Circularly polarized flat-topped beam phased-array antenna with center feed

Abstract

The invention relates to the technical field of communication, and discloses a center-feed circularly polarized flat-topped beam phased-array antenna, which comprises an upper dielectric substrate, a lower dielectric substrate, a middle dielectric substrate and a middle dielectric substrate, the radiation patch is printed on the upper surface of the upper-layer dielectric substrate; the grounding plane is printed on the lower surface of the upper-layer dielectric substrate; a lower dielectric substrate; wherein the grounding plane is connected with the radiation patch through the metal columns, the radiation patch is connected with the feed network on the lower surface of the lower-layer dielectric substrate through the metal columns, and the upper-layer dielectric substrate and the lower-layer dielectric substrate are bonded through the PP layer; and the feed network is printed on the lower surface of the upper-layer dielectric substrate and is connected with the metal columns. The circularly polarized antenna provided by the invention has the characteristics of wide bandwidth and simple feed network, the working bandwidth is 28-33GHz, the gain in the whole bandwidth is greater than 11dB, the reflection coefficient is less than-12dB, the range of a flat-topped beam is + / -10 degrees, and the AR in the whole range of the flat-topped beam is less than 3dB, and the ripple is less than 1.5 dB.

Description

Technical Field

[0001] The invention relates to the field of communication technology, and in particular to a center-fed circularly polarized flat-top beam phased array antenna. Background Art

[0002] Flat-top beam antennas can provide uniform signal coverage within a larger range, while the radiation intensity outside this area decreases rapidly, playing a role of spatial filtering, reducing interference to adjacent areas. Flat-top beam antennas have unique advantages in some specific scenarios, such as signal coverage in large venues.

[0003] There are three existing solutions for realizing flat-top beams: one is to realize flat-top beams by simultaneously regulating the amplitude and phase of the array antenna, that is, to coordinately optimize the amplitude and phase of each antenna unit in the array to obtain the flat-top beam array factor. This solution requires unequal power dividers, and its feeding network is complex and it is difficult to guarantee its working bandwidth; the second is to use a lens solution, but it can usually only realize a flat-top beam on a certain section, and the lens generally has a higher profile; the third is to realize a flat-top beam through current synthesis Sinc function, but this method can only realize a flat-top beam on one section, and the gain is low.

[0004] Circularly polarized antennas can achieve continuous phase changes of the units by rotating the antenna units, and optimize a flat-top beam array by combining different phase units. However, the feeding points of existing circularly polarized antenna units are all deviated from the geometric center of the antenna. When this circularly polarized antenna unit rotates, the position of its feeding point will move, so the design of the feeding network needs to be changed accordingly, which greatly increases the design complexity of the feeding network.

[0005] Therefore, the present invention designs a center-fed circularly polarized antenna unit and realizes a flat-top radiation beam by adopting a phase synthesis method. This solution can realize a flat-top radiation beam in a wider frequency band. Summary of the invention

[0006] The object of the present invention is to provide a center-fed circularly polarized flat-top beam phased array antenna to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a center-fed circularly polarized flat-top beam phased array antenna, comprising:

[0008] an upper dielectric substrate;

[0009] A radiation patch is printed and arranged on the upper surface of the upper dielectric substrate;

[0010] A ground plane is printed on the lower surface of the upper dielectric substrate;

[0011] a lower dielectric substrate;

[0012] The ground plane is connected to the radiation patch through a metal column, the radiation patch is connected to the feeding network on the lower surface of the lower dielectric substrate through the metal column, and the upper dielectric substrate and the lower dielectric substrate are bonded through a PP layer;

[0013] The feeding network is printed on the lower surface of the upper dielectric substrate, connected to the metal column, and combined through two 90° broadband power dividers and one 180° broadband power divider.

[0014] According to the above technical solution, the left half of the radiation patch is composed of a triangular radiation sheet and a bent radiation strip connected by a small rectangle, and the right half and the left half are symmetrical about the center.

[0015] According to the above technical solution, the radiating patch adopts a central feeding method, and the feeding network can remain unchanged when forming an array, thereby reducing the complexity of the design.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0017] 1. The present invention adopts a novel center-fed circularly polarized dipole antenna to realize a flat-top beam, has a wider bandwidth, and a simple feeding network.

[0018] 2. A flat-top beam is obtained by pure phase modulation, and different phases are achieved by rotating the circularly polarized radiation unit.

[0019] 3. The coupling between sub-arrays is reduced by changing the initial phase of adjacent sub-arrays, thereby improving the circular polarization axial ratio bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 is a side view of a flat-top beam antenna array unit of the present invention;

[0022] Figure 2 is a top view of a flat-top beam antenna array unit of the present invention;

[0023] Figure 3 It is a phase distribution diagram of a flat-top beam antenna array unit of the present invention;

[0024] Figure 4 It is a structural diagram of the flat-top beam antenna array feed network of the present invention;

[0025] Figure 5 is a top view of the flat-top beam antenna array of the present invention;

[0026] Figure 6 It is a reflection coefficient curve diagram of the flat-top beam antenna array unit of the present invention in the working frequency band;

[0027] Figure 7 is a graph of gain and axial ratio of the flat-top beam antenna array unit in the working frequency band of the present invention;

[0028] Figure 8 is a gain curve diagram of the flat-top beam antenna array unit of the present invention at 30.5 GHz;

[0029] Fig. 9 is an axial ratio curve diagram of the flat-top beam antenna array unit of the present invention at 30.5 GHz;

[0030] Fig.10 is a reflection coefficient curve diagram of the flat-top beam antenna array of the present invention in the working frequency band;

[0031] Fig.11 is a gain and axial ratio curve diagram of the flat-top beam antenna array of the present invention in the working frequency band;

[0032] Fig.12 is a gain curve diagram of the flat-top beam antenna array of the present invention at 28 GHz;

[0033] Fig.13 is a gain curve diagram of the flat-top beam antenna array of the present invention at 30.5 GHz;

[0034] Fig.14 is a gain curve diagram of the flat-top beam antenna array of the present invention at 33 GHz;

[0035] Fig.15 is an axial ratio curve diagram of the flat-top beam antenna array of the present invention at 28 GHz;

[0036] Fig.16 is an axial ratio curve diagram of the flat-top beam antenna array of the present invention at 30.5 GHz;

[0037] Fig.17 It is an axial ratio curve diagram of the flat-top beam antenna array of the present invention at 33 GHz. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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.

[0039] The present invention is a broadband circularly polarized flat-top beam array antenna. The unit structure of this embodiment is shown in FIG. Figure 1 , the radiation patch 1 is an electric dipole, and the metal column 3 is a magnetic dipole, and the two together constitute a magnetic electric dipole. The radiation patch 1 is placed on the upper surface of the upper dielectric substrate 4, wherein the thickness of the upper dielectric substrate 4 is 1.58 mm, and the metal ground plane 5 is placed on the lower surface of the upper dielectric substrate 4, and the metal ground plane 5 is connected to the radiation patch 1 through the metal column 3. The feeding port 8 is located at the center of the unit, and is connected to the radiation patch 1 through the feeding metal column 2 and feeds the radiation patch 1. The thickness of the dielectric substrate 7 is 0.13 mm, and the two dielectric substrates are bonded together by the PP layer 6, and the thickness of the PP layer is 0.1 mm.

[0040] See also Figure 2 A circular ring with a radius of 0.45mm is dug at the center of the metal ground plane 5 to ensure that the metal ground plane 5 is not conductive with the feeding metal column 2. The unit size of this embodiment is 5.5*5.5mm. The radiation patch 1 is composed of two centrosymmetrical radiators, each of which is composed of a large triangle of 1.25mm*1.35mm and a radiation strip with a length of 2.3mm and a 90° bend at 1.1mm connected by a 0.6mm*0.75mm rectangle. Through this setting, the surface current of the radiation patch can be decomposed into current components in the x and y directions with equal amplitudes and a phase difference of 90°, thereby obtaining circular polarization. The radiation patch 1 and the metal column 3 can be rotated at any angle along the feeding metal column 2, and the rotation angle corresponds to the radiation phase achieved, providing a flexible basic unit for the phase modulation array antenna.

[0041] Figure 3 The phase distribution of each unit in the array of this design is given. First, the phase of each unit is optimized by a convex optimization algorithm, with the flat-top pattern as the optimization target and the phase of each unit as the optimization variable, so that the array factor of a flat-top beam can be synthesized, thus obtaining Figure 3 Since the units are closely spaced, the coupling between the units causes the axial bandwidth of the array to become narrower. The present invention divides the array into 16 2*2 sub-arrays to ensure that the phases of each sub-array differ by 90°. Figure 3 The initial phase in FIG. 1 is shown here, thereby improving coupling between units and extending bandwidth.

[0042] like Figure 4In order to achieve the four phase outputs of 0°, 90°, 180°, and 270° for the initial phase of the 2*2 subarray, we designed a broadband phase-shifting equal-division power divider 11, which is composed of two 90° phase-shifting equal-division power dividers 9 and one 180° phase-shifting equal-division power divider 10. The "J"-shaped bend on one side of the power divider is to obtain a 90° phase difference, and the two side branches on the other side are to balance the impact of the bend on the power divider and increase the bandwidth of the power divider. The four phase-shifting equal-division power dividers 11 are connected by a one-to-four power divider to form a feeding network for the flat-top beam. The wider microstrip line is a 50Ω microstrip line with a line width of 0.53mm; the narrower microstrip line is a 70Ω microstrip line with a line width of 0.28mm and a line length of 1.48mm. After connecting to the feeding network, the overall performance of the array is optimized by rotating all units 270° clockwise at the same time, thereby obtaining Figure 3 The final phase in the array, the corresponding top view of the overall structure of the array at the final phase is as follows Figure 5 shown.

[0043] Reference Figure 6 and Figure 7 The reflection coefficient of the unit in the working frequency band of 28-33GHz of the embodiment of the present invention is lower than -14dB, the axial ratio is lower than 2dB, and the unit gain is greater than 5dBic. Figure 8 and Fig. 9 , the unit of this embodiment has good circular polarization performance and very small cross polarization.

[0044] Reference Fig.10 and Fig.11 In the working frequency band of 28-33 GHz, the reflection coefficient of the array in this embodiment is less than -14 dB, the gain is greater than 10 dBic, the axial ratio is basically less than 2 dB, and the working bandwidth is 16.4%. Figures 12 to 14 , the flat-top range of the array in this embodiment is greater than ±10° within the working bandwidth, and the flat-top ripple is less than 1.5dB. Left-hand circular polarization is the main polarization, and right-hand circular polarization is the cross-polarization. It can be seen from the figure that the cross-polarization is small within the flat-top beam range. Figures 15 to 17 The axial ratio of the array in this embodiment within the flat-top range is less than -3dB, so the array in this embodiment has good circular polarization performance.

[0045] To sum up: the embodiments provided by the present invention are applied to communications in large-area venues. The flat-top beam and circular polarization design of the antenna array of the present invention can achieve stable communication in a larger range. Benefiting from the central feed unit of the present invention, the feeding network of the array can be made simpler, reducing the complexity of the design.

[0046] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A center-fed circularly polarized flat-top beam array antenna, characterized by an upper layer A dielectric substrate (4) and a radiation patch (1) printed on its upper surface; a metal ground plane (5) printed on the lower surface of the dielectric substrate (4); the radiation patch (1) and the metal ground plane (5) are connected via a metal column (3); and are connected to a feeding port (8) on the lower surface of a lower dielectric substrate (7) via a feeding metal column (2); the two dielectric substrates are bonded together via a PP layer (6); the radiation patch (1) is an electric dipole; the metal column (3) is a magnetic dipole; the two together constitute a magneto-electric dipole; the angle at which the magneto-electric dipole rotates along the feeding metal column (2) corresponds to the radiation phase achieved by the magneto-electric dipole; a flexible basic unit is provided for a phase modulation array antenna; a flat-top beam radiation pattern is optimized by a phase modulation method; and an array is formed using the designed units; in order to reduce coupling between units, the array is divided into 16 2*2 sub-arrays; it is ensured that the initial phases between each adjacent sub-array differ by 90°; and a corresponding feeding network is designed.

2. A center-fed circularly polarized flat-top beam array antenna according to claim 1, characterized in that: The surface current of the radiation patch (1) can be decomposed into current components in the x and y directions with equal amplitudes and a phase difference of 90°, thereby obtaining a circularly polarized wave.

3. A center-fed circularly polarized flat-top beam array antenna according to claim 1, characterized in that: The feed port (8) is located at the center of the unit, so that the feed network can remain unchanged when forming an array, thereby reducing the complexity of the design.

4. The center-fed circularly polarized flat-top beam array antenna according to claim 1, characterized in that: The flat-top beam radiation pattern is optimized by phase modulation, and the phase of each unit is optimized by a convex optimization algorithm so that the array factor of a flat-top beam can be synthesized.

5. The center-fed circularly polarized flat-top beam array antenna according to claim 1, characterized in that: The feeding network uses two 90° phase-shifted equal-division power dividers (9) and one 180° phase-shifted equal-division power divider (10) to form a one-to-four broadband phase-shifted equal-division power divider (11), and the phase difference between adjacent output phases is 90°.

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