WO2023025386A1

WO2023025386A1 - Base-station antenna radio frequency, rf, device and a method for producing the base-station antenna rf device

Info

Publication number: WO2023025386A1
Application number: PCT/EP2021/073611
Authority: WO
Inventors: Qiangguo Zhou; Christian Helbig; Johann Baptist Obermaier; Bernhard Rist; Dieter Zierhut; Tekin ÖLMEZ; Serban REBEGEA; Sebastian ILSANKER
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-08-26
Filing date: 2021-08-26
Publication date: 2023-03-02

Abstract

Provided is a base-station antenna Radio Frequency, RF, device (400). The RF device (400) comprising a dielectric substrate (402, 804) and one or more metal layers (404). The one or more metal layers (404) including one or more patterned metal layers. The dielectric substrate (402, 804) is non-homogeneous. The one or more metal layers (404) and the dielectric substrate (402, 804) provide at least one of a RF signal line, a RF radiating element, a RF director and a RF isolator.

Description

BASE-STATION ANTENNA RADIO FREQUENCY, RE, DEVICE AND A METHOD FOR PRODUCING THE BASE-STATION ANTENNA RF DEVICE

TECHNICAE FIELD

The disclosure relates to antenna systems, and more particularly to a base-station antenna radio frequency (RF) device and a method for producing the base-station antenna RF device.

BACKGROUND

With development of antenna systems, the radiating or isolation parts become more and more complex. Especially with the rise of meta surfaces, printed circuit boards, PCBs, are more and more being used for antenna dipole and isolation components. For low band radiator, it needs a big size PCB to meet the 1/4 X principle, for example, 120mm* 120mm size PCB for one LB radiator. FIGS. 1A-1C illustrate an antenna circuit, according to a prior art implementation. For example, FIG. 1A illustrates an antenna circuit, where one antenna has tens of Low Band, LB, and High Band, HB, Printed Circuit Boards (PCBs). FIG. IB illustrates a typical PCB dipole. The PCB dipole includes three kinds of parts such as a dipole radiator, a dipole director, and an isolation part. These PCB dipole parts contribute to a large quantity of PCBs. FIG. 1C illustrates a PCB isolation bar in an antenna circuit. The PCB isolation bar includes isolation parts with metal surface structure, which are not suitable for sheet metal process, also use PCBs, although the requirements (such as, accuracy) for these isolation parts are not high.

FIGS. 2A-2B are schematic diagrams of a single impedance microstrip line of an antenna circuit, in accordance with a prior art implementation. The impedance of the antenna circuit is mainly decided by the dielectric constant a, the dielectric thickness h, the width of signal line w. The widely used antenna rigid PCB process always includes 2 main steps such as substrate lamination and etching. The laminate, for example, FR4 sheet, is a homogeneous substrate with fixed Radiofrequency, RF, properties, such as fixed Dk and Df. The PCB with a variable Dk and Df value substrate is not possible. For this reason, the impedance design of antenna PCB, which normally can tune the local width of signal line can only be tuned to obtain the suitable impedance and the other factors such as local dielectric constant or thickness cannot be tuned. The RF loss of the circuit is mainly decided by the dielectric material under the signal line. FIG. 2B illustrates field distribution of the signal line. Due to the high-frequency characteristic, the antenna design pursues low RF loss to obtain high efficiency. Low loss PCB substrate is selected, such as PTFE substrate PCB, Df <0.005 @l. lGHz). But due to the special material and special process, low loss substrate is relatively expensive.

FIGS. 3A-3B are schematic diagrams of an antenna dipole radiator PCB and PCB layer structuring, in accordance with a prior art implementation. Conventionally, for base station antenna PCB as shown in FIG. 3A, uses Copper (35pm) as a main circuit metal, in order to achieve high conductivity and solderability. Copper is relatively expensive compared to Aluminum. The production of PCB is a very complicated and long process, especially it needs electroplating Cu and tinning on the circuit area for etching purposes. That contributes to high cost of etching. Meanwhile, the widely used antenna PCB process is done one plate by plate, not roll to roll, because the laminates are rigid, which leads to low production efficiency. These factors, in turn, lead to high cost of antenna components, such as dipole radiator, director, and isolation parts which need large size PCBs. FIB 3B illustrates a typical antenna circuit layer structure, which includes a solder mask 302, copper layer with etched pattern 304, adhesives layer 306, fiber-reinforced substrate 308, and ground layer 310.

The conventional methods propose many methods for solving the difficulty of tuning the antenna circuit impedance and reduce the loss at the antenna circuit board. The existing methods perform the tuning of antenna circuit impendence by modification of geometry and width of the circuit. Further, the existing methods normally use lower loss substrate to reduce the loss. These methods however have the limitation of flexibility and high cost.

Therefore, there arises a need to address the aforementioned technical drawbacks in known techniques or technologies by providing an optimal antenna design with reduces the loss at the circuit and reduces the cost of the current antenna solution.

SUMMARY It is an object of the disclosure to provide a base-station antenna Radio Frequency, RF, device and a method for producing the base- station antenna Radio Frequency device while avoiding one or more disadvantages of prior art approaches.

This object is achieved by the features of the independent claims. Further, implementation forms are apparent from the dependent claims, the description, and the figures.

The disclosure provides a base-station antenna Radio Frequency, RF, device and a method for producing the base- station antenna Radio Frequency device.

According to a first aspect, there is provided a base- station antenna Radio Frequency, RF, device. The base-station antenna, RF, device includes a dielectric substrate and one or more layers. The one or more layers include one or more patterned metal layers. The dielectric substrate is non-homogeneous.

Thus, the base-station antenna, RF, device herein uses a non-homogeneous substrate under an antenna circuit to generate a multi-layer structure. The usage of the non- homogeneous substrate enables to obtain high flexibility of impedance tuning and lower RF loss in an antenna. The non-homogeneous substrate is the substrate with different Dk, Df, or with different thicknesses. By using air as the dielectric substrate under the metal circuit, the loss at the antenna circuit can be reduced. Due to this reason, expensive low loss substrate is not required which in turn reduces the cost of the overall circuit.

Optionally, the one or more metal layers and the dielectric substrate provide at least one of the following: a RF signal line, a RF radiating element, a RF director, and a RF isolator.

Optionally, the dielectric substrate is non-homogeneous in that it includes a first portion and a second portion arranged adjacent to each other and differing from each other in one or more of the following: thickness, dielectric constant, and dissipation factor.

Optionally, each of the first portion and the second portion is homogenous. Optionally, each of the first portion and the second portion has a planar extension greater than 1 mm.

Optionally, the second portion or a part of the second portion is arranged above or below at least one of the patterned metal layers. Optionally, the second portion of a dielectric supporting substrate is an empty space.

Optionally, the one or more patterned metal layer includes a metal foil laminated with a carrier foil. Optionally, the metal foil includes an etched circuit pattern.

Optionally, the lamination and etching of the metal foil are performed roll-to-roll. Optionally, the roughness of etched metal edge in the etched circuit pattern is less than or equal to 100 micrometers.

Optionally, the one or more patterned metal layers include a first patterned metal layer and a second patterned metal layer. Optionally, at least a portion of the first patterned metal layer is arranged on top of one of the one or more dielectric supporting substrates and at least a portion of the second patterned metal layer is arranged under the one of the one or more dielectric supporting substrates.

Optionally, the base-station antenna Radio Frequency device is multilayered includes more than one patterned metal layer of which at least one portion is arranged to act as a signal line and more than one non-homogeneous dielectric supporting substrate.

According to a second aspect, a method for producing a base- station antenna Radio Frequency device is provided. The method includes laminating a metal foil with a carrier foil. The method includes etching a circuit pattern into the metal foil. The method includes mounting the laminated metal foil on a non-homogeneous dielectric substrate.

Thus, the method herein uses a non-homogeneous substrate under an antenna circuit to generate a multi-layer structure. The usage of the non-homogeneous substrate enables to obtain high flexibility of impedance tuning and lower RF loss in an antenna. The non- homogeneous substrate is the substrate with different Dk, Df, or with different thicknesses. By using air as the dielectric substrate under the metal circuit, the loss at the antenna circuit can be reduced. By this method, it is very easy to tune the antenna impedance without changing the antenna circuit or obtain ultra-low loss without using an expensive low loss substrate.

Optionally, the method includes providing the non-homogeneous dielectric substrate through injection molding. Optionally, the method includes providing the non- homogeneous dielectric substrate through milling.

Optionally, the method includes providing the non-homogeneous dielectric substrate through extrusion. Optionally, the method includes laminating the metal foil with a carrier foil through a roll-to-roll process.

Optionally, the method further includes etching the circuit pattern into the metal foil through a roll-to-roll process. Optionally, the method further includes providing a metallization area on a portion of the metal layer by cutting an opening in the carrier foil at the portion of the metal layer and providing a metal in the cut opening. Optionally, the method includes providing the metal in the cut opening by plating or tinning.

A technical problem in the prior art is resolved, where the technical problem concerns on obtaining high flexibility of impedance tuning and lowering RF loss in an antenna circuit board.

Therefore, in contradistinction to the prior art, according to the base- station antenna Radio Frequency device RF device and method of producing the base- station antenna Radio Frequency device of the disclosure, provides for obtaining high flexibility of impedance tuning without change in the antenna circuit and lower RF loss in antenna without using expensive low loss substrate.

These and other aspects of the disclosure will be apparent from and the implementation(s) described below. BRIEF DESCRIPTION OF DRAWINGS

Implementations of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIGS. 1A-1C illustrate an antenna circuit, according to a prior art implementation;

FIGS. 2A-2B are schematic diagrams of a single impedance microstrip line of an antenna circuit, in accordance with a prior art implementation;

FIGS. 3A-3B are schematic diagrams of an antenna dipole radiator PCB and PCB layer structuring, in accordance with a prior art implementation;

FIG. 4 is a perspective diagram illustrating a base-station antenna Radio Frequency, RF, device, in accordance with an implementation of the disclosure;

FIGS. 5A-5C are exemplary illustrations of an antenna circuit component, in accordance with an implementation of the disclosure;

FIG. 6 is an exemplary illustration of an antenna circuit component, in accordance with an implementation of the disclosure;

FIGS. 7A-7C are another exemplary diagrams illustrating an antenna circuit component, in accordance with another implementation of the disclosure;

FIGS. 8A-8B are another exemplary diagrams illustrating an antenna circuit component, in accordance with another implementation of the disclosure; and

FIG. 9 is a flow diagram illustrating a method of producing a base-station antenna Radio Frequency device, in accordance with an implementation of the disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

Implementations of the disclosure provide a base-station antenna Radio Frequency, RF, device and a method for producing the base-station antenna Radio Frequency device.

To make solutions of the disclosure more comprehensible for a person skilled in the art, the following implementations of the disclosure are described with reference to the accompanying drawings.

Terms such as "a first", "a second", "a third", and "a fourth" (if any) in the summary, claims, and foregoing accompanying drawings of the disclosure are used to distinguish between similar objects and are not necessarily used to describe a specific sequence or order. It should be understood that the terms so used are interchangeable under appropriate circumstances, so that the implementations of the disclosure described herein are, for example, capable of being implemented in sequences other than the sequences illustrated or described herein. Furthermore, the terms "include" and "have" and any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, a method, a system, a product, or a device that includes a series of steps or units, is not necessarily limited to expressly listed steps or units but may include other steps or units that are not expressly listed or that are inherent to such process, method, product, or device.

FIG. 4 is a perspective diagram illustrating a base-station antenna Radio Frequency, RF, device 400, in accordance with an implementation of the disclosure. The base-station antenna Radio Frequency, RF, device 400 includes a dielectric substrate 402 and one or more metal layers 404. The one or more metal layers 404 include one or more patterned metal layers 408. The dielectric substance is non-homogenous.

The base-station antenna Radio Frequency (RF) device 400 herein uses a non- homogeneous substrate under an antenna circuit to generate a multi-layer structure. The non-homogeneous substrate is the substrate with different Dk, Df, or with different thicknesses. The non-homogeneous substrate provides for high flexibility of impedance tuning and lower RF loss in an antenna. Due to this reason, expensive low loss substrate is not required which in turn reduces the cost of overall circuit.

Optionally, the RF device 400 herein can be, for example, but not limited to, a filter director, dipole radiator, isolation part, or phase shifter strip line.

Optionally, the dielectric substrate 402 and the one or more metal layers 404 provide at least one of the following: a RF signal line, a RF radiating element, a RF director, and a RF isolator. Optionally, the dielectric substrate 402 is non-homogeneous in that it includes a first portion 406A and a second portion 406B arranged adjacent to each other. The first portion 406A and the second portion 406B differ from each other in one or more of the following, but not limited to, thickness, dielectric constant, and dissipation factor. The dielectric substrate 402 doesn’t need to be a single piece. The dielectric substrate 402 may include two or more pieces arranged adjacent to each other, where the two or more pieces may be arranged adjacent to each other possibly with air gaps as inhomogeneities of the dielectric substrate 402.

Optionally, each of the first portion 406A and the second portion 406B is homogenous. Optionally, each of the first portion 406A and the second portion 406B has a planar extension, e.g. width or length, but not thickness, having a size greater than 1 mm. Optionally, the second portion 406B, or a part of the second portion 406B is arranged above or below at least one of the patterned metal layers. Optionally, the second portion 406B of a dielectric supporting substrate is an empty space.

Optionally, the one or more patterned metal layers includes a metal foil 408 laminated with a carrier foil. The metal foil 408 includes an etched circuit pattern 410. Optionally, the lamination and etching of the metal foil 408 are performed roll-to-roll. Optionally, the roughness of etched metal edge in the etched circuit pattern is less than or equal to 100 micrometers.

Optionally, the one or more patterned metal layers include a first patterned metal layer and a second patterned metal layer. Optionally, at least one portion of the first patterned metal layer is arranged on top of one of the one or more dielectric supporting substrates and at least a portion of the second patterned metal layer is arranged under the one of the one or more dielectric supporting substrates.

Optionally, the base-station antenna Radio Frequency device 400 is multilayered. The multilayers include more than one patterned metal layer of which at least one portion is arranged to act as a signal line and more than one non-homogeneous dielectric supporting substrate. FIGS. 5A-5C are exemplary illustrations of an antenna circuit component, in accordance with an implementation of the disclosure. FIG. 5A illustrates a single side Al circuit component, whereas FIG. 5B illustrates a double-sided antenna circuit component and 5C illustrates a multi-layer circuit component. In FIG. 5A, an antenna circuit component includes a carrier layer 502 and a dielectric component 504 with variable dielectric factors. In RF transmission circuits, the dielectric component 504 has variable Dk and the loss factor Df can be achieved using a material with a perforated substrate, in which it is air 506 under a signal line 508 (as shown in FIG. 5C). The dielectric material under the signal line 508 is to be removed so that the RF loss in that area will be 0. This in turn reduces overall loss of the substrates, significantly. Once the air 506 is removed under the signal line 508, the Dk and Df of the supporting substrate are not significant anymore. Optionally, a normal plastic substrate can be used, thereby avoiding the use of ultra-low loss substrate, which contributes greatly to the cost. This can be applied to double sided circuit components or multi-layer circuit components, as shown in FIG. 5B and 5C respectively.

FIG. 6 is an exemplary illustration of an antenna circuit component, in accordance with an implementation of the disclosure. FIG. 6 illustrates a perforated substrate 602 and the antenna circuit component with perforated substrate superimposed. Optionally, a patterned metal circuit 604 is laminated to the perforated substrate 602. Optionally, most of the areas under the patterned metal circuit 604 are air thereby, enabling that RF loss under the patterned metal circuit 604 is close to 0.

FIGS. 7A-7C are another exemplary illustrations of an antenna circuit component, in accordance with an implementation of the disclosure. FIG. 7A illustrates a composite substrate 702 with a single-sided circuit component and FIG. 7B illustrates a composite substrate 702 with a double-sided Al circuit component. Optionally, variable components, Dk, Df are obtained by a composite substrate made from a double-shot molding process. The di-electric materials can be, for example, ceramics, dielectric plastics with different Dk and Df, and the like. FIG. 7C illustrates a composite substrate with a multi-layer substrate component. The Dk, Df variable component can also be obtained by differing thickness of the composite substrate by multi-layering. The multilayer substrate includes a substrate with variable thickness 704, an adhesive layer 706, an aluminum layer with etched pattern 708, and thin protection or carrier layer 710. The multi-layering of composite substrate provides for flexibility in impedance design.

FIGS. 8A-8B are another exemplary illustrations of an antenna circuit component, in accordance with an implementation of the disclosure. FIG. 8A illustrates a double-sided foil circuit component with a soldering pad 802. The double-sided foil circuit component includes, a dielectric substrate 804 with variable Dk and Df, a protection layer 806, a metal layer 808 with an etched pattern, and a laser cut window 810 on the protection foil for selective metallization on the metal layer 808. The soldering pad 802 is obtained by performing selective metallization on the metal layer 808 after combining the etched metal/carrier foil laminate to Dk, Df variable dielectric substrate, such as electro-less plating or ultrasonic soldering methods.

FIG. 8B illustrates a perspective view of a selectively metalized soldering pad 802 in accordance with an implementation of the disclosure. The soldering pad 802 includes metallized areas 812 on the metal layer 808. The metal layer 808 includes laser cut windows 810 on the protection foil for selective metallization on the metal layer 808 to obtain the soldering pad 802. The metal layer 808 includes electro-less plated Nickel and Tin layer on cut areas. Alternatively, the metal layer 808 includes ultrasonic soldering of the Tin layer on the cut areas.

FIG. 9 is a flow diagram illustrating a method of producing a base-station antenna Radio Frequency device, in accordance with an implementation of the disclosure. At a step 902, a metal foil is laminated with a carrier foil. At a step 904, a circuit pattern is etched into the metal foil. At a step 906, a laminated metal foil is moulded on a non-homogeneous dielectric substrate.

The method herein enables ultra- low loss of the antenna circuit by using air as a dielectric substrate under the metal circuit. Due to this reason, expensive low loss substrate is not necessary and the cost of overall circuit can be reduced. Further, high freedom of circuit impedance design by providing variable Dk, Df substrate, such as making smaller signal line width by using high Dk material locally. Moreover, the base station design herein reduces the cost of the current antenna solution by using cheap metal such as Aluminum (comparing to Cu) and R2R etched foil. Optionally, the method includes providing the non-homogeneous dielectric substrate through injection molding. Optionally, the method includes providing the non- homogeneous dielectric substrate through milling. Optionally, the method includes providing the non-homogeneous dielectric substrate through extrusion.

Optionally, the method further includes laminating the metal foil with a carrier foil through a roll-to-roll process. Optionally, the method includes etching the circuit pattern into the metal foil through a roll-to-roll process.

Optionally, the method further includes providing a metallization area on a portion of the metal layer by cutting an opening in the carrier foil at the portion of the metal layer and providing a metal in the cut opening.

Optionally, the method further includes providing the metal in the cut opening by plating or tinning.

It should be understood that the arrangement of components illustrated in the figures described are exemplary and that other arrangement may be possible. It should also be understood that the various system components (and means) defined by the claims, described below, and illustrated in the various block diagrams represent components in some systems configured according to the subject matter disclosed herein. For example, one or more of these system components (and means) may be realized, in whole or in part, by at least some of the components illustrated in the arrangements illustrated in the described figures.

In addition, while at least one of these components are implemented at least partially as an electronic hardware component, and therefore constitutes a machine, the other components may be implemented in software that when included in an execution environment constitutes a machine, hardware, or a combination of software and hardware.

Although the disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A base-station antenna Radio Frequency, RF, device (400) comprising: a dielectric substrate (402, 804); and one or more metal layers (404), the one or more metal layers (404) including one or more patterned metal layers, characterized in that the dielectric substrate (402, 804) is non-homogeneous.

2. The base- station antenna Radio Frequency device (400) according to claim 1, wherein the one or more metal layers (404) and the dielectric substrate (402, 804) provide at least one of the following: a RF signal line, a RF radiating element, a RF director, a RF isolator.

3. The base-station antenna Radio Frequency device (400) according to any preceding claim, wherein the dielectric substrate (402, 804) is non-homogeneous in that it comprises a first portion (406A) and a second portion (406B) arranged adjacent to each other and differing from each other in one or more of the following: thickness, dielectric constant, and dissipation factor.

4. The base- station antenna Radio Frequency device (400) according to claim 3, wherein each of the first portion (406A) and the second portion (406B) is homogenous.

5. The base-station antenna Radio Frequency device (400) according to claim 3 or 4, wherein each of the first portion (406 A) and the second portion (406B) has a planar extension greater than 1 mm.

6. The base station antenna Radio Frequency device (400) of claim 3, wherein the second portion (406B) or a part of the second portion (406B) is arranged above or below at least one of the patterned metal layers (408).

7. The base-station antenna Radio Frequency device (400) according to any preceding claim, wherein the second portion (406B) of a dielectric supporting substrate is an empty space.

8. The base-station antenna Radio Frequency device (400) according to any preceding claim, wherein the one or more patterned metal layer comprises a metal foil (408) laminated with a carrier foil, and wherein the metal foil (408) comprises an etched circuit pattern.

9. The base-station antenna Radio Frequency device (400) according to any preceding claim, wherein the lamination and etching of the metal foil (408) is performed roll-to-roll.

10. The base-station antenna Radio Frequency device (400) according to claim 8 or 9, wherein the roughness of etched metal edge in the etched circuit pattern is less than or equal to 100 micrometers.

11. The base- station antenna Radio Frequency device (400) according to any preceding claim, wherein the one or more patterned metal layers comprise a first patterned metal layer and a second patterned metal layer, wherein at least a portion of the first patterned metal layer is arranged on top of one of the one or more dielectric supporting substrates and at least a portion of the second patterned metal layer is arranged under the one of the one or more dielectric supporting substrates.

12. The base- station antenna Radio Frequency device (400) according to any preceding claim, wherein the base-station antenna Radio Frequency device (400) is multilayered comprising: more than one patterned metal layer of which at least one portion is arranged to act as a signal line; and more than one non-homogeneous dielectric supporting substrate.

13. A method for producing a base-station antenna Radio Frequency device (400), the method comprising: laminating a metal foil (408) with a carrier foil; etching a circuit pattern into the metal foil (408); and mounting the laminated metal foil on a non-homogeneous dielectric substrate (402, 804).

14. The method according to claim 13, further comprising providing the non- homogeneous dielectric substrate (402, 804) through injection molding.

15. The method according to claim 13, further comprising providing the non- homogeneous dielectric substrate (402, 804) through milling.

16. The method according to claim 13, further comprising providing the non- homogeneous dielectric substrate (402, 804) through extrusion.

17. The method according to any of claims 13 to 16, further comprising laminating the metal foil (408) with a carrier foil through a roll-to-roll process.

18. The method according to any of claims 13 to 17, further comprising etching the circuit pattern into the metal foil (408) through a roll-to-roll process.

19. The method according to any of claims 13 to 17, further comprising providing a metallization area on a portion of the metal layer by cutting an opening in the carrier foil at the portion of the metal layer and providing a metal in the cut opening.

20. The method according to claim 19, further comprising providing the metal in the cut opening by plating or tinning.

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