WO2020143903A1

WO2020143903A1 - Flat panel antenna and manufacturing method

Info

Publication number: WO2020143903A1
Application number: PCT/EP2019/050284
Authority: WO
Inventors: Fabio Morgia
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2019-01-08
Filing date: 2019-01-08
Publication date: 2020-07-16

Abstract

The present invention provides a radiating unit, a flat panel antenna comprising an array of the radiating units, and a method for manufacturing the flat panel antenna. The radiating unit comprises a power divider element and four elongated radiator elements. The power divider element comprises one input port and four elongated output ports. Further, each of the four radiator elements is attached to one output port of the power divider element, and wherein each radiator element is rotated by 45° with respect to each output port of the power divider element. The specific design of the radiating units allows to form flat panel antenna comprising an array of radiating units by an injection molding process using only two molds.

Description

FLAT PANEL ANTENNA AND MANUFACTURING METHOD

TECHNICAL FIELD

The present invention relates to a microwave antenna, and in particular, to a flat panel antenna used to transmit and/or receive electromagnetic radiation. The invention particularly proposes a radiating unit for the flat panel antenna. The radiating unit includes a power divider element and at least four radiator elements arranged according to a novel design.

BACKGROUND

Antennas are required for Backhaul Radio-links either at traditional microwave bands or at millimeter-wave bands. At the moment dish antennas are widely used for these applications, but dish antennas become less acceptable due to their high impact in urban environments. For this reason, an idea is to replace dish antennas by flat antenna arrays (FAA). A more attractive look of the FAA is not the only advantage. In particular, a FAA has lower dimensions and lower weight than a dish antenna as well. For instance, a 0.6m dish antenna weighs about 7 kg. With the same gain value, the FAA may be up to ten times lighter compared to the dish antenna. The lighter weight allows customers to save money by doing the installation themselves. Due to its much smaller dimensions, the FAA is twice as inexpensive in terms of storage, transportation and packing logistics. Another advantage of the FAA is that it can be fully pre-assembled at the factory.

Despite the advantages of the FFA, there are still two main reasons why the FAA has not yet replaced satellite dish antennas. The first reason is the price. The price of the FAA is still too high to mass market it. At the moment, the order cost of the FAA is more or less two times that of the dish antenna. The second reason is the Radiation Pattern Envelope (RPE) performance in terms of Class of the FAA. The ETSI document (ETSI EN 302 217- 4-2) addresses the requirements for directional fixed beam antennas to be utilized with new Point-to-Point (P-P) systems. The document defines the RPE in terms of co- and cross polarization. The values of these parameters define the Class of the antenna. FIG. 1 shows an example of the RPEs for a class 2 antenna. Currently, the conventional FAA is not able to meet the required class.

SUMMARY

In view of the above-mentioned problems and disadvantages, the present invention aims to improve the conventional FAA and its productions method. An objective is thereby to provide a radiating unit that allows building a FAA with the above-mentioned advantages and at the same time meeting the class requirements. The radiating unit should also enable building a flat panel antenna with higher electrical performance and reduced costs. It should be possible to fabricate the FAA using molds, wherein it should particularly be possible to use only two molds.

The objective is achieved by the solution provided in the enclosed independent claims. Advantageous implementations of the present invention are further defined in the dependent claims.

In particular the present invention proposes a hollow-waveguide slot array, where a full- corporate-feed waveguide is arranged, in order to achieve high gain and high efficiency antennas. Further, embodiments of the invention also propose a new kind of radiator element, which can satisfy the highest class of the ETSI requirements. Finally, embodiments of the invention provide a manufacturing method that uses as few as two molds, which allows the antenna to be easily built up by injection molding process (metal or plastic). It means cost reduction in terms of non-recurring engineering (NRE) and assembling.

A first aspect of the invention provides a radiating unit for a flat panel antenna for transmitting and/or receiving electromagnetic radiation, the radiating unit comprising a power divider element and four elongated radiator elements, wherein the power divider element comprises one input port and four elongated output ports; wherein each of the four radiator elements is attached to one output port of the power divider element, and wherein each radiator element is rotated by 45° with respect to each output port of the power divider element. The radiating unit is specifically designed to meet the requirements of wide bandwidth characteristic, high gain, high efficiency, and RPE Class 3/4. At the same time, the radiating unit is very compact, thus allowing to build a compact antenna. The radiator element allows rotation by 45° of the output ports of the power divider element, in order to realize a rhomboidal lattice during fabrication. The special shape of the radiating unit thus allows to implement the antenna with four radiator elements per radiating unit, using only two molds. It is also possible to provide more than four radiator elements per radiating unit, e.g. 8, 16, or generally 2^N, N being a natural number and N > 1. The number of molds at least needed depends on the amount of radiator elements per radiating unit. In particular, N molds are at least required for 2^N radiator elements per radiating unit. For instance, if each radiating unit has 8 radiator elements, it is beneficial to divide these radiator elements by 4 and 4 over two stacked molds.

In an implementation form of the first aspect, each output port of the power divider includes a ridge waveguide for feeding the radiator element attached to it.

In order to meet one of the fundamental requirements (i.e. ETSI class at least 3), it is beneficial to reduce as much as possible the distance between the radiator elements. For this reason the power divider has been implemented using a ridge waveguide, since this allows a smaller form factor.

In an implementation form of the first aspect, each elongated radiator element comprises a protrusion on each side, the protrusions being coupled to the ridge waveguide of the output port it is attached to.

In order to realize/fabricate the antenna in only two molds, the protrusions on the radiator elements are beneficial.

In an implementation form of the first aspect, each radiator elements is configured to guide a signal from the ridge waveguide to a standard waveguide.

The radiator elements thus move the signal from the ridge waveguide to the standard waveguide. In an implementation form of the first aspect, the radiating unit is formed by an injection molding process using two molds.

The special shape of the radiating unit allows to implement the injection molding process, i.e. obtaining the antenna, using only two molds.

A second aspect of the invention provides a flat panel antenna for transmitting and/or receiving electromagnetic radiation, comprising an array of radiating units, each radiating unit according to the first aspect or any one of implementation form of the first aspect.

In an implementation form of the second aspect, the array of radiating units is formed by an injection molding process using as few as two molds, particularly molds with a square shape.

The shape of the radiating unit allows to build the antenna using a rhomboidal lattice (see e.g. FIG. 5) in arranging the radiating units. This means that a high class in terms of RPE without any rotation of the radiator elements can be achieved (see e.g. FIG. 6).

In an implementation form of the second aspect, an upper mold comprises an array of the radiator elements and an upper part of an array of the power dividers, and a lower mold comprises a lower part of the array of the power dividers.

Molds may be provided on top of each other and attached. Several techniques can be used to merge the at least two molds: by screws, by conductive glue, by a diffusion bonding process or by a welding technique.

The antenna may particularly be an array antenna. Array antennas typically utilize either printed circuit technology or waveguide technology. The components of the array, which interface with free-space, includes the radiator elements, and may utilize micro-strip geometries, such as patches, dipoles or slots, or waveguide components such as horns, or slots respectively. The radiator elements may be interconnected by a feeding network, so that the resulting electromagnetic radiation characteristics of the antenna conform to desired characteristics, such as the antenna beam pointing direction, directivity, and side lobe distribution. A third aspect of the invention provides a method for manufacturing a flat panel antenna for transmitting and/or receiving electromagnetic radiation, comprising: forming an array of radiating units using two molds; wherein the forming of the array of radiating units comprises: forming an upper mold including an array of elongated radiator elements and an upper part of an array of the power dividers, and forming a lower mold including a lower part of the array of power divider elements, wherein each power divider element comprises one input port and four elongated output ports; wherein the upper and lower molds are attached to each other in a manner that the radiator elements are rotated by 45° with respect to the output ports of the power divider element.

Another advantage of this design is the number of the molds that is needed for the implementation of the antenna, in particular, as few as two molds are needed (see explanation above).

In an implementation form of the third aspect, the power divider element is implemented with ridge waveguides, wherein each output port includes at least one ridge waveguide.

In an implementation form of the third aspect, the array of radiating units is arranged aligned with the diagonal of the molds, wherein the long side of each radiator element is parallel to the diagonal of the molds.

In this way, the flat panel antenna can be built using rhomboidal lattice (as shown e.g. in FIG. 5), which means achieving high class in terms of RPE without any rotation of the radiator elements (see e.g. FIG. 6).

In an implementation form of the third aspect, forming the array of radiating units using two molds comprises an injection molding process using the two molds.

In an implementation form of the third aspect, the injection molding process is a metal injection molding process or a plastic injection molding process. In an implementation form of the third aspect, the upper mold and the lower mold are fixed together, particularly using screws, conductive glue, a diffusion bonding process or a welding technique. It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 shows an example of the RPEs for a class 2 antenna. FIG. 2 shows a schematic isometric view and a top view of a radiating unit according to an embodiment of the invention.

FIG. 3 shows a schematic isometric view of a power divider element of a radiating unit according to an embodiment of the invention.

FIG. 4 shows a schematic isometric view of a radiator element of a radiating unit according to an embodiment of the invention. FIG. 5 shows a rhomboidal lattice used to build a flat panel antenna according to embodiments of the present invention.

FIG. 6 shows an example of the RPEs of high class (class 3/4) antennas according to embodiments of the present invention.

FIG. 7 shows a top view and a bottom view of two molds used to form a flat panel antenna according to embodiments of the present invention. FIG. 8 shows a schematic block flowchart of a method for manufacturing a flat panel antenna according to embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS The embodiments of the present invention may realize an antenna, which is able to achieve wide bandwidth characteristic, high gain, high efficiency, and RPE Class 3/4. This antenna can be built up easily by injection molding process (metal or plastic) using as few as only two molds. FIG. 2 shows a design of a fundamental cell of the antenna according to an embodiment of the invention. In particular, FIG. 2 shows a radiating unit 200 according to an embodiment of the invention, which forms the basis for the fundamental cell. The antenna may comprise multiple such radiating units 200 arranged in an array. A radiating part (top side) and a first part of the feed waveguide (bottom side) particularly build up the radiating unit 200, which is specifically designed in order to meet all the requirements.

The radiating unit 200 may be composed of at least the following two parts: A power divider element 201 comprising an input port 2011 and four output ports 2012 (see FIG. 3), and four elongated radiator elements 202. Notably, FIG. 2 shows the smallest possible configuration of the radiating unit 200 with four radiator elements 202. This radiating unit 200 allows fabricating an antenna using only two molds. However, the radiating unit 200 may also be designed in a similar manner with more than four radiator elements 202, particularly 2^N radiator elements (N > 1). FIG. 3 shows in more detail the power divider element 201, and FIG. 4 shows in more detail one of the radiation elements 202 of the radiating unit 200 shown in FIG. 2. Each of the four radiator elements 202 is attached to one output port 2012 of the power divider element 201. In addition, each radiator element 202 is rotated by 45° with respect to each output port 2012 of the power divider element 201. That means, the elongation axis of each of the radiator elements 202 is rotated around the elongation axis of the elongated output ports 2012 by 45°.

As shown in FIG. 3, the power divider element 201 comprises one input port 2011 and four elongated output ports 2012. Optionally, the power divider 201 is composed by a union of rectangular waveguides. Each waveguide may work only in a range of frequencies, i.e. a frequency band of the rectangular waveguide. In order to reduce the size of the power divider 201, the size of the rectangular waveguide has been reduced. In particular, by using a ridge waveguide 2013, the size may be reduced without reducing the frequency band of the power divider 201. The ridge waveguide 2013 may be a uniform rectangular waveguide with one or two (double ridge) rectangular metal insets in the top and/or in the bottom of the rectangular housing. Compared to a rectangular waveguide of the same outer dimensions, the ridge waveguide 2013 can have a much lower cut-off frequency of its fundamental mode. In other words, for the same cut-off frequency of the fundamental mode, the cross-section of the ridge waveguide 2013 may be much smaller than that of the rectangular waveguide, which presents an opportunity for compact designs.

In order to meet one of the fundamental requirements (ETSI class 3) it is beneficial to reduce as much as possible the distance between the radiator elements. This is supported by implementing the power divider 201 using ridge waveguides 2013. Furthermore, this is achieved by the 45° rotation of the radiator elements 202 with respect to the power divider output ports 2012.

Referring to FIG. 4, each elongated radiator element 202 may comprise a protrusion 2021 on each of its (long) sides, the protrusions 2021 being beneficially coupled to the ridge waveguide 2013 of the output port 2012 it is attached to. Each radiator element 202 may in this way guide a signal from the ridge waveguide 2013 to a standard waveguide. The shape of the radiator elements 202 allows to form radiating units 200 by an injection molding process using as few as two molds.

According to an embodiment of the present invention, a flat panel antenna is provided. The flat panel antenna comprises an array of radiating units 200 as shown in FIG. 2. Each radiating unit 200 thereby may comprise a power divider element 201 as shown in FIG. 3 and four elongated radiator elements 202 as shown in FIG. 4.

Optionally, each output port 2012 of the power divider 201 includes a ridge waveguide 2013 for feeding the radiator element 202 attached to it. The dimension of the ridge waveguides 2013 may be determined according to a specific frequency requirement of the flat panel antenna. Optionally, each radiator element 202 may moves a signal from the ridge waveguide 2013 to a standard waveguide.

Optionally, the array of radiating units 200 is formed by an injection molding process using two molds, particularly molds with a square shape. The radiator elements 202 of the radiating unit 200 allow the rotation of the 45° of the output of the power divider 201. This special shape allows to build the flat panel antenna using a rhomboidal lattice of radiator elements 202 as shown in FIG. 5. In this way, a high class antenna in terms of RPE can be achieved. FIG. 6 shows an example of the RPEs of high class (class 3/4) antennas according to embodiments of the present invention.

FIG. 7 shows a top view and a bottom view of two molds used to form the flat panel antenna according to embodiments of the present invention. Optionally, an upper mold 701 comprises an array of the radiator elements 202 and an upper part of an array of the power dividers 201, and a lower mold 702 comprises a lower part of the array of the power dividers 201. The cutting plane is where the part of the ridge waveguide 2013 starts. An advantage of this design is the number of the molds needed for the implementation of the antenna. As shown in FIG. 7, only two molds are needed to build an antenna having multiple radiating units with four radiator elements 202 each. The upper mold 701 and lower mold 702 may have identical shapes, for instance, a square shape, with possibly different dimension of height. The height of upper mold 701 may depend on the dimension of the radiator elements 202 and the power divider 201, wherein the height of the lower mold 702 may depend on the dimension of the power divider 201. FIG. 8 shows a schematic block flowchart of a method 800 for manufacturing a flat panel antenna according to embodiments of the present invention. The method comprises the step 801 of forming an array of radiating units 200 using two molds; wherein the forming of the array of radiating units 200 comprises: the step 8011 of forming an upper mold 701 including an array of elongated radiator elements 202 and an upper part of an array of the power dividers 201, and the step 8012 of forming a lower mold 702 including a lower part of the array of power divider elements 201, wherein each power divider element 201 comprises one input port 2011 and four elongated output ports 2012; wherein the upper and lower molds 701, 702 are attached to each other in a manner that the radiator elements 202 are rotated by 45° with respect to the output ports 2012 of the power divider element 201.

The upper mold 701 and the lower mold 702 may be formed separately. Optionally, an injection molding process may be used to manufacture the flat panel antenna according to embodiments of the present invention. Optionally, the injection molding process may be a metal injection molding process or a plastic injection molding process.

Optionally, the power divider element 201 is implemented with ridge waveguides 2013, wherein each output port 2012 may include at least one ridge waveguide 2013. The dimension of the ridge waveguides 2013 may be determined according to a specific frequency requirement of the flat panel antenna.

Optionally, the array of radiating units 200 is arranged aligned with the diagonal of the molds 701, 702, wherein the long side of each radiator element 202 may be parallel to the diagonal of the molds. In other words, the elongation axis of radiator elements 202 may be parallel to one diagonal of the molds. In particular, the molds may be in a square shape. Therefore, the elongation axis of the output ports 2012 of the power divider 201 may be parallel to two sides of the molds.

Optionally, the upper mold 701 and the lower mold 702 are fixed together, particularly using screws, conductive glue, and a diffusion bonding process or a welding technique. 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

1. Radiating unit (200) for a flat panel antenna for transmitting and/or receiving electromagnetic radiation, the radiating unit (200) comprising a power divider element (201) and four elongated radiator elements (202),

wherein the power divider element (201) comprises one input port (2011) and four elongated output ports (2012);

wherein each of the four radiator elements (202) is attached to one output port (2012) of the power divider element (201), and

wherein each radiator element (202) is rotated by 45° with respect to each output port (2012) of the power divider element (201).

2. Radiating unit (200) according to claim 1, wherein

each output port (2012) of the power divider (201) includes a ridge waveguide (2013) for feeding the radiator element (202) attached to it.

3. Radiating unit (200) according to claim 1 or 2, wherein

each elongated radiator element (202) comprises a protrusion (2021) on each side, the protrusions being coupled to the ridge waveguide (2013) of the output port (2012) it is attached to.

4. Radiating unit (200) according to any of claims 1 to 3, wherein each radiator element (202) is configured to

guide a signal from the ridge waveguide (2013) to a standard waveguide.

5. Radiating unit (200) according to any of claims 1 to 4, wherein

the radiating unit (200) is formed by an injection molding process using two molds.

6. Flat panel antenna for transmitting and/or receiving electromagnetic radiation, comprising an array of radiating units (200), each radiating unit (200) according to any one of claims 1 to 5.

7. Flat panel antenna according to claim 6, wherein

the array of radiating units (200) is formed by an injection molding process using two molds, particularly molds with a square shape.

8. Flat panel antenna according to one of the claims 6 or 7, wherein

an upper mold (701) comprises an array of the radiator elements (202) and an upper part of an array of the power dividers (201), and

a lower mold (702) comprises a lower part of the array of the power dividers

(201).

9. A method (800) for manufacturing a flat panel antenna for transmitting and/or receiving electromagnetic radiation, comprising,

forming (801) an array of radiating units (200) using two molds;

wherein the forming of the array of radiating units (200) comprises:

forming (8011) an upper mold (701) including an array of elongated radiator elements (202) and an upper part of an array of the power dividers (201), and

forming (8012) a lower mold (702) including a lower part of the array of power divider elements (201),

wherein each power divider element (201) comprises one input port (2011) and four elongated output ports (2012);

wherein the upper and lower molds are attached to each other in a manner that the radiator elements (202) are rotated by 45° with respect to the output ports (2012) of the power divider element (201).

10. The method (800) according to claim 9, wherein

the power divider element (201) is implemented with ridge waveguides (2013), wherein each output port (2012) includes at least one ridge waveguide (2013).

11. The method (800) according to claims 9 or 10, wherein

the array of radiating units (200) is arranged aligned with the diagonal of the molds, wherein the long side of each radiator element (202) is parallel to the diagonal of the molds.

12. The method (800) according to one of the claims 9 to 11, wherein forming (801) the array of radiating units (200) using two molds comprises an injection molding process using the two molds. 13. The method (800) according to one of the claim 9 to 12, wherein the injection molding process is a metal injection molding process or a plastic injection molding process.

14. The method (800) according to one of the claim 9 to 13, wherein

the upper mold (701) and the lower mold (702) are fixed together, particularly using screws, conductive glue, a diffusion bonding process or a welding technique.