Waveguide Termination Arrangements for Array Antennas

Abstract

An array antenna (100) having a layered structure. The array antenna includes a radiating layer (110) including a plurality of radiating elements (111) and a distribution layer (120) facing the radiating layer. The distribution layer is configured to distribute a radio frequency (RF) signal to the plurality of radiating elements. The distribution layer includes at least one distribution layer feed (121) and at least one first waveguide (122) configured to guide the RF signal between the at least one distribution layer feed and the at least one radiating element. The array antenna further includes at least one second waveguide (130) coupled to the at least one distribution layer feed (121). Either the first waveguide (122) or the second waveguide (130) includes a plastic having a first type of surface treatment (313), the first type of surface treatment including metallization. At least one of the radiating elements is a dummy element terminated by an attenuation section coupled to the dummy element and disposed in one of the plastic-containing waveguides (122, 130). The attenuation section includes a second type of surface treatment (314) configured to attenuate the RF signal.

Description

[Technical field]

[0001] The present disclosure relates to antenna arrays, particularly waveguide-based array antennas, and waveguides in general, suitable for use in, for example, telecommunications transceivers and radar transceivers. [Background technology]

[0002] Wireless communication networks include radio frequency transceivers such as radio base stations used in cellular access networks, microwave radio link transceivers used for backhaul to, for example, core networks, and satellite transceivers that communicate with orbiting satellites. Radar transceivers are also radio frequency transceivers, since they transmit and receive radio frequency (RF) signals, i.e. electromagnetic signals.

[0003] The radiating arrangement of a transceiver often includes an array antenna, e.g. for high directivity, beam steering, and / or because the array allows for a high degree of control over shaping the radiation pattern to multiple beams. Array antennas typically include multiple antenna elements spaced apart at intervals smaller than the wavelength corresponding to the operating frequency of the transceiver.

[0004] It is desirable for each antenna element in an array to behave identically, where behavior means radiation pattern, impedance matching, etc. It is particularly desirable for each row of elements in an array that includes slot antennas to behave identically, but the outermost elements (or rows) will in practice exhibit unequal performance since they have fewer neighbors than the elements (or rows) in the center of the array.

[0005] This can be solved by adding a new set of outermost elements and turning them into dummy elements (or dummy strings). The dummy elements are terminated internally with matched attenuators, so that they appear to the adjacent active elements as normal active elements.

[0006] There is a need for improved waveguide termination arrangements for array antennas. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE DISCLOSURE An object of the present disclosure is to provide an improved waveguide termination for array antennas that is low cost, easy to manufacture and exhibits good performance. [Means for solving the problem]

[0008] This object is at least partially achieved by an array antenna having a layered structure. The array antenna includes a radiating layer including a plurality of radiating elements and a distribution layer facing the radiating layer. The distribution layer is configured to distribute a radio frequency (RF) signal to the plurality of radiating elements. The distribution layer includes at least one distribution layer feed and at least one first waveguide configured to guide the RF signal between the at least one distribution layer feed and the at least one radiating element. The array antenna further includes at least one second waveguide coupled to the at least one distribution layer feed. Either the first waveguide or the second waveguide includes a plastic having a first type of surface treatment, the first type of surface treatment including metallization. Furthermore, at least one radiating element is a dummy element terminated by an attenuation section. The attenuation section is coupled to the dummy element and disposed in either of the waveguides including the plastic. The attenuation section includes a second type of surface treatment configured to attenuate the RF signal.

[0009] The attenuation sections are used to make attenuators, to provide an attenuation function, or to provide a termination function and are directly integrated into the array antenna, which is advantageous because the attenuation sections are also easy and cost effective to manufacture.

[0010] According to an embodiment, the attenuation section is matched to a desired system impedance, such as 50 ohms, but can be any value, and thus can be used as a terminator that fits well with the waveguide.

[0011] To terminate the dummy element, the attenuation section can be placed on the radiating layer of the array antenna, but is preferably placed in the distribution layer, and more preferably in a second waveguide coupled to the distribution layer. The goal of the termination is to show that the dummy element is equal to any of the other adjacent elements.

[0012] According to an embodiment, the first type of surface treatment includes a primer and metallization. The primer can be used to allow the desired metal to adhere better to the plastic part.

[0013] According to an embodiment, the second type of surface treatment comprises untreated plastic, i.e. the attenuation section comprises a non-metallized section. This can be achieved by masking the attenuation section during metallization, which allows for a cost-effective and simple manufacturing process.

[0014] According to an embodiment, the second type of surface treatment comprises a primer, i.e. the attenuation section comprises a primer and does not comprise a metallization with a typically desired metal such as copper, silver, gold, etc. In this way, the entire waveguide, including the plastic, can first be coated with a primer. The attenuation section can then be masked so that it is not coated with a metallization. This provides an easy manufacturing process. The primer on the attenuation section can advantageously shield the attenuation section from the outside, e.g. from adjacent waveguides. This can reduce undesired coupling.

[0015] According to an embodiment, the second type of surface treatment comprises a metallization, the thickness of the metallization being configured to attenuate the RF signal. This provides good attenuation performance. Advantageously, the thickness of the coating does not substantially change the surface current distribution and therefore does not substantially change the characteristic impedance of the waveguide. Therefore, due to the thin metallization of the second surface treatment, there is no discontinuity due to the transition from the coating of the first surface treatment, which means that the match is maintained. Furthermore, the relatively thin metallization of the attenuation section can advantageously shield the attenuation section from the outside, e.g. from adjacent waveguides, which can reduce undesired coupling.

[0016] According to an embodiment, any of the plastic-containing waveguides include a lossy plastic, which advantageously attenuates unwanted signals, such as leakage from the attenuation section.

[0017] According to an embodiment, at least one dummy element is disposed around an outer periphery of the plurality of radiating elements, thereby improving the behavior of each active antenna element adjacent to the dummy element relative to the remaining elements in the array antenna.

[0018] According to an aspect, the array antenna includes a plurality of rows of radiating elements, at least one row being a dummy row terminated with an attenuation section. According to a further aspect, the at least one dummy row is disposed on an outer periphery of the plurality of rows, thereby improving the behavior of each active row adjacent to the dummy row relative to the remaining rows in the array antenna.

[0019] According to an embodiment, the first waveguide is a gap waveguide, and either the radiating layer or the distribution layer includes a metamaterial structure configured to form a gap waveguide intermediate the distribution layer and the radiating layer. The metamaterial structure is also configured to prevent electromagnetic radiation from propagating in any direction other than through the gap waveguide and the distribution layer feed and the radiating element in the operating frequency band. The metamaterial structure effectively seals the gap waveguide so that electromagnetic energy can pass more or less unhindered along the intended waveguiding path but not in other directions. The arrangement of the radiating layer and the distribution layer can be non-contacting and no electrical contact is required between these layers. This is an advantage since no high precision assembly is required, and the two layers can simply be coupled together with fastening means such as bolts or the like. Furthermore, there is no need to ensure electrical contact since the repeating structure seals the transition in a non-contact manner.

[0020] According to an embodiment, the metamaterial structure comprises a repeating structure of protruding elements. The repeating structure may for example be machined directly into one of the layers. This is an advantage since such machining can be performed with high mechanical precision and in a cost-effective manner. Also, such a monolithic repeating structure is mechanically stable, which is also an advantage.

[0021] Also disclosed herein is a telecommunications or radar transceiver including an antenna array as described above.

[0022] Also disclosed herein is a waveguide for guiding a radio frequency (RF) signal, the waveguide comprising a metallized plastic, the waveguide further comprising an attenuating section, the attenuating section comprising a second type of surface treatment, and a remainder of the waveguide comprising a first type of surface treatment, the first type of surface treatment comprising metallization, and the second type of surface treatment configured to attenuate the RF signal.

[0023] The present disclosure utilizes a surface treatment of plastic to create an attenuator, to obtain an attenuation function, or to obtain a termination function, which is advantageously integrated directly into the waveguide. According to an embodiment, the attenuation section is matched to a desired system impedance, such as 50 ohms, but can be any value. Thus, the attenuation section can be used as a terminator that fits well with the waveguide.

[0024] According to an embodiment, the waveguide includes first and second layers opposed to one another, wherein either the first or second layer includes a metamaterial structure configured to form a gap waveguide intermediate the first and second layers, and wherein the metamaterial structure is also configured to prevent electromagnetic radiation from propagating from the gap waveguide in directions other than along an intended waveguide path at an operating frequency band.

[0025] The metamaterial structure effectively seals the gap waveguide so that electromagnetic energy can pass more or less unimpeded along the intended waveguiding path but not in other directions. The arrangement of these layers can be non-contacting and no electrical contact is required between these layers. This is an advantage as it does not require high precision assembly, the two layers can simply be bonded together with fastening means such as bolts or the like. Furthermore, since the repeating structure seals the transition non-contacting, there is no need to ensure electrical contact.

[0026] According to an embodiment, the metamaterial structure of the waveguide comprises a repeating structure of protruding elements. The repeating structure may for example be machined directly into one of the layers. This is an advantage since such machining can be performed in a cost-effective manner with high mechanical precision. Also, such a monolithic repeating structure is mechanically stable, which is an advantage.

[0027] According to an embodiment, the first type of surface treatment of the waveguide includes a primer.

[0028] According to an embodiment, the surface treatment of the second type of waveguide includes untreated plastic. According to a further embodiment, the surface treatment of the second type of waveguide includes a primer. According to another embodiment, the surface treatment of the second type of waveguide includes a metallization, the thickness of the metallization being configured to attenuate the RF signal.

[0029] Also disclosed herein is a method of making a waveguide comprising plastic, the method comprising: performing a surface treatment of the attenuation section of the waveguide with a second type of surface treatment; surface treating a remainder of the waveguide with a first type of surface treatment; Including, The first type of surface treatment includes metallization, and the second type of surface treatment is configured to attenuate RF signals.

[0030] The methods disclosed herein relate to the same advantages as those discussed above in relation to the different measurement devices. Further disclosed herein is a controller configured to control some of the operations described herein.

[0031] Generally, all terms used in the claims should be interpreted according to their ordinary meaning in the art, unless expressly defined otherwise herein. All references to "a / an / the" "element, apparatus, component, means, step, etc." should be openly interpreted as referring to at least one instance of the element, apparatus, component, means, step, unless expressly specified otherwise. The steps of any method disclosed herein need not be performed in the order disclosed, unless expressly specified otherwise. Further features of the present invention and advantages associated with the present invention will become apparent upon review of the appended claims and the following description. Those skilled in the art will appreciate that different features of the present invention can be combined to create different embodiments than those described below without departing from the scope of the present invention. [Brief description of the drawings]

[0032] The present disclosure will now be described in more detail with reference to the accompanying drawings.

[0033] [Figure 1A] 1 illustrates an exemplary antenna array. [Figure 1B] 1 illustrates an exemplary antenna array. [Diagram 2] 1 illustrates an exemplary antenna array. [Figure 3A] 1 illustrates an exemplary antenna array. [Figure 3B] 1 illustrates an exemplary antenna array. [Figure 4A] 1 illustrates an example waveguide. [Figure 4B] 1 illustrates an example waveguide. [Figure 5A] 1 illustrates an example waveguide. [Figure 5B] 1 illustrates an example waveguide. [Figure 6] 1 is a flow chart illustrating a method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Aspects of the present disclosure will now be described in more detail with reference to the accompanying drawings. However, the various apparatus and methods disclosed herein may be embodied in many different forms and should not be construed as limited to the aspects set forth herein. Like numerals refer to like elements throughout the drawings.

[0035] The terminology used herein is merely for the purpose of describing aspects of the present disclosure and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include the plural forms unless the context clearly indicates otherwise.

[0036] As already mentioned, there is a need for improved waveguide termination arrangements for array antennas. In typical antenna arrays, low frequencies (<6 GHz) can be easily terminated, for example, using a PCB with surface mounted attenuators or coaxial terminators. In waveguide-based arrays, electromagnetic absorbing materials can be used. This can be done with many different materials and in many different ways, for example, using wedge-shaped absorbing materials at the ends of shorted waveguides. However, using absorbing materials is expensive and greatly complicates the manufacture of array antennas. Furthermore, providing sufficient attenuation using absorbing materials can be difficult due to limited space. Also, manufacturing tolerances can be an issue with absorbing materials, especially at higher frequencies, e.g., mmWave.

[0037] The present disclosure utilizes a surface treatment of plastic directly incorporated into the array antenna to create an attenuator, to provide an attenuation function, or to provide a termination function. More specifically, the antenna, the waveguide portion of the antenna, or the waveguide generally includes a metallized plastic and a section, hereafter referred to as the attenuation section, that has a different surface treatment compared to the remainder of the antenna, the waveguide portion of the antenna, the antenna, or the waveguide in general. For example, the attenuation section can simply be a section that is not metallized at all, or a section of primer only. In different examples, the attenuation section is metallized with a different material. In another example, the attenuation section is metallized such that the corresponding metal coating is thinner. In general, the attenuation section is configured to attenuate the RF signal by resistive losses.

[0038] According to an embodiment, the attenuation section is matched to a desired system impedance, such as 50 ohms, but can be any value, and thus can be used as a terminator that fits well with the waveguide.

[0039] The attenuation sections of the disclosed waveguides can be used to terminate a radiating element in an array antenna, thus making it a dummy element, or can be used to terminate an entire column, thus making it a dummy column. To terminate the dummy elements, the attenuation sections can be placed directly on the radiating layer of the array antenna, but are preferably placed in the distribution layer, and more preferably in a waveguide that is coupled to the distribution layer. The goal of the termination is to show that the dummy element is equivalent to any of the other adjacent elements.

[0040] According to an aspect of the present invention, an array antenna 100 having a layered structure as shown in the examples of Figures 1A, 1B, 2, 3A, and 3B is disclosed herein. The array antenna includes a radiating layer 110 including a plurality of radiating elements 111, and a distribution layer 120 facing the radiating layer. The distribution layer is configured to distribute a radio frequency (RF) signal to the plurality of radiating elements 111. The distribution layer includes at least one distribution layer feed 121 and at least one first waveguide 122 configured to guide the RF signal between the at least one distribution layer feed and the at least one radiating element. The array antenna further includes at least one second waveguide 130 coupled to the at least one distribution layer feed 121. Either the first waveguide 122 or the second waveguide 130 includes a plastic having a first type of surface treatment 313. In other words, one or both of the first waveguide and the second waveguide includes a first type of surface treatment. Here, the first type of surface treatment includes metallization. At least one of the radiating elements is a dummy element terminated by an attenuation section 312. The attenuation section is coupled to the dummy element and disposed in one of the waveguides 122, 130 including plastic. Preferably, the waveguide with the attenuation section is a hollow waveguide, which can be filled with air or some dielectric material. Examples of such waveguides are rectangular waveguide, circular waveguide, ridge waveguide, gap waveguide, ridge gap waveguide. The first waveguide of the distribution layer can confine the electromagnetic wave using a portion of the radiating layer. For example, the portion of the radiating layer can constitute one of the waveguide walls in a rectangular waveguide. Furthermore, the first waveguide can be a ridge waveguide in which one or more ridges are disposed on the distribution layer and / or the radiating layer. Furthermore, the attenuation section includes a second type of surface treatment 314 configured to attenuate the RF signal.

[0041] The disclosed array antenna is very cost effective since it does not require additional components such as surface mounted attenuators or electromagnetic absorbers. Also, the array antenna is easy to manufacture, which further reduces costs in many ways. Furthermore, the disclosed array enables superior performance at higher frequencies, e.g., millimeter waves.

[0042] Generally, as used herein, a waveguide is a structure that guides electromagnetic waves. A waveguide can be a hollow rectangular tube, as shown in Figures 4A and 4B. The cross section can be many other shapes, such as circular or more general shapes. The tube can be hollow or filled with a dielectric material. A waveguide can also be a gap waveguide.

[0043] A layer is a planar element with two faces and is associated with a thickness, which is much smaller than the dimensions of the faces, i.e., the layer is a flat or nearly flat element, i.e., it resembles an arcuate shape. According to some embodiments, the layer is rectangular or square. However, more general shapes are also applicable, including circular or elliptical disks.

[0044] At least one distribution layer feed 121 may be a waveguide arranged as a through hole configured to transmit a radio frequency signal through the distribution layer as shown in Figure 2. The distribution layer feed may also include an extension of the first waveguide 122 for transmitting the RF signal away from the distribution layer as shown in Figures 3A and 3B.

[0045] With reference to Figure 2, the attenuation section may be placed on the ridge gap waveguide 122 of the distribution layer. The attenuation section may also be placed on a waveguide that is coupled to the distribution layer feed (not shown). In this way, all elements in the figure are terminated in a good fit. Such a column may be useful as a dummy column in an array antenna containing multiple columns. With reference to Figures 3A and 3B, the attenuation section is placed on the second waveguide 130 of the leftmost column in a three column array.

[0046] The emissive layer and / or the plastic-free first waveguide 122 or second waveguide 130 may comprise a cast, molded, punched, and / or machined metal, such as copper, brass, etc. The metal may include a highly electrically conductive coating, such as silver or copper coated aluminum, or silver or copper coated zinc.

[0047] Either the first waveguide 122 or the second waveguide 130 comprises a plastic with a first type of surface treatment 313, the first type of surface treatment comprising metallization. The purpose of the metallization is to allow electromagnetic waves to propagate through the waveguide, thereby enabling the array antenna to function. Metallization is generally known and therefore will only be described briefly herein. The radiating layer may also comprise a metallized plastic. Metallization of plastic may be accomplished in many different ways. The plastic may be directly metallized, or a primer may first be applied to the plastic surface, which may then be coated with the desired metal. Preferred metals for metallizing plastic are those that have low loss and high electrical conductivity, such as copper, silver, and gold. Many other metals and alloys are also contemplated. Metallization is to be broadly construed herein. Metallization may also include disposing a conductive polymer on the surface. Such materials are included in the term "metallization" since they have the desired metallic conductivity.

[0048] Examples of suitable primers are nickel, chromium, palladium, and titanium, although many other materials are contemplated. Primers can be used to improve adhesion of the desired metal to the plastic part. There are many different ways to give the plastic surface the desired shape, such as casting, molding, and / or machining. Plastics are broadly construed herein as any of a variety of synthetic and semi-synthetic organic compounds that can be formed into a solid object.

[0049] At least one of the radiating elements 111 in the disclosed antenna array 100 may include an aperture. The aperture in the radiating layer 110 may be, for example, a slot-type aperture extending through the radiating layer. The slot-type aperture is preferably rectangular, although other shapes are also contemplated, such as square, round, or more general shapes. The slot-type aperture is preferably small compared to the size of the radiating layer 110 and is arranged on parallel lines on the radiating layer, although other arrangements are also possible. All the radiating elements include a slot, and the radiating layer 110 may include a metal sheet (e.g., of copper or brass). The radiating layer may include a cavity sublayer configured to form a cavity between each radiating element and the distribution layer. It is understood that other types of radiating elements are also contemplated.

[0050] The second waveguide can be coupled to at least one distribution layer feed 121 in many different ways. For example, the second waveguide can simply comprise a rectangular waveguide directly coupled to the distribution layer feed. Exemplary waveguides are shown in Figures 4A and 4B. Additionally, the second waveguide 130 can be disposed in a layer opposite the distribution layer 120, such as a printed circuit board (PCB) layer 131, and / or a shielding layer 132, or any other type of distribution / feed layer.

[0051] The radiating layer may be formed as a separate component from the distribution layer, as shown in Figure 2. However, the radiating layer and distribution layer may be integrally formed in one component. Similarly, the second waveguide may be separate from or integrally formed with the distribution layer feed. Figures 3A and 3B show an example where the second waveguide is integrally formed with the distribution layer feed.

[0052] According to an embodiment, the first type of surface treatment 313 includes a primer. In other words, the first type of surface treatment metallization includes the step of depositing a primer prior to metallization with a desired metal.

[0053] The second type of surface treatment 314 may comprise untreated plastic, i.e. the attenuation section is composed of a non-metallized section. In this way the attenuation section can be masked so that it is not coated with metallization (and eventually with primer). This provides an easy manufacturing process. The surface treatment process of the antenna array can be performed according to the following steps: the parts with the second surface treatment are masked and the parts with the first surface treatment are coated with a metallization of the desired thickness. Here an optional primer can be coated on these parts before metallization. This process involves only one masking, which is an advantage since it is simple and precise to process.

[0054] According to an embodiment, the second type of surface treatment 314 includes a primer, i.e., the attenuation section includes a primer and does not include a metallization with a typically desired metal such as copper, silver, gold, etc. In this way, the entire waveguide including the plastic can be first coated with a primer. Then, the attenuation section can be masked so that it is not coated with a metallization. This provides an easy manufacturing process. The primer of the attenuation section can advantageously shield the attenuation section from the outside, e.g., from adjacent waveguides. This can reduce undesired coupling. The surface treatment process of the antenna array can be performed according to the following steps: First, all parts with the first surface treatment and the second surface treatment are coated with a primer. Finally, the parts with the second surface treatment are masked and the parts with the first surface treatment are coated with a metallization of a desired thickness. This process includes only one masking.

[0055] The second type of surface treatment 314 may include metallization. In that case, the thickness of the metallization is configured to attenuate the RF signal. A relatively thin metallization of the attenuation section can advantageously shield the attenuation section from the outside, e.g., from adjacent waveguides. This can reduce undesired coupling. The surface treatment process of the antenna array can be performed according to the following steps: First, all parts with the first and second surface treatments can be optionally coated with a primer. Then, a thin layer of metallization is coated on all parts. Finally, the parts with the second surface treatment are masked and the parts with the first surface treatment are coated with a metallization of the desired thickness. This process includes only one masking.

[0056] According to embodiments, either the first surface treatment or the second surface treatment may include a protective coating. This protective coating may be used for protection against corrosion, mechanical wear, etc. Additionally, any of the coating steps described herein may include application of multiple layers. For example, a primer coating may include application of several layers.

[0057] As already mentioned, the second type of surface treatment 314 may include a thin layer of metallization configured to attenuate the RF signal. Here, the attenuation section is surface coated with one (or more) thin layers of metallization on top of the plastic. The thickness configured to attenuate the RF signal is related to the so-called skin depth. Skin depth describes how deep the electric field propagates in the material and depends on the frequency and material properties (the higher the frequency, the more the electric field is contained at the surface). In the absence of magnetic and dielectric losses, the skin depth can be expressed as:

[0058]

number

[0059] Here, ρ is the resistivity of the conductor, ω is the angular frequency, μ is the magnetic permeability of the conductor, and ε is the dielectric constant of the conductor.

[0060] In conventional waveguides, when low loss is desired, the metal (or conductive material) must be relatively thick, meaning several times thicker than the skin depth. The attenuation section may instead include a thin metal coating to provide high loss and superior termination. According to an embodiment, the thickness of the metallization configured to attenuate the RF signal is less than three times the skin depth, preferably less than the skin depth, and more preferably less than one-third the skin depth.

[0061] The loss introduced by the small thickness allows for use with materials having low electrical conductivity.

[0062] If the metallized coating has a thickness comparable to or less than the skin depth, the electric field will penetrate the entire metallized coating and current will also exist on the other side of the coating (i.e., the plastic side), which current may be able to radiate electromagnetic waves. Such radiation is a type of leakage and may be undesirable. However, such leakage may also be suppressed by external means. While leakage may reduce the intensity of the electromagnetic wave traveling along the attenuation section, resistive losses typically attenuate the wave significantly. Furthermore, it may be desirable not to make the metallization in the attenuation section too thin, since the metallized coating provides some shielding, for example, from adjacent waveguides or from self-interference due to leakage. Thus, there is a range of thicknesses that are thin enough to provide sufficient attenuation and do not suffer from harmful leakage or shielding problems.

[0063] Advantageously, the thickness of the coating does not substantially change the surface current distribution and therefore the characteristic impedance, so there is no discontinuity from the normal coating, which means that the fit is maintained.

[0064] The attenuation section may comprise a poor conductor having a normal thickness, i.e. several times the skin depth, in which case there are no problems with shielding or leakage.

[0065] As already mentioned, the second surface treatment can be untreated plastic, i.e. without any coating. This may result in some reflections at the transition from the first surface treatment to the second surface treatment. However, a gradual transition between the two surface treatments and / or a gradual change in the shape of the waveguide may improve the fit. The shape may be modified by flaring, similar to a horn. This may also be considered to provide an antenna for the purpose of attenuating the intensity. Furthermore, any of the plastic-containing waveguides 122, 130 may include a lossy plastic. In this way, unwanted leakage is attenuated. It is particularly advantageous to include a lossy plastic in the waveguide that includes the attenuating section. The lossy plastic may, for example, include a material with high dielectric loss and / or may be infused with carbon or the like.

[0066] At least one dummy element may be arranged on the periphery of the plurality of radiating elements 111. In other words, the dummy element is arranged in connection with the interface of the radiating layer. According to an embodiment, all elements on the periphery are dummy elements. In that case, all active elements are surrounded by dummy elements. Here, surrounding means forming a boundary around the surrounded object.

[0067] The array antenna 100 may include multiple rows of radiating elements 111, where at least one row is a dummy row terminated with an attenuation section. In some cases, it may only be necessary to place dummy elements along the two outermost rows of the array antenna to achieve the desired effect that all active elements in the array behave similarly. This may be the case for arrays including slot antennas. Therefore, at least one dummy row may be placed around the periphery of the multiple rows.

[0068] According to an embodiment, the first waveguide is a gap waveguide, and either the radiating layer 110 or the distribution layer 120 includes a metamaterial structure 124 configured to form a gap waveguide intermediate the distribution layer 120 and the radiating layer 110. The metamaterial structure is also configured to prevent electromagnetic radiation from propagating from the gap waveguide in any direction other than through the distribution layer feed 121 and the radiating element 111 at the operating frequency band.

[0069] Depending on the metamaterial structure, the distribution layer 120 may be placed in direct contact with the radiating layer 100 or may be placed at a small distance from the radiating layer 110, the distance being less than one quarter of a wavelength of the operating center frequency of the antenna array 100. Direct contact may mean that only a portion of the two layers are in contact.

[0070] The use of metamaterial structures in the distribution layer reduces losses from the waveguide and reduces interference between radio frequency signals between adjacent waveguides. The result is that a high signal to noise ratio can be maintained by using and arranging metamaterial structures in the distribution layer, which is advantageous. Another advantage is that no electrical contact is required between the two layers that make up the waveguide. This is an advantage because there is no need to check electrical contact and therefore no high precision assembly is required. However, electrical contact between multiple layers is also an option.

[0071] The metamaterial structure is configured to form a high impedance surface, such as an artificial magnetic conductor (AMC). When the high impedance faces a conductive surface (i.e., in the ideal case, a low impedance surface, such as a perfect electrical conductor (PEC)), and when the two surfaces are placed apart by a distance less than a quarter of the wavelength of the center frequency, in the ideal case, no electromagnetic waves in the operating frequency band propagate along or between the intermediate surface, since all parallel plate modes are blocked in that frequency band. In other words, the high impedance surface and the low impedance surface form an electromagnetic band gap between the two surfaces. Also, the two surfaces can be placed directly adjacent to each other, i.e., electrically connected to each other. The center frequency is usually in the middle of the operating frequency band. In a realistic scenario, the electromagnetic waves in the operating frequency band are attenuated according to the length along the intermediate surface. In this specification, attenuating is interpreted as a significant reduction in the amplitude or intensity of electromagnetic radiation, such as a radio frequency signal. Attenuation is preferably complete, in which case attenuation and blocking are synonymous, but it is understood that such complete attenuation is not always feasible.

[0072] Metamaterial structures can replace the walls of a waveguide to form a gap waveguide, which can include a ridge to form a ridge gap waveguide (RGW).

[0073] Example dimensions for a rectangular distribution layer 120 are 5mm thick and 100mm wide and long, although the distribution layer is not necessarily rectangular and other shapes such as circular or hexagonal are contemplated.

[0074] The metamaterial structure 124 may include a repeating structure of protruding elements 125. Such protruding elements may be integrally formed on the layer 110, 120 that includes the metamaterial structure 124, i.e., on the emitting layer 110 and / or the distribution layer 120. Either the distribution layer 120 or the emitting layer 110 optionally includes at least one waveguide ridge 123 that forms at least one first gap waveguide.

[0075] As already mentioned, the second waveguide 130 may be disposed on a printed circuit board (PCB) layer 131 opposite the distribution layer 120 and / or on a shielding layer 132 opposite the PCB layer 131. Thus, the antenna array 100 may further include a printed circuit board (PCB) layer 131 opposite the distribution layer 120, the PCB layer including at least one PCB layer feed.

[0076] The use of metamaterial structures in the distribution layer allows for efficient coupling from the PCB layer feed on the PCB layer 131 through the distribution feed 224 to the at least one first waveguide, which reduces losses. The PCB layer 131 optionally includes at least one RF integrated circuit (IC) disposed on one or both sides of the PCB layer. The at least one PCB layer feed can be configured to transmit radio frequency signals from the RF IC to the opposite side of the PCB to the distribution layer. According to one example, the at least one PCB layer feed is a through hole coupled to a corresponding opening in the distribution layer 120, which is fed by at least one microstrip line. Alternatively, or in combination, the at least one PCB layer feed can be configured to transmit radio frequency signals from the RF IC to the side of the PCB opposite the distribution layer to the distribution layer. According to an embodiment, the at least one PCB layer feed is configured to transmit radio frequency signals away from the antenna array 100, for example to a modem. The PCB layers may include stamped or etched metal plates as the ground plane or complementary ground planes.

[0077] The antenna array 100 may further include a shielding layer 132 facing the PCB layer 131. The shielding layer 132 may optionally include a second metamaterial structure configured to form a gap waveguide intermediate the shielding layer 132 and the PCB layer 131. The gap waveguide may form the second waveguide 130. The second metamaterial structure may also be configured to prevent electromagnetic radiation from propagating in any direction other than through at least one PCB layer feed in the operating frequency band from the gap waveguide. The second metamaterial structure allows for a compact design with low loss and low leakage, i.e., less unwanted electromagnetic propagation between adjacent waveguides or between adjacent RFICs, for example. Additionally, the second metamaterial structure shields the PCB layer from electromagnetic radiation outside the antenna array.

[0078] The second metamaterial structure optionally includes a repeating structure of protruding elements, and the PCB layer optionally includes a ground plane and at least one planar transmission line to form at least one gap waveguide between the shielding layer 132 and the PCB layer 131. The gap waveguide may be, for example, an inverted microstrip gap waveguide. The gap waveguide may be the second waveguide 130. The shielding layer may include two types of protruding elements, for example, narrow and tall pins and wide and short pins. The wider and shorter pins may be configured to fit an RFIC between the shielding layer and the PCB layer. The pins may contact the RFIC for heat transfer purposes.

[0079] According to an embodiment, the distribution layer 120 includes a third metamaterial structure, which is disposed on the opposite side of the first metamaterial structure 124, i.e., the third metamaterial structure faces the PCB layer 131. In this manner, a number of gap waveguides can be formed between the distribution layer 120 and the PCB layer 131. These gap waveguides can be used to couple electromagnetic signals between the RFICs on the PCB layer 131 and the PCB layer feed. Any such gap waveguide can constitute the second waveguide 130. The third metamaterial structure allows for a compact design with low loss and low leakage, i.e., less unwanted electromagnetic propagation between adjacent waveguides or between adjacent RFICs, for example. Additionally, the third metamaterial structure shields the PCB layer from electromagnetic radiation outside the antenna array.

[0080] According to an embodiment, a telecommunications transceiver or radar transceiver includes an antenna array 100.

[0081] Also disclosed herein is a method for fabricating an array antenna (100) having a layered structure, the method comprising: Providing a radiating layer 110 including a plurality of radiating elements 111; placing a distribution layer 120 opposite the radiating layer, the distribution layer configured to distribute a radio frequency (RF) signal to the plurality of radiating elements 111, the distribution layer including at least one distribution layer feed 121 and at least one first waveguide 122 configured to guide the RF signal between the at least one distribution layer feed and the at least one radiating element; Positioning at least one second waveguide 130 to be coupled to at least one distribution layer feed portion 121; Including, Either the first waveguide 122 or the second waveguide 130 comprises plastic, and the method further comprises: surface treating the waveguide comprising plastic with a first type of surface treatment 313 comprising metallization; Including, At least one radiating element is a dummy element terminated by an attenuation section 312, and the method further comprises: disposing an attenuation section in one of the plastic waveguides 122, 130 coupled to the dummy element, the attenuation section including a second type of surface treatment 314 configured to attenuate the RF signal; Includes.

[0082] Also disclosed herein are waveguides 300, 400 for guiding radio frequency (RF) signals, the waveguides including metallized plastic. The waveguide further includes an attenuating section 312. The attenuating section includes a second type of surface treatment 314, and the remainder of the waveguide includes a first type of surface treatment 313. The first type of surface treatment includes metallization, and the second type of surface treatment is configured to attenuate the RF signal.

[0083] The disclosed waveguides 300, 400 can be either rectangular waveguides, circular waveguides, or waveguides based on metamaterial structures such as repeated protruding pins. Many other types of waveguides are also possible. Figures 4A, 4B, 5A, and 5B show different examples of the disclosed waveguides.

[0084] According to an embodiment, the waveguides 300, 400 include opposing first and second layers 511 and 512. Either the first or second layer includes a metamaterial structure 521 configured to form a gap waveguide intermediate the first layer 511 and the second layer 512. The metamaterial structure is also configured to prevent electromagnetic radiation from propagating from the gap waveguide in directions other than along the intended waveguide path at the operating frequency band.

[0085] An intended waveguide path is a path along which electromagnetic radiation is intended to be guided. For example, if a microwave device includes two separate waveguides, the two separate waveguides are intended to be separated, and an intended waveguide path is along each waveguide. The metamaterial structure 521 separates the two waveguides. Another example of an intended waveguide path is a corporate power grid, where one waveguide connects a distribution feed to a radiating element, and one waveguide connects different integrated components on a PCB.

[0086] The metamaterial structure allows the first layer 511 and the second layer 512 to be placed in direct contact with each other or at a small distance from each other, which distance is less than a quarter of a wavelength of the operating center frequency of the disclosed waveguide 300, 400. Direct contact may mean that only a portion of the two layers are in contact.

[0087] The use of metamaterial structures in either the first layer 511 or the second layer 512 reduces losses from the waveguide as well as reduces interference between radio frequency signals in adjacent waveguides or circuits. One advantage is that no electrical contact is required between the two layers that make up the waveguide. This is an advantage because it does not require high precision assembly since there is no need to ensure electrical contact. However, electrical contact between multiple layers is also an option.

[0088] The metamaterial structure 521 of the waveguides 300, 400 may include a repeating structure of protruding elements 522. Such protruding elements may be integrally formed on the layer 511, 512 that includes the metamaterial structure 521. Either the first layer 511 or the second layer 512 optionally includes at least one waveguide ridge 523 that forms at least one first gap waveguide intermediate the first layer 511 and the second layer 512.

[0089] The first type of surface treatment 313 of the waveguide 300, 400 may include a primer. In other words, metallizing the first type of surface treatment includes depositing a primer prior to metallizing with a desired metal.

[0090] The second type of surface treatment 314 of the waveguide 300, 400 may include untreated plastic, ie, the attenuation section may be composed of untreated plastic.

[0091] According to an embodiment, the second type of surface treatment 314 of the waveguide 300, 400 may include a primer, ie, the attenuation section includes a primer and does not include metallization with typically desirable metals such as copper, silver, gold, etc.

[0092] The second type of surface treatment 314 of the waveguide 300, 400 may include metallization, where the thickness of the metallization is configured to attenuate the RF signal.

[0093] Also disclosed herein is a method for manufacturing a plastic-containing waveguide 300, 400, as shown in Figure 6. The method includes: performing a surface treatment of the attenuation section 312 of the waveguide with a second type of surface treatment 314 (S1); performing a surface treatment (S2) of the remaining portion 411 of the waveguide with a first type of surface treatment 313; Including, The first type of surface treatment includes metallization, and the second type of surface treatment is configured to attenuate RF signals.

Claims

1. a radiating layer (110) including a plurality of radiating elements (111); a distribution layer (120) facing the radiation layer, configured to distribute a radio frequency (RF) signal to the plurality of radiation elements (111), the distribution layer (120) including at least one distribution layer feed (121) and at least one first waveguide (122) configured to guide the RF signal between the at least one distribution layer feed and at least one of the radiation elements; At least one second waveguide (130) coupled to the at least one distribution layer feed portion (121); An array antenna (100) having a layered structure including: one of the first waveguide (122) and the second waveguide (130) comprises a plastic having a first type of surface treatment (313) including metallization; at least one of the radiating elements is a dummy element terminated by an attenuation section (312), the attenuation section being coupled to the dummy element and disposed in one of the waveguides (122, 130) including plastic, the attenuation section including a second type of surface treatment (314) configured to attenuate the RF signal; An array antenna (100).

2. The array antenna (100) of claim 1, wherein the first type of surface treatment (313) includes a primer and a metallization.

3. The array antenna (100) of claim 1, wherein the second type of surface treatment (314) comprises untreated plastic.

4. The array antenna (100) of claim 1, wherein the second type of surface treatment (314) comprises a primer.

5. The array antenna (100) of claim 1, wherein the second type of surface treatment (314) comprises a metallization, the thickness of the metallization being configured to attenuate the RF signal.

6. The array antenna (100) of claim 1 , wherein any of the waveguides (122, 130) comprising plastic comprises a lossy plastic.

7. The array antenna (100) according to any one of claims 1 to 6, wherein the at least one dummy element is arranged on an outer periphery of the plurality of radiating elements (111).

8. 2. The array antenna (100) of claim 1, comprising a plurality of rows of said radiating elements (111), at least one of said rows being a dummy row terminated by said attenuation section.

9. The array antenna (100) of claim 1 , wherein the at least one dummy row is disposed on an outer periphery of the plurality of rows.

10. 2. The array antenna of claim 1, wherein the first waveguide is a gap waveguide, and either the radiation layer or the distribution layer includes a metamaterial structure configured to form the gap waveguide intermediate the distribution layer and the radiation layer, the metamaterial structure also configured to prevent electromagnetic radiation from propagating from the gap waveguide in any direction other than through the distribution layer feed and the radiation element in an operating frequency band.

11. The array antenna (100) of claim 10, wherein the metamaterial structure (124) comprises a repeating structure of protruding elements (125).

12. A telecommunications transceiver or radar transceiver comprising an antenna arrangement (100) as described in claim 1.

13. A waveguide (300, 400) for guiding a radio frequency (RF) signal, the waveguide (300, 400) comprising a metallized plastic and further comprising an attenuation section (312), the attenuation section comprising a second type of surface treatment (314) and a remainder of the waveguide comprising a first type of surface treatment (313), the first type of surface treatment comprising metallization, the second type of surface treatment configured to attenuate the RF signal.

14. 14. The waveguide (300, 400) of claim 13, comprising a first layer (511) and a second layer (512) opposed to each other, either of the first layer and the second layer including a metamaterial structure (521) configured to form a gap waveguide intermediate the first layer (511) and the second layer (512), the metamaterial structure also configured to prevent electromagnetic radiation from propagating from the gap waveguide in directions other than along an intended waveguide path in an operating frequency band.

15. The waveguide (300, 400) of claim 14, wherein the metamaterial structure (521) comprises a repeating structure of protruding elements (522).

16. The waveguide (300, 400) of claim 13, wherein the first type of surface treatment (313) comprises a primer.

17. The waveguide (300, 400) of claim 13, wherein the second type of surface treatment (314) comprises untreated plastic.

18. The waveguide (300, 400) of claim 13, wherein the second type of surface treatment (314) comprises a primer.

19. The waveguide of claim 13 , wherein the second type of surface treatment (314) comprises a metallization, the thickness of the metallization being configured to attenuate the RF signal.

20. A method for manufacturing a waveguide (300, 400) comprising plastic, comprising the steps of: performing (S1) a surface treatment of the attenuation section (312) of the waveguide with a second type of surface treatment (314); performing (S2) a surface treatment of the remaining part (411) of said waveguide with a first type of surface treatment (313); Including, the first type of surface treatment includes metallization and the second type of surface treatment is configured to attenuate RF signals. method.

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