Multi-beam antenna

Abstract

The present disclosure relates to an antenna device. The antenna device includes a radiator array and a superstrate. The radiator array includes at least two unequal radiators for radiating radio waves. The at least two unequal radiators are coupled. The superstrate is arranged above the radiator in a main direction of radiation. A dense arrangement of the at least two coupled unequal radiators allows exploiting the spatial degrees of freedom of the aperture. The superstrate can contribute to increasing the directivity of radiation. In this way, the antenna device can emit beams with improved resolution of radiation patterns. Moreover, the beam directivity can be enhanced, and more control points (i.e. antenna ports) can be achieved whilst keeping a compact design of the antenna device.

Description

[0001] MULTI-BEAM ANTENNA

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to the field of communications technology. For instance, the present disclosure provides an antenna device and related devices.

[0004] BACKGROUND

[0005] Communication systems make use of various frequency ranges. High-frequency bands suffer from poor propagation characteristics. Low-frequency bands are more attractive in terms of propagation and coverage, but low-frequency bands require large antennas.

[0006] SUMMARY

[0007] There is a need to keep antennas within constrained dimensions. However, the restricted dimensions of a communications device may impose difficult challenges to antenna design. For instance, the radiators or antenna arrays may influence each other strongly, which makes it challenging to reduce the active return loss at antenna ports.

[0008] Further, it is also desirable to achieve an optimized spatial resolution. A better spatial resolution with respect to user distribution is often beneficial in terms of system performance. For instance, a better spatial resolution may increase beam directivity, and, in MIMO communication systems, allow serving more users jointly (at the same time and / or the same frequency band).

[0009] Further, it is also desirable to have an antenna design with a larger number of control points (i.e., ports).

[0010] Considering the three factors above, it is challenging to design antennas to achieve a better spatial resolution with a greater number of ports under constrained dimensions. In view of the above-mentioned problems and disadvantages, the present disclosure aims to improve multi-beam antenna design. An objective may be to provide a multi-beam antenna device with an increased radiator density without causing performance degradation.

[0011] These and other objectives are achieved by this disclosure, for instance, as described in the independent claims. Advantageous implementations are further described in the dependent claims.

[0012] A first aspect of the present disclosure provides an antenna device comprising a radiator array and a superstrate. The radiator array comprises at least two unequal radiators for radiating radio waves. The at least two unequal radiators are coupled. The superstrate is arranged above the radiator in a main direction of radiation.

[0013] By coupling the at least two radiators, a dense arrangement of radiators can be achieved. Moreover, since the at least two coupled radiators are unequal, spatial degrees of freedom of aperture can be exploited, not only in the boresight direction but also in angles away from the boresight direction.

[0014] In an implementation form of the first aspect, the at least two unequal coupled radiators may be unequal with respect to one or more of: radiator dimension; pointing direction; and half power beam width.

[0015] In this way, the beam steering limits of conventional arrays can be overcome.

[0016] In an implementation form of the first aspect, the at least two unequal radiators may be tightly coupled or connected.

[0017] In this way, by placing the at least two radiators nearly in contact with each other, only the active return loss matters, and not the passive S-parameters. Because the active return loss accounts for the addition of both the passive return loss and the coupling among the at least two radiators, and informs of the radiator’s efficiency within its environment; whilst the passive return loss only provides partial information. Thus, the limitations of dense arrays due to excessive coupling can be bypassed.

[0018] It is noted that the at least two unequal radiators may be tightly coupled such that a mutual coupling between the at least two unequal radiators is introduced. In this disclosure, the existence of the mutual coupling is admitted. The combination of the mutual coupling and the passive return loss is considered, in order to achieve an acceptable active return loss. In this way, the size of the antenna device can be even smaller.

[0019] In an implementation form of the first aspect, the at least two unequal radiators may be dualpolarized radiators.

[0020] In an implementation form of the first aspect, the antenna device may further comprise an impedance-matching strate arranged between the radiator array and the superstrate. The impedance-matching strate is configured to match the impedance of the radio waves, to obtain impedance-matched radio waves.

[0021] In this way, the active return loss at different steering directions can be reduced.

[0022] In an implementation form of the first aspect, the impedance-matching strate comprises at least one block adapted to match the return loss of the radio waves at different steering directions.

[0023] In an implementation form of the first aspect, the at least one block is a dielectric block or an artificial dielectric block.

[0024] In an implementation form of the first aspect, the impedance-matching strate may comprise a plurality of layers. In an implementation form of the first aspect, the superstrate may be adapted to increase the directivity of the radio waves. When the impedance-matching strate is present, the directivity of the impedance-matched radio waves is increased by the superstrate.

[0025] In an implementation form of the first aspect, the superstrate may comprise a microwave lens or a metasurface.

[0026] It is noted that the microwave lens or the metasurface may be adapted to increase the effective aperture, in order to increase the directivity of the radio waves.

[0027] In an implementation form of the first aspect, the microwave lens may comprise a shaped dielectric or a gradient-index (GRIN) lens.

[0028] In an implementation form of the first aspect, the metasurface may comprise an arrangement of printed conductive shapes. Optionally, the printed conductive shapes may be Jerusalem crosses.

[0029] In an implementation form of the first aspect, the printed conductive shapes may be of unequal configurations.

[0030] In an implementation form of the first aspect, the superstrate may comprise a plurality of layers.

[0031] A second aspect of this disclosure provides a communication device comprising one or more antenna devices each according to the first aspect or any implementation form thereof.

[0032] Optionally, the communication device may further comprise a feeding network coupled to each antenna device. The feeding network is adapted to feed input signals to the antenna device. Multiple antenna devices and the multiple corresponding feeding networks may form an antenna array. BRIEF DESCRIPTION OF DRAWINGS

[0033] The above-described aspects and implementation forms will be explained in the following description in relation to the enclosed drawings, in which

[0034] FIG. 1 A shows an example of at least a part of an antenna device of this disclosure;

[0035] FIG. IB shows a top view of at least two coupled unequal radiators;

[0036] FIG. 2 shows an exploded view of at least a part of an antenna device of this disclosure;

[0037] FIG. 3 shows a further exploded view of at least a part of an antenna device of this disclosure;

[0038] FIG. 4 shows a side view of at least a part of an antenna device of this disclosure;

[0039] FIG. 5 shows at least a part of an antenna device and components thereof; and

[0040] FIG. 6 shows a top view of an antenna array.

[0041] DETAILED DESCRIPTION OF EMBODIMENTS

[0042] FIG. 1 A shows an example of at least a part of an antenna device 100 of this disclosure, which is a 3D exploded view thereof.

[0043] The antenna device 100 comprises a radiator array 110 and a superstate 130. The radiator array 110 comprises at least two unequal radiators 111, 112 for radiating radio waves. The at least two unequal radiators 111, 112 are coupled. The superstate 130 is arranged above the radiator 110 in a main direction of radiation.

[0044] Optionally, the at least two unequal radiators 111, 112 may be tightly coupled. The wording of “tightly coupled” is a term widely used in the field of antenna design. It may be understood that the at least two unequal radiators are spaced close to each other, such that a mutual coupling between the at least two unequal radiators is introduced. Optionally, the at least two unequal radiators may be connected (or attached to each other).

[0045] By arranging the unequal radiators nearly in contact with each other, only the active return loss matters. The passive S-parameters do not matter anymore. In this way, the limitation of dense arrays due to excessive coupling can be bypassed. Moreover, more control points (i.e. antenna ports) can be achieved for low-frequency bands.

[0046] Further, by tightly coupling the unequal (or different) radiators, the beam steering limitation can be overcome. Thus, a higher directivity can be achieved.

[0047] The superstate 130 may be adapted to increase the effective aperture of the antenna device 100. Thus, the directivity of the radio waves from the radiator array can be increased. In this way, an even higher directivity can be achieved.

[0048] FIG. IB shows a top view of at least two coupled unequal radiators 111, 112. Optionally, the at least two coupled unequal radiators 111, 112 may be unequal (or different) with respect to the radiator dimension, and / or pointing direction, and / or half power beam width (HPBW). Optionally, the at least two coupled unequal radiators 111, 112 may be dual-polarized radiators. Alternatively, radiators of other kinds of polarization may be used, e.g., single polarization.

[0049] FIG. 2 shows a further example of an antenna device 100 of this disclosure, which is a 3D exploded view thereof. FIG. 2 may be built based on FIG. 1A and IB. In FIGs 1 A, IB and 2, corresponding elements may share the same features and function likewise.

[0050] As depicted in FIG. 2, the radiator array 110 exemplarily comprises four radiators 111, 112, 113, 114. Optionally, every two coupled radiators may be unequal (or different) from each other. That is, radiator 111 and radiator 112 are different; radiator 112 and radiator 113 are different; and radiator 113 and radiator 114 are different. Optionally, it is also possible that each and every radiator 111, 112, 113, 114 is different from each other.

[0051] Optionally, the antenna device 100 may comprise an impedance-matching state 120 arranged between the radiator array 110 and the superstate 130. The impedance-matching state 120 is configured to match the impedance of the radio waves from the radiator array 110, to obtain impedance-matched radio waves.

[0052] Optionally, the impedance-matching strate 120 may comprise at least one block adapted to match the return loss of the radio waves from the radiator array 110 at different steering directions. Optionally, the at least one block may be a dielectric block or an artificial dielectric block. In FIG. 2, four blocks 121, 122, 123, 124 are exemplarily shown.

[0053] Optionally, the superstrate 130 may comprise one or more layers. In FIG. 2, three layers are exemplarily shown. Each layer may comprise sub-parts 131, 132 that are of different configurations.

[0054] FIG. 3 shows a further example of an antenna device 100 of this disclosure. The left-hand side of FIG. 3 shows a 3D exploded view thereof. FIG. 3 may be built based on FIG. 2. In FIGs 1 A, IB, 2 and 3, corresponding elements may share the same features and function likewise.

[0055] Optionally, the superstrate 130 may comprise a microwave lens or a metasurface. The microwave lens may comprise a shaped dielectric lens or a GRIN lens.

[0056] Optionally, the metasurface may comprise an arrangement of printed conductive shapes, such as Jerusalem crosses that are separately and exemplarily illustrated in the top right-hand side of FIG. 3.

[0057] Optionally, the impedance-matching strate may comprise one or more layers. For example, the impedance-matching strate may consist in a metalens. Optionally, the metalens may comprise one or more layers. In FIG. 3, three layers are exemplarily shown. Each layer may comprise a plurality of unit cells. The plurality of unit cells composing an artificial dielectric lens by a plurality of layers may take the form of different patches at the center, side, and edge in order to match the active return loss of radio waves at different steering directions. In this way, the power loss is reduced. Moreover, a lightweight antenna design can be achieved.

[0058] FIG. 4 shows a side view of at least a part of an antenna device 100 of this disclosure. FIG. 4 is built based on FIG. 3. FIG. 5 shows an antenna device and components thereof. In particular, an assembled view of the antenna device 100 is shown on the left-hand side of FIG. 5, and each part thereof is separately shown on the right-hand side of FIG. 5.

[0059] In summation, this disclosure proposes an antenna device 100 with a dense arrangement of coupled unequal radiators 110, which allows exploiting the spatial degrees of freedom of the aperture, not only in boresight direction but also in angles away from it. Further, the antenna device 100 comprises a superstate 130 that contributes to increasing the directivity of radiation, and therefore the achievable resolution of the radiation patterns. Optionally, the antenna device 100 may further comprise an active impedance matching state between the radiators 110 and the superstate 120, which allows for keeping the active return loss under control, whilst maintaining a compact size. For instance, the antenna device 100 shown in FIG. 5 with four coupled unequal radiators may be in a size of 500mm along the x-axis, 200mm along the -axis, and 125mm along the z-axis. The impedance matching state may be 67.5mm along the -axis. It is noted that the size mentioned above are for illustration purposes only, the antenna device 100 may be in various sizes depending on different configurations.

[0060] An application scenario of the antenna device 100 of this disclosure is for a multi-user communication system, in particular a MIMO communication system. The antenna device may be used for low-frequency bands in cellular communication systems, e.g. sub- 1 GHz. Nevertheless, it is noted that the antenna device 100 of this disclosure may be applied to any other suitable frequency band.

[0061] FIG. 6 shows an application scenario of an antenna device of this disclosure. As an example, a panel antenna, which is built based on the structure of the antenna device 100, may be used for low- frequency (e.g., sub- 1 GHz) cellular communications. The panel antenna shown on the lefthand side of FIG. 6 comprises a 4x 16 antenna array with dual polarization. That is, the panel antenna comprises a radiator array of 4x 16 coupled radiators. It is noted that the 4x 16 antenna array herein may also be referred to as an 8x l6-port antenna array. The superstate and the optional impedance-matching state arranged on top of the radiator array are also comprised in the panel antenna but are not shown in FIG. 6. The panel antenna may be compact in size. For instance, the panel antenna may be in a size of 2100mm x 500 mm. On the right-hand side of FIG. 6, a sub-array is separately and exemplarily shown with its feeding network. It is noted that the feeding network is separately depicted for illustration purposes only and does not represent an actual assemble configuration. For instance, the feeding network may be assembled beneath the sub-array (in the main direction of radiation).

[0062] A further aspect of this disclosure provides an antenna array comprising multiple antenna devices 100 that are coupled and arranged on a plane.

[0063] A further aspect of this disclosure also provides a communication device comprising at least one antenna device 100, or an antenna array built based on the antenna device 100. For instance, the communication device may be a user equipment, or a base station.

[0064] It is noted that the antenna device 100 introduced in this disclosure may be reciprocally used as a receiving antenna device.

[0065] The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

CLAIMS1. An antenna device (100) comprising a radiator array (110) and a superstate (130), wherein the radiator array (110) comprises at least two unequal radiators (111, 112) for radiating radio waves, wherein the at least two unequal radiators (111, 112) are coupled; and wherein the superstate (130) is arranged above the radiator in a main direction of radiation.

2. The antenna device (100) according to claim 1, wherein the at least two unequal radiators (111, 112) are unequal with respect to one or more of:- radiator dimension;- pointing direction; and- half power beam width.

3. The antenna device (100) according to claim 1 or 2, wherein the at least two unequal radiators (111, 112) are tightly coupled or connected.

4. The antenna device (100) according to any one of claims 1 to 3, wherein the at least two unequal radiators (111, 112) are dual-polarized radiators.

5. The antenna device (100) according to any one of claims 1 to 4, wherein the antenna device (100) further comprises an impedance-matching strate (120) arranged between the radiator array (110) and the superstate (130), wherein the impedance-matching strate (120) is configured to match the impedance of the radio waves, to obtain impedance-matched radio waves.

6. The antenna device (100) according to claim 5, wherein the impedance-matching strate (120) comprises at least one block adapted to match the return loss of the radio waves at different steering directions.

7. The antenna device (100) according to claim 6, wherein the at least one block is a dielectric block or an artificial dielectric block.

8. The antenna device (100) according to any one of claims 4 to 7, wherein the impedancematching strate (120) comprises a plurality of layers.

9. The antenna device (100) according to any one of claims 1 to 8, wherein the superstate (130) is adapted to increase the directivity of the radio waves.

10. The antenna device (100) according to any one of claims 1 to 9, wherein the superstate (130) comprises a microwave lens or a metasurface.

11. The antenna device (100) according to claim 10, wherein the microwave lens comprises a shaped dielectric or a gradient-index, GRIN, lens.

12. The antenna device (100) according to claim 10, wherein the metasurface comprises an arrangement of printed conductive shapes, wherein optionally, the printed conductive shapes are Jerusalem crosses.

13. The antenna device (100) according to claim 12, wherein the printed conductive shapes are of unequal configurations.

14. The antenna device (100) according to any one of claims 1 to 13, wherein the superstate (130) comprises a plurality of layers.

15. A communication device comprising one or more antenna devices (100) according to any one of claims 1 to 14.

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