Automotive sensor module having absorbing and / or non-reflective layer

Abstract

An antenna assembly for a vehicle, such as a RADAR sensor antenna assembly. In some embodiments, the assembly may include an array of antenna slots and a waveguide block defining an array of waveguide grooves. Each antenna slot in the array of antenna slots may be at least partially aligned with a waveguide groove in the array of waveguide grooves of the waveguide block. The assembly may also include an absorber layer including an array of openings corresponding to the array of antenna slots. The absorber layer may be configured to dissipate surface current on the waveguide block, such as, for example, by a material used to form the absorber layer and / or a thickness of the absorber layer, and / or configured to suppress instrument panel reflections.

Description

Summary of the Invention

[0001] Various embodiments of sensor assemblies and related elements, sub - assemblies, and manufacturing methods are disclosed herein. In preferred embodiments and specific implementations, such assemblies may include a RADAR sensor module for a vehicle, including one or more novel and inventive features disclosed herein.

[0002] For example, in some embodiments disclosed herein, the antenna block may include a casting and may have features designed to establish a foundation for one or more waveguides and / or antenna slots. For example, an array of one or more waveguide grooves may be formed, such grooves being formed, for example, by relatively arranged cylindrical members or grooved waveguide grooves. Alternatively, a film or other layer (such as a conductive adhesive layer) may be used to couple a conductive sheet including an antenna slot to the block. The principles disclosed herein may also be used in combination with more traditional patch - antenna RADAR modules.

[0003] The block / component may also include an absorption layer that is configured to suppress such currents on the block by, for example, absorbing energy from surface currents and converting it into heat. This suppression of surface currents between the antennas of the sensor / module may reduce or eliminate crosstalk within the antennas. In some embodiments, the absorption layer may also or alternatively be used to neutralize the adverse effects of strong reflections originating from the vehicle dashboard.

[0004] In some embodiments, the top layer may include a sticky plastic film and may form an antenna cover or weather seal for the component.

[0005] In a more specific example of a vehicle sensor module according to some embodiments, the module may include an antenna slot array and a waveguide block defining a waveguide groove array. Each antenna slot in the antenna slot array may be aligned or at least partially aligned with a waveguide groove of the waveguide groove array of the waveguide block. In some embodiments, each antenna slot in the antenna slot array may extend from a first side and / or surface of the antenna block to a second side and / or surface of the waveguide block to allow electromagnetic radiation to propagate through the antenna slot array. The module may also include an absorption layer, which in some embodiments may include an opening array corresponding to the antenna slot array. The absorption layer may be configured to suppress surface currents on the waveguide block.

[0006] Some embodiments may also include an antenna cover layer positioned on top of the absorption layer, which in some such embodiments may be without openings to provide a weather seal and / or a liquid seal for the waveguide block. In some such embodiments, the antenna cover layer may include a laminate including a plurality of sub - layers. For example, in some embodiments, at least one of the sub - layers may be configured to adhere the antenna cover layer to the absorption layer and / or at least one of the sub - layers may be configured to increase the strength of the antenna cover layer.

[0007] In some embodiments, the waveguide groove array may include a plurality of waveguide grooves.

[0008] In some embodiments, the thickness of the absorption layer may be equal to an odd multiple of one - quarter of the wavelength of the electromagnetic radiation used in the vehicle sensor module, or approximately equal to an odd multiple of one - quarter of the wavelength of the electromagnetic radiation used in the vehicle sensor module.

[0009] In some embodiments, the absorption layer may comprise a lossy material. For example, the absorption layer may comprise a material having a dielectric constant between 6 and 9 and a dielectric loss tangent between 0.3 and 0.6. In some embodiments, the absorption layer may comprise a material having a dielectric constant between approximately 9 and approximately 14 and / or may include a dielectric loss tangent between approximately 0.2 and approximately 0.3.

[0010] In some embodiments, the module alternatively includes a slotted layer that includes a plurality of slots that may be at least partially aligned with the waveguide grooves of the waveguide block.

[0011] In some embodiments, one or more antenna slots (in some cases, all antenna slots) may be located on a raised island that includes a raised wall extending over a recessed area. In some such embodiments, the absorption layer may be located within the recessed area.

[0012] Some embodiments may also include a raised lip extending around the perimeter of the waveguide block and / or a radome layer positioned above the absorption layer. In some embodiments that include a radome layer and a recessed area, the radome layer may be located within the recessed area and / or slightly below the raised lip.

[0013] In a specific example of a vehicle sensor antenna assembly according to some embodiments, the assembly may include a metal waveguide block that defines a waveguide groove array and an antenna assembly that includes at least one antenna slot that is configured to receive electromagnetic radiation through the antenna slot from the waveguide groove array. The assembly may also include an absorption layer that is configured to generate a destructive interference pattern to reduce the reflectivity of electromagnetic radiation incident on the vehicle sensor antenna assembly.

[0014] In some embodiments, the antenna assembly may include an antenna slot corresponding to each waveguide groove of the waveguide groove array.

[0015] In some embodiments, the absorption layer may include one or more openings positioned such that each of the at least one antenna slot is positioned below an opening of the one or more openings. In some such embodiments, the absorption layer may include one or more openings configured to accommodate a plurality of antenna slots, such as an array or a plurality of arrays of antenna slots.

[0016] In some embodiments, the antenna assembly may be part of a metal waveguide block such that at least one antenna slot is formed within the metal waveguide block and extends between opposite sides and / or surfaces of the metal waveguide block.

[0017] In some embodiments, the metal waveguide block includes a recessed region that, in some embodiments, may be defined by a lip extending around the perimeter of the metal waveguide block and / or a raised wall extending around the perimeter of each antenna slot (or each antenna slot array) of the at least one antenna slot. In some embodiments, the absorption layer may be positioned within the recessed region.

[0018] In some embodiments, the recessed region may include a height greater than the thickness of the absorption layer. In some cases, the height of the recessed region may be greater than the thickness of all layers, or greater than the thickness of all layers except the top layer / radome layer that are applied to the block.

[0019] In some embodiments, the absorption layer may include a dielectric constant between about 6 and about 14 and / or a dielectric loss tangent between about 0.2 and about 0.6. In some such embodiments, the absorption layer may include a dielectric constant between about 6 and about 9 and / or a dielectric loss tangent between about 0.3 and about 0.6. In some such embodiments, the absorption layer may comprise a material having a dielectric constant between about 9 and about 14 and / or may include a dielectric loss tangent between about 0.2 and about 0.3.

[0020] In a specific example of a vehicle RADAR module according to some embodiments, the module may include a metal waveguide block defining one or more waveguide grooves. In some embodiments, the module may further include a recessed region that may be defined by the waveguide block. Some embodiments may include one or more antenna slots, one or more of which or each of which may be at least partially aligned with a corresponding waveguide groove of the metal waveguide block. The antenna slots may extend completely through the metal waveguide block from a first side and / or surface of the metal waveguide block to a second side and / or surface of the metal waveguide block opposite the first side and / or surface to allow electromagnetic radiation to propagate through the antenna slots. Some embodiments may further include an absorption layer, which, for embodiments including one absorption layer, may be located within the recessed region. The absorption layer may comprise a lossy material.

[0021] In some embodiments, the absorber layer may include one or more openings, each or a subset of which may be at least partially aligned with a corresponding antenna slot and / or waveguide recess. In some embodiments, the absorber layer may be configured to contact the metal waveguide block to suppress surface currents on the metal waveguide block. The absorber layer may also include a thickness configured to suppress reflection of electromagnetic radiation by creating destructive interference between the reflection of electromagnetic radiation above the absorber layer and the reflection of electromagnetic radiation below the absorber layer. Some embodiments may also include a radome layer configured to provide a weather seal to the vehicle RADAR module.

[0022] In some embodiments, the absorber layer may have a thickness that is approximately an odd multiple of one quarter of the wavelength of the electromagnetic radiation used in the vehicle RADAR module.

[0023] In some embodiments, the absorber layer may be formed from a liquid that, in some cases, is injected into and / or cured within a recessed area of the metal waveguide block, which in some embodiments may be defined by a lip extending around the perimeter of the waveguide block and / or a raised wall extending around the perimeter of one or more antenna slots.

[0024] In some embodiments, the absorber layer may be positioned to contact the topmost surface of the block, such as the metal surface of the block in some such embodiments. This configuration may be configured to suppress reflections from the vehicle dashboard and / or dissipate currents flowing on the surface of the block.

[0025] In some embodiments, the waveguide recess may be formed by providing a plurality of adjacent cylindrical members that collectively define one or more such recesses.

[0026] Alternatively, the recess may be formed by simply forming one or more grooves within the surface of the antenna block. Some embodiments may also include a second array of waveguide recesses positioned on a second side of the antenna block opposite the first side.

[0027] Features, structures, steps, or characteristics disclosed herein in connection with one embodiment may be combined in any suitable manner in one or more alternative embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Reference is made to the accompanying drawings, which describe, without limitation and without exhaustion, embodiments of the present disclosure, including various embodiments of the present disclosure, wherein:

[0029] Figure 1 is a perspective view of an antenna / waveguide assembly that may be incorporated into a more complete antenna module, such as a vehicle RADAR sensor module, according to some embodiments;

[0030] Figure 2 is an exploded perspective view of an antenna / waveguide assembly;

[0031] Figure 3 is a graph depicting the return loss as a function of the angle of incidence of a module incorporating an absorption layer according to some embodiments;

[0032] Figure 4 is an enlarged perspective view of a corner of the antenna / waveguide assembly;

[0033] Figure 5 is along Figure 1 a cross-sectional view taken along line 5-5 in

[0034] Figure 6A is along Figure 5 an enlarged cross-sectional view taken along the area shown in

[0035] Figure 6B is along Figure 5 another enlarged cross-sectional view taken along the area shown in

[0036] Figure 7 is an exploded perspective view of an antenna / waveguide assembly according to other embodiments; and

[0037] Figure 8 is Figure 7 an enlarged cross-sectional view of the antenna / waveguide assembly of DETAILED DESCRIPTION

[0038] A detailed description of apparatuses, systems, and methods consistent with various embodiments of the present disclosure is provided below. While several embodiments are described, it should be understood that the present disclosure is not limited to any particular embodiment of the disclosed specific embodiments, but rather encompasses many alternatives, modifications, and equivalents. Additionally, while many specific details are set forth in the following description to provide a thorough understanding of the embodiments disclosed herein, some embodiments may be practiced without some or all of these details. Further, certain technical materials known in the prior art are not described in detail to avoid unnecessarily obscuring the present disclosure.

[0039] As used herein, the term "substantially" refers to the full or nearly full scope or degree to which a function, characteristic, property, state, structure, item, or result acts as indicated. For example, an object that is "substantially" cylindrical or "substantially" vertical will mean that the object / characteristic is cylindrical / vertical or nearly cylindrical / vertical, such that the same or nearly the same function results. The exact allowable degree of deviation provided by this term may depend on the particular context. When used in a negative sense, "substantially" applies equally, referring to being completely or nearly completely free of a particular function, characteristic, property, state, structure, item, or result. For example, a structure that is "substantially without" a bottom either completely lacks a bottom or nearly completely lacks a bottom, such that its effect is substantially the same as completely lacking a bottom.

[0040] Similarly, the term "about" as used herein is employed to provide flexibility to the endpoints of a numerical range, i.e., a given value can be "slightly higher" or "slightly lower" than the endpoint while still achieving the function associated with the range.

[0041] The embodiments of the present disclosure may be best understood by reference to the accompanying drawings, where like parts may be designated by like numerals. It will be readily understood that, as generally described and illustrated in the drawings herein, the components of the disclosed embodiments may be arranged and designed in a wide variety of different configurations. Accordingly, the following detailed description of the embodiments of the apparatus and method is not intended to limit the scope of the present disclosure (as claimed), but is merely a representative illustration of possible embodiments of the present disclosure. Additionally, unless otherwise specified, the steps of a method need not be performed in any particular order, or even in sequence, nor need they be performed only once. Certain preferred embodiments and additional details of specific implementations will now be described in more detail with reference to the accompanying drawings.

[0042] Figure 1 Module 100 for a sensor assembly (such as a RADAR sensor assembly for a vehicle) according to some embodiments is depicted. Module 100 includes block 110, which may wholly or in part define one or more waveguides and / or one or more antennas. Thus, as Figure 1 depicted, block 110 includes a plurality of cylindrical members 113 arranged to define a plurality of waveguide grooves therebetween.

[0043] More specifically, block 110 includes two sets of functional waveguides, one set for the RX portion and the other set for the TX portion. The RX portion includes a series of waveguide grooves 112A, which are also defined by opposing rows of cylindrical members 113, but may be defined in any other manner available to one of ordinary skill in the art. Similarly, the TX portion includes a series of waveguide grooves 112B, which are also defined by opposing rows of cylindrical members 113.

[0044] It should be understood that although in the preferred embodiments, multiple antennas may be provided, and thus multiple corresponding antenna and / or waveguide structures - such as multiple waveguides, grooves, etc. may be provided, however, for example, it is conceivable that some embodiments may include an array having a single antenna and thus only a single waveguide. In some embodiments, such antennas / waveguides / grooves may be curved around the block / component rather than in a series of parallel lines. As another example, in some embodiments, the grooves, slots, etc. may be arranged in a disk-like form or any other suitable form, including linear forms, curved forms, etc.

[0045] In the depicted embodiments, each of the grooves is defined by a first plurality of cylindrical members 113 extending in one row and a second plurality of cylindrical members 113 extending in another row. In some embodiments, the second plurality of cylindrical members may be parallel to the first plurality of cylindrical members 113. However, it should be understood that in the same embodiment or in other embodiments, other grooves and / or antennas may not be defined by any of the cylindrical members 113 or other feature portions shared with other grooves / antennas. It should also be understood that in some embodiments, the antenna and / or waveguide may be a partial antenna / waveguide. In other words, these antennas may only include a part of the structure that will ultimately be used to define the entire antenna / waveguide structure used in a functional RADAR or other vehicle sensor assembly and are still referred to as "antennas" herein.

[0046] Furthermore, although not shown in the drawings, some embodiments may also include a waveguide ridge that extends through the groove between the opposing structures (whether cylindrical members or grooved walls) that define the groove. Additionally, if desired, any or all of the waveguide and / or antenna structures discussed herein may be formed or otherwise disposed on both sides of the block 110.

[0047] In the preferred embodiments, the block 110 may include a casting, such as a casting comprising zinc or other suitable preferred metallic material. However, in other contemplated embodiments, the block 110 may comprise plastic or other materials. In some such embodiments, metal inserts, coatings, etc. may be used if desired.

[0048] In a typical sensor assembly, as previously mentioned, the sensor assembly may be specifically configured for a vehicle, and other structures may be combined with the block / casting 110. For example, as Figure 2 shown, various additional layers may be coupled to the block 110 to form the antenna assembly and / or module 100, as discussed in more detail below.

[0049] In some embodiments, a conductive plastic coating may be used. In some such embodiments, the conductive coating may be selectively applied only to certain regions of the antenna module and not to other regions. For example, in some embodiments, the conductive coating may be used for the waveguide and / or antenna portions, but not for the entirety of the rear portion of the module. Some embodiments may also or alternatively include two or more different types of coatings. For example, a first coating configured to facilitate signal propagation in the waveguide and / or antenna portions may be applied, and a second coating configured to absorb radio signals may be applied.

[0050] Figure 2 is an exploded view depicting various additional layers that may be provided in some preferred embodiments. However, before describing these layers, consider the antenna slot structures formed on block 110, although in the depicted embodiments, these structures are formed on the opposite side / surface of block 110 from the side / surface on which the foregoing waveguide structures are formed, in various contemplated embodiments, this may vary significantly.

[0051] As Figure 2 shown, the RX portion of block 110 on the surface opposite the waveguide includes a series of elongated antenna slots 120A that extend through block 110 and connect to at least a portion of the corresponding waveguide 112A on the opposite side / surface of block 110. Similarly, the TX portion of block 110 on this same surface includes a series of elongated antenna slots 120B that extend through block 110 and connect to at least a portion of the corresponding waveguide 112B on the opposite side / surface of block 110.

[0052] However, in the depicted embodiments, the antenna slots 120B differ from the slots 120A in that they are oscillating and also include phase compensation features. This may be achieved by applying one or more angled and / or tapered portions (such as tapered grooves or notches) along the slots. Additional details regarding these phase compensation features can be found in U.S. Patent Application Serial No. 17 / 370,922, entitled "PHASE-COMPENSATED WAVEGUIDES AND RELATED SENSOR ASSEMBLIES," which is incorporated herein by reference in its entirety. Of course, in order to take advantage of the benefits of the inventive subject matter disclosed herein, it is not necessary to use these features. In fact, the antenna slots 120B (and / or 120A, for that matter) may be replaced by straight antenna slots, staggered antenna slots (discussed below), antenna slots formed in separate layers of the module / component 100, or any other suitable antenna structure.

[0053] The slots 120A and 120B are positioned on raised islands of a raised wall 117 having a defined recessed area 116. In the depicted embodiment, a raised lip 115 is also provided that extends around the perimeter of the block 110 to define the outer boundary of the recessed area 116. Although Figure 2 the depicted embodiment includes a recessed area 116 defined by both raised islands for antenna slots and an outer raised lip 115, it is envisioned that other embodiments may include only the raised islands without the outer raised lip, or vice versa. Similarly, although it may be beneficial to provide a certain type of recessed area configured to receive one or more additional layers (such as an absorption layer) as described below, it is also envisioned that some embodiments may be completely devoid of recessed areas.

[0054] Also as Figure 2 shown, preferably, as depicted, the absorption layer 140 is disposed directly against the preferred metallic material defining the block 110. By constructing the layer as described herein, an improvement in RADAR sensor performance can be achieved. For example, by using a preferred material and / or thickness, the layer 140 can be configured to act as a metal-backed non-reflective layer (MBNRL) for incident radiation and / or can be configured to suppress these surface currents by absorbing energy from the surface currents on the block 110 and converting it to heat. This suppression of the surface currents between the antennas of the sensor / module is believed to reduce or eliminate crosstalk within the antennas. Some embodiments of such layers can also be used to neutralize the adverse effects of strong reflections originating from the vehicle dashboard.

[0055] In a preferred embodiment, the thickness of the layer 140 can be approximately (2n + 1) quarter-wavelengths of the radiation used in the sensor in the medium (where n = 0, 1, 2,...). Thus, for incident radiation, the layer 140 can effectively act as a non-reflective surface. Without being limited by theory, it is expected that the incident radiation will experience partial reflection from the top surface, and the remaining radiation will pass through the medium and return after reflection from the medium-metal interface. If the intensities of the two reflected signals are equal and the conditions are such that they have opposite phases, the reflected waves will cancel each other out due to destructive interference.

[0056] Furthermore, it can be expected that this effect can extend well beyond normal incidence angles. The broadest angular performance can be achieved with the fewest solutions (n = 0). In a preferred embodiment, the effects of one or more additional layers (such as a radome film layer) preferably on top of the sensor assembly / module can also be considered. It should be understood that the thickness can be optimized for any azimuthal incidence angle (such as, for example, 20° or 45°), and the corresponding thickness can then be configured to be suitable for the angular range in the region of the defined azimuthal angle. By considering non-zero incident elevation angles, the thickness can be further optimized.

[0057] Layer 140 also includes a series of openings for various antenna slots, namely, openings 142 for each respective antenna slot 120A of the RX portion and a single wider opening 144 for each antenna slot 120B of the TX portion. Although the use of a single opening 144 for each antenna slot in antenna slots 120B of the TX portion is attributed to the closer spacing of these antenna slots 120B, separate openings can be used for each slot if desired. In embodiments including the depicted embodiment, including raised features such as wall 117, preferably, the opening is configured to fit within the recessed area 116 (excluding the outer lip 115 if present) by extending around each of the raised features and being at least substantially matched in shape to each of the raised features. In other words, preferably, layer 140 includes a conforming shape to accommodate any characteristics of the shape of the various antenna slots of module 100. It is also contemplated that some embodiments may include an absorbing layer that does not include an opening for the antenna slot.

[0058] In a preferred embodiment, the absorbing layer 140 may comprise a lossy material preferably having a dielectric constant between about 6 and about 14. In some such embodiments, the dielectric constant may be between about 9 and about 14 or between about 6 and about 9. Some embodiments may include an absorbing layer having a dielectric constant between about 6 and about 8.

[0059] In a preferred embodiment, in addition to or instead of having a preferred dielectric constant, the absorbing layer 140 may comprise a material having a dielectric loss tangent between about 0.2 and about 0.6. In some such embodiments, the dielectric loss tangent of the material may be between about 0.3 and about 0.6, or between about 0.2 and about 0.3.

[0060] Without being limited by theory, the reason for providing two different nested ranges for these material parameters is thought to be due to whether broader azimuth performance or stronger dashboard reflection suppression is preferred. For sensors with broader azimuth performance, an absorbing material with a dielectric constant between about 9 and about 14 and a dielectric loss tangent between about 0.2 and about 0.3 may be preferred. However, stronger suppression of dashboard reflections at the expense of the viewing angle can be achieved with an absorbing material having a dielectric constant between about 6 and about 9 and a dielectric loss tangent between about 0.3 and about 0.6. Additionally, it should be understood that in a given design, either or both of these parameters can vary within about + / - 20%.

[0061] In some embodiments, the absorption layer 140 may include a carbon-loaded absorption medium, which may take the form of a plastic sheet, a sticky tape, or a liquid microwave absorber. Some such materials are available from, for example, Witcom Wittenburg Group (Netherlands), RTP (USA), and Laird (USA).

[0062] In certain embodiments, another group of materials suitable for absorption materials are paints for automotive and stealth applications, which include metal particles and / or hexagonal ferrite powder content. Some suitable barium ferrite and strontium ferrite materials may have strong self-resonant characteristics in the millimeter-wave band. In some embodiments and related specific implementations of some manufacturing methods, the absorption material may be applied to the block 110 in liquid form, such as in some cases, by pouring a controlled amount of liquid medium into the recessed area 116 on the upper surface of the housing / block 110. After curing, the formed MBNR / absorption layer 140 will become an inseparable part of the housing / block.

[0063] Yet another example of a material that can form the absorption layer 140 includes a polypropylene material, preferably including carbon materials loaded therein, such as carbon fiber materials. Specific examples of this material are available in the form of granules from the RTP Company, and these granules can be rolled into thin sheets, in one specific example, into thin sheets with a thickness of about 0.25 mm. A thin layer of adhesive can be added to the thin sheet to form a laminate that can be stamped, laser cut, or otherwise formed into the desired shape. In some cases, various openings 142 / 144 can also be stamped, laser cut, or otherwise formed into the thin sheet.

[0064] In certain embodiments, the depth of the recessed area 116 may also be important. For example, in some embodiments, the depth of the recessed area 116 on the top surface of the block 110 can be configured such that the top of the absorption layer 140 and / or in some cases the top of any layer above the absorption layer (such as the radome layer 160) is flush with the top of the antenna plane including various antenna slots. Such dimensions can prevent or at least inhibit the obstruction of antenna radiation by a lossy environment. However, in some applications, the absorption layer 140 and / or any of the above layers may extend above the antenna plane to allow beam pattern control.

[0065] The absorption layer 140 can be held in its desired position by, for example, applying an adhesive or an adhesive film to the absorption layer 140 or by using other known fixing means.

[0066] In a preferred embodiment, the upper / radome layer 160 does not contain the opening of the absorption layer 140. The radome layer 160 can be adhered, for example, to the top of the absorption layer 140, preferably covering and enclosing the entire top surface and making each of the antenna slots 120A / 120B in the antenna slot airtight.

[0067] In some embodiments, each of the various layers above the block / case 110 (which, as described below, may include two or more than two layers) can be laminated or otherwise combined together into a self - contained cap or seal for the assembly.

[0068] Figure 3 A graph is provided showing the functional relationship of the return loss varying with the incident angle for an exemplary embodiment, which exemplary embodiment includes an absorption / MBNR layer having a thickness of about 0.35 mm, and an upper layer (see Figure 2 layer 160 in, which will be discussed in more detail below), the top layer of which is a radome film having a thickness of about 0.2 mm. This exemplary thickness can be used in the RADAR frequency band of 76 GHz - 81 GHz. Some embodiments can be configured for RADAR of 76 GHz - 77 GHz, while other embodiments can be configured for RADAR of 77 GHz - 81 GHz.

[0069] The figure shows how the return loss remains below - 17 dB at incident angles up to 55 degrees, which in fact covers the entire operating range of the RADAR sensor. As the reflectivity is reduced to - 17 dB and below in such a wide range of incident angles, the characteristics of the dashboard geometry and paint become irrelevant, or at least less important. Therefore, almost no modification to the vehicle dashboard is required to accommodate the sensor.

[0070] Although the required layer thickness of the absorption / MBNR layer generally varies according to the electromagnetic radiation used in the sensor, the required layer thickness of this layer can vary by about + / - 15%. Therefore, using the nominal value of 0.35 mm referenced above, a thickness between about 0.3 mm and about 0.4 mm may be appropriate.

[0071] As previously mentioned, the absorption / MBNR layer is thought to have two mechanisms of action. The first mechanism is a reflection suppression mechanism that deals with incident electromagnetic waves that pass through and are reflected from the absorption / MBNR layer. This mechanism relies on a specific preferred thickness or thickness range (preferably close to an odd multiple of a quarter wavelength of the associated radiation) required for the absorption layer to function as an MNBR layer. The second mechanism is a mechanism for dissipating surface currents when the surface currents propagate tangentially to the metal surface of the sensor. This mechanism does not rely on any specific thickness of the layer. The end result in the preferred embodiments is the result of the combined action of these two mechanisms. Thus, in some embodiments, the thickness requirements can be substantially less stringent to accommodate possible MNBR production variants.

[0072] In some embodiments that include the outer lip 115, the lip can extend slightly above the uppermost layer of the assembly 100 above the block / case 110. This can be seen Figure 4 in the enlarged perspective view of a corner of the assembly 100 shown in the figure. As can be seen more clearly in this figure, in some embodiments, the lip 115 can extend slightly above the top surface of the uppermost layer of the assembly 100 (in this case the radome layer 160). This can provide protection to the various layers located within the recessed area 116 or otherwise within the portion of the assembly 100 located inside the lip 115. In some embodiments, the height of the lip 115 can be between about 0.2 mm and about 0.6 mm above the upper surface of the radome layer 160. In some such embodiments, the height of the lip 115 can be about 0.4 mm above the upper surface of the radome layer 160.

[0073] Figure 5 is a cross-sectional view showing how the waveguide grooves 112A / 112B are at least partially aligned with the corresponding antenna slots 120A / 120B. Although in the depicted embodiments both the waveguide grooves and the antenna slots are formed in the same block / structure 110, it is contemplated that in other embodiments such elements can be provided in separate elements and / or layers. For example, in some embodiments, a slotted layer can be coupled to the block, casting, and / or other elements that include the waveguide grooves. In some embodiments, such a slotted layer can include one or more rows of slots that can correspond in number and / or position to the waveguide partially defined by the block 110. When present, the slotted layer can be applied to the absorption layer and / or any other layer of the assembly 100, in some cases by composite lamination.

[0074] Regarding the configuration of the lip 115 along the perimeter of the block 110 relative to the layers 140 and 160, in Figure 6Acan be seen more clearly. Similarly, the interrelationship between the specific waveguide / antenna slot pair 112B / 120B and the layers 140 / 160, including the opening 144 formed in the layer 140, can be seen most clearly in Figure 6B in the enlarged view of.

[0075] In Figure 7 an alternative embodiment of the module 200 for a sensor assembly (such as a RADAR sensor assembly for a vehicle) is shown. The module 200 also includes a block 210, which may wholly or partly define one or more waveguides and / or one or more antennas. Although Figure 7 the waveguide portion of the block 210 is not depicted in, this portion may be defined by a plurality of cylindrical members arranged to define one or more waveguide grooves therebetween, the same as in the case of the block 110. Alternatively, as previously mentioned, the waveguide portion of the block 210 may be defined in other ways, such as by a trench-type waveguide having continuous walls, or any other waveguide available to those of ordinary skill in the art.

[0076] Similar to the case of the block 110, the block 210 may include two sets of functional waveguides, one set for the RX portion and the other set for the TX portion. The antenna sides of these functional waveguide portions are shown in Figure 7 However, this embodiment differs from the block 110 in that the antenna slots are arranged in an array with staggered slots. Thus, each of the arrays 220A includes a plurality of antenna slots extending in two rows offset relative to each other. Also as shown in Figure 7 some of the arrays themselves may be offset relative to each other. Similarly, the array 220B may include staggered antenna slots extending in two offset rows. Similar to the case of the block 110, each of the arrays 220A / 220B in the block 210 may be positioned to extend above the bottom plate of the block 210, where the raised wall 217 defines the recessed area 216.

[0077] In the depicted embodiment, a raised lip 215 is also provided, which extends around the perimeter of the block 210 to define the outer boundary of the recessed area 216, which is also depicted in the enlarged cross-sectional view of Figure 8 Although the embodiment depicted in Figure 7 includes a recessed area 216 defined by both the raised islands (formed by the wall 217) for the antenna slot array and the outer raised lip 215, it is contemplated that other embodiments may include only the raised islands without the outer raised lip, or vice versa. Similarly, although it may be beneficial to provide some type of recessed area configured to receive one or more additional layers (such as an absorption layer) as described above, it is also contemplated that some embodiments may be completely without a recessed area.

[0078] Also as shown inFigure 7 As shown, preferably, as shown, an absorption layer 240 is disposed directly against the preferred metallic material of the defining block 210. As previously mentioned, by using a preferred material and / or thickness, layer 240 can be configured to act as a metallic backplane non-reflective layer (MBNRL) for incident radiation, and / or can be configured to suppress these currents by absorbing energy from the surface currents on block 210 and converting it to heat. This suppression of the surface currents between the antennas of the sensor / module can also reduce or eliminate crosstalk within the antennas and / or can be used to neutralize or at least reduce the detrimental effects of strong reflections from the vehicle dashboard.

[0079] In a preferred embodiment, the thickness of layer 240 can be approximately (2n + 1)1 / 4 times the wavelength of the radiation used by the sensor in the medium (where n = 0, 1, 2...). Thus, for incident radiation, layer 240 can effectively act as a non-reflective surface.

[0080] Layer 240 can also include a series of openings for the various antenna slot arrays, i.e., openings 242 for each respective antenna slot array 220A of the RX portion and a series of corresponding openings 244 for each antenna slot array 220B of the TX portion. As Figure 7 shown, one or more of these openings 242 / 244 can be configured to accommodate more than one antenna slot array.

[0081] In embodiments including the depicted embodiment and including raised features such as wall 217, preferably, the aforementioned openings in layer 240 are configured to fit within the recessed regions 216 by extending around each of the raised features and at least substantially matching the shape of each of the raised features (in some embodiments, excluding the outer lip 215 if present). It is also contemplated that some embodiments can include an absorption layer that does not include openings for the antenna slot arrays.

[0082] In a preferred embodiment, absorption layer 240 can include a lossy material preferably having a dielectric constant between about 6 and about 14. In some such embodiments, the dielectric constant can be between about 9 and about 14 or between about 6 and about 9. In a preferred embodiment, in addition to or instead of having a preferred dielectric constant, absorption layer 240 can include a material having a dielectric loss tangent between about 0.2 and about 0.6. In some such embodiments, the dielectric loss tangent of the material can be between about 0.3 and about 0.6, or between about 0.2 and about 0.3. Additionally, it should be understood that in a given design, either or both of these parameters can vary within about + / - 20%.

[0083] In some embodiments, the absorption layer 240 can comprise a carbon-bearing absorption medium, which can take the form of a plastic sheet, a sticky tape, or a liquid microwave absorber. Another material suitable for the absorption layer includes paint for automotive and stealth applications, which contains metal particles and / or hexagonal ferrite powder content, such as barium ferrite and strontium ferrite materials. In some embodiments of some methods of manufacture and related specific implementations, the absorption material can be applied to the block 210 in liquid form, such as in some cases, by pouring a controlled amount of the liquid medium into the recessed area 216 on the upper surface of the housing / block 210. After curing, the formed MBNR / absorption layer will become an inseparable part of the housing / block.

[0084] Yet another example of a material that can form the absorption layer 240 includes a polypropylene material, preferably including a carbon material loaded therein, such as a carbon fiber material. Specific examples of this material can be purchased from the RTP Company in the form of pellets, which can be rolled into sheets, in one specific example, sheets with a thickness of about 0.25 mm. A thin adhesive layer can be added to the sheet to form a laminate that can be stamped, laser cut, or otherwise formed into the desired shape. In some cases, various openings 242 / 244 can also be stamped, laser cut, or otherwise formed into the sheet.

[0085] The assembly 200 further includes a top layer 260, which can be used to provide a radome or a liquid seal / weather seal for the assembly 200. Thus, in some embodiments, the layer 260 can include a plastic film or other non-conductive material. In some such embodiments, the layer 260 can include a sticky plastic film. However, alternatively, the layer 260 can be applied by using a separate adhesive or other coupling means. Preferably, the layer 260 applies a waterproof seal to the assembly 200 or at least a part thereof to protect the unit from damage, which can allow the assembly 200 to be mounted to the exterior of a vehicle.

[0086] However, different from the assembly 100, the assembly 200 further includes an additional layer 250. In some embodiments, the layer 250 can include an adhesive layer configured to adhere the radome layer 260 to the absorption layer 240. Such an adhesive layer can include, for example, a tape, such as a conductive tape, or other suitable materials. Although the openings are not shown, in some embodiments, the layer 250 can include openings corresponding to and / or at least partially aligned with the above-mentioned openings. Additionally, the layer 250 can be located at another position in the assembly 200, or if needed, additional adhesive layers or other layers can be present.

[0087] In some embodiments and related manufacturing methods, a sub-component can be provided that includes multiple layers forming a self - contained weather seal or "label". For example, all three layers 240, 250, and 260 can be formed in a sandwich configuration during manufacturing, which can be simply applied to the top of the antenna block 210 by using an adhesive. In some such embodiments, the adhesive can be part of the sandwich assembly such that the weather seal assembly can be applied to the antenna block 210 similar to a label. Additionally, in some embodiments, fewer than Figure 7 all of the layers depicted in Figure 7 or in other embodiments, additional layers can be included in the weather seal / label assembly.

[0088] Any one of the various layers (such as layer 240) can be coupled to the block 210 in a variety of possible ways. For example, an adhesive, solder, heat stakes, screws, other fasteners, etc. can be used. In some embodiments, another layer (such as a tape layer) can be inserted between any one of the various layers, which can be used in whole or in part to provide the coupling.

[0089] The foregoing specification has been described with reference to various embodiments and specific implementations. However, those of ordinary skill in the art will understand that various modifications and changes can be made without departing from the scope of the invention. For example, depending on the particular application or any cost function associated with the operation of the system, the various operation steps and the components for performing these operation steps can be implemented in a variety of ways. Thus, any one or more steps can be deleted, modified, or combined with other steps. Additionally, this disclosure should be considered illustrative rather than restrictive, and all such modifications are intended to be included within its scope. Similarly, benefits, other advantages, and solutions to problems have been described above with respect to various embodiments. However, benefits, advantages, solutions to problems, and any element that may cause any benefit, advantage, or solution to occur or become more pronounced should not be construed as critical, essential, or fundamental features or elements.

[0090] Those of ordinary skill in the art will understand that many changes can be made to the details of the above - described embodiments without departing from the basic principles of the invention. Therefore, the scope of the invention should be determined solely by the following claims.

Claims

1. A vehicle sensor module, the vehicle sensor module comprising: A waveguide block that defines an array of waveguide grooves; An array of antenna slots, each antenna slot in the array of antenna slots being at least partially aligned with a waveguide groove in the array of waveguide grooves of the waveguide block, wherein each antenna slot in the array of antenna slots extends from a first side of the antenna block to a second side of the waveguide block to allow electromagnetic radiation to propagate through the array of antenna slots; And An absorption layer that includes an array of openings corresponding to the array of antenna slots, wherein the absorption layer is configured to suppress surface currents on the waveguide block.

2. The vehicle sensor module according to claim 1, the vehicle sensor module further comprising an antenna cover layer positioned on top of the absorption layer, wherein the antenna cover layer is free of openings so as to provide a seal for the waveguide block.

3. The vehicle sensor module according to claim 2, wherein the antenna cover layer includes a laminate that includes a plurality of sub-layers, wherein at least one of the sub-layers is configured to adhere the antenna cover layer to the absorption layer, and wherein at least one of the sub-layers is configured to increase the strength of the antenna cover layer.

4. The vehicle sensor module according to claim 1, wherein the array of waveguide grooves includes a plurality of waveguide grooves.

5. The vehicle sensor module according to claim 1, wherein the thickness of the absorption layer is equal to approximately an odd multiple of one quarter of the wavelength of the electromagnetic radiation used in the vehicle sensor module.

6. The vehicle sensor module according to claim 1, wherein the absorption layer comprises a lossy material.

7. The vehicle sensor module according to claim 6, wherein the absorption layer comprises a material having a dielectric constant between 6 and 14 and a dielectric loss tangent between 0.2 and 0.

6.

8. The vehicle sensor antenna assembly according to claim 1, wherein at least a subset of the antenna slots are positioned on raised islands that include raised walls extending over a recessed area, and wherein the absorption layer is positioned within the recessed area.

9. The vehicle sensor antenna assembly according to claim 8, the vehicle sensor antenna assembly further comprising: A raised lip that extends around the perimeter of the waveguide block; And An antenna cover layer that is positioned above the absorption layer, wherein the antenna cover layer is positioned within the recessed area and below the raised lip.

10. A vehicle sensor antenna assembly, the vehicle sensor antenna assembly comprising: A metal waveguide block that defines an array of waveguide grooves; An antenna assembly that includes at least one antenna slot configured to receive electromagnetic radiation through the antenna slot from the array of waveguide grooves; And An absorption layer configured to generate a destructive interference pattern to reduce the reflectivity of the electromagnetic radiation incident on the vehicle sensor antenna assembly.

11. The vehicle sensor antenna assembly according to claim 10, wherein the antenna assembly includes antenna slots corresponding to each waveguide groove in the waveguide groove array.

12. The vehicle sensor antenna assembly according to claim 10, wherein the absorption layer includes one or more openings positioned such that each antenna slot in the at least one antenna slot is positioned below an opening of the one or more openings.

13. The vehicle sensor antenna assembly according to claim 10, wherein the antenna assembly is part of the metal waveguide block such that the at least one antenna slot is formed within the metal waveguide block and extends between opposite surfaces of the metal waveguide block.

14. The vehicle sensor antenna assembly according to claim 13, wherein the metal waveguide block includes a recessed area defined by a lip extending around a perimeter of the metal waveguide block and a raised wall extending around a perimeter of each antenna slot of the at least one antenna slot, and wherein the absorption layer is positioned within the recessed area.

15. The vehicle sensor antenna assembly according to claim 14, wherein the recessed area includes a height greater than a thickness of the absorption layer.

16. The vehicle sensor antenna assembly according to claim 10, wherein the absorption layer includes a dielectric constant between about 6 and about 14.

17. The vehicle sensor antenna assembly according to claim 10, wherein the absorption layer includes a dielectric loss tangent between about 0.2 and about 0.

6.

18. A vehicle RADAR module, the vehicle RADAR module comprising: A metal waveguide block that defines waveguide grooves and includes a recessed area; Antenna slots that are at least partially aligned with the waveguide grooves of the metal waveguide block, wherein the antenna slots extend completely through the metal waveguide block from a first surface of the metal waveguide block to a second surface of the metal waveguide block opposite the first side to allow electromagnetic radiation to propagate through the antenna slots; An absorption layer that is located in the recessed area, the absorption layer containing a lossy material, wherein the absorption layer includes openings that are at least partially aligned with the antenna slots and the waveguide grooves, wherein the absorption layer is configured to contact the metal waveguide block to suppress surface currents on the metal waveguide block, and wherein the absorption layer has a thickness that is configured to suppress reflection of the electromagnetic radiation by creating destructive interference between a reflection of the electromagnetic radiation above the absorption layer and a reflection of the electromagnetic radiation below the absorption layer; and An antenna radome layer that is configured to provide weather sealing to the vehicle RADAR module.

19. The vehicle RADAR module according to claim 18, wherein the thickness of the absorption layer is equal to about an odd multiple of one quarter of a wavelength of the electromagnetic radiation used in the vehicle RADAR module.

20. The vehicle RADAR module according to claim 18, wherein the absorption layer is formed from a liquid cured within the recessed area of the metal waveguide block.

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