual coupling and maintain stable unit performance when the unit rotates.

[0011] A further technical solution is that the metal holes are four groups of cylindrical metal connecting rods, connecting the first layer of metal sheets and the second layer of metal sheets, so as to increase the reflection amplitude and expand the phase shift range of the reflection array unit.

[0012] Preferably, the dielectric constant ε of the dielectric plate thickness is 0.50 mm. r The F4B220 is 2.2.

[0013] Preferably, the size of the antenna unit is 0.3λ0×0.3λ0×0.15λ0.

[0014] A further technical solution is to adjust the arm lengths in the x and y directions of the cross-sector electric dipole structure to control the reflection phase of two orthogonal linear polarization incidents, thereby generating a phase difference of 180° that does not change with frequency. The central angles of the sector electric dipole patches in the x and y directions of the cross-sector electric dipole structure are both 67°.

[0015] Preferably, the frequency band range of the −1dB return loss of the antenna unit is 86.6GHz-110.0GHz, and the maximum reflection amplitude loss of the antenna unit is -0.84 dB.

[0016] The beneficial effects of adopting the above technical solution are as follows: the antenna unit in the array antenna of the present invention adopts an asymmetric cross-sector dual-polarization electric dipole structure to control the reflection phase of two orthogonal linear polarizations, generate a phase difference of 180°, and realize circularly polarized radiation that does not change with frequency in the millimeter wave frequency band, and has a constant frequency characteristic; metal holes are used to connect the upper and lower layers of metal sheets to increase the reflection amplitude, reduce the loss, and have a low loss characteristic; a slotted fishbone structure is used to change the current path on the surface of the dipole structure, thereby achieving miniaturization; by taking the unit geometric center as the origin, rotating different angles to achieve rotational phase modulation, and achieving 360° full phase coverage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 It is a schematic diagram of the exploded structure of the antenna unit in the antenna of the present invention;

[0019] Figure 2 It is a curve diagram showing the change of the reflection phase of the antenna unit of the present invention with the rotation angle under left-hand circular polarization incidence;

[0020] Figure 3 A curve diagram showing the relationship between the reflection amplitude, the incident angle and the rotation angle of the antenna unit of the present invention under left-hand circular polarization incidence;

[0021] Figure 4 It is a schematic diagram of the change of the axial ratio of the circularly polarized wave of the antenna unit of the present invention within the working frequency band;

[0022] Figure 5 It is a schematic diagram of the feed structure of the array antenna of the present invention;

[0023] Figure 6a It is a schematic diagram of the side view structure of the array antenna of the present invention;

[0024] Figure 6b It is a schematic diagram of the top view structure of the array antenna of the present invention;

[0025] Figure 7 is the E-plane radiation pattern of the array antenna of the present invention at a frequency of 90.0 GHz;

[0026] Figure 8 is the H-plane radiation pattern of the array antenna of the present invention at a frequency of 90.0 GHz;

[0027] Among them: 1. first metal layer; 2. dielectric layer; 3. metallized through hole; 4. second metal layer; 5. cross-sector electric dipole structure; 6. fishbone patch structure; 61. first metal strip; 62. second metal strip; 7. square patch. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] The embodiment of the present invention discloses a millimeter wave miniaturized circularly polarized reflectarray antenna based on a fishbone-shaped magnetoelectric dipole, comprising a plurality of antenna units, such as Figure 1 As shown, the antenna unit unit includes a dielectric layer 2, a first metal layer 1 is formed on the upper surface of the dielectric layer 2, and a second metal layer 4 is formed on the lower surface of the dielectric layer 2. The first metal layer 1 and the second metal layer 4 are interconnected through a metallized through hole 3 located in the dielectric plate 2; further, as Figure 1 As shown, the first metal layer 1 includes a cross-sector electric dipole structure 5, and the cross-sector electric dipole structure 5 includes four circumferentially arranged sector-shaped electric dipole patches, and a fishbone-shaped patch structure 6 is formed at the end of each of the electric dipole patches. The fishbone-shaped patch structure 6 includes a first metal strip 61 and a plurality of second metal strips 62, one end of the first metal strip 61 is connected to the inner end of the corresponding sector-shaped electric dipole patch, and the other end of the first metal strip 61 is connected to the square patch 7 at the center of the first metal layer, and the length of the second metal strip 62 gradually decreases from the outside to the inside, and is vertically connected to the first metal strip 61.

[0031] The first metal sheet 1 is composed of a cross-sector electric dipole structure 5 with square grooves etched therein and a square patch 7. Figure 1; The proposed first layer of metal sheet 1 is placed horizontally along the xoy plane, presenting an asymmetric cross-sector structure; by adjusting the two arm lengths of the cross-sector electric dipole structure 5, it can be used to control the reflection phases of two orthogonal linear polarizations, generating a phase difference of 180° that does not change with frequency; 5 pairs of square grooves 6 are respectively etched on the arm lengths in the x-direction and y-direction of the cross-sector electric dipole structure 5 to construct a fishbone structure, thereby changing the current path on the surface of the electric dipole structure to achieve miniaturization; a square patch 7 is added at the center of the cross-sector electric dipole structure 5 to reduce the change in mutual coupling and maintain stable unit performance when the unit rotates;

[0032] In this example, the cross-sector electric dipole structure 5 is connected through a square patch 7 at the center of the circle, and the length and width of the square patch 7 are both 0.03 mm, which ensures the stability of the structure; by adjusting the arm lengths in the x-direction and y-direction of the cross-sector electric dipole structure 5, the lengths of the arm lengths in the two directions are 0.39 mm and 0.46 mm, respectively, which can be used to control the reflection phase of two orthogonal linear polarization incidents, produce a phase difference of 180° and do not change with frequency, and the arm lengths in the x-direction and y-direction of the cross-sector electric dipole structure 5, and the center angles in the x-direction and y-direction are both 67°; 5 pairs of etched square grooves are introduced on the arm lengths in the x-direction and y-direction of the cross-sector electric dipole structure 5, and the flow path of the current on the surface of the electric dipole structure is increased by the slotted structure, so as to achieve miniaturization of the structure, and the length and width of the square grooves are 0.02 mm and 0.01 mm, respectively, and the spacing between each pair of etched square grooves is 0.01 mm;

[0033] In this example, the thickness of the dielectric plate is selected to be 0.15 wavelengths, i.e., 0.50 mm, and the dielectric plate is selected to be F4B220 with a dielectric constant εr of 2.2;

[0034] The metallized through holes 3 are a group of cylindrical metal connecting rods with a diameter of 0.02 mm and a height of 0.50 mm, which are distributed in the dielectric plate 2 and connect the first metal sheet 1 and the second metal sheet 4; by introducing a pair of metallized through holes 3 in the x direction and the y direction in the first metal sheet 1 and the second metal sheet 4, respectively, the current distribution on the first metal sheet 1 is changed. The introduction of the metal holes 3 can increase the reflection amplitude and expand the phase shift range of the reflection array unit; the second metal sheet 4 acts as a metal ground to ensure complete reflection of energy; in the example, the length and width of the second metal sheet 4 are taken as 0.30 wavelengths, that is, 1.00 mm.

[0035] Figure 2This is a reflection phase curve of the antenna unit of the present invention under left-hand circular polarization at 90.0 GHz. It can be seen that the reflection phase of the antenna unit changes approximately in a straight line with the rotation angle of the unit. The simulation results verify that the millimeter-wave miniaturized circularly polarized reflectarray antenna unit based on the fishbone-shaped magnetoelectric dipole has 360° phase full coverage and wideband characteristics;

[0036] Figure 3 This is a curve diagram of the reflection amplitude of the antenna unit of the present invention under left-hand circular polarization at 90.0 GHz. It can be seen that the reflection amplitude of the unit has a good fit when the incident angles are 0°, 20° and 30° respectively, and the reflection amplitude of the unit has good stability within the range of 0°-180° rotation of the unit. Therefore, the simulation results verify that the millimeter-wave miniaturized circularly polarized reflectarray antenna unit based on fishbone-shaped magnetoelectric dipole has a good characteristic of being insensitive to the incident angle and rotation angle;

[0037] Figure 4 The schematic diagram of the change of the axial ratio of the circularly polarized wave of the antenna unit of the present invention in the working frequency band. The axial ratio bandwidth of the reflect array unit proposed by the present invention is less than 3 dB in the frequency band of 65.6 GHz - 91.7 GHz, the degree of circular polarization is high, and the 3 dB axial ratio bandwidth is 29%;

[0038] Figure 5 The conical horn antenna structure diagram of the antenna of the present invention is composed of a circular waveguide and a horn structure waveguide. The gradually opened transition section can not only ensure the good matching of the waveguide and the space, but also obtain a larger aperture size to enhance the directivity of radiation. The feed source is left-handed circular polarization excitation. The diameter of the circular waveguide is D1 = 1.00 mm and the length is L1 = 2.00 mm. The elevation angle of the horn structure waveguide is 25° and the length is L2 = 2.50 mm.

[0039] Figure 6a-6b It is a schematic diagram of the reflectarray antenna of the present invention. Figure 6a This is a side view of the 28×28 element array antenna structure. To reduce the impact of feed source shielding, the rectangular horn antenna feed is placed at a 20° offset. The feed focal length is F = 25.0 mm, the array antenna aperture is D = 28.0 mm, and the focal length ratio (F / D) is 0.89. Figure 6bThe top view of the 28×28 element array antenna structure. The proposed 28×28 element array antenna aperture consists of 28×28 elements, with an element spacing of 0.3 λ0. The elements in the box are blocked by the feed source, and the antenna blocking rate is 1.79%. In order to obtain a high-gain focused beam, according to array theory, the element is rotated at different angles around the geometric center to obtain different circularly polarized reflection phases to compensate for the phase delay caused by the spatial feed source and the phase delay in the outgoing direction;

[0040] Figure 7 This is the E-plane left-handed circularly polarized radiation pattern of the antenna of the present invention at 90.0 GHz. It can be seen that the millimeter-wave miniaturized circularly polarized reflectarray antenna based on the fishbone-shaped magnetoelectric dipole has a good gain pattern at the operating frequency, and the half-power beamwidth is 7.0°;

[0041] Figure 8 This is the H-plane left-handed circularly polarized radiation pattern of the array antenna of the present invention at 90.0 GHz. It can be seen that the millimeter-wave miniaturized circularly polarized reflectarray antenna based on fishbone-shaped magnetoelectric dipole has a good gain pattern at the operating frequency, and the half-power beamwidth is 7.0°;

[0042] It can be seen from the above that the millimeter wave miniaturized circularly polarized reflectarray antenna based on the fishbone-shaped magnetoelectric dipole of the present invention has the characteristics of 360° full phase coverage, wide bandwidth and miniaturization.

Claims

1. A millimeter-wave miniaturized circularly polarized reflectarray antenna, characterized in that: The invention comprises a plurality of antenna units, wherein the antenna units comprise a dielectric layer (2), a first metal layer (1) is formed on the upper surface of the dielectric layer (2), a second metal layer (4) is formed on the lower surface of the dielectric layer (2), the first metal layer (1) and the second metal layer (4) are interconnected via a metallized through hole (3) located in the dielectric layer (2); the first metal layer (1) comprises a cross-sector electric dipole structure (5), the cross-sector electric dipole structure (5) comprises four circumferentially arranged sector-shaped electric dipole patches, the inner end of each of the electric dipole patches A fishbone patch structure (6) is formed, the fishbone patch structure (6) comprising a first metal strip (61) and a plurality of second metal strips (62), one end of the first metal strip (61) is connected to the inner end of the corresponding fan-shaped electric dipole patch, the other end of the first metal strip (61) is connected to a square patch (7) at the center of the first metal layer, the length of the second metal strip (62) gradually decreases from the outside to the inside, and is vertically connected to the first metal strip (61), and four of the fishbone patch structures (6) are connected together through the square patch (7); The fan-shaped electric dipole patch is arranged in an asymmetrical cross; five pairs of square grooves are respectively etched on the arm lengths in the x-direction and y-direction of the cross-shaped fan-shaped electric dipole structure (5) to form the fishbone-shaped patch structure (6), thereby changing the current path on the surface of the electric dipole structure to achieve miniaturization; By adjusting the arm lengths in the x-direction and y-direction of the cross-sector electric dipole structure (5), the reflection phases of two orthogonal linear polarization incidents are controlled to generate a phase difference of 180° that does not vary with frequency. The center angles of the sector electric dipole patches in the x-direction and y-direction of the cross-sector electric dipole structure (5) are both 67°. The frequency band range of the −1dB return loss of the antenna unit is 86.6GHz-110.0GHz, and the maximum reflection amplitude loss of the antenna unit is −0.84 dB.

2. The millimeter wave miniaturized circularly polarized reflectarray antenna according to claim 1, characterized in that: The cross-sector-shaped electric dipole structure (5) is formed by an etching process.

3. The millimeter wave miniaturized circularly polarized reflectarray antenna according to claim 1, characterized in that: A square patch (7) is added at the center of the cross-sector electric dipole structure (5) to reduce the variation of mutual coupling and maintain stable unit performance when the unit rotates.

4. The millimeter wave miniaturized circularly polarized reflectarray antenna according to claim 1, characterized in that: The metallized through holes (3) are four groups of cylindrical metal connecting rods, connecting the first metal layer (1) and the second metal layer (4), and are used to increase the reflection amplitude and expand the phase shift range of the reflection array unit.

5. The millimeter wave miniaturized circularly polarized reflectarray antenna according to claim 1, characterized in that: The dielectric layer (2) has a dielectric constant ε of 0.50 mm in thickness. r The F4B220 is 2.2.

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