A center-fed circularly polarized flat-top beam phased array antenna

Abstract

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

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular to a center-fed circularly polarized flat-beam phased array antenna. BACKGROUND

[0002] The flat-beam antenna can provide uniform signal coverage in a larger range, and the radiation intensity outside the range decreases rapidly, which plays a role of spatial filtering, reduces interference on adjacent areas, and the flat-beam antenna has unique advantages in some specific scenarios, such as signal coverage in large venues.

[0003] There are three existing flat-beam implementation schemes: one is to realize flat-beam by simultaneously controlling the amplitude and phase of the array antenna, that is, to cooperatively optimize the amplitude and phase of each antenna element in the array to obtain a flat-beam array factor, which requires unequal power dividers, and the feed network is complex and it is difficult to guarantee the working bandwidth; the second is to use a lens scheme, but it can only realize flat-beam in a certain section, and the lens generally has a high profile; the third is to realize flat-beam by current synthesis Sinc function, but this way can only realize flat-beam in a section, and the gain is low.

[0004] The circularly polarized antenna can realize continuous phase change of the unit by rotating the antenna unit, and optimize a flat-beam array by combining different phase units, however, the feed points of the existing circularly polarized antenna units are offset from the geometric center of the antenna, and when the circularly polarized antenna unit rotates, the position of the feed point will move, so the design of the feed network needs to be changed accordingly, which greatly increases the design complexity of the feed network.

[0005] Therefore, the present application designs a center-fed circularly polarized antenna unit, and realizes flat radiation beam by phase synthesis, which can realize flat radiation beam in a wide frequency band. SUMMARY

[0006] The present application aims to provide a center-fed circularly polarized flat-beam phased array antenna to solve the problems in the background art.

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

[0008] an upper dielectric substrate;

[0009] a radiation patch printed on the upper surface of the upper dielectric substrate;

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

[0011] Lower layer dielectric substrate;

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

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

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

[0015] According to the above technical scheme, the radiation patch adopts a center-fed mode, the feed network can remain unchanged when the array is formed, and the design complexity is reduced.

[0016] Compared with the prior art, the present application has the following advantages:

[0017] 1. The present application realizes a flat-top beam by using a new type of center-fed circularly polarized dipole antenna, has a wide bandwidth, and the feed network is simple.

[0018] 2. The flat-top beam is obtained by using a pure phase modulation mode, and different phases are realized by rotating the circularly polarized radiation unit.

[0019] 3. The initial phase of adjacent subarrays is changed to reduce the coupling between the subarrays and improve the circular polarization axial ratio bandwidth. DETAILED DESCRIPTION

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0039] The embodiment of the application is a broadband circularly polarized flat-top beam array antenna. The unit structure of the embodiment is shown in Figure 1 The radiation patch 1 is an electric dipole, and the metal column 3 is a magnetic dipole, which together form 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, 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 with the radiation patch 1 through the metal column 3. The feed port 8 is located at the center of the unit, is connected with the radiation patch 1 through the feed 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 into one through the PP layer 6, and the thickness of the PP layer is 0.1 mm.

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

[0041] Figure 3 The phase distribution of each unit in the array of the design is given. First, the phase of each unit is optimized through a convex optimization algorithm, taking the flat-top pattern as the optimization target and the phase of each unit as the optimization variable, so that an array factor of a flat-top beam can be synthesized, thereby obtaining the optimized phase in Figure 3 Due to the close spacing between the units, the coupling between the units causes the axial ratio bandwidth of the array to be narrow. The array is divided into 16 2*2 sub-arrays in the application, and the phase difference between each sub-array is 90°, as shown in the initial phase in Figure 3 , so as to improve the coupling between the units and expand the bandwidth.

[0042] As shown in Figure 4In order to realize the 0°, 90°, 180° and 270° phase outputs of the 2*2 subarray initial phase, a broadband phase shift equal power divider 11 is designed, which is composed of two 90° phase shift equal power dividers 9 and a 180° phase shift equal power divider 10. The "few" sub-bends on one side of the power divider are used to obtain a 90° phase difference, and the two side branches connected on the other side are used to balance the influence of the bend on the power divider and increase the bandwidth of the power divider. Four phase shift equal power dividers 11 are connected by a one-to-four power divider to form a flat beam feeding network. 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 the feeding network, the overall performance of the array is optimized by simultaneously rotating all units clockwise by 270°, so that the final phase is obtained Figure 3 The overall structure of the array in the final phase is shown in Figure 5 .

[0043] Referring to Figure 6 and Figure 7 , the unit has a reflection coefficient less than -14dB, an axial ratio less than 2dB and a unit gain greater than 5dBic in the working frequency band of 28-33GHz. Referring to Figure 8 and Figure 9 , the unit has good circular polarization performance and small cross polarization.

[0044] Referring to Figure 10 and Figure 11 , the array has a reflection coefficient less than -14dB, a gain greater than 10dBic and an axial ratio less than 2dB in the working frequency band of 28-33GHz. Referring to Figures 12 to 14 , the array has a flat range greater than ±10° and a flat ripple less than 1.5dB in the working bandwidth. The left-handed circular polarization is the main polarization and the right-handed circular polarization is the cross polarization. As shown in the figure, the cross polarization is small in the flat beam range. Referring to Figures 15 to 17 , the axial ratio of the array in the flat range is less than -3dB, so the array has good circular polarization performance.

[0045] In summary: the embodiments provided by the application are applied to communication in a large area venue. The flat beam and circular polarization design of the antenna array can realize stable communication in a large range. The central feeding unit of the application can make the feeding network of the array simpler and reduce the design complexity.

[0046] It is to be noted that, in the present text, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0047] Finally, it should be noted that the above-mentioned only constitutes preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications, equivalent replacements, improvements and the like of the technical solutions described in the foregoing embodiments can still be made. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A centrally fed circularly polarized flat-top beam array antenna, characterized by Multiple unit structures, each unit structure includes an upper layer dielectric substrate (4) and its upper surface printed radiation patch (1), the surface current of the radiation patch (1) can be decomposed into x, y two direction current components with equal amplitude and 90° phase difference, so as to obtain circularly polarized wave, the metal ground plane (5) is printed on the lower surface of the upper layer dielectric substrate (4), the radiation patch (1) is connected with the metal ground plane (5) through the metal column (3), and is connected with the feed port (8) on the lower surface of the lower layer dielectric substrate (7) through the feed metal column (2), the radiation patch (1) and the metal column (3) are rotated at any angle along the feed metal column (2), the angle of rotation corresponds to the radiation phase realized by it, a flexible basic unit is provided for the phase modulation array antenna, the feed port (8) is located at the center position of the unit, the feed network can remain unchanged when the array is assembled, the design complexity is reduced, the two layer dielectric substrates are adhered together through the PP layer (6), wherein the radiation patch (1) is an electric dipole, the metal column (3) is a magnetic dipole, and the two together constitute a magneto-electric dipole, the angle of rotation of the magneto-electric dipole along the feed metal column (2) corresponds to the radiation phase realized by it, a flexible basic unit is provided for the phase modulation array antenna, a flat-top beam radiation pattern is optimized by using the phase modulation method, and the unit structure is designed to assemble, in order to reduce the coupling between the units, the array is divided into 16 2*2 subarrays, the initial phase difference between each adjacent subarray is ensured to be 90°, and the corresponding feed network is designed, the feed network adopts two 90° phase shift equal division power dividers (9) and one 180° phase shift equal division power divider (10) to form a one-to-four broadband phase shift equal division power divider (11), and the phase difference between adjacent output phases is 90°.

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

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