Patent Publication Number: US-2023144495-A1

Title: Waveguides and waveguide sensors with signal-improving grooves and/or slots

Description:
SUMMARY 
     Disclosed herein are various embodiments of waveguide and/or antenna structures having features for altering and/or improving signal transmission and/or receiving characteristics, such as increasing signal strength within one or more particular, desired angle ranges. In preferred embodiments, such structures may be used in sensor assemblies, such as RADAR or other sensor modules for vehicles. 
     In some embodiments, such features may comprise grooves configured to mimic antenna slots, such as by providing an identical, substantially identical, or at least similar length, width, and/or shape. Alternatively, or additionally in some embodiments, one or more isolation grooves may be provided, such as arrays of isolation grooves that may be positioned in between adjacent antenna slots. Some embodiments may further comprise oscillating/“wavy” antenna slots having corresponding similar oscillating/wavy antenna slot grooves. 
     It should also be understood that any of the mimicking grooves may, in some embodiments, be replaced with slots that extend all the way through the structure into which they are formed. However, it is important to note that such slots should be distinguished from the “antenna slots” described herein in that they do not accept or direct electromagnetic radiation to or from electronics of the assembly. In other words, unlike an antenna slot, other slots or grooves disclosed herein, including but not limited to a mimicking slot extending through an antenna slot of a RADAR or other sensor assembly, is configured to alter, improve, and/or redirect signals from an antenna slot in the assembly rather than to simply accept and/or transmit signals to and/or from the electronic circuits of the assembly. 
     Thus, as used herein, the term “antenna slot” should be considered to encompass slots that are configured to transmit and/or receive electromagnetic signals/energy to and/or from electronics on the assembly, such as circuits on a printed circuit board of the assembly. By contrast, as used herein, an “auxiliary slot” or an “auxiliary groove” should be considered to encompass a slot or groove that facilitates a desired improvement, alternation, and/or adjustment of electromagnetic signals/energy being transmitted and/or received from an antenna slot of the same assembly, such as in some cases an adjacent antenna slot. The distinction between an “auxiliary slot” and an “auxiliary groove” is that an “auxiliary groove” may or may not extend entirely through the structure into which it is formed to form an opening, whereas an “auxiliary slot,” like an antenna slot, does form such as opening. 
     In a more particular example of a waveguide assembly, such as a waveguide assembly and/or an antenna module for a vehicle sensor module, the assembly/module may comprise a waveguide block or other structure comprising a first surface on a first side of the waveguide block and a second surface on a second side of the waveguide block opposite the first side. One or more waveguides may be at least partially formed along the first surface of the waveguide block. The assembly may further comprise one or more antenna slots, wherein each of the one or more antenna slots is operably coupled with a waveguide of the one or more waveguides, and wherein each of the one or more antenna slots extends through the waveguide block between the first and second sides of the waveguide block. The assembly may further comprise one or more antenna grooves. The antenna groove(s) may be positioned adjacent to at least one of the one or more antenna slots. Each of the one or more antenna grooves preferably extends into the waveguide block without extending entirely through the waveguide block. The antenna groove(s) may at least substantially mimic at least one of the one or more antenna slots in both length and width. 
     Some embodiments may further comprise one or more antenna grooves, such as antenna isolation grooves, wherein each of the one or more antenna grooves extends into the waveguide block without extending entirely through the waveguide block. Each of the one or more antenna grooves may differ in at least one of length, width, and depth relative to each of the one or more antenna grooves. For example, the antenna grooves may be longer, narrower, and shallower than some or all of the antenna grooves in some embodiments. 
     In some embodiments, at least a subset of the one or more antenna grooves may vary in depth. For example, one or more arrays of antenna grooves may be provided that may vary in depth in a stepwise manner from one side of the array(s) to the other. 
     In some embodiments, a plurality of antenna grooves may be positioned between at least two adjacent antenna grooves of the one or more antenna grooves. 
     In some embodiments, each of the plurality of antenna grooves may vary in depth relative to each adjacent antenna groove of the plurality of antenna grooves. 
     In some embodiments, at least one of the one or more antenna slots may comprise a shifted antenna slot that is shifted in a direction at least substantially corresponding to a direction of an elongated axis of at least one of the one or more antenna slots relative to the other antenna slots of the one or more antenna slots. In some such embodiments, at least a subset of the one or more antenna grooves may be greater in length than each of the one or more antenna slots. A first subset of the one or more antenna slots may be at least substantially aligned with a first end of the at least a subset of the one or more antenna grooves. In some such embodiments, the shifted antenna slot may be at least substantially aligned with a second end of the at least a subset of the one or more antenna grooves opposite the first end. 
     In another specific example of an antenna assembly according to some embodiments, the antenna assembly may comprise a waveguide and an antenna structure operably coupled with the waveguide. The antenna structure may comprise an antenna slot array comprising one or more antenna slots extending between opposing surfaces of a unitary structure of the antenna assembly, such as a waveguide and/or antenna block of the assembly. A first antenna groove may be positioned at a first end of the antenna slot array, wherein the first antenna groove extends into the unitary structure without extending entirely through the unitary structure. An antenna groove array, such as an antenna isolation groove array, may also be provided, which may comprise one or more antenna grooves, wherein each antenna groove of the antenna groove array differs in at least one of length and width relative to the first antenna groove. 
     In some embodiments, the antenna slot array may comprise a plurality of antenna slots and the antenna groove array may comprise a plurality of antenna grooves. In some such embodiments, at least one antenna groove may be positioned between each adjacent antenna slot of the antenna slot array. 
     In some embodiments, each antenna groove of the antenna groove array may extend into the unitary structure without extending entirely through the unitary structure. 
     The antenna assembly may comprise a transmit or TX portion and a receive or RX portion, wherein the transmit portion is configured to transmit electromagnetic signals therethrough, and wherein the receive portion is configured to receive electromagnetic signals therethrough. In some such embodiments, the antenna slot array may be positioned on the transmit portion. A second antenna slot array may be positioned on the receive portion, wherein a plurality of antenna grooves is positioned between each adjacent antenna slot of the second antenna slot array. 
     In some embodiments, a single antenna groove may be positioned between each adjacent antenna slot of the antenna slot array. 
     In another specific example of an antenna assembly, the assembly may comprise a first antenna array comprising one or more elongated antenna slots each extending along an elongated axis, wherein each elongated antenna slot of the first antenna array is positioned and configured to deliver electromagnetic radiation therethrough. Each elongated antenna slot of at least a subset of the one or more elongated antenna slots of the first antenna array may be intermittently oscillate on opposite sides of its respective elongated axis along at least a portion of its respective elongated axis. An elongated groove may be positioned adjacent to at least one of the one or more elongated slots and may extend along an elongated axis. The elongated groove may intermittently oscillate on opposite sides of its elongated axis along at least a portion of its elongated axis. 
     Some embodiments may further comprise one or more waveguides each extending along a respective elongated axis, wherein each waveguide of the one or more waveguides is operably coupled with a respective elongated antenna slot of the first antenna array. 
     In some embodiments, the elongated groove (or a similar elongated slot) may at least substantially mimic at least one of the one or more elongated antenna slots in shape (and/or in length and/or width). In some such embodiments, the elongated groove may at least substantially mimic each of the one or more elongated antenna slots in shape (and/or in length and/or width). In some such embodiments, the elongated groove may at least substantially mimic at least one of the one or more elongated antenna slots in length, width, and shape. 
     In some embodiments, the elongated groove may extend into a structure defining both the elongated groove and the first antenna array, such as an antenna block, without extending entirely through the structure. 
     In some embodiments, the first antenna array may comprise a plurality of elongated antenna slots. In some such embodiments, an elongated groove may be positioned at each of two opposing ends of the first antenna array. 
     The 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 
       Non-limiting and non-exhaustive embodiments of the disclosure are described, including various embodiments of the disclosure with reference to the figures, in which: 
         FIG.  1    is a perspective view of an antenna module according to some embodiments; 
         FIG.  2    is a close-up view of an RX section of the antenna module of  FIG.  1   ; 
         FIG.  3    is a plan view of an antenna module according to other embodiments; 
         FIG.  4    is a cross-sectional view taken through the RX section of the antenna module of  FIG.  3   ; 
         FIG.  5    is a cross-sectional view taken through the TX section of the antenna module of  FIG.  3   ; 
         FIG.  6    is a cross-sectional view of an alternative RX section of the antenna module of  FIG.  3    in which the isolation grooves vary in depth; 
         FIG.  7    is a graph comparing the signal strength per angle for the embodiment of  FIG.  5    vs. the embodiment of  FIG.  6   ; 
         FIG.  8    is a cross-sectional view of an alternative TX section of the antenna module of  FIG.  5   ; 
         FIG.  9    is a graph comparing the signal strength per angle for the embodiment of  FIG.  5    vs. the embodiment of  FIG.  8   ; 
         FIG.  10    is a perspective view of yet another example of an antenna module according to still other embodiments; 
         FIG.  11    is a close-up view of the TX section of the antenna module of  FIG.  10   ; and 
         FIG.  12    is a plan view of the antenna module of  FIG.  10    showing the side opposite from that shown in  FIG.  10   . 
     
    
    
     DETAILED DESCRIPTION 
     It will be readily understood that the components of the present disclosure, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus is not intended to limit the scope of the disclosure but is merely representative of possible embodiments of the disclosure. In some cases, well-known structures, materials, or operations are not shown or described in detail. 
     As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result to function as indicated. For example, an object that is “substantially” cylindrical or “substantially” perpendicular would mean that the object/feature is either cylindrical/perpendicular or nearly cylindrical/perpendicular so as to result in the same or nearly the same function. The exact allowable degree of deviation provided by this term may depend on the specific context. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, structure which is “substantially free of” a bottom would either completely lack a bottom or so nearly completely lack a bottom that the effect would be effectively the same as if it completely lacked a bottom. 
     Similarly, as used herein, the term “about” is used to provide flexibility to a numerical range endpoint by providing that a given value may be “a little above” or “a little below” the endpoint while still accomplishing the function associated with the range. 
     The embodiments of the disclosure may be best understood by reference to the drawings, wherein like parts may be designated by like numerals. It will be readily understood that the components of the disclosed embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the apparatus and methods of the disclosure is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments of the disclosure. In addition, the steps of a method do not necessarily need to be executed in any specific order, or even sequentially, nor need the steps be executed only once, unless otherwise specified. Additional details regarding certain preferred embodiments and implementations will now be described in greater detail with reference to the accompanying drawings. 
       FIG.  1    depicts an antenna and/or waveguide assembly  100  that defines, either in whole or in part, one or more waveguides therein and may comprise a portion of, for example, an antenna module, which antenna module may comprise one or more antennae. Waveguide/antenna/sensor assembly  100  may therefore be incorporated into or otherwise used with a vehicle sensor, such as a RADAR sensor assembly, according to some embodiments. 
     As depicted in  FIG.  1   , assembly  100  comprises a portion, such as a layer, casting, and/or block, that comprises and/or defines a series of antenna slots and/or grooves that are configured to transmit, receive, and/or alter electromagnetic signals. In the depicted embodiment, a body  110  containing such slots/grooves is depicted having a series of mounting tabs  112  protruding therefrom. Any of the various slots, grooves, waveguides, or other structures and/or features described herein may be formed directly into the body  110 , such as by way of a die cast mold or the like, or may be formed into one or more layers or other structures coupled to body  110 . 
     In the depicted embodiment, assembly  100  comprises a receiving or “RX” section  115  and an adjacent transmission or “TX” section  117 . RX section  115  comprises a series of elongated slots, each of which is positioned and configured to receive electromagnetic radiation therethrough and may therefore be considered an example of an “antenna structure” of assembly  100 . It should be understood, however, that one or more slots or another antenna structure may be, in alternative embodiments, formed in another portion of the assembly/module and/or formed in an alternative manner. For example, in some embodiments, a slot may be formed within a lid/plate or other separate layer, which may be coupled to one or more adjacent waveguides rather than incorporating the waveguides into the same, unitary structure defining the antenna slots, as is the case with preferred embodiments disclosed herein. 
     RX section  115  of assembly  100  comprises four elongated antenna slots  120 A, each of which is spaced apart from one or more adjacent slots  120 A and, as discussed in greater detail below, has various other functional features spaced in between and/or otherwise throughout section  115 . More particularly, a series of antenna grooves  130 A are formed adjacent to the aforementioned antenna slots  120 A of RX section  115 . 
     Antenna grooves  130 A extend parallel, or in other embodiments at least substantially parallel, to antenna slots  120 A. Moreover, unlike antenna slots  120 A, which extend all the way through the structure of assembly  100  in which they are formed, such as a waveguide and/or antenna block or a layer of assembly  100 , antenna grooves  130 A extend into this structure without extending entirely through the structure (hence, the use of the term “groove” rather than “slot”). However, as previously mentioned, in some embodiments, structures intended to alter one or more aspects of an electromagnetic signal in an antenna slot may also comprise a slot. Such slots are referred to herein as “auxiliary slots.” 
     Each antenna groove  130 A also at least substantially mimics one or more (in the depicted embodiment, all) of the antenna slots  120 A in length. As discussed in connection with other embodiments below, some antenna grooves are configured to mimic, or at least substantially mimic, one or more of the antenna slots  120 A in both length and width. However, antenna grooves  130 A of assembly  100  only mimic or resemble antenna slots  120 A in length and are primarily configured to isolate the antenna grooves  130 A from their surroundings, which may be useful in reducing bearing errors and narrowing the antenna pattern to reduce the field of view. Thus, antenna grooves  130 A may be referred to herein as “antenna isolation grooves.” 
     TX section  117  of assembly  100  comprises antenna slots  120 B at opposing ends of the section  117  and further comprises a high-gain, squinted antenna  140  in between these opposing antenna slots  120 B. Antenna  140  comprises an array of radiating slots  142  formed in a portion, such as a top layer, thereof. In the depicted embodiment, this array is formed into parallel columns that are offset from one another. Thus, a first column, such as the column shown on the left side of antenna  140 , may comprise slots  142  that are positioned adjacent to spaces in between adjacent slots  142  in the adjacent column. The pattern of alternative/offset columns may repeat throughout the array such that, as shown in  FIG.  1   , slots  142  from the array in a column with an intermediate column therebetween may be aligned with the slots from the column, and so on. However, it is contemplated that, in other embodiments, the array of slots  142  may comprise columns and/or rows that are aligned with one another rather than offset with respect to adjacent columns and/or rows. 
     Although not shown in  FIG.  1   , it is contemplated that antenna  140  may comprise various waveguides or other features that may be present below the layer shown in  FIG.  1   . For example, each of the antenna slots may comprise an associated waveguide, which may comprise a “trench-like” waveguide defined by solid opposing sidewalls or, as discussed later, may comprise a waveguide formed by rows of adjacent posts forming a waveguide therebetween. In embodiments in which waveguides are formed by rows of posts, two rows of posts may form a waveguide therebetween or, alternatively, multiple rows of adjacent posts may be positioned on either side of the waveguide defined therebetween. 
     Similarly, with respect to antenna  140 , a waveguide may be formed thereunder to feed the array of radiating slots  142 . In some embodiments, this waveguide may comprise a self-contained, feed waveguide, which may be formed within a tunnel formed within a body or other portion of the antenna  140 . A series of feed slots may also be formed along this waveguide to allow electromagnetic energy to be introduced from the waveguide into another waveguide, such as a parallel plate waveguide formed between upper surface of the antenna  140  and a lower surface of, for example, a cover, which may comprise the layer visible in  FIG.  1   . These feed slots may be arranged in a straight line and preferably extend along the tunnel waveguide at a position near, but not precisely along, the center of the waveguide. 
     In addition, in some embodiments, an array of protrusions may be formed within the underlying structure of antenna  140 . In some such embodiments, like slots  142 , these protrusions may be formed in an array having offset columns. In preferred embodiments, these protrusions may also have one or more parameters that correlate with slots  142 . For example, the protrusions may have the same shape, a substantially identical shape, or at least a similar shape as slots  142 . Preferably, however, one or both of slots  142  and the underlying protrusion may be elongated in one direction to provide an identifiable elongated axis. Thus, it may be preferred to avoid circular shapes, for example. 
     It may also be preferred that the protrusions have the same or a similar size with respect to the slots  142 . Thus, although it may be preferred that they have the same, or at least substantially the same size (within about ±15% of one or more dimensions such as length, width, and/or area/footprint). However, it is contemplated that, in some embodiments, one or more of the length, width, and area of the protrusions may be between about 50% and about 150% of the corresponding length, width, and/or area of the slots  142 . 
     As another preferred matching parameter, preferably, most or all of protrusions are positioned directly, or at least substantially directly, under a corresponding slot  142 . However, it is contemplated that, in some embodiments, the positioning of each protrusion may be shifted slightly (preferably less than about 0.5 mm in automotive applications; for other applications, such as applications using radiation at a frequency of around 30 GHz, for example, the shifting may be 1 mm or more) relative to one or more (in some cases, each) corresponding slot  142 . In addition, although it may be preferred to have an equal number of protrusions as slots  142 , it is contemplated that some protrusions may be omitted. Moreover, in some embodiments, protrusions may be omitted altogether. However, when present, preferably sufficient numbers of protrusions are formed such that there is an equal number of columns and/or rows of protrusions as columns and/or rows of slots  142 . 
     Preferably, when present, protrusions are between about 0.1 mm and about 0.4 mm in height for automotive applications operating in the frequency range of 76-81 GHz. However, as those of ordinary skill in the art will appreciate, the height of the protrusions may vary in accordance with the frequency of the electromagnetic radiation being used. The height used may also vary depending upon the desired use of the antenna, since the height of the protrusions may be used as a parameter to control the amplitude and/or phase of the excitation of the radiating slots  142  and/or may be used to direct a squint of a main lobe of the antenna, the shape of the main lobe, and/or the level of side lobes and/or the grating lobe. The preferred sizes of the protrusions may be identified using 3-D simulation software, such as HFSS, and may be selected among results of various simulations or using an optimization procedure. 
     The desired sizes of the radiating slots  142  of squinted antenna  140  may be found using, for example, 3-D simulation software. Although the locations of the slots  142  are preferably synchronized with the locations of the protrusions such that they are aligned with one another, the slot-to-slot distance (as well as the protrusion-to-protrusion distance) is preferably constant (although may be non-uniform in other contemplated embodiments, which may provide for another degree of freedom to shape the desired radiation pattern) and may vary from about one-fourth to about a full wavelength of the parallel-plate waveguide wavelength. This distance may effectively impact the squint angle and may therefore be a prime design parameter determining the squint value. The slot-to-slot distance (as well as the protrusion-to-protrusion distance) in a perpendicular direction is also preferably constant and may be, for example, about a half wavelength of the wave propagating in the internal, tunnel waveguide mentioned above. 
     In the depicted embodiments, the number of feed slots from the tunnel waveguide is equal to the number of columns of protrusions and/or the number of columns of radiating slots  142 . However, as will be apparent from a review of all embodiments disclosed herein, this need not be the case for all contemplated embodiments. In addition, the size/footprint of feed slots may be identical, or at least substantially identical, to that of the protrusions and/or radiating slots  142 , but this need not always be the case either. 
     For some applications, it may also be preferred that the tunnel/internal waveguide is positioned adjacent to a peripheral edge of antenna  140  rather than at or near the center. Although there are embodiments contemplated in which this internal waveguide is not positioned adjacent to an outer edge of antenna  140 , it is thought that some of the parameters of assembly  100  may need to be adjusted if this modification is made. 
     It may also be preferred to have all of the protrusions and/or radiating slots  142  positioned on one side of the feed slots from the internal/tunnel waveguide. However, it is contemplated that, in some embodiments, one or more protrusions and/or radiating slots  142  may instead be positioned on the opposite side of these feed slots and/or the internal/tunnel waveguide. However, it is preferably that at least most of the radiating slots  142  and, when present, protrusions, are positioned on one side of the internal/tunnel waveguide and/or feed slots, which may be facilitated by placement of the internal/tunnel waveguide adjacent to a peripheral edge, as previously mentioned. Thus, in preferred embodiments, at least 90% of the radiating slots  142  and/or protrusions are positioned on just one side of the internal and/or tunnel waveguide and/or feed slots. 
     Further details regarding squinted antenna assemblies, which may be used to create various alternative embodiments of antenna  140 , can be found in U.S. patent application Ser. No. 17/206,599 titled PARALLEL PLATE SLOT ARRAY ANTENNA WITH DEFINED BEAM SQUINT, which was filed on Mar. 19, 2021, and which is incorporated herein by reference in its entirety. 
     Various grooves, all of which may be considered isolation grooves in the depicted embodiment, are also shown formed along TX section  117 . Thus, a single groove  130 B is positioned on opposing ends of section  117 . In addition, another isolation single groove  130 B is positioned immediately adjacent to antenna  140  on opposing sides thereof. Thus, an isolation groove  130 B is positioned on either side of each antenna slot  120 B, and on either side of high-gain, squinted antenna  140 . Additional isolation grooves  132  are formed at each opposing end of each antenna slot  120 B that extend perpendicular, or at least substantially perpendicular in alternative embodiments, to antenna slots  120 B. 
     By providing two distinct types of TX antennae, the possibility of providing for two distinct TX modes in an associated sensor assembly may be provided. Thus, for example, high-gain, squinted antenna  140  may be used for long-range detection, which may be particularly useful for positioning in the front region of a vehicle. The particular squint may be selected by altering various parameters in order to direct the beam in a desired direction. A second mode may be associated with use of the wide antenna slots  120 B on either side of the squinted-beam antenna  140 . 
     As shown in the close-up view of  FIG.  2   , multiple isolation grooves  130 A may be positioned between some or, in other contemplated embodiments, all adjacent antenna slots  120 A. Thus, in the depicted embodiment, a single isolation groove  130 A may be positioned at a first end of RX section  115  and a pair of isolation grooves  130 A may be positioned at the opposite end adjacent to the TX section  117 , which may reduce coupling between the TX section  117  and the RX section  115 , which can improve the signal-to-noise ratio and/or improve range. In addition, a single isolation groove  130 A is positioned between the two center antenna slots  120 A, but multiple isolation grooves  130 A are positioned between these antenna slots  120 A and the outermost antenna slots  120  of RX section  115 . This may be helpful in reducing overall coupling/interaction between adjacent antennae, which can, for example, improve bearing estimations. 
     In some embodiments, the isolation grooves  130 A and/or  130 B may be between about 0.4 mm and about 1.0 mm wide and may be between about 0.7 mm and about 1.0 mm deep. In a particular, preferred embodiment, the isolation grooves may be about 0.5 mm wide and about 0.75 mm deep. 
     Of course, as those of ordinary skill in the art will appreciate, a wide variety of alternative options are possible. For example, multiple isolation grooves and/or auxiliary slots may be positioned between each adjacent antenna and/or antenna slot if desired. Similarly, different numbers of isolation grooves and/or antenna slots may be used as desired. These specifications may be determined by the groove width and spacing and/or by the space available between antennae. 
       FIG.  3    depicts an alternative embodiment of a waveguide/antenna/sensor assembly  200 . Assembly  200  comprises various antenna slots and grooves, as previously mentioned. In addition, assembly  200  further comprises one or more antenna grooves, wherein each of the one or more antenna grooves is positioned adjacent to at least one of the one or more antenna slots, wherein each of the one or more antenna grooves that are designed to resemble one or more of the antenna slots but without extending all the way through the structure in which they are formed similar to the antenna slots. 
     More particularly, assembly  200  comprises a body  210 , which may comprise a casting, layer, or the like. Assembly  200  further comprises an RX section  215  and a TX section  217 . RX section  215  comprises four antenna slots  220 A. Each of the four antenna slots  220 A has essentially the same shape—i.e., the same length and width. However, three of the antenna slots  220 A are aligned with one another—i.e., they begin and end at the same points along the structure into which they are formed—and the last of the antenna slots ( 220 A′) is shifted vertically. Vertically shifted antennae may be used to calculate elevation bearing. 
     An array of isolation grooves  230 A is positioned adjacent to each antenna slot  220 A and in between each pair of adjacent antenna slots  220 A. In the depicted embodiment, five isolation grooves  230 A are positioned on the outer edge of RX section  215 , after which four isolation grooves  230 A are positioned in between each pair of adjacent antenna slots  220 A thereafter. As those of ordinary skill in the art will appreciate, the number of isolation grooves  230 A used may vary according to the desired results but, as shown in the depicted embodiment, a larger number of isolation grooves  230 A may be used in portions of the assembly  200  that delimit or are adjacent to boundaries, such as exterior boundaries of the assembly  200  and/or boundaries between different functional portions of the assembly  200 . 
     It is also worth noting that the isolation grooves  230 A are substantially longer and thinner than the antenna slots  220 A. Moreover, the first three (from the perspective of  FIG.  3    starting at the left side of the figure) antenna slots  220 A are aligned with the lower ends of the adjacent array(s) of isolation grooves  230 A and the fourth antenna slot  220 A′ is aligned with the upper end of the adjacent arrays of isolation grooves  230 A. 
     Grooves  230 A arranged into relatively dense arrays, as shown in  FIG.  3   , may be useful to help isolate the adjacent antennae from one another and/or improve bearing estimation for both azimuth and elevation. These grooves may also be configured to reduce ripple in azimuth patterns. In some embodiments, isolation grooves  230 A may be between about 0.4 mm and about 1.0 mm wide and may be between about 0.7 mm and about 1.0 mm deep. In a particular, preferred embodiment, the isolation grooves may be about 0.5 mm wide and about 0.75 mm deep. 
     Although from the plan view of  FIG.  3   , groove  222 A appears similar to antenna slots  220 A and  220 A′, it should be understood that, unlike these antenna slots  220 A and  220 A′, groove  222 A does not form an opening that extends all the way through the structure/layer into which each of these features is formed. Thus, this groove  222 A should be considered to resemble or mimic the antenna slots  220 A and  220 A′ without actually comprising a slot. Groove  222 A may therefore be considered a “fake” or “parasitic” slot, which may, in some cases along with the aforementioned isolation grooves, be used to better match the shifted antenna slot  220 A′ to its adjacent antenna slot  220 A. The term “parasitic” antenna may be used to indicate the positioning of these grooves next to functional antennas, such as at the end of an antenna array, so that the last (and first) antenna on the array “sees” similar surroundings relative to the antenna in the middle of the array. In this manner, the edge antennas may be able to achieve similar performance with the rest of the antennas in the array. 
     However, again, it should be understood that, in alternative embodiments, groove  222 A may instead extend all of the way through the structure/layer into which it is formed and may therefore be considered an “auxiliary slot” that may have the same or a similar purpose. 
     In addition, comparing detections received from the shifted antenna slot  220 A′ to detections from other antenna slots  220 A, such as the antenna slot  220 A adjacent to shifted antenna slot  220 A′, may be used to estimate elevation bearing. For example, the better matched shifted antenna slot  220 A′ is to one or more of the adjacent antenna slots  220 A, the better the elevation bearing estimate will be. 
     As previously mentioned, assembly  200  further comprises a TX section  217 . TX section  217  also comprises a plurality of antenna slots  220 B, a plurality of grooves  230 B, and a plurality of “fake” or mimicking grooves  222 B, which, as mentioned, may be configured to match or at least substantially resemble the antenna slots  220 B, preferably in both length and width but most preferably in at least width, but without extending all the way through the structure into which they are formed, unlike the antenna slots  220 B. 
     In the depicted embodiment, there are three TX antenna slots  220 B, each of which has a pair of adjacent grooves  230 B adjacent thereto, one on either side. In addition, a single mimicking groove  222 B is positioned at each opposing end of the outermost, single grooves  230 B previously mentioned. These grooves  222 B mimic/match the antenna slots  220 B, again, without extending all the way through the structure into which they are formed. Thus, it may be desirable to include at least one peripheral mimicking groove  222 B on or adjacent to each opposing end of the outermost antenna slots  220 B of TX section  217  and/or of TX section  217  itself. It should be understood that more than one isolation groove may be positioned adjacent and/or on either side of each antenna slots  220 B, if desired. 
     In addition, an array of additional grooves  230 B is positioned on the opposing outermost edges of the opposing mimicking grooves  222 B. The array of grooves  230 B to the left, which is in between TX section  217  and RX section  215 , may be considered a part of either section. Four grooves  230 B are positioned on the right side of TX section  217 , thereby delineating the outermost edge of this functional section, whereas three grooves  230 B are positioned on the left side in between TX section  217  and RX section  215 , thereby again either being considered an intermediate section or a functional part of either of these sections. 
     TX grooves  230 B are preferably not as deep as the RX isolation grooves. These TX grooves may used to manipulate the interaction between adjacent slots and shape the azimuth pattern. Their depth may be adjusted to adjust the interaction between antennas in a way that optimizes the pattern. They may function as delay elements or additional scatterers. 
     Although not visible in  FIG.  3   , in some embodiments, one or more of the various grooves  230 B (and/or isolation grooves  230 A) may have a different depth from one or more of the other isolation grooves. For example, in some embodiments, shallower grooves may be interspersed throughout assembly  200 , or any of the other embodiments depicted and/or described herein. In some such embodiments, the shallower grooves may be primarily, or exclusively, found in the TX section  217 . 
     For example, in a particular contemplated embodiment, each of the single grooves  230 B immediately adjacent to an antenna slot  220 B may be shallower than some, most, or all of the other isolation grooves. In addition, one (or, in other contemplated embodiments, a plurality) of grooves  230 B of an array on one or both outer ends of TX section  217  may be shallower than the other grooves  230 B in such arrays and/or shallower than the isolation grooves  230 A in RX section  215 . Preferably, the shallower isolation grooves  230 A in these arrays consist of only the innermost isolation grooves  230 A. For example, in the embodiment of  FIG.  2   , only the single, innermost isolation groove  230 A in each of the outermost arrays adjacent and outside of the fake/slot mimicking grooves  222 B may be shallower than the others. These shallower grooves may be, in preferred embodiments, between about 20% and about 60% less deep than the other grooves. Thus, in an embodiment in which the deeper grooves are about 0.75 mm deep, the shallower grooves may be about 0.5 mm deep. These differences in depth are visible in the cross-sectional view of  FIG.  4   . 
       FIG.  4    further illustrates the waveguide structures formed on the opposite surface (lower)/side of the assembly  200 . Although the distance scale shown in  FIG.  4    may be useful for certain preferred embodiments and should be considered applicable to  FIG.  5    as well, it should be understood that the distances shown may vary widely in accordance with the field and preferred features of a particular application. 
       FIG.  5    is another cross-sectional view of another embodiment taken from the opposite side of assembly  200  with respect to that of  FIG.  4    and therefore primarily depicts the structures and features of the TX section  217  of the assembly  200 . This figure therefore better illustrates the relative depths and positioning of the various grooves and slots of the TX section  217 , including grooves  230 B, the antenna slots  220 B, and the fake/slot mimicking grooves  222 B. 
     As best seen in this figure, some of the grooves  230 B may be deeper than others. Thus, the three outermost grooves  230 B are substantially deeper than the grooves  230 B positioned in between adjacent antenna slots  220 B and those between a fake/slot mimicking groove  222 B and an antenna slot  220 B. These grooves  230 B may therefore be considered isolation grooves. In addition, one of the grooves  230 B in the outermost array of grooves  230 B (the innermost groove  230 B) is also substantially shallower than the rest of the grooves  230 B in this array. It should be understood, however, that in alternative embodiments, more than one of the isolation grooves in these boundary arrays (whether forming the boundary of the assembly and/or a functional section of the assembly, such as between the RX and TX sections) may be shallower. For example, two (preferably inner) grooves  230 B may be shallow and three (or more; preferably outer) grooves  230 B in one or more of the arrays may be deeper. Preferably, however, the number of deeper grooves in these boundary arrays is greater than the number of shallower grooves and preferably the deeper grooves are positioned outside of the shallower grooves. 
     In this particular embodiment, for the TX section the shallow grooves may function as tuning elements that adjust the interaction between antennas in a favorable way, so that broad patterns may be produced, whereas the outer grooves  230 B that are deep may be configured to isolate the TX antennas from their surroundings (RX antennas and/or the edge of the housing and/or assembly). 
       FIG.  6    presents a view of an alternative embodiment of a waveguide/antenna/sensor assembly  300 . This embodiment is similar to assembly  200 , and the view of  FIG.  6    is the same as the view of assembly  200  shown in  FIG.  4   . Thus, assembly  300  again comprises a body  310 , which may comprise a casting, layer, or the like. Assembly  300  may further comprise an RX section and a TX section (although in this view it is primarily the RX section being shown). 
     As with assembly  200 , the RX section of assembly  300  comprises four antenna slots  320 A. Each of the four antenna slots  320 A has essentially the same shape—i.e., the same length and width. However, three of the antenna slots  320 A are aligned with one another—i.e., they begin and end at the same points along the structure into which they are formed—and the last of the antenna slots (antenna slot  320 A′) is shifted vertically to be aligned, at least at its upper end, with the adjacent isolation grooves  330 A. 
     However, unlike assembly  200 , the isolation grooves  330 A are formed so as to intentionally vary in depth. More particularly, isolation grooves  330 A are formed in arrays, some of which contain isolation grooves  330 A that vary in a stepwise manner from one side of each array to the other. Thus, whereas the outermost array of isolation grooves  330 A on the left side of assembly  310  contains three relatively deeper grooves  330 A on the outer edge of the array and two progressively shallower grooves  330 A, each of the other arrays contains isolation grooves  330 A that each varies from one another. In the depicted embodiment, the leftmost isolation groove  330 A of each array is the deepest, the rightmost isolation groove  330 A is most shallow, and the isolation grooves  330 A in between progressively decrease in depth from left to right, as shown in  FIG.  6   . 
     By varying their depth, grooves  330 A may be used for two purposes at once. In particular, grooves  330 A may be used to shape the antenna pattern (or squint) and also provide isolation between RX antennae. This may be used to create an intentional skew in the groove depths that, in turn, results in a corresponding skew in the antenna pattern. 
     Other features of assembly  300  may be similar to those previously mentioned, including providing one or more fake/slot mimicking grooves  322 A/ 322 B (and/or auxiliary slots), isolation grooves  330 B on the TX section/side of the assembly  300 , and TX antenna slots  320 B. Again, it should be understood that these inventive principles may, in combination with the knowledge of those of ordinary skill in the art, result in a wide variety of alternative features and embodiments. In addition, although the distance scale shown in  FIG.  6    may be useful for certain preferred embodiments, it should be understood that the distances shown, including for purposes of the depths of various grooves and spacing between various functional elements, may vary widely in accordance with the field and preferred features of a particular application. 
       FIG.  7    is a graph illustrating how the use of varying isolation groove depths, as taught herein, may be useful to increase signal strength at one or more preferred angles. The graph of  FIG.  7    includes a line  50  that represents the signal strength (y axis) at particular angles (x axis) for the assembly  200  depicted in  FIGS.  3 - 5   ).  FIG.  7    also includes, for purposes of comparison, another line  60  that represents the signal strength at each angle for the assembly  300  having variability in the depth of the isolation grooves  330 A, as discussed above. As demonstrated by comparing lines  50  and  60 , a substantial boost in signal strength can be obtained by the variable-depth isolation grooves at certain angles, such as, for example, particularly the region between about 45 degrees and about 75 degrees. 
       FIG.  8    is another cross-sectional view of another embodiment, which may be the same embodiment as  FIG.  6   , taken from the opposite side of assembly  300  with respect to that of  FIG.  6   . Of course, this section, or one or more features thereof, may be combined with the features of any other embodiment taught or suggested herein. Thus, for example, the features of  FIG.  8    may be combined with the RX section  215  of assembly  200  and/or one or more features thereof, instead of from assembly  300  if desired. 
       FIG.  8    primarily depicts the structures and features of the TX section of the assembly  300 . This figure therefore better illustrates the relative depths and positioning of the various grooves and slots of the TX section, including the isolation grooves  330 B, the antenna slots  320 B, and the fake/slot mimicking grooves  322 B. However, unlike the TX section of assembly  200 , the TX section depicted in  FIG.  8    has the isolation grooves that were positioned in between each pair of adjacent antenna slots removed, along with the boundary isolation grooves that were, in the embodiment of  FIG.  5   , positioned in between the slot-mimicking grooves  222 B and the antenna slots  220 B. Finally, one of the shallow isolation grooves in the boundary array has also been removed. It should be noted that these removed grooves are outlined, even though not technically present, in the drawings for purposes of comparison with other embodiments. 
     Thus, the TX section depicted in  FIG.  8    comprises three antenna slots  320 B, two opposing slot-mimicking grooves  322 B (one on each end of the array of antenna slots  320 B), and opposing arrays of isolation grooves  330 B. Again, one or more of the slot-mimicking grooves may be replaced with a similar auxiliary slot instead, if desired. 
       FIG.  9    is a graph illustrating how the removal and/or addition of certain isolation grooves, as taught herein, may be useful to increase signal strength at one or more preferred angles. The graph of  FIG.  9    includes a line  70  that represents the signal strength (y axis) at particular angles (x axis) for the assembly  300  depicted in  FIG.  8    in which certain isolation grooves have been removed, as discussed above.  FIG.  7    also includes, for purposes of comparison, another line  80  that represents the signal strength at each angle for the assembly  200  having isolation grooves in between each adjacent pair of antenna slots, and additional isolation grooves, as also discussed above. As demonstrated by comparing lines  70  and  80 , a substantial boost in signal strength at certain angles can be obtained by removing certain isolation grooves. Thus, as shown in  FIG.  9   , and particularly the two circled regions of  FIG.  9   , by sacrificing signal strength at a boresight direction (zero degrees), an increase in signal strength can be achieved at higher angles, particularly those between about 75 and about 90 degrees. 
       FIG.  10    depicts yet another embodiment of a waveguide/antenna/sensor assembly  400 . Assembly  400  comprises various antenna slots and grooves, as previously mentioned. In addition, assembly  400  further comprises one or more antenna grooves, wherein each of the one or more antenna grooves is positioned adjacent to at least one of the one or more antenna slots, wherein each of the one or more antenna grooves (or, in alternative embodiments, auxiliary slots) that are designed to resemble one or more of the antenna slots but without extending all the way through the structure in which they are formed similar to the antenna slots. 
     More particularly, assembly  400  comprises a body  410 , which may comprise a casting, layer, or the like, from which mounting tabs  412  protrude, which may allow for mounting of assembly  400  to a suitable location on a vehicle, for example. 
     Assembly  400  further comprises an RX section  415  and a TX section  417 . RX section  415  may be similar or identical to RX section  215  of assembly  200 . Thus, RX section  415  comprises four antenna slots  420 A, each of which may have essentially the same shape—i.e., the same length and width. However, three of the antenna slots  420 A are aligned with one another—i.e., they begin and end at the same points along the structure into which they are formed—and the last of the antenna slots ( 420 A′) is shifted vertically. 
     An array of isolation grooves  430 A is positioned adjacent to each antenna slot  420 A and in between each pair of adjacent antenna slots  420 A. In the depicted embodiment, five isolation grooves  430 A are positioned on the outer edge of RX section  415  on the left side of the figure, after which four isolation grooves  430 A are positioned in between each pair of adjacent antenna slots  420 A thereafter. As those of ordinary skill in the art will appreciate, the number of isolation grooves  430 A used may vary according to the desired results but, as shown in the depicted embodiment, a larger number of isolation grooves  430 A may be used in portions of the assembly  400  that delimit or are adjacent to boundaries, such as exterior boundaries of the assembly  400  and/or boundaries between different functional portions of the assembly  400 . 
     It is also worth noting that the isolation grooves  430 A are longer and thinner than the antenna slots  420 A. Moreover, the first three (from the perspective of  FIG.  10    starting at the left side of the figure) antenna slots  420 A are aligned with the lower ends of the adjacent array(s) of isolation grooves  430 A and the fourth antenna slot  420 A′ is aligned with the upper end of the adjacent arrays of isolation grooves  430 A. 
     Grooves  430 A arranged into relatively dense arrays, as shown in  FIG.  10   , may be useful to help isolate the adjacent antennae from one another and/or improve bearing estimation for both azimuth and elevation. These grooves may also be configured to reduce ripple in azimuth patterns, as discussed above. In some embodiments, isolation grooves  430 A may be between about 0.4 mm and about 1.0 mm wide and may be between about 0.7 mm and about 1.0 mm deep. In a particular, preferred embodiment, the isolation grooves may be about 0.5 mm wide and about 0.75 mm deep. 
     Although from the perspective view of  FIG.  10   , groove  422 A appears similar to antenna slots  420 A and  420 A′, it should be understood that, unlike these antenna slots  420 A/ 420 A′, groove  422 A does not form an opening that extends all the way through the structure/layer into which each of these features is formed. Thus, this groove  422 A should be considered to resemble or mimic the antenna slots  420 A and  420 A′ without actually comprising a slot. Groove  422 A may therefore be considered a “fake slot” or an “antenna slot mimicking groove” which may, in some cases along with the aforementioned isolation grooves, be used to better match the shifted antenna slot  420 A′ to its adjacent antenna slot  420 A. Again, alternatively, one or more of the “fake slots” or an “antenna slot mimicking grooves” may be replaced with one or more auxiliary slots. 
     In addition, comparing detections received from the shifted antenna slot  420 A′ to detections from other antenna slots  420 A, such as the antenna slot  420 A adjacent to shifted antenna slot  420 A′, can be used to estimate elevation bearing. For example, the better matched shifted antenna slot  420 A′ is to one or more of the adjacent antenna slots  420 A, the better the elevation bearing estimate will be. 
     Assembly  400  further comprises a TX section  417 . TX section  417  also comprises a plurality of antenna slots  420 B, a plurality of grooves  430 B, and a pair of “fake” or mimicking grooves  422 B, which, as mentioned, may be configured to match or at least substantially resemble the antenna slots  420 B, preferably in both length and width but most preferably in at least width, but without extending all the way through the structure into which they are formed, unlike the antenna slots  420 B. 
     In the depicted embodiment, there are three TX antenna slots  420 B, each of which has a pair of adjacent grooves  430 B adjacent thereto, one on either side. In addition, a single mimicking groove  422 B is positioned at each opposing end of the outermost, single isolation grooves  430 B previously mentioned. These grooves  422 B mimic/match the antenna slots  420 B, again, without extending all the way through the structure into which they are formed. It should be understood that more than one isolation groove may be positioned adjacent and/or on either side of each antenna slots  420 B, if desired. 
     Unlike the antenna slots and fake/antenna slot mimicking grooves previously mentioned, however, antenna slots  420 B are curved or “wavy.” More particularly, slots  420 B and, because they are intended to mimic slots  420 B, grooves  422 B as well, oscillate back and forth between opposing sides of an elongated axis. As shown in  FIG.  12   , which depicts the opposite side of assembly  400 , slots  420 B are also positioned directly above respective waveguide grooves  470 B. Any of the mimicking grooves, such as grooves  422 B, may be replaced with auxiliary slots instead that may similarly mimic the antenna slots in one or more aspects but, unlike grooves  422 B, extend entirely through the structure into which they are formed. 
     Similar waveguide grooves  470 A are formed in the depicted embodiment by opposing rows of posts  460  on the RX section  415  of the assembly  400  with antenna slots  420 A centered therein. 
     It is contemplated that these waveguides may be formed in the same block/structure as the slots  420 B or may be formed in separate structures, such as layers, in alternative embodiments. In the depicted embodiment, waveguide grooves  470 B are formed between a plurality of rows of posts  460 . However, in alternative embodiments, waveguides may be formed as “trench”-like waveguides defined by forming grooves defined by continuous opposing walls. 
     In the depicted embodiment, a single waveguide groove  470 B is defined by two or more opposing rows of posts  460  on each side of each waveguide groove  470 B. However, alternative embodiments are contemplated in which a single row of posts  460  on either side of each waveguide groove is used, or others in which more rows of posts  460  that are depicted in  FIG.  12    are used. 
     In addition, although this need not be the case for other embodiments, in the depicted embodiment, each antenna slot  420 B is centered, or at least substantially centered, with respect to adjacent groove  470 B and oscillates towards the opposing walls defined by posts  460  in an intermittent manner. 
     Each antenna slot  420 B and, due to the desire to mimic these antenna slots  420 B, each groove  422 B, further comprises a phase-compensating feature. In the depicted embodiment, this is accomplished by applying one or more angled and/or tapered sections, such as tapered grooves or cutouts, along the slots. Thus, the depicted embodiment illustrates a tapered and/or angled section/surface  421  that is formed along both opposing sidewalls defining each antenna slot  420 B, along with each slot-mimicking groove  422 B, at respective points of maxima for the oscillating pattern of the respective slot/groove. 
     These tapering sections  421  may comprise a stepped taper or ledge, as shown in  FIG.  11   , or may comprise a smoothly transitioning taper. In other words, a ledge may be formed at the starting point of the taper and therefore, rather than a smooth taper between the outer surface of the structure defining the slot/groove and the starting point of section  421 , the transition of tapering section  421  may be immediate from the starting point, which is at a ledge of section  421  to the outer surface of the structure forming the slot/groove. 
     In some embodiments, all of the peaks/maxima of the oscillating pattern of slots  420 B and/or grooves  422 B may comprise a phase-compensating feature, such as a tapering section  421 . Alternatively, in some embodiments, only a subset of the peaks/maxima defined by slots  420 B and/or grooves  422 B may comprise such a feature. 
     In addition, slots  420 B and/or grooves  422 B may intermittently oscillate on opposite sides of its respective elongated axis and/or adjacent waveguide (see  FIG.  12   ) along at least a portion thereof. In some such embodiments, each of at least a subset of the plurality of the tapering surfaces/sections  421  may be spaced apart in a manner that coincides with the intermittent oscillation of the slots  420 B and/or grooves  422 B. In some such embodiments, all of the tapering surfaces/sections  421  may be spaced apart in a manner that coincides with the intermittent oscillation of the slots  420 B and/or grooves  422 B. 
     It should be understood, however, that the stepped taper of assembly  400  is but an example for purposes of illustration and that a wide variety of alternative embodiments are contemplated. For example, although only a single step is used in the tapered section  421  of assembly  400 , any number of steps may be used in between the one step shown in this embodiment and an effectively infinite number of steps involved in a smooth taper. 
     Each of the tapering sections  421  of assembly  400  may comprise a stepped taper extending between a first edge of the ledge formed by tapering section  421 , which first edge may be positioned in between the external surface of the structure forming slots  420 B and/or grooves  422 B and the internal surface of this structure, and a second edge of a concavely curved surface (in some cases, a semi-circular concavely curved surface), the second edge extending along the external surface of the aforementioned structure. Again, any number of intermediate steps may be used as desired. 
     In preferred embodiments, these sections/surfaces  421  are positioned so as to alternate and be staggered along the opposing slot sidewalls such that each section  421  is positioned at a particular point along the axis of along only one sidewall of each respective slot  420 B and/or groove  422 B, as best seen in  FIG.  11   . In addition, even more preferably, each section  421  is formed along one of the peaks of each oscillating respective slot  420 B and/or groove  422 B. Thus, for example, if the slot defines, or at least substantially defines, a sine wave, each of the sections  421  is preferably formed along one of the peaks of the sine wave extending towards the axial center of the slot  420 B and/or accompanying waveguide  470 B. 
     In some embodiments, all of the aforementioned peaks may comprise a phase-compensating feature, such as a tapering section  421 . Alternatively, only a subset of the peaks defined by each respective slot  420 B and/or groove  422 B may comprise such a feature. 
     In some embodiments, each respective slot  420 B and/or groove  422 B may intermittently oscillate on opposite sides of the elongated axis of each respective slot  420 B, groove  422 B, and/or adjacent waveguide  470 B along at least a portion thereof. In some such embodiments, each of at least a subset of the plurality of the tapering surfaces/sections  421  may be spaced apart in a manner that coincides with the intermittent oscillation of each respective slot  420 B and/or groove  422 B. In some such embodiments, all of the tapering surfaces/sections  421  may be spaced apart in a manner that coincides with the intermittent oscillation of each respective slot  420 B and/or groove  422 B. 
     Thus, for example, in some embodiments, each of the plurality of tapering sections surfaces  421  may comprise a first set of tapering surfaces on a first side of each respective slot  420 B and/or groove  422 B and a second set of tapering surfaces  421  on a second side of each respective slot  420 B and/or groove  422 B opposite the first side. Preferably, the tapering surfaces/sections  421  alternate such that each tapering surface of first set of tapering surfaces is positioned adjacent to one or more tapering surfaces of the second set of tapering surfaces along the axis of each respective slot  420 B and/or groove  422 B and each tapering surface of the second set of tapering surfaces is positioned adjacent to one or more tapering surfaces of the first set of tapering surfaces along the axis, again, preferably alternating back and forth across each respective slot  420 B and/or groove  4228 . 
     Each of the plurality of tapering surfaces/sections  421  may comprise a curved, tapering surface, as shown in  FIG.  12   . Indeed, in the depicted embodiment, each of the tapering surfaces/sections  421  is defined, at least in part, by a semi-circular cutout, which may be formed at the exterior surface of each respective slot  420 B and/or groove  422 B, as a concave region from the convex region of the curve defined by each respective slot  420 B and/or groove  422 B, and then may taper down to a corner, edge, or starting point of the taper. Thus, preferably, the tapers of sections  421  do not extend all the way between opposing surfaces of the structure of assembly  400  defining slots  420 B, but rather start at a point between the opposing surfaces of this structure and extend to the upper/outer portion of slots  420 B on the side opposite the aforementioned waveguides  470 B. 
     However, in embodiments in which one or more of the tapering sections  421  has a starting point between opposing surfaces of the structure defining the slot(s)  420 B, it may be desirable from a manufacturing standpoint that the starting point(s) of the tapering sections  421  be sufficiently spaced from the (typically inner) surface from which the slot(s)  420 B originates. Thus, in some embodiments, the starting point may be located at a point no less than 20%, or no less than about 20%, of the distance from the lower/inner and/or originating surface of the slot(s) to the upper/outer and/or terminating surface of the slot(s). 
     As discussed below in connection with later figures, other embodiments are contemplated in which the tapering surfaces/sections  421  may instead be straight or non-curved. In addition, in some embodiments, the curvature of the tapering sections  421  may extend in multiple dimensions. In other words, a semi-spherically curved surface may be formed within one or more of these sections  421  if desired. Additional details regarding these phase-compensating features can be found in U.S. patent application Ser. No. 17/370,922 titled PHASE-COMPENSATED WAVEGUIDES AND RELATED SENSOR ASSEMBLIES, the entire contents of which are hereby incorporated by reference herein. 
     As further illustrated best by  FIG.  11   , grooves  430 B may, in some embodiments, include one or more portions that extend perpendicular to the elongated axis of slots  420 B and/or grooves  422 B, such as groove portions  432 , which extend at one or both opposing ends of grooves  432 B. In addition, a portion of one or more grooves  432 B may extend into one or both ends of one or more of the slots  420 B and/or grooves  422 B, as shown at  433 . 
     This may be desired for certain applications and/or embodiments to allow all of the grooves and/or slots to be connected together for venting purposes. In other words, this may allow for connection of the air in the grooves and/or slots to the air in the housing of the assembly, which may prevent or at least inhibit pressure build up when the air heats up. If the grooves were not connected to the slots by these channels, then the air may become trapped in the grooves, which may expand and push the radome of the assembly (in embodiments in which the assembly is used for a vehicle RADAR sensor, for example) away. 
     Other features of TX section  417  may be similar to other TX sections previously discussed. Thus, an array of additional grooves  430 B may be positioned on the opposing outermost edges of the opposing mimicking grooves  422 B. Such grooves  430 B may, or may not, comprise interconnecting groove sections for venting, as previously discussed. 
     The array of grooves  430 A to the left, which is in between TX section  417  and RX section  415 , may be considered a part of either section. Four grooves  430 B are positioned on the right side of TX section  417 , thereby delineating the outermost edge of this functional section, whereas three grooves  430 A are positioned on the left side in between TX section  417  and RX section  415 , thereby again either being considered an intermediate section or a functional part of either of these sections. 
     As mentioned above, although not visible in  FIG.  10  or  11   , in some embodiments, one or more of the various grooves  430 B (and/or isolation grooves  430 A) may have a different depth from one or more of the other grooves. For example, in some embodiments, shallower grooves may be interspersed throughout assembly  400 , or any of the other embodiments depicted and/or described herein. In some such embodiments, the shallower grooves may be primarily, or exclusively, found in the TX section  417 . 
     For example, in a particular contemplated embodiment, each of the single grooves  430 B immediately adjacent to an antenna slot  420 B may be shallower than some, most, or all of the other grooves. In addition, one (or, in other contemplated embodiments, a plurality) of isolation grooves  430 B of an array on one or both outer ends of TX section  417  may be shallower than the other grooves  430 B in such arrays and/or shallower than the isolation grooves  430 A in RX section  415 . Preferably, the shallower isolation grooves  430 A in these arrays consist of only the innermost isolation grooves  430 A. 
     Additional elements of assembly  400  can be seen in the opposite plan view of  FIG.  12   . For example, in addition to the waveguides  470 A and  470 B created by the aforementioned rows of posts  460 ,  FIG.  12    depicts a hub region  450  from which each of these waveguides initiates and/or terminates to allow for sending and receiving of electromagnetic signals. It should be understood that hub region  450  would typically include various electrical components, such as electromagnetic generation chips or other elements, that are not shown in the figures to avoid obscuring the disclosure. A suitable electromagnetic feed or transition structure may also be used to facilitate transitioning electromagnetic waves/signals to the waveguide grooves as needed. 
     It should also be understood that alternative embodiments are contemplated in which the slots  420 B and/or grooves  422 B oscillate in a non-smooth manner. For example, slots  420 B and/or grooves  422 B may define, or at least substantially define, a square wave in some contemplated embodiments. 
     In addition, the taper of sections  421  may extend the entire distance between the upper and lower surfaces of the portion/layer/structure defining the slots  420 B and/or grooves  4226 . Or, alternatively, the taper may start/stop at a particular point in between these two surfaces. 
     Various other alternative features/embodiments are also contemplated. For example, in some embodiments, a series of spaced slots may be provided rather than a single, elongated slot, for a given waveguide. Such spaced slots may, but need not, oscillate. In addition, the aforementioned tapered/angled sections/surfaces may be formed in some or all such spaced slots. For example, in some embodiments, the tapering sections may be formed in every slot but may alternate on sides such that every other slot and/or groove has a cutout/tapering section formed on an opposite side relative to the adjacent slot(s) and/or groove(s). In addition, arrays of grooves may be formed that resemble or mimic, in one aspect or more, the oscillation of the slots, rather than providing straight grooves, such as grooves  430 B, for example. 
     As those of ordinary skill in the art will appreciate, antenna/waveguide/sensor assemblies incorporating the waveguide/antenna structures described herein may further comprise a PCB or other electromagnetic-generating element from which electromagnetic waves may be generated to feed one or more waveguide structures. These elements may be provided in a separate layer or, alternatively, may be provided in the same layer. 
     It should also be understood that, whereas the block structures shown in the accompanying figures are generally shown with a single groove, which may be thought of as providing a single “antenna” when coupled with one or more adjacent slots, any number of waveguide grooves and/or adjacent slot and/or antenna structures may be provided as desired, and each such waveguide and/or waveguide groove may be associated with a different antenna of the antenna block/assembly. 
     It should also be understood that whereas preferred embodiments may be used in connection with vehicle sensors, such as vehicle RADAR modules or the like, the principles disclosed herein may be used in a wide variety of other contexts, such as other types of RADAR assemblies, including such assemblies used in aviation, maritime, scientific applications, military, and electronic warfare. Other examples include point-to-point wireless links, satellite communication antennas, other wireless technologies, such as 5G wireless, and high-frequency test and scientific instrumentation. Thus, the principles disclosed herein may be applied to any desired communication sub-system and/or high-performance sensing and/or imaging systems, including medical imaging, security imaging and stand-off detection, automotive and airborne radar and enhanced passive radiometers for earth observation and climate monitoring from space. 
     The foregoing specification has been described with reference to various embodiments and implementations. However, one of ordinary skill in the art will appreciate that various modifications and changes can be made without departing from the scope of the present disclosure. For example, various operational steps, as well as components for carrying out operational steps, may be implemented in various ways depending upon the particular application or in consideration of any number of cost functions associated with the operation of the system. Accordingly, any one or more of the steps may be deleted, modified, or combined with other steps. Further, this disclosure is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope thereof. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments. However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced, are not to be construed as a critical, a required, or an essential feature or element. 
     Those having skill in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present inventions should, therefore, be determined only by the following claims.