A dual-fed circularly polarized filtering antenna and its array and application

Abstract

The present invention discloses a dual-fed circularly polarized filtering antenna and its array and application. The antenna includes a multi-layer printed circuit board arranged from top to bottom. The upper surface of the first layer of printed circuit board is provided with a first radiation patch and a super-surface structure, the lower surface is provided with a second radiation patch, any layer of the middle several layers of printed circuit boards is provided with two filter branches, and the bottom layer of printed circuit boards is provided with two coplanar waveguide feed lines with ground; the antenna also includes two quasi-coaxial feeding structures, the top of the quasi-coaxial feeding structure is connected to the second radiation patch, and the bottom end is connected to the coplanar waveguide feed line with ground. The antenna adopts a super-surface structure, which is helpful to suppress surface waves, realize large-angle scanning and antenna miniaturization, adopts a double-layer radiation patch to enhance the radiation capability, adopts a dual feed line structure to realize circularly polarized waves and polarization reconstruction capabilities, and adopts a filtering branch to realize isolation of high-frequency signals. The above design can achieve circular polarization reconfigurability, large scanning angle, high isolation and other performances, making the antenna array more suitable for satellite communications.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a dual-fed circularly polarized filtering antenna and an array and application thereof. Background Art

[0002] In satellite communication systems, two different frequency band signals are usually required to realize uplink and downlink information transmission, and two different circularly polarized beams are used to enhance signal isolation, which means that the antenna terminal needs to have circular polarization reconfiguration capabilities; at the same time, due to the particularity of its operation, satellite communication needs to achieve scannability within a large angle, which means that the antenna is required to have wide circular polarization scanning angle performance, but in most previous designs, it is difficult to realize functions such as circular polarization reconfiguration and wide circular polarization scanning angle at the same time; in addition, satellite communications generally require dual-band signals to realize signal reception and transmission respectively, but good isolation between the dual bands is difficult to achieve. Summary of the invention

[0003] The purpose of the present invention is to provide a dual-fed circularly polarized filtering antenna and its array and application. The design of its metasurface, the structure of the dual feed points, and the design of the filtering branches realize the characteristics of circular polarization reconfiguration, wide circular polarization scanning angle, and high isolation, which is more suitable for satellite communication. The loaded printed circuit board structure is conducive to the integration of the antenna and the chip, realizing an integrated design.

[0004] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0005] A dual-fed circularly polarized filtering antenna, the antenna comprises a plurality of layers of printed boards arranged in sequence from top to bottom, wherein: a first radiation patch and a metasurface structure are arranged on the upper surface of the first layer of printed boards, a second radiation patch is arranged on the lower surface of the first layer of printed boards, an antenna metal ground is arranged on the lower surface of the second layer of printed boards, two filtering branches are arranged on any layer of the middle layers of printed boards, and two coplanar waveguide feed lines with ground are arranged on the bottom layer of printed boards;

[0006] The antenna also includes two quasi-coaxial feeding structures, the top ends of which are connected to the second radiation patch, and the bottom ends of which are connected to the coplanar waveguide feeding line with ground to realize antenna excitation.

[0007] A further improvement is that the antenna is square, the first radiation patch and the second radiation patch are both circular with the center of the circle located at the center of the antenna, and the second radiation patch is provided with a protruding branch at a diagonal position of the circumference;

[0008] The metasurface structure is composed of a plurality of square metal patches distributed in a matrix, and a circular area is left in the center of the metasurface structure for placing the first radiation patch, and the top surface of the metasurface structure is at the same height as the top surface of the first radiation patch.

[0009] A further improvement is that the printed board is composed of a double-layer dielectric substrate, a double-layer prepreg sandwiched between the double-layer dielectric substrate, and multiple copper layers etched on the front and back surfaces of the dielectric substrate.

[0010] A further improvement is that the grounded coplanar waveguide feed line includes a metal ground located on the upper surface of the bottom printed board and a microstrip line located on the lower surface of the bottom printed board, and the quasi-coaxial feed structure includes a coaxial core and a metallized via located on the periphery of the coaxial core;

[0011] Among them, the upper end of the coaxial core is connected to the second radiation patch, the middle is connected to the filter branch, the lower end is connected to one end of the microstrip line, the other end of the microstrip line is connected to the RF chip, and the metallized via runs through the antenna metal ground on the lower surface of the second layer of printed circuit board and the metal ground on the upper surface of the bottom layer of printed circuit board.

[0012] A further improvement is that the coaxial cores of the two quasi-coaxial feeding structures are arranged at an angle of 90° to the center of the antenna.

[0013] A further improvement is that the metallized vias are divided into three types, which are respectively arranged around the coaxial core, around the filter branches and around the microstrip line.

[0014] A further improvement is that the lower end of the coaxial core is connected to the microstrip line through a transition structure, and the transition structure includes a transition disk sleeved on the coaxial core and an impedance matching section provided between the transition disk and the microstrip line.

[0015] A further improvement is that the starting part of the filter branch is led out from the coaxial inner core, and the leading directions of the two filter branches are at an angle of 90°. Each filter branch is led out from a wide line segment and then turned into a thin line segment. The inside of the wide line segment is hollowed out, and the thin line segment is bent and folded, so that the filter branch as a whole is shaped like a fishhook.

[0016] The present invention also provides a dual-fed circular polarization filter antenna array, wherein the antenna array is formed by two-dimensionally periodically expanding the dual-fed circular polarization filter antenna.

[0017] The present invention also provides an application of the dual-fed circularly polarized filter antenna in satellite communications, wherein the application is to deploy the dual-fed circularly polarized filter antenna as a ground terminal antenna for satellite communications to achieve satellite-to-ground interconnection communications.

[0018] The beneficial effects of the present invention are as follows: the dual-feed circularly polarized filtering antenna adopts a metasurface structure, which helps to reduce surface waves, improve the antenna's large-angle scanning performance, and also helps to miniaturize the antenna; the dual-feed structure helps the antenna to achieve circularly polarized waves and obtain circular polarization reconfiguration capabilities; the double-layer radiation patch helps to enhance the radiation performance of the antenna itself; the filtering branches help to filter out signals outside the required signal frequency band and enhance isolation; the lower half of the antenna integrates a multi-layer dielectric board, which is convenient for integration with the circuit; the above advantages combined make the antenna particularly suitable for the deployment of satellite communication ground terminals. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional exploded diagram of the dual-fed circular polarization filter antenna structure;

[0020] Figure 2 It is a side view of the dual-fed circular polarization filter antenna structure;

[0021] Figure 3 It is a bottom view of the dual-fed circular polarization filtering antenna structure;

[0022] Figure 4 A top view of a super surface structure and a first radiation patch in a dual-fed circularly polarized filtering antenna structure;

[0023] Figure 5 It is a top view of the second radiation patch in the dual-fed circular polarization filtering antenna structure;

[0024] Figure 6 It is a filter branch and surrounding metallized via structure in a dual-fed circular polarization filter antenna structure;

[0025] Figure 7 It is a top view of the coaxial-to-microstrip structure in the dual-fed circularly polarized filtering antenna structure;

[0026] Figure 8 It is a stereogram of a 2×2 array of dual-fed circularly polarized filter antennas;

[0027] Fig. 9 It is a stereogram of the 8×8 array of dual-fed circularly polarized filter antennas;

[0028] Fig.10 This is the return loss simulation result of the dual-fed circularly polarized filter antenna;

[0029] Fig.11 This is the axial ratio simulation result of the dual-fed circularly polarized filter antenna;

[0030] Fig.12 This is the gain simulation result of the dual-fed circularly polarized filter antenna;

[0031] Fig.13It is the radiation pattern of the dual-fed circularly polarized filter antenna at 19.35 GHz frequency and xz plane;

[0032] Fig.14 It is the radiation pattern of the double-fed circularly polarized filter antenna at 19.35 GHz frequency and yz plane;

[0033] In the figure: 1. Metasurface structure; 2. Radiating patch; 3. Coaxial core; 4. Metallized vias around the coaxial core; 5. Metallized vias around the microstrip line; 6. Fixed position of the chip interface; 7. Printed circuit board; 8. Filter branch; 9. Metallized vias around the filter branch; 10. Microstrip line. DETAILED DESCRIPTION

[0034] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0035] Example 1

[0036] like Figure 1-7 As shown, a dual-fed circularly polarized filtering antenna comprises a plurality of layers of printed boards arranged in sequence from top to bottom, wherein: a first radiation patch 2 and a metasurface structure 1 are provided on the upper surface of the first layer of printed boards, a second radiation patch 2 is provided on the lower surface of the first layer of printed boards, an antenna metal ground is provided on the lower surface of the second layer of printed boards, two filtering branches 8 are provided on any layer of the middle layers of printed boards, i.e., located at a layer between the third layer of printed boards and the bottom layer of printed boards, and two coplanar waveguide feed lines with ground are provided on the bottom layer of printed boards;

[0037] The antenna also includes two quasi-coaxial feeding structures, the top of which is connected to the second radiation patch 2, and the bottom is connected to the coplanar waveguide feeding line with ground, thus forming a dual coaxial to microstrip feeding structure to achieve antenna excitation.

[0038] Preferably, the antenna in the present invention is square, the first radiation patch 2 and the second radiation patch 2 are both circular and the center of the circle is located at the center of the antenna, the two radiation patches 2 have different sizes, and the second radiation patch 2 is respectively provided with a protruding branch at a diagonal position of the circumference, and the protruding branch is a square perturbation structure, which can enhance the generation of circularly polarized waves; in addition, the second radiation patch 2 is directly in contact with the quasi-coaxial feeding structure, and the circularly polarized wave and circularly polarized reconfigurable performance can be achieved through the dual coaxial to microstrip feeding structure;

[0039] The metasurface structure 1 is composed of a number of square metal patches distributed in a matrix, with the same size and spacing, and a circular area is left in the center of the metasurface structure 1 for placing the first radiation patch 2. The top surface of the metasurface structure 1 is at the same height as the top surface of the first radiation patch 2, which helps to reduce the surface waves of the top layer of the antenna and improve the scanning performance.

[0040] The antenna directly integrates the printed circuit board 7 structure at the lower end of the antenna, making the antenna and the chip more integrated and more convenient for beam switching and phase control. The printed circuit board 7 is composed of a double-layer dielectric substrate, a double-layer prepreg sandwiched between the double-layer dielectric substrate, and a multi-layer copper layer etched on the front and back of the dielectric substrate. This structure directly integrates the antenna and the chip to achieve an integrated design. It should be noted that the plate material of the bottom layer of the dielectric substrate is different from that of other dielectric substrates. Its dielectric constant is 3.32, while the dielectric constant of other substrates is 3.34. Similarly, the thickness of each plate material is also different.

[0041] Preferably, the coplanar waveguide feed line with ground in the present invention includes a metal ground located on the upper surface of the bottom printed board, and a microstrip line 10 located on the lower surface of the bottom printed board. The two coplanar waveguide feed lines with ground are different in the microstrip line 10 part and are connected at a fixed point according to different routing methods. The quasi-coaxial feeding structure includes a coaxial core 3 and a metallized via located on the periphery of the coaxial core 3.

[0042] The upper end of the coaxial core 3 is connected to the second radiation patch 2, the middle is connected to the filter branch 8, and the lower end is connected to one end of the microstrip line 10. The other end of the microstrip line 10 is connected to the RF chip through the fixed position 6 of the chip interface. The metallized vias penetrate the antenna metal ground on the lower surface of the second printed circuit board and the metal ground on the upper surface of the bottom printed circuit board. The height of the entire dual coaxial to microstrip structure is from the second radiation patch 2 to the bottom layer of the antenna, making the antenna more compact. It is worth noting that the microstrip line 10 is hollowed out all around, which is equivalent to forming a coplanar waveguide structure. If the gap is not enough, it may have a certain impact on the performance of the feed line and the antenna.

[0043] Preferably, the coaxial cores 3 of the two quasi-coaxial feeding structures in the present invention are arranged at an angle of 90° to the center of the antenna.

[0044] Preferably, the metallized vias in the present invention are designed for different antenna parts respectively, and are divided into three types, namely, metallized vias 4 arranged around the coaxial core, metallized vias 9 arranged around the filter branch, and metallized vias 5 arranged around the microstrip line. Correspondingly, the hollowing depths of different metallized vias are different. The first type passes through the PCB structure, the second type passes through the metal copper layer where the filter branch 8 is located, the upper semi-cured sheet and the metal copper layer, and the third type passes through the bottom dielectric board.

[0045] The antenna adopts a dual coaxial to microstrip structure, the lower end of the coaxial core 3 is connected to the microstrip line 10 through a transfer structure, and the microstrip line 10 adopts a specially designed routing. Among them, the transfer structure includes a transition disk sleeved on the coaxial core 3 and an impedance matching section arranged between the transition disk and the microstrip line 10. The diameter of the transition disk is slightly larger than the coaxial core 3 to ensure the smoothness and correctness of the transition. The impedance matching section is designed with microstrip lines 10 of different widths to ensure that the port impedance is fifty ohms. The specially designed routing is designed according to the position of the feeding point, and the routing is flexible, while ensuring the correct connection between the antenna and the chip.

[0046] Preferably, the starting part of the filter branch 8 described in the present invention is led out from the coaxial inner core 3, and the leading directions of the two filter branches 8 are at an angle of 90°. Each filter branch 8 is led out from a wide line segment and then turned into a thin line segment, and the inside of the wide line segment is hollowed out to improve the filtering effect. The thin line segment is bent and folded to make the filter branch 8 as a whole have a fishhook shape, which not only ensures the filtering effect but also ensures that the total length of the filter branch 8 does not exceed the limit that the antenna unit can accommodate.

[0047] In terms of specific dimensions, the following implementation schemes may be adopted:

[0048] like Figure 1 As shown, the dielectric substrates are all square substrates with a side length of 7 mm. From top to bottom, their thicknesses are 0.6 mm, 0.5 mm, 0.1 mm, 0.127 mm, and 0.132 mm, respectively, and the thickness of the prepreg is 0.1 mm. The metal coating including the radiation patch 2 has a thickness of 0.035 mm, 0.018 mm, 0.035 mm, 0.025 mm, 0.018 mm, 0.018 mm, 0.025 mm, 0.025 mm, and 0.035 mm, respectively, from top to bottom.

[0049] like Figure 4 and Figure 5 As shown, the side length of the unit in the metasurface structure 1 is 1.2 mm, the spacing is 0.2 mm, the radius of the first radiation patch 2 is 1.96 mm, the radius of the second radiation patch 2 is 2.44 mm, and the perturbation structure is 0.335 mm long and 0.663 mm wide.

[0050] like Figure 6 As described above, in the structure of the filter branch 8, the width of the wide line segment is 0.55 mm, the width of the thin line segment is 0.2 mm, and the total size of the gap of the metal block dug out around is 1 mm×3.7 mm.

[0051] like Figure 2 As shown, the height of the coaxial core 3 is from the second radiation patch 2 to the bottom of the antenna, and its radius is 0.15 mm. The positions of the two coaxial cores 3 are respectively located on the x and y axes, and are both 1.56 mm away from the origin;

[0052] like Figure 7 The transition disk in the transition structure shown has a thickness of 0.035 mm and a radius of 0.2 mm; the impedance matching section in the transition structure has a width of 0.14 mm, and the subsequent microstrip line 10 has a width of 0.23 mm.

[0053] like Figure 1 and Figure 2 As shown, the diameters of the metallized vias 4 around the coaxial core and the metallized vias 5 around the microstrip line are both 0.2 mm, and the heights are 0.705 mm and 0.192 mm respectively.

[0054] like Fig.10 As shown in the figure, it is the return loss simulation result of the dual-fed circularly polarized filter antenna. It can be seen from the figure that the antenna unit has a wide working bandwidth. In the 17.7-21GHz receiving signal band, S11 is less than -10dB, and in the 27.7-31GHz transmitting signal band, S11 is basically greater than -1dB, which has a good filtering effect.

[0055] like Fig.11 As shown, the axial ratio simulation results of the dual-fed circularly polarized filter antenna are shown. It can be seen that the axial ratio of the antenna unit is less than 3dB in the range of 15GHz-21.5GHz, and it has good circularly polarized wave performance.

[0056] like Fig.12 As shown in the figure, it is the gain simulation result of the dual-fed circularly polarized filter antenna. It can be seen that the antenna unit gain is approximately 2dBi in the 17.7-21GHz receiving signal band, and is less than -10.5dBi in the 27.7-31GHz transmitting signal band. The suppression effect can reach nearly -13dB.

[0057] like Fig.13 and 14 As shown in the figure, the radiation pattern of the xz plane and the radiation pattern of the yz plane of the dual-fed circularly polarized filter antenna at the frequency of 19.35GHz. By controlling the phase and amplitude of the dual feed points, left-hand and right-hand circular polarization can be achieved. It can be seen from the figure that the antenna itself has good circular polarization characteristics. While the antenna forms left-hand circularly polarized waves, it also has strong suppression on right-hand circularly polarized waves.

[0058] Example 2

[0059] A dual-fed circular polarization filter antenna array is provided, wherein the dual-fed circular polarization filter antenna is expanded in two dimensions to form a phased array antenna array. The antenna units are firstly formed into a 2×2 small array (such as Figure 8 As shown in the figure), further strengthen the formation of circularly polarized waves, and then use this 2×2 small array to form an 8×8 two-dimensional array (as shown in the figure). Fig. 9As shown in the figure), the phase control method of the phased array is used to control the phase of each feeding point.

[0060] When rotating, it should be noted that the antenna substrate can be rotated directly, but the dual coaxial to microstrip feeding structure and the filter branch structure need to be mirrored. This is because the position of the feeding point is fixed, which lays the foundation for subsequent chip integration.

[0061] Example 3

[0062] An application of the dual-fed circularly polarized filter antenna in satellite communications, the application being to deploy the dual-fed circularly polarized filter antenna as a ground terminal antenna for satellite communications to achieve satellite-to-ground interconnection communications. The antenna adopts a metasurface structure, which greatly reduces surface wave interference and antenna size, and achieves antenna miniaturization; the introduction of a dual coaxial to microstrip feeding structure enables the antenna to have circularly polarized reconfigurable characteristics; the designed filter branch structure effectively suppresses interference with signals in the transmission frequency band and improves isolation, so the antenna unit has application value in the field of satellite communications.

[0063] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A dual-fed circularly polarized filtering antenna, characterized in that: The antenna comprises a plurality of printed boards arranged in sequence from top to bottom, wherein: a first radiation patch and a metasurface structure are arranged on the upper surface of the first printed board, a second radiation patch is arranged on the lower surface of the first printed board, an antenna metal ground is arranged on the lower surface of the second printed board, two filter branches are arranged on any one of the middle several printed boards, and two coplanar waveguide feed lines with ground are arranged on the bottom printed board; The antenna also includes two quasi-coaxial feeding structures, the top end of the quasi-coaxial feeding structure is connected to the second radiation patch, and the bottom end is connected to the coplanar waveguide feeding line with ground to achieve antenna excitation; The grounded coplanar waveguide feed line includes a metal ground located on the upper surface of the bottom printed board and a microstrip line located on the lower surface of the bottom printed board. The quasi-coaxial feed structure includes a coaxial core and a metallized via located on the periphery of the coaxial core. Among them, the upper end of the coaxial core is connected to the second radiation patch, the middle is connected to the filter branch, the lower end is connected to one end of the microstrip line, the other end of the microstrip line is connected to the RF chip, and the metallized via runs through the antenna metal ground on the lower surface of the second layer of printed circuit board and the metal ground on the upper surface of the bottom layer of printed circuit board.

2. A dual-fed circularly polarized filtering antenna according to claim 1, characterized in that: The antenna is square, the first radiation patch and the second radiation patch are both circular with the center of the circle located at the center of the antenna, and the second radiation patch is provided with a protruding branch at a diagonal position of the circumference; The metasurface structure is composed of a plurality of square metal patches distributed in a matrix, and a circular area is left in the center of the metasurface structure for placing the first radiation patch, and the top surface of the metasurface structure is at the same height as the top surface of the first radiation patch.

3. A dual-fed circularly polarized filtering antenna according to claim 1, characterized in that: The printed board consists of a double-layer dielectric substrate, a double-layer prepreg sandwiched between the double-layer dielectric substrate, and multiple copper layers etched on the front and back surfaces of the dielectric substrate.

4. The dual-fed circularly polarized filtering antenna according to claim 1, characterized in that: The coaxial cores of the two quasi-coaxial feeding structures are arranged at an angle of 90° with respect to the center of the antenna.

5. The dual-fed circularly polarized filtering antenna according to claim 1, characterized in that: The metallized vias are divided into three types, which are respectively arranged around the coaxial core, around the filter branches and around the microstrip line.

6. A dual-fed circularly polarized filtering antenna according to claim 1, characterized in that: The lower end of the coaxial inner core is connected to the microstrip line through a transition structure, and the transition structure comprises a transition disk sleeved on the coaxial inner core and an impedance matching section arranged between the transition disk and the microstrip line.

7. The dual-fed circularly polarized filtering antenna according to claim 1, characterized in that: The starting part of the filter branch is led out from the coaxial inner core, and the leading directions of the two filter branches are at an angle of 90°. Each filter branch is led out from a wide line segment and then turns into a thin line segment. The inside of the wide line segment is hollowed out, and the thin line segment is bent and folded, so that the filter branch is overall shaped like a fishhook.

8. A dual-fed circularly polarized filtering antenna array, characterized in that: The antenna array is composed of the dual-fed circularly polarized filter antenna described in any one of claims 1 to 7, which is expanded in a two-dimensional periodic manner.

9. An application of the dual-fed circularly polarized filter antenna according to any one of claims 1 to 7 in satellite communications, characterized in that: The application is to deploy a dual-fed circularly polarized filter antenna as a ground terminal antenna for satellite communications to achieve satellite-to-ground interconnection communications.

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