Patent Grant
8217852
Embodiments of the invention generally relate to devices, systems, and methods for providing antenna elements. More particularly, the invention relates to devices, systems and methods for structures and devices providing a compact and simple to manufacture element for dual-band phased array antennas.
Modern commercial and military systems such as radar systems, and satellite communication systems, often perform multiple functions that can require a plurality of different radar beams at different wavelengths. Examples of these functions include surveillance of targets and objects at various ranges/distances, air traffic control, navigation, weapons control, weather surveillance, satellite uplink and downlink signaling, telecommunications, and Internet communications. In many of the environments in which such systems are deployed, it can be difficult to provide multiple antennas to support the multiple different beams because of space and/or cost limitations. Consequently, it is advantageous to employ a phased array antenna in such environments.
As is well-known, a single phased-array antenna can simultaneously radiate and receive multiple radar beams, because of its control of the phase of multiple radiating elements. One complicating factor in design of phased arrays, however, is that many radar functions require simultaneous availability of beams spanning two or more radar bands. For example, long-range surveillance conventionally requires longer wavelengths (λ), e.g., S band, whereas precision-tracking and target-recognition radars generally operate most efficiently at shorter wavelengths, e.g., C band. Weapons control and Doppler navigation are typically performed at still shorter wavelengths, e.g., X band and Ku band. However, for systems that require wide scan angle such as ±60° from boresight, combining radiating elements of two bands into a single aperture is a real challenge because of the constraints on element spacing and size. Furthermore, providing isolation between the two bands can be difficult and, as further explained below, it is possible to have interference and cross-coupling between the beams of the two different bands.
Phased array designs are typically limited in element spacing and size to avoid grating lobes. For example, some conventional phased array elements are approximately λ/2 apart and can occupy the entire space allocated to an element in a wide angle scanned array. If such conventional elements are spaced at greater than λ/2 wavelengths, the power of the radar signals can divide and, at wide scan angles, grating lobes can occur: as the beam is scanned further from broadside, a point is reached at which a second symmetrical main lobe (grating lobe) is developed. This unwanted condition can reduce antenna gain by several decibels (dBs) due to the second lobe. For dual-band military applications in particular, grating lobes can be a problem because the broad frequency bandwidth requirements mean that at the high end of the frequency band, the elements may be spaced greater than λ/2. The presence of grating lobes can cause a radar system to produce ambiguous responses to a radar target. Such a radar system also can be more prone to interference.
Still another bandwidth issue for phased array designs is the problem of beam distortion with scan angle. Beam distortion with scan angle results in spread of the beam shape and a consequent reduction in gain known as “scan loss”. For an ideal array element, scan loss is equal to the aperture size reduction (projected) in the scan direction, which varies based at least in part on the scan angle.
An additional complicating factor in the design of antenna elements, including elements for phased arrays, involves transitions between different types of transmission lines in the system. In many high frequency systems, it is necessary to implement part of the system in coaxial transmission lines and another part of the system in waveguide transmission systems. To transfer signals from one of these mediums to the other, a coaxial transmission line to waveguide adaptor (also referred to as a coax to waveguide transition) is provided. Waveguide to coax transitions are known in the art, where the waveguide is a thin rectangular member having conductive surfaces, and the coax includes an inner pin conductor and an outer conductor. Generally, the output of the transition contains the configuration of a conventional waveguide type transmission line; the input of the transition contains the structure of the conventional coaxial type transmission line containing a central conductor surrounded by a dielectric.
In known transition implementations from waveguide to the coax, such as the transition 12 shown in
Still referring to
In addition, as shown in
In known implementations, the coax-to-waveguide adaptors are typically larger than the space available in the phased array environment. Again, this is mainly due to the element spacing constraint to avoid grating lobes. Another challenge is that elements having a narrow aperture generally have a higher impedance and it is harder to provide an impedance match to free space over a large scan angle.
The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
It would be advantageous to be able to integrate low-band sensors into a high-band array so that all high and low-band elements share the same aperture while both bands could be scanned to wide angles. Such a dual-band system could provide greater flexibility for multi-function missions, reduce aperture area, and may allow re-use of back-end electronics. To achieve this integration, the low-band element preferably should be very compact to minimize interference to high-band performance. The low-band element also needs to have the desired wide scan angle performance over a broad bandwidth. No such an element is known to exist that meets these difficult requirements.
Previous design attempts for dual-band phased arrays have not been found to meet all of the necessary requirements for some applications. For example, in radar search and tracking applications, a wide scan angle (>60°) over a wide bandwidth (>15%) for both bands is required. One proposed design combines an annual ring microstrip (for low-band) with an open waveguide element (for high-band), including design examples for 15 GHz, and 20 GHz. However, for this design, like many others, there are limitations of high-band performance, because at high-band, the scan performance will be limited due to grating lobes.
A second requirement of the above exemplary application is the requirement that the array be capable of independently steering both antenna beams (i.e., the low-band and high-band beams). A third requirement is that there should be no blockage (i.e., physical interference) caused by one band to the other. For example, one known design for a dual-band array uses L-band dipoles embedded in front of an X-band aperture. However, it is possible that the dipoles can cause blockage to X-band, resulting in severe (and undesirable) interaction between L and X bands.
A final requirement of the above exemplary application is that such a design should be producible using proven manufacturing techniques with reasonable cost in production.
In one aspect, the invention provides an array antenna constructed and arranged to operate at a high-band wavelength λH and a low-band wavelength λL, the antenna comprising a first array and a second array. The first array comprises a plurality of high-band radiators, each high-band radiator constructed and arranged to radiate at λH, at least a portion of the high-band radiators having a first predetermined spacing between each other. The second array comprises a plurality of low-band radiators, each respective low-band radiator in the plurality being disposed so as to be interleaved between the high-band radiators and being sized to fit within the first predetermined spacing so as to share an aperture with the high-band radiators, each low-band radiator having an input and output.
Each respective low-band radiator comprises a coaxial section, a dielectric section, a waveguide, and a planar section. The coaxial section is disposed at the input to the low-band radiator, the coaxial section being constructed and arranged to provide a coaxial connection adapted to receive radiated signals, wherein the coaxial connection comprises a coaxial conductor. The dielectric section is operably coupled to the coaxial section via the coaxial conductor, the dielectric section being formed of a continuous piece of dielectric material and cooperating with the coaxial section and a waveguide to provide a coaxial to waveguide transition.
The dielectric section comprises a first opening, a second opening, and a plurality of step transitions. The first opening is sized to receive the coaxial conductor. The second opening is formed in an orientation that is substantially perpendicular to the first opening, the second opening being formed in a first portion of the dielectric section, wherein the second opening is substantially hollow and has a lining comprising an electrically conductive material that is operably coupled to the coaxial conductor disposed in the first opening.
The plurality of step transitions is disposed after the first portion of the dielectric section, the plurality of step transitions cooperating to provide impedance matching and to reduce the height of the respective low-band radiator from a first height at the input to the respective low-band radiator to a second height at the output of the respective low-band radiator, wherein at least one of the step transitions is adapted to be disposed within the waveguide and to be operably coupled between the dielectric section and the planar section, wherein the at least one step transition partially fills an interior first portion of the waveguide at the first end, wherein at least a second portion of the waveguide adjacent to the first portion is filled with air, and wherein the size of the step transition that partially fills the waveguide is selected at least in part to provide impedance matching between the dielectric section and the waveguide.
The waveguide is operably coupled to the dielectric section, the waveguide having first and second ends, the first end being operably coupled to the dielectric section and the second end being operably coupled to the planar section.
The planar section is disposed at the output of the low-band radiator is operably coupled to the second end of the waveguide and is further operably coupled to at least a portion of the first array of high-band radiators, wherein the planar section is oriented to the portion of high-band radiators such that the output of the respective low-band radiator is disposed between and within the spacing between adjacent high-band-radiators, such that the low-band radiator and the high-band radiators share the same aperture.
In one embodiment of this aspect, the low-band radiator is constructed and arranged to have an overall height less than or equal to 0.06λL, a width less than or equal to 0.5λL, and a length less than or equal to λL. In another embodiment, the first predetermined spacing is selected to limit a scan loss of the antenna to less than 2.0 dB plus cos1.5 (θ), where θ is the scan angle of the high-band array. In a further embodiment, the low-band elements are spaced a second predetermined spacing apart from each other, wherein the second predetermined spacing is selected to limit the scan loss of the antenna to less than 2.0 dB plus cos1.5 (θ), where θ is the scan angle of the low-band array.
In a further embodiment, each high-band radiator has a side length and each low-band radiator has a height, wherein the height of the low-band radiator is approximately half the height of the high-band radiator.
In a still further embodiment, the plurality of step transitions further comprises first, second, and third step transitions. The first step transition is disposed near the second opening and spaced approximately 0.22λL from the coaxial portion that is coupled to the dielectric portion, the first step transition having a step down height of approximately 0.08λL and a length of approximately 0.47λL. The second step transition is disposed adjacent to the first step transition, the second step transition having a step up height of approximately 0.02λL and a length of approximately 0.08λL. The third step transition is disposed adjacent to the second step transition, the third step transition having a step down height of 0.04λL and a length of approximately 0.14λL, wherein the third step transition corresponds to the step transition that is disposed within and partially fills the waveguide.
In still further embodiments, the waveguide has a cross-section wherein the width is at least approximately 7 times the height. The first portion of the dielectric section can have a length of approximately 0.22λL. At least one of the orientation, lining and size of the second opening can be selected to provide impedance matching to the coaxial section. The antenna can be a phased array antenna.
In at least one embodiment, the high-band corresponds to a frequency range that is approximately 2.5 to 5 times the size of the frequency range of the low-band. The high-band wavelength and the low-band wavelength can each be associated with a respective one of the following frequency bands: X band, S band, L band, C band, Ku band, K band, Ka band, Q band, and mm band.
In one embodiment, at least one of the high-band radiating array and the low-band radiating array has a size and spacing enabling the antenna to be operable to scan at scan angles greater than or equal to sixty degrees from boresight with a bandwidth greater than or equal to 15%.
In another aspect, the invention provides an antenna element having an input and an output and comprising a coaxial section, a dielectric section, a waveguide, and a planar section. The coaxial section is disposed at the input, the coaxial portion being constructed and arranged to provide a coaxial connection adapted to receive radiated signals, wherein the coaxial connection comprises a coaxial conductor. The dielectric section is operably coupled to the coaxial section via the coaxial conductor, the dielectric section being formed of a continuous piece of dielectric material and cooperating with the coaxial section and a waveguide to provide a coaxial to waveguide transition. The dielectric section comprises a first opening, a second opening, and a plurality of step transitions.
The first opening is sized to receive the coaxial conductor. The second opening is formed in an orientation that is substantially perpendicular to the first opening, the second opening being formed in a first portion of the dielectric section, wherein the second opening is substantially hollow and has a lining comprising an electrically conductive material that is operably coupled to the coaxial conductor disposed in the first opening. The plurality of step transitions are disposed after the first portion of the dielectric section, the plurality of step transitions cooperating to provide impedance matching and reduce the height of the respective antenna element from a first height at the input to the antenna element to a second height at the output of the antenna element, wherein at least one of the step transitions is adapted to be disposed within the waveguide and to be operably coupled between the dielectric section and a planar section, wherein the at least one step transition partially fills an interior first portion of the waveguide at the first end, wherein at least a second portion of the waveguide adjacent to the first portion is filled with air, and wherein the size of the step transition that partially fills the waveguide is selected at least in part to provide impedance matching between the dielectric section and the waveguide.
The waveguide is coupled to the dielectric section, the waveguide having first and second ends, the first end operably coupled to the dielectric section and the second end operably coupled to a planar section. The planar section is disposed at the output, the planar section being operably coupled to the second end of the waveguide.
In one embodiment, the plurality of step transitions further comprises a first step transition disposed near the second opening and spaced approximately 0.22λ from the coaxial section that is coupled to the dielectric portion, the first step transition having a step down height of approximately 0.08λ and a length of approximately 0.47λ; a second step transition disposed adjacent to the first step transition, the second step transition having a step up height of approximately 0.02λ and a length of approximately 0.08λ; and a third step transition disposed adjacent to the second step transition, the third step transition having a step down height of 0.04λ and a length of approximately 0.14λ, wherein the third step transition corresponds to the step transition that is disposed within and partially fills the waveguide.
The antenna element can be adapted to operate over at least a wavelength λ, wherein the antenna element is constructed and arranged to have an overall height less than or equal to 0.06λ, a width less than or equal to 0.5λ, and a length less than or equal to λ. At least one of the orientation, lining and size of the second opening can be selected to provide impedance matching to the coaxial section.
In a further aspect, the invention provides a coaxial to waveguide transition having first and second ends and comprising a coaxial section at the first end, a dielectric section, and a waveguide.
The coaxial section is constructed and arranged to provide a coaxial connection adapted to receive radiated signals, wherein the coaxial connection comprises a coaxial conductor. The dielectric section operably is coupled to the coaxial section via the coaxial conductor, the dielectric section being formed of a continuous piece of dielectric material and cooperating with the coaxial section and a waveguide to provide a coaxial to waveguide transition. The dielectric section comprises a first opening, a second opening, and a plurality of step transitions.
The first opening is sized to receive the coaxial conductor. The second opening is formed in an orientation that is substantially perpendicular to the first opening, the second opening being formed in a first portion of the dielectric section, wherein the second opening is substantially hollow and has a lining comprising an electrically conductive material that is operably coupled to the coaxial conductor disposed in the first opening. The plurality of step transitions is disposed after the first portion of the dielectric section, the plurality of step transitions cooperating to provide impedance matching and reduce the height of coaxial to waveguide transition from a first height at the first end to a second height at the second end, wherein at least one of the step transitions is adapted to be disposed within and to partially fill a waveguide operably coupled to the dielectric section, wherein the size of the step transition that partially fills the waveguide is selected at least in part to provide impedance matching between the dielectric section and the waveguide.
The waveguide is operably coupled to the dielectric section, the waveguide having first and second ends, the first end operably coupled to the dielectric section and the second end located at the output of the waveguide.
Details relating to this and other embodiments of the invention are described more fully herein.
The advantages and aspects of the invention, as well as the invention itself, will be more fully understood in conjunction with the following detailed description and accompanying drawings, wherein:
In the drawings, like reference numbers indicate like elements. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. The above reference to first, second, third, and fourth steps are in no way indicative of any required order of manufacturing steps.
In the following description, many dimensions, relative dimensions, etc., are expressed in terms of wavelengths, such as where λ0 (or, as applicable, λL for the low-band or λH for the high-band) is used to indicate the wavelength at the middle of the operating frequency band. As those of skill in the art are aware, the wavelength is dependent on the antenna frequency and/or frequency band in question. It is intended that the dimensions and relative dimensions given herein are applicable over a number of bands and wavelengths, and it is not intended for the invention to be limited to any particular wavelengths. For example, the embodiments of the invention can be constructed for virtually any required frequency, by scaling the size of the device based on the wavelength that corresponds to the frequency being used. Thus, if an embodiment lists an overall device length, for example, of one wavelength (λ), a first further embodiment for a device at a first frequency may be about three inches long to correspond with a first wavelength of 3″, whereas a different embodiment for a device used at a second frequency is scaled to 8″ long to correspond to a wavelength that is that long.
In at least one embodiment, the invention is especially advantageous for a dual-band antenna that includes (but is not limited to) high-band elements radiating in the X band (approximately 7 GHz to 12.5 GHz) and low-band elements radiating in the S band (approximately 2 GHz to 4 GHz). However, those of skill in the art will readily appreciate that the invention has applicability in and can be adapted to work with many other frequency bands, including but not limited to L band (approximately 1-2 GHz), C band (approximately 4 GHz to 8 GHz), Ku band (approximately 12 GHz to 18 Ghz), K band (approximately 18 GHz to 24 GHz), Ka band (approximately 24-40 GHz), Q band (approximately 40-60 GHz) and mm bands (approximately 40-300 GHz). As those of skill in the art will appreciate, adapting the embodiments of the invention disclosed herein to work with other frequency bands may require, for example, changing the relative sizes of the elements of the invention (as certain features are sized based on wavelength). In addition, the invention is especially advantageous where the ratio of the high-band to the low-band is about 2.5:1 to 5:1.
In accordance with one embodiment of the invention, a compact loaded-waveguide radiating element for the low-band is provided that has been designed to meet at least some of the aforementioned requirements, which requirements included integrating low-band elements into a high-band array so that all high and low-band elements share the same aperture while both bands could be scanned to wide angles, providing a compact low-band element to minimize interference to high-band performance, and having desired wide scan angle performance over a broad bandwidth.
In one aspect, a difficult challenge met by at least one embodiment of the inventive design described herein is being able to limit the height of the low-band radiating aperture to be approximately only 0.06 wavelengths (λL) (where λL is the wavelength in the middle of the low-band operating frequency band) so that it can fit in between high-band radiators, without increasing the high-band element spacing. This is further shown in
Referring briefly to
Advantageously, in one embodiment, the width of the low-band element 56 (taken along the x-axis, see
For example, in one embodiment, the element spacing is limited to 0.5λ (one half wavelength) at both high-band and low-bands, to ensure a wide scan angle with limited scan loss. As those of skill in the art will appreciate, the dimensions of the high-band element ultimately affect the dimensions of the low-band element. In one advantageous embodiment, the high-band element is limited to a maximum size of λH/4 (e.g., one side length of a square-shaped high-band element), to ensure that there is sufficient room for the low-band aperture. Generally, for at least some embodiments of the invention, the height of the low-band radiating aperture is approximately one half of the side length of the high-band element.
For one embodiment, a loaded waveguide approach is used due to its low loss and wide bandwidth performance.
The low-band element 56 includes a dielectric portion 68 having several step transitions (also known in the art as step junctions) 92, 94, 96 (which are described further herein). The dielectric portion 68 includes a waveguide portion 70 that is inserted into waveguide 55, and is shown with slightly modified shading in
In addition, the low-band element 56 of
Generally, the illustrated dimensions of the low-band element 56 of
The innovative coax to waveguide transition and impedance matching portion 75 of the low-band element 56 is designed to make the low-band element 56 easily producible while having good impedance match. Production of this coax to waveguide transition 75 is described further below in connection with
Instead of using a traditional coax to waveguide adaptor, which typically is too large for phased array application, the dielectric section 68 also includes a very compact and innovative adaptor. It includes an opening or hole 66 (which in the illustrated embodiments is substantially cylindrical) to be formed (e.g., for a cylindrically-shaped hole, drilled) within of the first machined section 84 (see
In addition, although the hole 66 is illustrated and described herein as being substantially cylindrical, the invention is not so limited. It has been found that having a hole 66 with a substantially cylindrical shape is readily manufactured (e.g., via drilling), but other shaped holes are usable, as well. After the hole 66 is formed in the machined section 84, the surfaces of the cylindrical hole 66 are metallically plated with plating material 106 (
As those of skill in the art will appreciate, instead of forming the substantially cylindrical hole 66, a similarly positioned and sized metallic post could be used in its place. Use of such a metallic post may increase the overall weight of the element 56 and may require additional manufacturing steps, as will be appreciated.
As discussed further herein, a series of steps in the first dielectric section 68 and ending at the second dielectric section 70 also serve as a compact way to match the coax to waveguide adaptor 75 to a compact radiating element. The first dielectric section 68 includes a first step transition, 92, a second step transition 94, and a third step transition 96 (the third step transition 96 is disposed within the waveguide 55).
Referring again to
Continuing with dimensional references, the length L8 of the dielectric section 68 is approximately 0.61λL wavelengths. The thickness L9 of the dielectric section 68 near its connection to the coax connector 62 is approximately 0.27λL wavelengths. The depth L1 of the dielectric section 68 is approximately 0.48λL wavelengths. The length L11 of the board section 74C that is between the slots 76 is approximately 0.06λL wavelengths. The length L12A and width 12B of the boards 74 and 80 are both 0.5λL wavelengths. The height L13 of the hole 66 is approximately 0.15λL wavelengths. The diameter L14 of the hole 66 is approximately 0.07λL wavelengths. The height L15 of the waveguide 55 is approximately 0.06λL wavelengths (essentially corresponding to the length L11 of the board section 74C that is between slots 76). The length L16 of the waveguide 55 is approximately 0.53λL wavelengths.
The waveguide portion 55 of the low-band element 56 is formed using an open rectangular waveguide that is partially filled with dielectric material (i.e., the second dielectric section 70 of the dielectric portion 68). As indicated previously, the sections 68 and 70 are formed from the same piece of dielectric material, which in an advantageous embodiment is quartz. The waveguide 55, in one embodiment, is made of aluminum. The waveguide 55 also includes an air section 72. As
The opening of waveguide 55 of the low-band element is covered by dielectric layer 74 that has been bonded to the high-band array 80 (to form a board layer 82). The dielectric layer 74 serves as another dielectric section at the radiator aperture. The dielectric layer 74 is, in one embodiment, made from a material capable of being bonded to the high-band array 80. The dielectric layer 74 could, in some embodiments, be made of quartz, but it is preferably made of a material capable of being bonded to the high-band array.
Good simulation results have been obtained using HFSS (which is a three-dimensional full-wave electromagnetic field simulation software product available from ANSOFT of Pittsburgh, Pa.) and PARANA (a rigorous finite element modeling tool). Very good agreement between HFSS and PARANA has been achieved for boresight, 30°, and 60° scan angles in the E- and H-planes. Some of the calculated HFSS results are shown in
It is believed that the embodiments of the invention described herein are innovative for a number of different reasons. For example, it is believed that that no other known phased array element design has such a small radiating aperture (relative to frequency) while providing good scan performance at wide scan angles over a very wide bandwidth. In addition, it is believed that the coax to waveguide transition 75 described herein is more compact than known designs, and unique in its particular design. In addition, the low-band element designs described herein are configured and arranged for easy fabrication and low cost manufacturing processes. For example, traditional board lay-up, machining, and plating could be used to produce this element as shown in
Throughout the present disclosure, absent a clear indication to the contrary from the context, it should be understood individual circuit elements as described may be singular or plural in number. For example, the terms “circuit” and “circuitry” may include either a single component or a plurality of components, which are either active and/or passive and are connected or otherwise coupled together to provide the described function. Additionally, the term “signal” may refer to one or more currents, one or more voltages, or a data signal. Within the drawings, like or related elements have like or related alpha, numeric or alphanumeric designators. Further, while the present invention has been discussed in the context of implementations using discrete electronic circuitry (preferably in the form of one or more integrated circuit chips), the functions of any part of such circuitry may alternatively be implemented using one or more appropriately programmed processors, depending upon the signal frequencies or data rates to be processed.
Similarly, in addition, in the Figures of this application, in some instances, a plurality of system elements may be shown as illustrative of a particular system element, and a single system element or may be shown as illustrative of a plurality of particular system elements. It should be understood that showing a plurality of a particular element is not intended to imply that a system or method implemented in accordance with the invention must comprise more than one of that element, nor is it intended by illustrating a single element that the invention is limited to embodiments having only a single one of that respective elements. In addition, the total number of elements shown for a particular system element is not intended to be limiting; those skilled in the art can recognize that the number of a particular system element can, in some instances, be selected to accommodate the particular user needs.
In describing the embodiments of the invention illustrated in the figures, specific terminology (e.g., language, phrases, etc.) may be used for the sake of clarity. These names are provided by way of example only and are not limiting. The invention is not limited to the specific terminology so selected, and each specific term at least includes all grammatical, literal, scientific, technical, and functional equivalents, as well as anything else that operates in a similar manner to accomplish a similar purpose. Furthermore, in the illustrations, Figures, and text, specific names may be given to specific features, processes, military programs, etc. Such terminology used herein, however, is for the purpose of description and not limitation.
Although the invention has been described and pictured in a preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form, has been made only by way of example, and that numerous changes in the details of construction and combination and arrangement of parts may be made without departing from the spirit and scope of the invention. Those of ordinary skill in the art will appreciate that the embodiments of the invention described herein can be modified to accommodate and/or comply with changes and improvements in the applicable technology and standards referred to herein. Variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed.
The particular combinations of elements and features in the above-detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the referenced patents/applications are also expressly contemplated. Although the foregoing description makes reference to various embodiments of the invention, the invention is not limited to specific described embodiments. In addition, although embodiments of the invention may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the invention. As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. The technology disclosed herein can be used in combination with other technologies. Accordingly, the foregoing description is by way of example only and is not intended as limiting. Likewise, reference to “the invention” or to any “innovative” aspects of the embodiments described herein should not be construed as a generalization of any inventive subject matter disclosed herein and should not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).
In addition, all publications and references cited herein are expressly incorporated herein by reference in their entirety.
Having described and illustrated the principles of the technology with reference to specific implementations, it will be recognized that the technology can be implemented in many other, different, forms, and in many different environments. Having described the preferred embodiments of the invention, it will now become apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may be used. These embodiments should not be limited to the disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims. The invention's scope is defined in the following claims and the equivalents thereto.
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