Antenna system

Abstract

An object of the present disclosure is to realize low cost and low power consumption in an antenna system that tilts a radiation beam, and to realize a satellite communication antenna for which low power consumption is particularly desired.SOLUTION: The present disclosure is an antenna system including an antenna including one or a plurality of antenna elements, a plane wave conversion metasurface P including a conductor structure concentrically arranged on a dielectric substrate, the plane wave conversion metasurface P being arranged in front of the antenna and converting a radiation beam of the antenna into a plane wave, and a beam tilting metasurface B including a conductor structure periodically arranged on the dielectric substrate, the beam tilting metasurface B being arranged in front of the antenna, being arranged on a side opposite to the antenna when viewed from the plane wave conversion metasurface P, and tilting the radiation beam of the antenna.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to antennas that tilt their radiation beams. [Background technology]

[0002] A phased array antenna that electronically scans a radiation beam is disclosed in Patent Document 1. In Patent Document 1, the phased array antenna includes a plurality of antenna elements and a plurality of electronic phase shifters, and electronically scans the radiation beam according to the setting values ​​of the plurality of electronic phase shifters. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-200950 [Non-patent literature]

[0004] [Non-Patent Document 1] Muhammad U.Afzal,etc.,“Steering the Beam of Medium-to-High Gain Antennas Using Near-Field Phase Transformation”,IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION,VOL.65,NO.4,APRIL 2017. [Non-patent document 2] Muhammad U.Afzal, etc., “A Low-Profile Printed Planar Phase Correcting Surface to Improve Directive Radiation Characteristics of Electromagnetic Band Gap Resonator Antennas”, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL.64, NO.1, January 2016. Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the phased array antenna includes a plurality of electronic phase shifters, which are active elements, and electronically scans the radiation beam according to the setting values ​​of the plurality of electronic phase shifters. Therefore, the phased array antenna in Patent Document 1 cannot achieve low cost and low power consumption, and cannot be realized as a satellite communication antenna, for which low power consumption is particularly desirable.

[0006] Therefore, in order to solve the above problems, the present disclosure aims to realize an antenna system that tilts its radiation beam at low cost and with low power consumption, and to realize it as a satellite communication antenna in which low power consumption is particularly desirable. [Means for solving the problem]

[0007] To solve the above problem, a beam tilting metasurface, which is a passive element, is placed in front of an antenna having one or more antenna elements.

[0008] Here, in order to precisely control the passing phase in a beam-tilting metasurface, a plane wave must be incident. However, an antenna (especially an array antenna, where multiple antenna elements are discontinuously arranged) will radiate one or more spherical waves. Therefore, the distance between the antenna and the beam-tilting metasurface must be approximately twice the wavelength used in the antenna system, making it impossible to make the antenna thin.

[0009] To solve the above problem, a separate passive element, a plane wave transformation metasurface, is placed in front of an antenna having one or more antenna elements, and between the antenna and the passive element, a beam tilt metasurface.

[0010] Specifically, the present disclosure relates to an antenna system comprising: an antenna having one or more antenna elements; a plane wave conversion metasurface having conductor structures concentrically arranged on a dielectric substrate, arranged in front of the antenna, and converting the radiation beam of the antenna into a plane wave; and a beam tilting metasurface having conductor structures periodically arranged on a dielectric substrate, arranged in front of the antenna and on the opposite side of the antenna from the plane wave conversion metasurface, and tilting the radiation beam of the antenna.

[0011] With this configuration, the antenna system can achieve low cost and low power consumption by using a beam tilting metasurface, does not require a long propagation distance to form a plane wave, and can be made thinner by using a plane wave conversion metasurface.

[0012] The present disclosure also provides an antenna system, wherein the antenna is an array antenna that directs the main lobe of the radiation beam only forward.

[0013] This configuration enables array antenna systems to achieve low cost and low power consumption by using only beam tilting metasurfaces.

[0014] The present disclosure also relates to an antenna system characterized in that the distance between the antenna and the plane wave conversion metasurface and the distance between the plane wave conversion metasurface and the beam tilting metasurface are greater than or equal to 1 / 4 of the wavelength used by the antenna system, and the distance between the antenna and the beam tilting metasurface is less than twice the wavelength used by the antenna system.

[0015] According to this configuration, the antenna system can be made thinner to about one-quarter of the conventional size by using a plane wave conversion metasurface.

[0016] The present disclosure also relates to an antenna system characterized in that the antenna, the plane wave conversion metasurface, and the beam tilting metasurface rotate the radiation beam of the antenna tilted by rotating the antenna, the plane wave conversion metasurface, and the beam tilting metasurface themselves with the in-plane direction of the antenna, the plane wave conversion metasurface, and the beam tilting metasurface and the direction perpendicular to the plane direction of the antenna, the beam tilting metasurface as the rotation axis direction.

[0017] With this configuration, the beam tilting metasurface and the plane wave conversion metasurface can be used to control the rotation angle of the radiation beam over a wide range, with the in-plane direction and the perpendicular direction of the beam tilting metasurface and the plane wave conversion metasurface as the rotation axis direction.

[0018] Here, we discovered that when enlarging an antenna with multiple antenna elements, if the beam tilt metasurface is repeatedly arranged, there is no need to redesign the beam tilt metasurface, but the sidelobe characteristics of the antenna with multiple antenna elements deteriorate.

[0019] This is because, when the beam tilt metasurface is repeatedly arranged, the coupling between the maximum and minimum conductor structures has a large effect, resulting in discontinuity in the excitation phase of the maximum and minimum conductor structures. Therefore, when the beam tilt metasurface is repeatedly arranged, a coupling shielding member is arranged to shield the coupling between the maximum and minimum conductor structures.

[0020] Specifically, the present disclosure is an antenna system characterized in that the antenna comprises a plurality of antenna elements, and the beam tilt metasurface further comprises a coupling shielding member that shields coupling between the largest and smallest conductor structures.

[0021] According to this configuration, when the beam-tilting metasurface is repeatedly arranged, the coupling between the maximum and minimum conductor structures is shielded, so the excitation phases of the maximum and minimum conductor structures become almost continuous. Therefore, when an antenna having multiple antenna elements is enlarged, even if the beam-tilting metasurface is repeatedly arranged, there is no need to redesign the beam-tilting metasurface, and the sidelobe characteristics of the antenna having multiple antenna elements can be improved.

[0022] The present disclosure also provides an antenna system in which the coupling shielding member shields coupling between adjacent conductor structures.

[0023] This configuration also shields the coupling between adjacent conductor structures, preventing ripples in the excitation phase of the conductor structures of the beam-tilting metasurface, thereby further improving the sidelobe characteristics of an antenna with multiple antenna elements.

[0024] The present disclosure also provides an antenna system characterized in that the antenna system is applied as a satellite communication antenna.

[0025] This configuration makes it possible to realize a satellite communication antenna in an antenna system where low power consumption is particularly desirable.

[0026] The above-disclosed inventions can be combined as much as possible. [Effects of the Invention]

[0027] In this way, the present disclosure can achieve low cost and low power consumption in an antenna system that tilts a radiation beam, and can be realized as a satellite communication antenna in which low power consumption is particularly desirable. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an array antenna system of a comparative example. [Figure 2] FIG. 1 is a diagram illustrating a problem to be solved in an array antenna system of a comparative example. [Figure 3] FIG. 10 is a diagram showing the directivity of an array antenna system of a comparative example. [Figure 4] FIG. 1 illustrates a solution of an array antenna system according to the present disclosure. [Figure 5] FIG. 2 is a diagram illustrating the directivity of the array antenna system of the present disclosure. [Figure 6] FIG. 10 illustrates the detailed configuration of the plane wave transforming metasurface of the present disclosure. [Figure 7] FIG. 10 illustrates elevation control of a radiation beam according to the present disclosure. [Figure 8] FIG. 1 illustrates the azimuthal control of a radiation beam according to the present disclosure. [Figure 9] FIG. 1 is a diagram showing the configuration of a large array antenna system according to the present disclosure. [Figure 10] FIG. 10 illustrates the coupling shielding between conductor structures of the beam-tilting metasurface of the present disclosure. [Figure 11] FIG. 10 shows the excitation phase of each conductor structure of the beam tilting metasurface of the present disclosure. [Figure 12] FIG. 1 illustrates the directivity of a large array antenna system of the present disclosure. [Figure 13] FIG. 10 illustrates the arrangement of coupling shielding members in the beam tilting metasurface of the present disclosure. [Figure 14] FIG. 10 illustrates the arrangement of coupling shielding members in the beam tilting metasurface of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0029]

[0023] The following embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0030] (Configuration of an array antenna system as a comparative example) The configuration of the array antenna system of the comparative example is shown in Figure 1. The array antenna system S includes an array antenna A and a beam-tilting metasurface B, and can be used as a satellite communication antenna, particularly where low power consumption is desired.

[0031] The array antenna A comprises a plurality of antenna elements 1 and a plurality of equal-length lines 2, does not comprise a plurality of electronic phase shifters, and directs the main lobe of the radiation beam only forward. In this disclosure, the plurality of antenna elements 1 are patch antenna elements disposed on a dielectric substrate 3. As a variant, the plurality of antenna elements 1 may be slot antenna elements formed in a rectangular waveguide.

[0032] Beam-tilting metasurface B includes conductor structures 4 periodically arranged on a dielectric substrate 5, and is placed in front of array antenna A to tilt the radiation beam of array antenna A. Conductor structures 4 change the phase of the radiation beam depending on the size of their rectangular conductors. Non-Patent Document 1 discloses a technology for tilting the radiation beam of a single patch antenna element using only a beam-tilting metasurface placed in front of the single patch antenna element.

[0033] Here, in array antenna A, the distance between adjacent antenna elements 1 is d, and the wave number of the radiation beam in the front direction is k0. Then, in beam-tilting metasurface B, the phase change difference between adjacent conductor structures 4 is Δφ, and the wave number of the radiation beam tilted by an angle θ from the front direction is k0. Then, between these, Δφ=k0dsinθ holds.

[0034] That is, a beam tilt metasurface B, which is a passive element, is placed in front of an array antenna A, which has multiple antenna elements 1 but does not have multiple electronic phase shifters.

[0035] Therefore, in the array antenna system S, low cost and low power consumption can be achieved by using only the beam tilt metasurface B, and it can be realized as a satellite communication antenna where low power consumption is particularly desired. Furthermore, the configuration of the comparative example in Figure 1 can also be adopted for an antenna system with a single antenna element.

[0036] (Problems to be solved by the array antenna system of the comparative example) The problem to be solved by the array antenna system of the comparative example is shown in Figure 2. The directivity of the array antenna system of the comparative example is shown in Figure 3. The array antenna system S of the comparative example includes an array antenna A and a beam-tilting metasurface B, similar to the array antenna system S shown in Figure 1.

[0037] Here, in order to precisely control the passing phase in the beam tilt metasurface B, it is necessary to input a plane wave. However, in the array antenna A, the antenna elements are arranged discontinuously, so multiple spherical waves are radiated.

[0038] In the left column of Figure 2, the distance between array antenna A and beam-tilted metasurface B is approximately twice the wavelength λ used by array antenna system S. Therefore, a nearly plane wave can be incident on beam-tilted metasurface B, and the passing phase can be controlled with high precision. The solid line in Figure 3 shows the directivity for the left column of Figure 2, which forms a main lobe in the direction of approximately 15° and suppresses side lobes in other directions.

[0039] In the right column of Figure 2, the distance between array antenna A and beam-tilted metasurface B is approximately half the wavelength λ used by array antenna system S. Therefore, an imperfect plane wave is incident on beam-tilted metasurface B, making it impossible to control the passing phase with high precision. The dashed line in Figure 3 shows the directivity for the case of the right column of Figure 2, which forms a main lobe in the direction of approximately 15° and produces side lobes in other directions.

[0040] As described above, the array antenna system S of the comparative example cannot be made thin because the distance between the array antenna A and the beam tilt metasurface B needs to be about twice the wavelength λ used by the array antenna system S. Furthermore, the problem to be solved in the comparative example of Figure 2 also exists for antenna systems equipped with a single antenna element.

[0041] (Solution of the array antenna system of the present disclosure) The solution of the array antenna system of the present disclosure is shown in Figure 4. The directivity of the array antenna system of the present disclosure is shown in Figure 5. Unlike the array antenna system S shown in Figure 1, the array antenna system S of the present disclosure comprises an array antenna A, a beam tilting metasurface B, and a plane wave transforming metasurface P. The right column of Figure 4 shows a configuration similar to that of the left column of Figure 2 for comparison with the left column of Figure 4.

[0042] The plane wave conversion metasurface P has conductor structures arranged concentrically on a dielectric substrate (in Figure 6, in the plane wave conversion metasurface P, a single concentric arrangement of conductor structures is arranged for the entire array antenna A), and is placed in front of the array antenna A and between the array antenna A and the beam tilt metasurface B, to convert the radiation beam of the array antenna A into a plane wave. The conductor structures change the phase of the radiation beam depending on the size of their rectangular conductor. Non-patent document 2 discloses a technology for converting the radiation beam of a single patch antenna element into a plane wave using only a plane wave conversion metasurface placed in front of the single patch antenna element.

[0043] Here, in the plane wave conversion metasurface P, the rectangular conductors located at the center of the concentric circle arrangement are larger in size and have a larger phase delay, while the rectangular conductors located at the periphery of the concentric circle arrangement are smaller in size and have a smaller phase delay. Therefore, the plane wave conversion metasurface P can convert the radiation beam of the array antenna A into a plane wave.

[0044] In other words, a separate passive element, a plane wave conversion metasurface P, is placed in front of an array antenna A, which has multiple antenna elements but does not have multiple electronic phase shifters, and between the array antenna A and a passive element, a beam tilt metasurface B.

[0045] In this way, the array antenna system S does not require a long propagation distance to form a plane wave, and can be made thinner by using the plane wave transforming metasurface P. The configuration of the present disclosure shown in FIG. 4 can also be adopted for an antenna system having a single antenna element.

[0046] In the left column of Figure 4, the distance between the array antenna A and the plane-wave transforming metasurface P and the distance between the plane-wave transforming metasurface P and the beam-tilting metasurface B are more than 1 / 4 times the operating wavelength λ of the array antenna system S. However, unlike the right column of Figure 4, the distance between the array antenna A and the beam-tilting metasurface B is less than twice the operating wavelength λ of the array antenna system S.

[0047] Therefore, even if an imperfect plane wave is incident on the plane wave conversion metasurface P, an almost plane wave will be incident on the beam tilt metasurface B, allowing the passing phase to be controlled with high precision. The dashed line in Figure 5 shows the directivity for the case in the left column of Figure 4, which forms a main lobe in the direction of approximately 15° and suppresses side lobes in other directions.

[0048] In this way, the array antenna system S can be made thinner to about 1 / 4 of the conventional thickness by using the plane wave converting metasurface P. Furthermore, the configuration of the present disclosure shown in FIG. 4 can also be adopted for an antenna system having a single antenna element.

[0049] (Details of the configuration of the plane wave transforming metasurface of the present disclosure) The detailed configuration of the plane wave conversion metasurface of the present disclosure is shown in Figure 6. In the array antenna A, the spacing between the antenna elements is d, as in Figure 1, and in the plane wave conversion metasurface P, the size of the single concentric arrangement of the conductor structures 6 (disposed on the dielectric substrate 7) is equivalent to the overall size of the array antenna A. Therefore, in the plane wave conversion metasurface P, the single concentric arrangement of the conductor structures 6 (disposed on the dielectric substrate 7) is arranged relative to the entire array antenna A.

[0050] Here, in the vicinity of the array antenna A, multiple spherical waves are radiated because the antenna elements are arranged discontinuously. The distance between the array antenna A and the plane wave conversion metasurface P is 1 / 4 times or more the wavelength λ used by the array antenna system S. Therefore, in the vicinity of the plane wave conversion metasurface P, the multiple spherical waves are combined to form a single spherical wave. Then, in the plane wave conversion metasurface P, the phase of the single spherical wave is changed to form an approximately plane wave.

[0051] In Non-Patent Document 2, a single patch antenna element is arranged in the antenna, and therefore a partial reflecting surface (resonant structure) is arranged in addition to the plane wave converting metasurface P to further improve the radiation gain, but in the present disclosure, multiple antenna elements are arranged in the array antenna A, and therefore the radiation gain does not need to be further improved, and a partial reflecting surface (resonant structure) does not need to be arranged in addition to the plane wave converting metasurface P. Therefore, in the array antenna system S, although the plane wave converting metasurface P is used, the partial reflecting surface does not need to be used, and the system can be made thinner.

[0052] (Control of Elevation Angle of Radiation Beam According to the Present Disclosure) The elevation angle control of the radiation beam according to the present disclosure is shown in Figure 7. Array antenna A directs the main lobe of the radiation beam only in the forward direction. Plane wave conversion metasurface P converts the radiation beam of array antenna A into a plane wave. Beam tilting metasurface B tilts the radiation beam of array antenna A by a predetermined fixed angle (here, the elevation angle).

[0053] In the first column of Figure 7, an array antenna A forms a radiation beam in the z direction (front and vertical directions), and the radiation beam in the z direction (front and vertical directions) is converted into a plane wave by a plane wave conversion metasurface P. In this way, a plane wave conversion metasurface P is placed in front of it, but a beam tilt metasurface B is not placed.

[0054] In the second column of Figure 7, in addition to the first column of Figure 7, in the beam tilting metasurface B1, the radiation beam in the z direction (front direction and vertical direction) is tilted by a fixed angle θ in the xz plane (vertical horizontal plane), and the tilt angle of the radiation beam is θ. The tilt direction of the tilt angle θ of the radiation beam will be explained using Figure 8.

[0055] In the third column of Figure 7, in addition to the second column of Figure 7, in the beam tilt metasurface B2, which is the same as the beam tilt metasurface B1, the radiation beam in the z direction (front direction and vertical direction) is further tilted by a fixed angle θ in the xz plane (vertical horizontal plane), so that the total tilt angle of the radiation beam is 2θ. The tilt direction of the radiation beam tilt angle 2θ will be explained using Figure 8.

[0056] In the fourth column of Figure 7, in addition to the third column of Figure 7, in the beam tilt metasurface B3, which is the same as the beam tilt metasurface B1, the radiation beam in the z direction (front direction and vertical direction) is further tilted by a fixed angle θ in the xz plane (vertical horizontal plane), so that the total tilt angle of the radiation beam is 3θ. The tilt direction of the radiation beam tilt angle 3θ will be explained using Figure 8.

[0057] That is, the beam tilting metasurface B can be used to control the tilt angle of the radiation beam, while the plane wave converting metasurface P can be used to convert the radiation beam into a plane wave. The configuration of the present disclosure in Figure 7 can also be adopted for an antenna system having a single antenna element.

[0058] Furthermore, depending on the nearly constant elevation angle of the geostationary satellite captured by the satellite communication antenna, the number of beam tilt metasurfaces B may be set to one, two, three, etc., as shown in Figure 7.

[0059] Here, a spherical wave with directivity in an almost frontal direction is incident on the plane wave conversion metasurface P, and is converted into a plane wave with directivity in an almost frontal direction. The distance between the beam tilt metasurfaces B1 and B2 and the distance between the beam tilt metasurfaces B2 and B3 may be less than 1 / 4 of the wavelength λ used by the array antenna system S, but not more than 1 / 4, as long as the effect of combining the incident wave and the reflected wave at the beam tilt metasurfaces B2 and B3 is small.

[0060] Azimuthal Orientation Control of Radiation Beams of the Present Disclosure The control of the azimuth direction of the radiation beam according to the present disclosure is shown in Figure 8. The array antenna A, the plane wave conversion metasurface P, and the beam tilting metasurface B rotate the radiation beam of the tilted array antenna A by rotating the array antenna A, the plane wave conversion metasurface P, and the beam tilting metasurface B themselves with the in-plane direction (here, the azimuth direction) and the vertical direction (here, the vertical direction) of the array antenna A, the plane wave conversion metasurface P, and the beam tilting metasurface B as the rotation axis directions.

[0061] The left column of Fig. 8 shows a perspective view of the array antenna system S, and the right column of Fig. 8 shows a plan view of the array antenna system S. The array antenna A forms a radiation beam in the z direction (front and vertical direction), the plane wave conversion metasurface P converts the radiation beam in the z direction (front and vertical direction) into a plane wave, the beam tilting metasurface B1 tilts the radiation beam in the z direction (front and vertical direction) by a fixed angle θ in the xz plane (vertical horizontal plane), and the beam tilting metasurface B2 further tilts the radiation beam in the z direction (front and vertical direction) by a fixed angle θ in the xz plane (vertical horizontal plane).

[0062] Then, the array antenna A, the plane wave conversion metasurface P, and the beam tilt metasurfaces B1 and B2 are rotated in the same direction and by the same angle (rotation angle φ) with the in-plane direction (xy direction) and the vertical direction (z direction) of the array antenna A, the plane wave conversion metasurface P, and the beam tilt metasurfaces B1 and B2 as the rotation axis direction. A =φ P =φ B1 =φ B2 ) Then, the radiation beam of the array antenna A with tilted beam tilting metasurfaces B1 and B2 is rotated in the same direction and by the same angle (rotation angle φ) as the array antenna A, plane wave converting metasurface P, and beam tilting metasurfaces B1 and B2, with the in-plane direction (xy direction) and the vertical direction (z direction) of the array antenna A, plane wave converting metasurface P, and beam tilting metasurfaces B1 and B2 as the rotation axis direction. A =φ P =φ B1 =φ B2 ).

[0063] Here, the direction of the tilt angle of the radiation beam shown in FIG. 7 is determined by the rotation angle φ of the array antenna A, the plane wave conversion metasurface P, and the beam tilt metasurfaces B1 and B2 shown in FIG. A =φ P =φ B1 =φ B2 =0°, corresponding to 180°.

[0064] In other words, by using the plane wave converting metasurface P and the beam tilting metasurface B, the rotation angle of the radiation beam can be controlled over a wide range, with the in-plane direction and the perpendicular direction of the plane wave converting metasurface P and the beam tilting metasurface B as the rotation axis directions. Furthermore, the configuration of the present disclosure in Figure 8 can also be adopted for antenna systems having a single antenna element.

[0065] In addition, when installing a satellite communication antenna, it is desirable to perform horizontal adjustment, and a stepping motor or the like can be used to rotate the array antenna A, plane wave conversion metasurface P, and beam tilt metasurfaces B1 and B2.

[0066] (Configuration of the large array antenna system of the present disclosure) The configuration of the large-scale array antenna system of this disclosure is shown in Figure 9. The large-scale array antenna system S has array antennas A1 and A2 repeatedly arranged, and beam-tilting metasurfaces B1 and B2 repeatedly arranged. Note that the large-scale array antenna system S also has a large plane-wave transforming metasurface P arranged, which will be explained later.

[0067] Here, we discovered that when enlarging the array antenna system S, if beam-tilting metasurfaces B1 and B2 (each similar to the beam-tilting metasurface B in Figure 1) are repeatedly arranged, there is no need to redesign a single beam-tilting metasurface (the size of the dielectric substrate 5 is doubled compared to Figure 1, but the excitation phase of the conductor structure 4 is set to only one period instead of two periods from 0° to 360°-Δφ), but the sidelobe characteristics of the array antenna system S will deteriorate (see Figure 12).

[0068] This is because, when the beam-tilted metasurfaces B1 and B2 are repeatedly arranged, the coupling between the maximum and minimum conductor structures 4 has a large effect at the boundary between the beam-tilted metasurfaces B1 and B2, causing discontinuity in the excitation phase of the maximum and minimum conductor structures 4 (see Figures 10 and 11). Therefore, when the beam-tilted metasurfaces B1 and B2 are repeatedly arranged, a coupling shielding member 8 is arranged at the boundary between the beam-tilted metasurfaces B1 and B2 to shield the coupling between the maximum and minimum conductor structures 4 (see Figures 13 and 14).

[0069] (Coupling shielding between conductor structures of the beam tilt metasurface of the present disclosure) The coupling shielding between the conductor structures of the beam-tilting metasurfaces of the present disclosure is shown in Figure 10. In Figure 10, the beam-tilting metasurface B1 is placed on the left side, and the beam-tilting metasurface B2 is placed on the right side. In the beam-tilting metasurface B1, the smallest conductor structure 4, ..., the largest conductor structure 4 are placed on the dielectric substrate 5 from left to right, and a surface current flows. On the other hand, in the beam-tilting metasurface B2, the smallest conductor structure 4, ..., the largest conductor structure 4 are placed on the dielectric substrate 5 from left to right, and a surface current flows.

[0070] In the upper part of Figure 10, the influence of coupling between the largest and smallest conductor structures 4 (high size discontinuity) is large at the boundaries of the beam tilt metasurfaces B1 and B2. On the other hand, within each of the beam tilt metasurfaces B1 and B2, the influence of coupling between adjacent conductor structures 4 (low size discontinuity) is small and is overshadowed by the influence of coupling between the largest and smallest conductor structures 4 (high size discontinuity).

[0071] In the middle of Figure 10, a coupling shielding member 8 is further placed at the boundary between the beam tilt metasurfaces B1 and B2 to shield the coupling between the largest and smallest conductor structures 4 (high size discontinuity). As a result, the coupling between the largest and smallest conductor structures 4 (high size discontinuity) is shielded at the boundary between the beam tilt metasurfaces B1 and B2. On the other hand, within each of the beam tilt metasurfaces B1 and B2, the influence of the coupling between adjacent conductor structures 4 (low size discontinuity) is small, but is apparent because the influence of the coupling between the largest and smallest conductor structures 4 (high size discontinuity) is reduced.

[0072] In the lower part of Figure 10, a coupling shielding member 8 is further arranged inside each of the beam tilt metasurfaces B1 and B2 to shield the coupling between adjacent conductor structures 4 (with low size discontinuity). As a result, the coupling between adjacent conductor structures 4 (with low size discontinuity) is shielded inside each of the beam tilt metasurfaces B1 and B2. Meanwhile, the coupling between the largest and smallest conductor structures 4 (with high size discontinuity) at the boundaries of the beam tilt metasurfaces B1 and B2 is also shielded.

[0073] The excitation phase of each conductor structure of the beam-tilting metasurface of the present disclosure is shown in Figure 11. In Figure 11, the beam-tilting metasurface B1 is arranged on the left side, and the beam-tilting metasurface B2 is arranged on the right side. In the beam-tilting metasurface B1, the smallest conductor structure 4, ..., up to the largest conductor structure 4, are arranged on the dielectric substrate 5 from left to right. On the other hand, in the beam-tilting metasurface B2, the smallest conductor structure 4, ..., up to the largest conductor structure 4, are arranged on the dielectric substrate 5 from left to right.

[0074] In Figure 11, we modeled the beam tilt metasurface B1 or B2 for one sector, set periodic boundary conditions for the beam tilt metasurface B1 or B2 for one sector, and repeated the beam tilt metasurfaces B1 and B2 for two sectors to perform a simulation.

[0075] The upper left column of Figure 11 shows an ideal sawtooth phase distribution that reflects the size of the conductor structures 4. The excitation phase of the smallest first conductor structure 4 is 0°..., the excitation phase of the largest seventh conductor structure 4 is approximately -310°, the excitation phase of the smallest eighth conductor structure 4 is 0°..., and the excitation phase of the largest fourteenth conductor structure 4 is approximately -310°.

[0076] 11 shows an ideal linear phase distribution that does not take into account the folding of the phase distribution. The excitation phase of the smallest first conductor structure 4 is 0°, ..., the excitation phase of the largest seventh conductor structure 4 is approximately -310°, the excitation phase of the smallest eighth conductor structure 4 is -360°, ..., and the excitation phase of the largest fourteenth conductor structure 4 is approximately -670°.

[0077] The upper right column of Figure 11 shows the phase distribution in the upper part of Figure 10 compared to an ideal linear phase distribution. At the boundaries of the beam-tilted metasurfaces B1 and B2, the excitation phases of the largest and smallest conductor structures 4 (with high size discontinuities) become discontinuous. Meanwhile, within each of the beam-tilted metasurfaces B1 and B2, the excitation phases of adjacent conductor structures 4 (with low size discontinuities) become rippled. However, the impact of the discontinuity in the excitation phases of the largest and smallest conductor structures 4 (with high size discontinuities) is greater than the impact of the ripple in the excitation phases of adjacent conductor structures 4 (with low size discontinuities).

[0078] The right-middle column of Figure 11 shows the phase distribution in the middle of Figure 10 compared to an ideal linear phase distribution. At the boundaries of the beam-tilted metasurfaces B1 and B2, the excitation phases of the largest and smallest conductor structures 4 (with high size discontinuity) are nearly continuous. On the other hand, within each of the beam-tilted metasurfaces B1 and B2, the excitation phases of adjacent conductor structures 4 (with low size discontinuity) ripple. The influence of the ripple in the excitation phase of adjacent conductor structures 4 (with low size discontinuity) is greater than the influence of the continuity in the excitation phase of the largest and smallest conductor structures 4 (with high size discontinuity).

[0079] The lower right column of Figure 11 shows the phase distribution in the lower part of Figure 10 compared to an ideal linear phase distribution. Within each of the beam-tilted metasurfaces B1 and B2, the excitation phases of adjacent conductor structures 4 (with low size discontinuity) are nearly continuous, with no ripples compared to the middle right column of Figure 11 and equivalent ripples compared to the upper right column of Figure 11. Meanwhile, at the boundaries of the beam-tilted metasurfaces B1 and B2, the excitation phases of the largest and smallest conductor structures 4 (with high size discontinuity) are also nearly continuous. In other words, an ideal linear excitation phase distribution is obtained throughout the entire beam-tilted metasurfaces B1 and B2.

[0080] The directivity of the large-scale array antenna system of the present disclosure is shown in Figure 12. In Figure 12, a beam-tilted metasurface B1 or B2 for one sector is modeled, periodic boundary conditions are set for the beam-tilted metasurface B1 or B2 for one sector, and the beam-tilted metasurfaces B1 and B2 for two sectors are repeated to perform a simulation.

[0081] The dashed line in Figure 12 shows the side lobe characteristics of the array antenna system S in the upper part of Figure 10. It can be seen that the side lobe characteristics have deteriorated. The solid line in Figure 12 shows the side lobe characteristics of the array antenna system S in the middle part of Figure 10. It can be seen that the spacing between adjacent conductor structures 4 is narrower than 0.5 times the radiation wavelength λ, so no grating lobes occur and the side lobe characteristics have been improved. Although not shown in Figure 12, consider the side lobe characteristics of the array antenna system S in the lower part of Figure 10. Coupling shielding members 8 are provided between adjacent conductor structures 4, which shield coupling, and therefore it is believed that the side lobe characteristics have been further improved.

[0082] In this way, when the beam-tilting metasurfaces B1 and B2 are repeatedly arranged, the coupling between the maximum and minimum conductor structures 4 is shielded, so the excitation phases of the maximum and minimum conductor structures 4 become almost continuous. Therefore, when the array antenna system S is increased in size, even if the beam-tilting metasurfaces B1 and B2 are repeatedly arranged, there is no need to redesign a single beam-tilting metasurface (one in which the size of the dielectric substrate 5 is increased but the excitation phase of the conductor structures 4 is set to only one period of 0° to 360°-Δφ), and the sidelobe characteristics of the array antenna system S can be improved.

[0083] Furthermore, since the coupling between adjacent conductor structures 4 is also shielded, the excitation phase of the conductor structures 4 of the beam tilt metasurfaces B1 and B2 does not generate ripples, thereby further improving the sidelobe characteristics of the array antenna system S.

[0084] (Arrangement of coupling shielding members of the beam tilt metasurface of the present disclosure) The arrangement of the coupling shielding members of the beam tilting metasurface of the present disclosure is shown in Figure 13. The left column of Figure 13 particularly shows the boundaries of the beam tilting metasurfaces B1 and B2, i.e., the area between the largest and smallest conductor structures 4. The right column of Figure 13 particularly shows the area between the largest and smallest conductor structures 4 of the beam tilting metasurface B, which integrates the beam tilting metasurfaces B1 and B2 in a single dielectric substrate 5. The upper left and upper right columns of Figure 13 show side views of the metasurface, and the lower left and lower right columns of Figure 13 show plan views of the metasurface.

[0085] In the left column of Figure 13, a metal wall, metal tape, metal plating, or the like that penetrates the dielectric substrate 5 is arranged at the boundary between the beam tilt metasurfaces B1 and B2 as a coupling shielding member 8 that shields the coupling between the largest and smallest conductor structures 4. Here, the height of the coupling shielding member 8 in the direction parallel to the thickness direction of the dielectric substrate 5 is sufficiently high to shield the coupling between the largest and smallest conductor structures 4 via the dielectric substrate 5, and may protrude up to the height of the conductor structures 4. Furthermore, it is desirable that the width of the coupling shielding member 8 in the direction perpendicular to the thickness direction of the dielectric substrate 5 is sufficiently thin so that the coupling shielding member 8 does not function as an electrode, unlike the conductor structures 4.

[0086] In the right column of Figure 13, a metal wall, metal tape, metal plating, or the like is arranged through a part of the dielectric substrate 5 (the side of the dielectric substrate 5 where the conductor structures 4, not the equal-length line 2, are arranged) as a coupling shielding member 8 for shielding the coupling between the largest and smallest conductor structures 4 of the beam-tilting metasurface B. Here, the height of the coupling shielding member 8 in the direction parallel to the thickness direction of the dielectric substrate 5 is desirably high enough to shield the coupling between the largest and smallest conductor structures 4 via the dielectric substrate 5, and it may protrude up to the height of the conductor structures 4. Furthermore, the width of the coupling shielding member 8 in the direction perpendicular to the thickness direction of the dielectric substrate 5 is desirably thin enough so that the coupling shielding member 8 does not function as an electrode, unlike the conductor structures 4.

[0087] The arrangement of the coupling shielding members of the beam tilting metasurface of the present disclosure is also shown in Figure 14. Figure 14 particularly shows the area between the largest and smallest conductor structures 4 of beam tilting metasurface B, which integrates beam tilting metasurfaces B1 and B2 on a single dielectric substrate 5. The top and bottom of Figure 14 show a plan view and a side view of the metasurface, respectively.

[0088] 14, a metal pattern or the like is arranged to surround the periphery of each of the largest and smallest conductor structures 4 as a coupling shielding member 8 that shields the coupling between the largest and smallest conductor structures 4 of the beam-tilting metasurface B. Here, the height of the coupling shielding member 8 in the direction parallel to the thickness direction of the dielectric substrate 5 does not need to be very high (it can sufficiently shield the coupling between the largest and smallest conductor structures 4), but only needs to be about the same as the height of the conductor structures 4. Furthermore, it is desirable that the width of the coupling shielding member 8 in the direction perpendicular to the thickness direction of the dielectric substrate 5 is narrow enough so that the coupling shielding member 8 does not function as an electrode, unlike the conductor structures 4.

[0089] 9 to 14, a coupling shielding member 8 is provided at the boundary between the beam tilt metasurfaces B1 and B2 to shield the coupling between the largest and smallest conductor structures 4. On the other hand, in FIG. 9, there is no discontinuity in size or excitation phase between adjacent antenna elements 1 at the boundary between the array antennas A1 and A2, so there is no need to provide a coupling shielding member to shield the coupling between adjacent antenna elements 1.

[0090] In addition, in Figure 9, in a large plane wave converting metasurface P (in which the size of the dielectric substrate 5 is doubled compared to Figure 1, but the excitation phase of the conductor structure 6 is maintained at 0° to several tens of degrees), there is little discontinuity in size and excitation phase between adjacent conductor structures 6, so there is no need to provide a coupling shielding member to shield the coupling between adjacent conductor structures 6. [Industrial Applicability]

[0091] The antenna system disclosed herein uses a combination of a beam tilting metasurface and a plane wave conversion metasurface to tilt the radiation beam, achieving low cost and low power consumption, and can be realized as a satellite communication antenna, where low power consumption is particularly desirable. [Explanation of symbols]

[0092] S: Array antenna system A, A1, A2: Array antenna B, B1, B2, B3: Beam tilt metasurface P: Plane wave transforming metasurface 1: Antenna element 2: Equal length track 3: Dielectric substrate 4: Conductor structure 5: Dielectric substrate 6: Conductor structure 7: Dielectric substrate 8: Coupling shielding member

Claims

1. an antenna comprising one or more antenna elements; a plane wave transformation metasurface including conductor structures concentrically arranged on a dielectric substrate, the metasurface being arranged in front of the antenna and transforming a radiation beam of the antenna into a plane wave; a beam tilting metasurface comprising conductor structures periodically arranged on a dielectric substrate, the beam tilting metasurface being arranged in front of the antenna and on the opposite side of the antenna from the plane wave converting metasurface, the beam tilting metasurface tilting the radiation beam of the antenna; An antenna system comprising:

2. The antenna is an array antenna that directs the main lobe of the radiation beam only forward.

2. An antenna system according to claim 1, characterized in that:

3. The distance between the antenna and the plane wave transforming metasurface and the distance between the plane wave transforming metasurface and the beam tilting metasurface are equal to or greater than 1 / 4 of the wavelength used by the antenna system, and the distance between the antenna and the beam tilting metasurface is less than twice the wavelength used by the antenna system.

3. An antenna system according to claim 1 or 2, characterized in that it comprises:

4. The antenna, the plane wave conversion metasurface, and the beam tilting metasurface rotate themselves around a rotation axis direction that is perpendicular to the in-plane direction of the antenna, the plane wave conversion metasurface, and the beam tilting metasurface, thereby rotating the radiation beam of the antenna tilted by the beam tilting metasurface.

3. An antenna system according to claim 1 or 2, characterized in that it comprises:

5. The antenna includes a plurality of antenna elements, and the beam-tilting metasurface further includes a coupling shield that shields coupling between the largest and smallest conductor structures.

3. An antenna system according to claim 1 or 2, characterized in that it comprises:

6. The coupling shielding member shields coupling between adjacent conductor structures.

6. An antenna system according to claim 5, characterized in that:

7. The antenna system is applied as a satellite communication antenna.

3. An antenna system according to claim 1 or 2, characterized in that it comprises:

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