Antenna element and antenna array for wireless communication system

Abstract

According to an exemplary aspect of the present invention, there is provided an antenna element for an antenna array, comprising a transmission line and an antenna, wherein one end of the transmission line is coupled to a substrate of the antenna array, and the other end of the transmission line is coupled to the antenna, and a first portion of the transmission line is bent approximately 90 degrees compared to a second portion of the transmission line, and the transmission line and the antenna are located on or in a single flexible film.

Description

Technical Field

[0001] Generally speaking, embodiments of the present invention relate to antenna elements and antenna arrays for wireless communication systems. Background Art

[0002] By utilizing antenna arrays to transmit and / or receive on wireless channels, the performance of wireless communication systems can be enhanced. If antenna arrays are used for both transmission and reception, the system can be referred to as a multiple-input multiple-output MIMO system. With the increase in demand for wireless communications, the use of MIMO has become even more important than before. For example, the Third Generation Partnership Project 3GPP has developed 5G technology (which may also be referred to as new air interface, NR, radio access technology) and is considering the use of MIMO for this technology. Similar enhancements can also be used in other cellular networks and in several other wireless communication networks such as, for example, wireless local area networks WLAN. Therefore, it is expected that the use of MIMO will increase in the future. However, current antenna arrays are heavy and expensive to manufacture. Therefore, it is necessary to provide lightweight antenna arrays that are inexpensive to manufacture. Summary of the Invention

[0003] According to certain aspects, the subject matter of the independent claims is provided. Some embodiments are defined in the dependent claims.

[0004] According to a first aspect of the present invention, there is provided an antenna element for an antenna array, comprising a transmission line and an antenna, wherein one end of the transmission line is coupled to a substrate of the antenna array, and the other end of the transmission line is coupled to the antenna, and a first portion of the transmission line is bent approximately 90 degrees compared to a second portion of the transmission line, and the transmission line and the antenna are located on or in a single flexible film.

[0005] According to the first aspect of the present invention, the antenna element may further include at least a portion of a support element between the substrate of the antenna array and the antenna, wherein the transmission line may be bent along one side of the portion of the support element.

[0006] According to the first aspect of the invention, the single flexible membrane may be made of plastic.

[0007] According to the first aspect of the present invention, the single flexible membrane may include an opening, and the transmission line is arranged to pass through the opening.

[0008] According to the first aspect of the present invention, the single flexible film may be made of polyethylene terephthalate (PET) material.

[0009] According to the first aspect of the present invention, the thickness of a single flexible film may be approximately 50 microns or less, such as 25 microns.

[0010] According to the first aspect of the present invention, the antenna may be a dipole antenna.

[0011] According to the first aspect of the invention, the antenna and the substrate may be at a distance from each other, the distance preferably being comparable to a quarter of a wavelength.

[0012] According to the first aspect of the present invention, the transmission line may include copper or silver paste.

[0013] According to the first aspect of the present invention, the antenna element may further include a parasitic element connected in parallel with the antenna.

[0014] According to a second aspect of the present invention, an antenna array may comprise a plurality of antenna elements according to the first aspect.

[0015] According to a third aspect of the present invention, a radio network node may include an antenna array according to the second aspect. In some embodiments, the radio network node may be a base station configured to operate according to a 3rd Generation Partnership Project 3GPP standard. Furthermore, the 3GPP standard may be a 5G standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 illustrates exemplary antenna elements according to at least some embodiments of the present invention;

[0017] Figure 2a shows a first example of two antenna elements in accordance with at least some embodiments of the present invention;

[0018] Figure 2b shows a second example of two antenna elements in accordance with at least some embodiments of the present invention;

[0019] Figure 3a showing a third example of two antenna elements in accordance with at least some embodiments of the present invention;

[0020] Figure 3b showing a fourth example of two antenna elements in accordance with at least some embodiments of the present invention;

[0021] Figure 4a A first example of an antenna array including 8*8 antenna elements is shown according to at least some embodiments of the present invention;

[0022] Figure 4b A second example of an antenna array including 8*8 antenna elements is shown in accordance with at least some embodiments of the present invention. DETAILED DESCRIPTION

[0023] Some embodiments of the present invention relate to antenna elements of antenna arrays. More specifically, the transmission line and antenna of the antenna element can be located on or in a single flexible film (such as a 50 or 25 micron thick polyethylene terephthalate (PET) material). The transmission line and possibly a portion of the antenna can be bent downward 90 degrees toward the substrate of the antenna array and coupled to the substrate. Thus, one end of the transmission line can be coupled to an antenna such as a dipole antenna or a cross dipole, while the other end of the transmission line can be coupled to the substrate of the antenna array, thereby enabling operation of the antenna element. At the same time, due to the use of a single flexible film, the antenna element and the antenna array can be lightweight and inexpensive to manufacture.

[0024] According to some embodiments of the present invention, one end of the transmission line can be coupled to the antenna using a physical connection (e.g., a galvanic connection). Similarly, the other end of the transmission line can be coupled to the substrate of the antenna array using a physical connection. For example, the other end of the transmission line can be coupled to a feeder on the substrate. Thus, according to at least some embodiments of the present invention, the coupling need not be capacitive or inductive.

[0025] Embodiments of the present invention can be used in various wireless communication networks, such as in the context of 5G (i.e., 5G New Radio NR, 5G network), and can also be used in future cellular networks. However, embodiments of the present invention are not limited to cellular networks and can be used in any wireless system.

[0026] For example, a wireless communication network may include one or more wireless terminals, base stations, relay nodes, and / or core network elements. The wireless terminal may be connected to the base station and / or relay node via an air interface. The antenna element and / or antenna array may then be used to perform wireless communication over the air interface using a radio access technology (RAT). In the case of a cellular network, the RAT may be, for example, Long Term Evolution (LTE), New Radio (NR), or MultiFire. In the case of a non-cellular network, the RAT may be, for example, a wireless wireless area network (WLAN).

[0027] Using NR as an example of a cellular RAT, a base station may be referred to as a gNB, and a wireless terminal may be referred to as a user equipment (UE). In the context of WLAN, a base station may be referred to as an access point. In general, base stations, relay nodes, and access points may be referred to as radio network nodes. In any case, embodiments of the present invention are not limited to any particular wireless technology. Rather, embodiments of the present invention may be used in any wireless communication network in which antenna elements and / or antenna arrays are used for wireless communication.

[0028] The use of antenna arrays is expected to increase in various wireless communication systems. For example, massive multiple-input multiple-output (MIMO) systems can be used in 5G / NR BS. Therefore, the antenna elements of the antenna array should be cheap to manufacture and preferably lightweight. Therefore, an embodiment of the present invention provides an antenna element for an antenna array, wherein the antenna and the transmission line of the antenna element can be manufactured on a single flexible film. The single flexible film can be thin. For example, the single flexible film can be made of PET material. In an embodiment of the present invention, the thickness of the single flexible film is not critical, but to ensure flexibility, the thickness of the single flexible film can be 50 microns or less. For example, a thickness of 25 microns or any other thickness that facilitates bending the transmission line 90 degrees can be used. Although PET film is relatively inexpensive, the material of the single flexible film can be any low-loss RF material (e.g., polyimide). The supporting material may slightly affect the antenna characteristics and should therefore be taken into consideration in the antenna design.

[0029] The antenna element may include a transmission line for connecting an antenna (e.g., a dipole antenna) to the substrate of the antenna array. In some embodiments, the transmission line may be fabricated using copper etching or silver paste roll-to-roll printing. In other words, the transmission line may be made of copper or silver.

[0030] In some embodiments of the present invention, the transmission line can be partially separated from the single flexible film, for example, by using a punching tool, and then bent downward 90 degrees. Thus, the transmission line can be coupled or connected to the antenna from one end and can be coupled or connected to the substrate of the antenna array from the other end.

[0031] In some embodiments of the present invention, the pair line impedance can be approximately 150 ohms, with a 0.2 mm gap between the antenna array substrate and the antennas. In some embodiments, a meander line can be used to adjust the length of the transmission line. When the transmission line length is 180 degrees, the antenna input impedance returns to its original value. The transmission line length is a design issue and can be selected to facilitate impedance matching on the antenna array substrate.

[0032] In some embodiments of the present invention, an antenna element or antenna array may require a support element between the substrate of the antenna array and one or more antennas. A 3D printer may be used to manufacture the support element or a portion thereof. Alternatively, the support element or a portion thereof may be made of a substrate such as It is formed by lightweight bulk materials (relative dielectric constant close to 1).

[0033] Regarding antenna elements, Figure 1 1 shows an exemplary antenna element according to at least some embodiments of the present invention. Antenna element 100 may be used in an antenna array (in Figure 1(not shown in FIG. 1 ). In some embodiments, the exemplary single antenna element 100 is linearly polarized. Figure 1 An exemplary antenna element 100 of may include an antenna 110, such as a dipole antenna, on a single flexible film 120. The antenna 110 may be above ground and above a substrate of the antenna array.

[0034] The single flexible film 120 may be a plastic film, such as a PET film. In some embodiments, the thickness of the single flexible film 120 may be typically 50 microns or less, such as 25 microns. Figure 1 The exemplary antenna element 100 may also include a transmission line 130 (e.g., a meander line) located on or within the single flexible film 120. The transmission line 130 may include a first portion 132 and a second portion 134. Thus, in some embodiments, the first portion 132 may be located on or within the single flexible film, and the second portion 134 may be located on or within the single flexible film.

[0035] Furthermore, in some embodiments, with or without the matching element(s) 140 and / or the support element or at least a portion of the support element 150, Figure 1 In some embodiments, for example in the case of a dual-band antenna or an enhanced single-band bandwidth, Figure 1 The exemplary antenna element 100 may also include a parasitic element 160. On the other hand, when the target bandwidth of a single-band antenna can be achieved without parasitic element 160, this element may not be advantageous. In other words, in the case of a single-band antenna, the exemplary antenna element 100 may or may not include parasitic element 160. For example, parasitic element 160 may add resonance at higher frequencies. Therefore, parasitic element 160 is optional.

[0036] In some embodiments of the present invention, one end of the transmission line 130 (such as the end associated with the second portion 134 of the transmission line 130) may be coupled or connected to the substrate of the antenna array (at Figure 1 The other end of the transmission line (such as the end associated with the first portion 132 of the transmission line 130) may be coupled or connected to the antenna 110. Figure 1 As shown in FIG, the first portion 132 of the transmission line 130 may be bent approximately 90 degrees compared to the second portion 134 of the transmission line.

[0037] In some embodiments, the support element 150 or at least a portion of the support element 150 may be located between the substrate of the antenna array and the antenna 110. In such a case, the transmission line 130 may be bent along a side of the support element 150 or a portion of the support element 150. In other words, the transmission line 130 may be bent over an edge of the support element 150 or a portion of the support element 150.

[0038] exist Figure 1 , H represents the height of the exemplary antenna element 100, L represents the length of the exemplary antenna element 100, and W represents the width of the exemplary antenna element 100. Since the size of the antenna depends on the operating frequency, the electronic size (i.e., relative to the wavelength) can be used to define the antenna size. For example, for a dipole antenna element on a reflective base, for optimal bandwidth and radiation efficiency, at the center frequency, L can be close to half the wavelength and H can be close to one-quarter of the wavelength (e.g., at 3.5 GHz, L ~ 40 mm and H ~ 20 mm). The minimum W is determined by the antenna (dipole) width and possible parasitic elements. The distance can also be referred to as a gap. In some embodiments, the gap can be filled with a support element 150.

[0039] Figure 2a and 2b 1 and 2 show first and second examples of two antenna elements, respectively, according to at least some embodiments of the present invention. Figure 2a and 2b 3 , the first antenna is represented by 210a, the second antenna is represented by 210b, the first transmission line connected or coupled to the first antenna 210a is represented by 230a, and the second transmission line connected or coupled to the second antenna 210b is represented by 230b. The first antenna 210a and the second antenna 210b may correspond to the antenna 210 of FIG. 3 , and the first transmission line 230a and the second transmission line 230b may correspond to Figure 1 transmission line 130. In addition, Figure 2b , a first feeder 240a and a second feeder 240b are shown. The first feeder 240a and the second feeder 240b may correspond to Figure 1 Feeder 140.

[0040] exist Figure 2a and 2b In FIG. 1 , the first parasitic element is represented by 260a, and the second parasitic element is represented by 260b. The first parasitic element 260a and the second parasitic element 260b may correspond to Figure 1 The parasitic element 160. Similar to the Figure 1 In the case of the exemplary antenna element of FIG. 1 , the first parasitic element 260 a and the second parasitic element 260 b are optional, such as may be used in the case of a bandwidth enhancement or dual-band antenna.

[0041] like Figure 2a As shown in FIG, the first antenna 210a, the second antenna 210b, the first transmission line 230a and the second transmission line 230b may be located on a single flexible film 220. The single flexible film 220 may correspond to Figure 1 A single flexible membrane 120. Figure 2a An example is depicted where transmission lines 230a and 230b are inflexible.

[0042] Figure 2b An example is depicted in which the first portion of the first transmission line 230a can be bent approximately 90 degrees relative to the second portion of the first transmission line 230a. Similarly, the first portion of the second transmission line 230a can be bent approximately 90 degrees relative to the second portion of the second transmission line 230a. Thus, the first transmission line 230a and the second transmission line 230b can be connected or coupled to the substrate 270 of the antenna array after being bent.

[0043] Final matching can be accomplished on the antenna array substrate 270, or in some cases directly on a transmission line attached to a flexible film. Matching can be accomplished using discrete components (such as inductors and capacitors) or distributed components (such as transmission lines), or a combination of both. For example, in some embodiments of the present invention, matching can be accomplished using a single microstrip line bobbin end printed (or etched) perpendicular to the feed lines 140, 240, and 240b. The feed line itself can also be part of the matching circuit. Thus, embodiments of the present invention enable simple and cost-effective manufacturing.

[0044] Figure 3a and 3b A third example and a fourth example, respectively, of two antenna elements are shown, in accordance with at least some embodiments of the present invention. Figure 3a The example of can be called an example of a stamped antenna film or sheet, while Figure 3b The example of may be referred to as an example of a curved antenna film or sheet.

[0045] Similar to Figure 2a and 2b in Figure 3a and 3b , the first antenna is represented by 310a, the second antenna is represented by 310b, the first transmission line connected or coupled to the first antenna 310a is represented by 330a, and the second transmission line connected or coupled to the second antenna 310b is represented by 330b. The first antenna 310a and the second antenna 310b may correspond to Figure 1 The antenna 110, and the first transmission line 330a and the second transmission line 330b may correspond to Figure 1 The transmission line 130. Figure 3aIn FIG. 1 , a single flexible film 320 is also shown, and the single flexible film may correspond to Figure 1 A single flexible film 120. In addition, Figure 3b , a first opening 380a and a second opening 380b are shown on a single flexible sheet.

[0046] Figure 3a A first dipole antenna 310a, a second dipole antenna 310b, a first transmission line 330a, and a second transmission line 330b are shown on a single flexible film 320 (ie, sheet). The single flexible film 320 may be referred to as a stamped antenna sheet.

[0047] Then, Figure 3b The first antenna 310a, the second antenna 310b, the first transmission line 330a, and the second transmission line 330b on a single flexible film 320 (i.e., sheet) are shown when the first portion 332a of the first transmission line 330a is bent 90 degrees compared to the second portion 334a of the first transmission line 330b. The first portion 332b of the second transmission line 330b is also bent 90 degrees compared to the second portion 334b ​​of the second transmission line 330b. Figure 3b As shown in the example of , a single flexible film 310b can be bent, and the first transmission line 330a is arranged to pass through the first opening 380a, while the second transmission line 330b is arranged to pass through the second opening 380b.

[0048] That is, for example, before being bent, the first portion 332a of the first transmission line 330a may be located at the same level as the second portion 334a of the first transmission line 330a, i.e., as in Figure 3a Likewise, the first transmission line 330a may be located at the same level as the antenna 310a before being bent. However, as Figure 3b As shown in FIG, after the first portion of the first transmission line 330a is bent, it may be perpendicular to the second portion of the first transmission line 330a and perpendicular to the antenna 310a.

[0049] Figure 4a and 4b First and second examples of antenna arrays including 8x8 antenna elements, respectively, are shown in accordance with at least some embodiments of the present invention. However, embodiments of the present invention may generally be used with antenna arrays including any number of antenna elements. For example, embodiments of the present invention may be used with antenna arrays including 128 antenna elements (e.g., for a 6 GHz sub-band, such as for single-band 3.2–3.8 GHz and dual-band 3.3–5.0 GHz).

[0050] exist Figure 4a and 4b, an antenna array is represented by 400, an antenna is represented by 410, a single flexible film is represented by 420, and a transmission line is represented by 430. The antenna 410, the single flexible film 420, and the transmission line 430 may correspond to Figure 1 The antenna 110, the single flexible film 120 and the transmission line 130. Figure 4b , a substrate 470 is shown, and the substrate 470 may correspond to the substrate 270 of FIG. 2 . Figure 4b , spacers 490 are also shown. In some embodiments, spacers 490 may be referred to as support elements. Furthermore, spacers 490 may be located between substrate 470 and one or more antennas 410. In some embodiments, spacers 490 may be required to support a single film 420 (i.e., in the form of an antenna film). Spacers 490 may be printed using a 3D printer.

[0051] Thus, embodiments of the present invention provide antenna elements for antenna arrays, wherein the antenna elements can be made from inexpensive and lightweight materials. Furthermore, embodiments of the present invention provide antenna elements and antenna arrays suitable for mass production. For example, if a single flexible film is copper-plated, conventional etching processes can be employed on the single flexible film. Alternatively, if some metal loss can be tolerated, roll-to-roll silver printing can be employed.

[0052] Although the essence of the present invention is that the structure is light, the production cost is low and it is suitable for mass production, another aspect is that the transmission line connecting the antenna element and the substrate can be printed / etched as a pair of lines on the same side of the flexible sheet (i.e. film) that serves as the antenna. In addition, since the antenna transmission line pattern can be only on one side of the flexible sheet, there is no need for alignment of printing as in a two-layer or multi-layer structure. The impedance level of such a transmission line can be higher (~150 ohms) instead of the more convenient ~50 ohms, but when the transmission line is half a wavelength long, the antenna input impedance is close to the original impedance. Since the distance L is about a quarter of the wavelength, the missing quarter can be achieved by line meandering. In addition, the line length can be tuned to tune the rest of the antenna on the substrate (for example, using the transmission line shaft end). In some cases, matching can be performed on the antenna sheet.

[0053] It should be understood that the embodiments of the present invention disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but extend to equivalents thereof as recognized by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0054] Throughout this specification, reference to an embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Where terms such as "approximately" or "substantially" are used to refer to values, the exact value is also disclosed.

[0055] As used herein, for convenience, multiple items, structural elements, synthetic elements, and / or materials may be present in common lists. However, these lists should be interpreted as if each member of the list is independently identified as a separate and unique member. Therefore, in the absence of contrary instructions, any individual member on such a list should not be interpreted as being in fact equivalent to any other member on the same list simply based on its presentation in a common group. In addition, various embodiments and examples of the present invention, along with alternatives to its various components, may be mentioned herein. It should be understood that such embodiments, examples, and alternatives are not to be interpreted as de facto equivalents of each other, but rather should be viewed as independent and autonomous representations of the present invention.

[0056] In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the previous description, many specific details are provided, such as examples of length and width, shape, etc. as electrical dimensions (i.e., as a function of the wavelength used), to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art will recognize that the present invention can be implemented without one or more of the specific details, or using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the present invention.

[0057] Although the above examples illustrate the principles of the present invention in one or more specific applications, it is obvious to those skilled in the art that, without exercising inventive power, numerous modifications may be made to the form, usage, and implementation details without departing from the principles and concepts of the present invention. Therefore, the present invention is not intended to be limited except by the claims set forth below.

[0058] The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the presence of unrecited features. The features recited in the dependent claims are freely combinable with each other unless expressly stated otherwise. Furthermore, it should be understood that throughout this document, the use of "a" (i.e., the singular) does not exclude a plurality.

[0059] Industrial Applicability

[0060] At least some embodiments of the present invention have industrial applications in wireless communication networks. Examples of wireless communication networks include 5G / NR and WLAN networks. For example, antenna elements or antenna arrays according to at least some embodiments of the present invention are particularly suitable for wireless communication networks using massive MIMO, such as 5G base stations.

[0061] List of abbreviations

[0062] 3GPP Third Generation Partnership Project

[0063] 5G 5th Generation

[0064] LTE Long Term Evolution

[0065] MIMO Multiple Input Multiple Output

[0066] NR New Radio

[0067] PET polyethylene terephthalate

[0068] RAT Radio Access Technology

[0069] RF

[0070] UE User Equipment

[0071] WLAN Wireless Local Area Network

[0072] Reference Signs List

[0073]

[0074]

Claims

1. An antenna element for an antenna array, comprising: A transmission line and an antenna, wherein one end of the transmission line is coupled to a substrate of the antenna array, the other end of the transmission line is coupled to the antenna, and a first portion of the transmission line is bent approximately 90 degrees compared to a second portion of the transmission line, and the transmission line and the antenna are located on or in a single flexible film, wherein The single flexible membrane includes an opening, and the transmission line is arranged to pass through the opening and the opening is a hole. 2 . The antenna element according to claim 1 , further comprising at least a portion of a support element between a substrate of the antenna array and the antenna, wherein the transmission line is bent along one side of the portion of the support element.

3. The antenna element according to claim 1 or claim 2, wherein: The single flexible membrane is made of plastic.

4. The antenna element according to claim 1 or 2, wherein: The single flexible film is made of polyethylene terephthalate (PET) material.

5. The antenna element according to claim 1 or 2, wherein: The thickness of the single flexible film is about 50 microns or less.

6. The antenna element according to claim 1 or 2, wherein: The thickness of the single flexible film is approximately 25 microns.

7. The antenna element according to claim 1 or 2, wherein: The antenna is a dipole antenna.

8. The antenna element according to claim 1 or 2, wherein: The antenna and the substrate are spaced a distance apart from each other.

9. The antenna element according to claim 8, wherein The distance is one quarter of the wavelength.

10. The antenna element according to claim 1 or 2, wherein: The transmission line includes copper or silver paste.

11. The antenna element according to claim 1 or 2, wherein: The antenna element also includes a parasitic element connected in parallel with the antenna.

12. An antenna array comprising a plurality of antenna elements according to any preceding claim.

13. A wireless network node comprising the antenna array according to claim 12.

14. The wireless network node according to claim 13, wherein: The radio network node is a base station configured to operate according to the 3rd Generation Partnership Project 3GPP standard.

15. The wireless network node according to claim 14, wherein: The 3GPP standard is the 5G standard.

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