A wide-beam back-cavity antenna unit and phased array antenna thereof

Abstract

This application discloses a wide-beam cavity antenna element and its phased array antenna. The cavity antenna element includes a first radiating patch, a first dielectric layer, a second radiating patch, an adhesive layer, a second dielectric layer, and a metal ground layer arranged sequentially. The first radiating patch has a first chamfer on each diagonal and a first U-shaped slot in its center. The second radiating patch has a second chamfer on each diagonal and a second U-shaped slot in its center. This application adopts a dual-radiating patch structure, with the first and second radiating patches located in different dielectric layers, effectively expanding the antenna bandwidth and improving radiation efficiency. The double-layer square microstrip patch design is compact and facilitates miniaturization and integration. The first radiating patch incorporates the first chamfer and the first U-shaped slot, while the second radiating patch incorporates the second chamfer and the second U-shaped slot, increasing the current path and transforming the original single resonant point into three resonant points within the frequency band, significantly widening the antenna's impedance bandwidth.

Description

Technical Field

[0001] This application relates to the field of antenna technology, and in particular to a wide-beam cavity antenna element and its phased array antenna. Background Technology

[0002] With the rapid development of satellite communication technology, satellite terminals are placing increasingly higher demands on antennas, and various types of antennas are playing an increasingly important role in communication systems. Traditional microstrip patch antennas are very popular and widely used in integrated arrays due to their advantages such as small size, light weight, low profile, easy integration with active circuits, and conformal design with the carrier. However, traditional microstrip patch antennas typically have narrow operating bandwidths and beamwidths, as well as low power capacity; these inherent drawbacks limit their application. Considering communication with satellites in different locations, or maintaining good communication with satellites even during motion and fluctuations, satellite terminal antennas usually need to have a wide beamwidth. Traditional microstrip patch antennas generally have a beamwidth of around 70 degrees, which is narrow and insufficient for wide-angle communication needs. Therefore, beamwidth widening is necessary to meet the requirement of wider satellite communication coverage.

[0003] For phased array antennas, in order to overcome signal loss caused by polarization deflection during satellite signal propagation, satellite terminals typically require the use of circularly polarized antennas. This is because circularly polarized antennas can receive electromagnetic waves in any polarization direction, offering advantages such as avoiding multipath interference, polarization mismatch, and eliminating the Faraday effect, thus improving communication efficiency while ensuring communication quality. However, traditional circularly polarized phased array antennas, due to beamwidth limitations and mutual coupling effects between antenna elements, have a circular polarization scanning range of only about ±45 degrees, and experience significant fluctuations during gain reduction. Summary of the Invention

[0004] The main technical problem addressed by this application is to provide a wide-beam cavity antenna element and its phased array antenna, thereby solving the aforementioned problem.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is to provide a wide-beam cavity antenna element and its phased array antenna, including a first radiating patch, a first dielectric layer, a second radiating patch, an adhesive layer, a second dielectric layer and a metal ground layer arranged sequentially; a grounding ring is provided on the outer ring of the first radiating patch, the first radiating patch and the grounding ring are located on the upper surface of the first dielectric layer, and the second radiating patch is located on the lower surface of the first dielectric layer; a first chamfer is provided on each diagonal of the first radiating patch, and a first U-shaped groove is provided in the middle of the first radiating patch; a second chamfer is provided on each diagonal of the second radiating patch, and a second U-shaped groove is provided in the middle of the second radiating patch.

[0006] In some embodiments, the first dielectric layer and the second dielectric layer are connected by the adhesive layer, and a plurality of spaced metal pillars are provided on the lower side of the grounding ring. The metal pillars surround the first radiating patch and the second radiating patch, and the metal pillars penetrate the first dielectric layer, the second dielectric layer and the adhesive layer. One end of the metal pillar is connected to the grounding ring and the other end is connected to the metal ground layer.

[0007] In some embodiments, a coaxial feed post is provided at the center of the antenna element. The coaxial feed post penetrates the first radiating patch, the first dielectric layer, the second radiating patch, the adhesive layer, the second dielectric layer, and the metal ground layer. The lower end of the coaxial feed post is electrically connected to the metal ground layer, the upper end of the coaxial feed post is electrically connected to the first radiating patch, and the upper part of the coaxial feed post is electrically connected to the second radiating patch.

[0008] In some embodiments, the first chamfer and the second chamfer are arranged intersectingly.

[0009] In some embodiments, both the first chamfer and the second chamfer are isosceles right triangles.

[0010] In some embodiments, the size of the first U-shaped groove is smaller than the size of the second U-shaped groove.

[0011] In some embodiments, the orientation of the first U-shaped groove is the same as the orientation of the second U-shaped groove.

[0012] In some embodiments, the grounding ring has a square ring structure, and a rectangular portion extends inward from the center of the inner edge of the grounding ring, and the rectangular portions are symmetrically distributed.

[0013] This application also provides a phased array antenna, including multiple cavity antenna elements, wherein the grounding ring, the first dielectric layer, the adhesive layer, the second dielectric layer and the metal ground layer are all integral structures; four first radiating patches are grouped together, and the first U-shaped grooves in a group of first radiating patches have different orientations.

[0014] In some embodiments, the phased array antenna includes eight cavity antenna elements, which are arranged in an H-plane configuration using rotating feed to form a 2×4 phased array antenna. The phased array antenna applies 0°, 90°, 180°, and 270° phases to each feed port clockwise to achieve right-hand circular polarization scanning, or applies 0°, 90°, 180°, and 270° phases to each feed port counterclockwise to achieve left-hand circular polarization scanning.

[0015] The beneficial effects of this application are as follows: This application employs a dual-radiating patch structure, with the first and second radiating patches located in different dielectric layers, effectively expanding the antenna bandwidth and improving radiation efficiency. The dual-layer square microstrip patch design is compact and facilitates miniaturized integration. The first radiating patch incorporates a first chamfer and a first U-shaped slot, while the second radiating patch incorporates a second chamfer and a second U-shaped slot, increasing the current flow path and transforming the original single resonant point into three resonant points within the frequency band, significantly broadening the antenna's impedance bandwidth. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a cavity antenna element according to an embodiment of this application;

[0017] Figure 2 This is a top view of a cavity antenna unit according to an embodiment of this application;

[0018] Figure 3 This is a bottom view of the structure of a cavity antenna element according to an embodiment of this application;

[0019] Figure 4 This is an exploded view of a cavity antenna element according to an embodiment of this application;

[0020] Figure 5 This is an exploded view of the metal structure in a cavity antenna element according to an embodiment of this application;

[0021] Figure 6 This is a top view of the second radiating patch of a cavity antenna element according to an embodiment of this application;

[0022] Figure 7 This is a schematic diagram of the structure of a phased array antenna according to an embodiment of this application;

[0023] Figure 8 This is a top view of a phased array antenna according to an embodiment of this application;

[0024] Figure 9 This is a bottom-view structural schematic diagram of a phased array antenna according to an embodiment of this application;

[0025] Figure 10 This is an exploded view of a phased array antenna according to an embodiment of this application;

[0026] Figure 11 This is a schematic diagram of the S-parameters and gain of a cavity antenna element according to an embodiment of this application;

[0027] Figure 12 This is a schematic diagram of the 3dB beamwidth of a cavity antenna element at 19.5GHz according to an embodiment of this application;

[0028] Figure 13 This is a schematic diagram of the radiation direction of a cavity antenna element in the yoz plane at a frequency of 19.5 GHz, according to an embodiment of this application.

[0029] Figure 14 This is a schematic diagram of the S-parameters and gain of a phased array antenna according to an embodiment of this application;

[0030] Figure 15 This is a schematic diagram of the axial ratio parameters of a phased array antenna according to an embodiment of this application;

[0031] Figure 16 This is a schematic diagram of the axial ratio of a phased array antenna in a left-hand circularly polarized scan of the yoz plane at a frequency of 19.5 GHz, according to an embodiment of this application.

[0032] Figure 17 This is a schematic diagram of the gain of a phased array antenna according to an embodiment of this application during left-hand circular polarization scanning in the yoz plane at a frequency of 19.5 GHz.

[0033] Reference numerals: In the cavity antenna unit, 1, first radiating patch, 11, first chamfer, 12, first U-shaped groove, 2, first dielectric layer, 3, second radiating patch, 31, second chamfer, 32, second U-shaped groove, 4, adhesive layer, 5, second dielectric layer, 6, metal ground layer, 7, grounding ring, 71, rectangular part, 8, metal pillar, 9, coaxial feed pillar;

[0034] In a phased array antenna, 10 is the first radiating patch, 20 is the first dielectric layer, 30 is the second radiating patch, 40 is the adhesive layer, 50 is the second dielectric layer, 60 is the metal ground layer, 70 is the grounding ring, 80 is the metal pillar, and 90 is the coaxial feed pillar. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0036] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component.

[0037] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0039] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0040] For the description of this application, the terms used are not limiting. Figure 1 The labels “front,” “back,” “up,” “down,” “left,” and “right” shown are used to facilitate understanding of this embodiment and are not intended to limit this application. Specifically, front-back indicates longitudinal direction, left-right indicates lateral direction, and up-down indicates vertical direction.

[0041] Figure 1 - Figure 17 This illustration shows an embodiment of the wide-beam cavity antenna element and its phased array antenna of this application. The cavity antenna element includes, from top to bottom, a first radiating patch 1, a first dielectric layer 2, a second radiating patch 3, an adhesive layer 4, a second dielectric layer 5, and a metal ground layer 6. A grounding ring 7 is provided around the outer side of the first radiating patch 1. The first radiating patch 1 and the grounding ring 7 are located on the upper surface of the first dielectric layer 2, and the second radiating patch 3 is located on the lower surface of the first dielectric layer 2. The first radiating patch 1 and the second radiating patch 3 constitute the antenna radiator. Both the first radiating patch 1 and the second radiating patch 3 are square microstrip patches. The first radiating patch 1 has a first chamfer 11 at each diagonal and a first U-shaped groove 12 in the middle. The second radiating patch 3 has a second chamfer 31 at each diagonal and a second U-shaped groove 32 in the middle.

[0042] This application employs a dual-radiating patch structure, with the first and second radiating patches located in different dielectric layers, effectively expanding the antenna bandwidth and improving radiation efficiency. The double-layer square microstrip patch design is compact and facilitates miniaturized integration. The first radiating patch 1 introduces a first chamfer 11 and a first U-shaped slot 12, while the second radiating patch 3 introduces a second chamfer 31 and a second U-shaped slot 32, increasing the current flow path and transforming the original single resonant point into three resonant points within the frequency band, significantly broadening the antenna's impedance bandwidth.

[0043] In some embodiments, the first chamfer 11 and the second chamfer 31 are arranged intersectingly. The first chamfer 11 is located at the upper right and lower left corners of the first radiating patch 1, and the second chamfer 31 is located at the lower right and upper left corners of the second radiating patch 3. The first chamfer 11 and the second chamfer 31 can change the current flow path on the surface of the patch, and the excited degenerate modes form a 90° phase difference to achieve the effect of circularly polarized radiation. At the same time, the perturbation of the first chamfer 11 and the second chamfer 31 disrupts the perfect symmetry of the patch, which can cause frequency separation of the originally excited degenerate orthogonal modes, thus widening the bandwidth of the antenna.

[0044] If the chamfer is only applied to a single layer, perturbation can only be introduced on a single patch, resulting in limited mode separation and narrow axial ratio bandwidth. The cross chamfering of the first chamfer 11 and the second chamfer 31 is equivalent to applying independent perturbation to the two orthogonal modes of the excitation on two coupled patches, which can broaden the axial ratio bandwidth of circular polarization.

[0045] In some embodiments, both the first chamfer 11 and the second chamfer 31 are isosceles right triangles. This ensures the symmetry of the antenna patch and achieves stable circularly polarized radiation.

[0046] In some embodiments, the size of the first U-shaped groove 12 is smaller than the size of the second U-shaped groove 32. The first radiating patch 1 is a parasitic coupling patch. The second radiating patch 3 is a main radiating patch. The different sizes of the first U-shaped groove 12 and the second U-shaped groove 32 can respectively control the resonant frequency excited within the frequency band, broaden the bandwidth, and optimize interlayer coupling for better impedance matching.

[0047] In some embodiments, the orientation of the first U-shaped slot 12 is the same as that of the second U-shaped slot 32. This allows the current directions of the first radiating patch 1 and the second radiating patch 3 to be synchronized, and the radiated fields to be superimposed in phase, ensuring consistent gain and polarization direction, avoiding pattern distortion and increased cross-polarization, while suppressing stray radiation and making the antenna performance more stable.

[0048] In some embodiments, the grounding ring 7 has a square ring structure, and a rectangular portion 71 extends inward from the center of the inner edge of the grounding ring 7, with the four rectangular portions 71 symmetrically distributed. The rectangular portions 71 broaden the 3dB beamwidth of the antenna.

[0049] In some embodiments, the first dielectric layer 2 and the second dielectric layer 5 are connected by an adhesive layer 4. A plurality of spaced metal pillars 8 are correspondingly disposed on the lower side of the grounding ring 7. The metal pillars 8 surround the first radiating patch 1 and the second radiating patch 3, and penetrate the first dielectric layer 2, the second dielectric layer 5, and the adhesive layer 4. One end of each metal pillar 8 is connected to the grounding ring 7, and the other end is connected to the metal ground layer 6. The grounding ring 7 achieves electrical contact with the metal ground layer 6 through the metal pillars 8. The metal pillars 8 enclose a square area, which constitutes the SIW cavity.

[0050] In some embodiments, a coaxial feed post 9 is disposed at the center of the antenna. The coaxial feed post 9 penetrates the first radiating patch 1, the first dielectric layer 2, the second radiating patch 3, the adhesive layer 4, the second dielectric layer 5, and the metal ground layer 6. The lower end of the coaxial feed post 9 is electrically connected to the metal ground layer 6, serving as a feed port. The upper end of the coaxial feed post 9 is electrically connected to the first radiating patch 1, and the upper part of the coaxial feed post 9 is electrically connected to the second radiating patch 3. The feed port on the metal ground layer 6 is excited, and electromagnetic waves are radiated by direct coupling between the first radiating patch 1 and the second radiating patch 3 through the coaxial feed post 9. By using coaxial feeding and directly connecting the coaxial feed post 9 to the first radiating patch 1 and the second radiating patch 3, buried blind holes are avoided, reducing manufacturing costs.

[0051] In some embodiments, the first dielectric layer 2 and the second dielectric layer 5 are both made of Rogers 3003 dielectric material with a dielectric constant of 3 and a loss tangent of 0.0013, and the adhesive layer 4 is made of Rogers 4450F dielectric material with a dielectric constant of 3.52 and a loss tangent of 0.0041.

[0052] In some embodiments, the thickness of the first dielectric layer 2 is 0.254 mm, the thickness of the second dielectric layer 5 is 0.889 mm, and the thickness of the adhesive layer 4 is 0.1 mm.

[0053] In some embodiments, Figure 11 The S-parameters and gain diagram of the wide-beam cavity antenna element of this application are shown. It can be seen that the wide-beam cavity antenna element has S11 < -10dB in the frequency band from 17.7GHz to 22.41GHz, and the relative bandwidth reaches 23%. It can effectively radiate in this frequency band, and the maximum gain is 8.7dBi at the 21.75GHz frequency point.

[0054] In some embodiments, Figure 12 The diagram shows the 3dB beamwidth of the wide-beam cavity antenna element of this application at a frequency of 19.5 GHz. It can be seen that the 3dB beamwidth in the yoz plane covers -62 degrees to 64 degrees, reaching 126 degrees.

[0055] In some embodiments, Figure 13The radiation pattern of the wide-beam cavity antenna element of this application in the yoz plane at a frequency of 19.5 GHz is shown. It can be seen that the common polarization radiation gain is much greater than the cross polarization radiation gain, which has good anti-interference capability.

[0056] This application features wide bandwidth, wide beam, small size, and simple structure. Furthermore, the substrate-integrated waveguide cavity can effectively suppress surface waves and improve the radiation efficiency of the antenna, providing a good option for wide-angle scanning phased arrays.

[0057] This application also uses the aforementioned cavity antenna elements to form a phased array antenna. The phased array antenna is composed of multiple cavity antenna elements. When multiple cavity antenna elements form a phased array antenna, the grounding ring 70 can be set as an integral structure, forming multiple placement holes.

[0058] In some embodiments, the first radiating patch 10 is correspondingly disposed within the placement hole, and four first radiating patches 10 form a group. The orientation of the first U-shaped groove 12 in the four first radiating patches 10 can be up, down, left, and right, respectively, and the orientation of the first U-shaped groove 12 can be set as needed. The orientation of the second U-shaped groove 32 can be set based on the orientation of the first U-shaped groove 12, so that the orientation of the second U-shaped groove 32 is the same as the orientation of the first U-shaped groove 12.

[0059] In some embodiments, the first dielectric layer 20, the adhesive layer 40, the second dielectric layer 50, and the metal ground layer 60 can all be an integral structure. Adjacent first radiating patches 10 can share a metal post 80. Coaxial feed posts 90 are used corresponding to the first radiating patch 10 and the second radiating patch 30.

[0060] In some embodiments, the phased array antenna consists of eight wide-beam cavity antenna elements. The phased array is formed by rotating the wide-beam cavity antenna elements and arranging them in an H-plane configuration to form a 2×4 linear array. By using an external amplitude and phase control chip, applying 0°, 90°, 180°, and 270° phases clockwise to each feed port enables right-hand circular polarization scanning, while applying 0°, 90°, 180°, and 270° phases counterclockwise enables left-hand circular polarization scanning.

[0061] This application employs PCB technology, resulting in a simple structure. Based on a wide-beam cavity antenna, a 2×4 phased array is formed using rotating feed and H-plane arrangement. By optimizing the distance between antenna elements on the H-plane, the coupling effect between antenna elements is improved, avoiding excessive grating gain during scanning. This enables 1D circularly polarized wide-angle scanning, helping to solve the problems of narrow impedance bandwidth and 3dB beamwidth, small scanning angle, and large gain changes during scanning in traditional microstrip patch antennas.

[0062] In some embodiments, Figure 14The S-parameters and gain diagram of the phased array antenna of this application are shown. It can be seen that the phased array antenna has S11 < -10dB in the frequency band from 18GHz to 21.56GHz, and the relative bandwidth reaches 18%. It can effectively radiate in this frequency band, and the maximum gain is 14.2dBi at the 20.3GHz frequency point.

[0063] In some embodiments, Figure 15 The diagram shows the axial ratio parameters of the phased array antenna of this application. Due to the use of rotating feed, the axial ratio is below 3dB within the frequency band covered by the phased array, resulting in significant circular polarization. The SIW cavity antenna has wide beam characteristics, and the phased array antenna composed of rotating feed has a wider circular polarization scanning range.

[0064] In some embodiments, Figure 16 and Figure 17 The diagram shows the axial ratio and gain of the phased array antenna of this application during left-hand circular polarization scanning in the yoz plane at a frequency of 19.5 GHz. It is fed with a 90-degree phase difference in a counterclockwise direction. Due to the symmetry of the antenna's radiation characteristics, it can be seen from the diagram that the phased array antenna can achieve a wide-angle scan of ±55 degrees in the yoz plane. During the scanning process, the axial ratio is below 3 dB, which meets the requirements of circular polarization. At the same time, the gain drops by less than 3 dB during the scanning process.

[0065] Therefore, this application discloses a wide-beam cavity antenna element and its phased array antenna. This application employs a dual-radiating patch structure, with the first and second radiating patches located in different dielectric layers, effectively expanding the antenna bandwidth and improving radiation efficiency. The double-layer square microstrip patch design is compact and facilitates miniaturization and integration. The first radiating patch incorporates a first chamfer and a first U-shaped slot, while the second radiating patch incorporates a second chamfer and a second U-shaped slot, increasing the current path and transforming the original single resonant point into three resonant points within the frequency band, significantly widening the antenna's impedance bandwidth.

[0066] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A wide-beam cavity antenna element, characterized in that, The device includes a first radiating patch, a first dielectric layer, a second radiating patch, an adhesive layer, a second dielectric layer, and a metal ground layer arranged sequentially. A grounding ring is provided around the outer edge of the first radiating patch. The first radiating patch and the grounding ring are located on the upper surface of the first dielectric layer, and the second radiating patch is located on the lower surface of the first dielectric layer. A first chamfer is provided at each diagonal of the first radiating patch, and a first U-shaped groove is provided in the middle of the first radiating patch. A second chamfer is provided at each diagonal of the second radiating patch, and a second U-shaped groove is provided in the middle of the second radiating patch.

2. The wide-beam cavity antenna element according to claim 1, characterized in that, The first dielectric layer and the second dielectric layer are connected by the adhesive layer. A plurality of spaced metal pillars are provided on the lower side of the grounding ring. The metal pillars surround the first radiating patch and the second radiating patch. The metal pillars penetrate the first dielectric layer, the second dielectric layer and the adhesive layer. One end of the metal pillar is connected to the grounding ring and the other end is connected to the metal ground layer.

3. The wide-beam cavity antenna element according to claim 1, characterized in that, A coaxial feed post is provided at the center of the antenna unit. The coaxial feed post passes through the first radiating patch, the first dielectric layer, the second radiating patch, the adhesive layer, the second dielectric layer, and the metal ground layer. The lower end of the coaxial feed post is electrically connected to the metal ground layer, the upper end of the coaxial feed post is electrically connected to the first radiating patch, and the upper part of the coaxial feed post is electrically connected to the second radiating patch.

4. The wide-beam cavity antenna element according to claim 1, characterized in that, The first chamfer and the second chamfer are arranged intersectingly.

5. The wide-beam cavity antenna element according to claim 1, characterized in that, Both the first and second tangent angles are isosceles right triangles.

6. The wide-beam cavity antenna element according to claim 1, characterized in that, The size of the first U-shaped groove is smaller than the size of the second U-shaped groove.

7. The wide-beam cavity antenna element according to claim 1, characterized in that, The orientation of the first U-shaped groove is the same as that of the second U-shaped groove.

8. The wide-beam cavity antenna element according to claim 1, characterized in that, The grounding ring has a square ring structure, and rectangular portions extend inward from the center of the inner edge of the grounding ring, with the rectangular portions being symmetrically distributed.

9. A phased array antenna, characterized in that, The phased array antenna includes a cavity antenna unit as described in any one of claims 1-8, wherein the grounding ring, the first dielectric layer, the adhesive layer, the second dielectric layer, and the metal ground layer are all integral structures; four first radiating patches form a group, and in a group of first radiating patches, the first U-shaped grooves have different orientations.

10. The phased array antenna according to claim 9, characterized in that, The phased array antenna includes eight cavity antenna elements, which are arranged in an H-plane configuration using rotating feeds to form a 2×4 phased array antenna. The phased array antenna applies 0°, 90°, 180°, and 270° phases to each feed port clockwise to achieve right-hand circular polarization scanning, or applies 0°, 90°, 180°, and 270° phases to each feed port counterclockwise to achieve left-hand circular polarization scanning.

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