SYSTEM AND METHOD FOR PROVIDING IMPROVED COMMUNICATION SYSTEM COMPONENT INTERFACING
REFERENCE TO RELATED APPLICATION
The present application is related to copending and commonly assigned United States patent application serial number 09/034,471 entitled System and Method for Per Beam Elevation Scanning, filed March 4, 1998, the disclosure of which is hereby incorporated herein by reference.
TECHNICAL FIELD
The present invention relates generally to radio wave communication and more particularly to providing communication system component interfacing eliminating or mitigating the generation of intermodulations.
BACKGROUND
Communication of signals, such as through the use of wireless radio wave communication, requires an often complex system of components. For efficient communication of signals, such as high frequency radio frequency (RF) signals, these components must typically be properly matched and connected to avoid degradation of the transmitted signal, such as through generation of intermodulations and echos. However, it is often difficult and/or expensive to configure a system to mitigate or avoid undesired signal degradation. Often such problems are compounded due to the environment in which the components are deployed.
For example, wireless communication systems generally utilize an aerial or antenna system, such as may be composed of an array of individual radiation elements (e.g., patch, dipole, helical coil, etcetera) and their associated feed system which are disposed in a harsh environment. Specifically, antenna systems are typically exposed to the environment and, therefore, a wide range of operating temperatures and conditions. Such conditions can result in repeated expansion and contraction of individual components, corrosive effects, and the like. Moreover, such antenna systems are subject to substantial stresses, such as wind loading, which can result in individual component movement etcetera.
Antenna elements and/or other components, such as antenna element feed systems, utilized in antenna systems are often made of aluminum because it is light weight, relatively inexpensive, resistant to corrosion caused by most environmental conditions, and presents an acceptable electrical conductor. However, aluminum is a notoriously soft metal which presents problems with respect to coupling components made thereof to other components of the system. For example, pressure fitting of components is prone to degradation, and therefore loosening of the component interface, over time due to the soft nature of the metal and/or the effects of the environment in which it is deployed. This problem is compounded by the usually small size of one or more of the components to be connected in an antenna system causing there to be a relatively high concentration of signal current at the point of interface.
Alternative means of fastening such components are also often ineffective or unavailable.
For example, welding of aluminum parts is very difficult and typically cost prohibitive and soldering of aluminum parts is typically impossible due to the aluminum not accepting the metals most commonly used in solder. Additionally, components to be interfaced may be made
of different materials presenting problems with respect to alternative fastening means. For example, a copper transmission line or other conductor generally cannot be effectively soldered to an aluminum antenna bus. Of course, the aluminum component could be replaced with one made of a compatible material or could be coated with a compatible material to facilitate soldering. However, such solutions have often met with disfavor. Specifically, as discussed above, aluminum has been utilized for particular advantages associated therewith, i.e., cost and weight, which are not typically available with other materials. Additionally, coatings, such as silver, suitable for providing desired connectability, such as through accepting solder, and providing protection against corrosion are often expensive to implement. Accordingly, providing an interface between one system component and another system component can be problematic. For example, permanently interfacing aluminum components using a pressure fit often results in the formation of small gaps in the interface or an otherwise loose fit resulting from the above described stresses commonly experienced by such components. A poor connection between communication components often results in unacceptable transmission characteristics, such as the production of intermodulations of the transmitted signal. Specifically, the metal of the antenna feed system itself produces intermodulations at very high E fields due to the limitations on the rate at which the metal can generate or absorb electrons (i.e., conduct). Accordingly, a need exists in the art for providing communication system component interfacing without introducing undesired results. In particular a need exists in the art for systems and methods providing interfacing of antenna components which mitigate the generation of intermodulations and/or other spurious signals.
A further need exists in the art for the systems and methods utilized in providing communication system component interfacing which is easily implemented, relatively inexpensive, and/or is well suited for deployment in harsh environments.
SUMMARY OF THE INVENTION
These and other objects, features and technical advantages are achieved by a system and method which is adapted to increase the surface area of a component to component interface to thereby mitigate undesired effects. For example, a preferred embodiment of the present invention provides an interface between antenna feed elements, such as an antenna element feed bus and antenna element coupler, which is adapted to provide an increased interface surface and, thereby, distribute signal currents over a greater area. Accordingly, undesired results, such as intermodulations, are appreciably decreased while maintaining an interface which is easily implemented, relatively inexpensive, and well suited for deployment in harsh environments. A preferred embodiment of the present invention utilizes an interface member, disposed between the components to be interfaced, providing an increased interface area. Preferably the interface member is adapted for connection to each component interfaced. Accordingly, a preferred embodiment, useful where interfacing of an antenna feed bus and an antenna element coupler is desired, provides an interface member adapted to easily and reliably couple to an antenna element coupler, such as by solder connection, and also adapted to easily and reliably couple to an antenna feed bus, such as by a plurality of fasteners.
A preferred embodiment the interface member is shaped to provide an increased surface area at positions thereof associated with the production of undesired effects. For example, an interface member of the present invention may include tabs or other surface extensions disposed at distal ends thereof to provide an increased surface area where spark gaps, such as may result in generation of intermodulations, are likely to occur.
Additionally or alternatively, either or both components to be interfaced may be adapted to cooperate with the interface member of the present invention. Accordingly, in a preferred embodiment at least a portion of an antenna feed bus is shaped to correspond to the shape of the interface member. Such shaping of the antenna feed bus may include providing a recess into which the interface member is accepted. Additionally or alternatively, the shaping of the antenna feed bus may include provision of corresponding surface areas, such as tabs corresponding to tabs of the interface member of the preferred embodiment described above.
A preferred embodiment of the present invention includes adaption of either or both of the components to be interfaced to mitigate undesired effects resulting from the use of the
interface member. For example, where the interface member provides tabs as described above with respect to a preferred embodiment, the antenna feed bus may include corresponding tabs disposed thereon a predetermined f action of a signal wavelength apart to provide cancellation of undesired spurious signals. Accordingly, a technical advantage is realized according to the present invention in providing communication system component interfacing without introducing undesired results.
A further technical advantage of the present invention is providing interfacing of antenna feed components while mitigating the generation of intermodulations.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWING
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which: FIGURE 1 shows a typical prior art panel antenna array;
FIGURE 2 shows a feed system useful with the antenna array of FIGURE 1 ;
FIGURE 3 shows an alternative embodiment feed system useful with the antenna array of FIGURE 1;
FIGURE 4 shows a preferred embodiment interface member of the present invention; FIGURE 5 shows the interface member of FIGURE 4 in a preferred embodiment deployment;
FIGURE 6 shows a cross section view of the preferred embodiment interface member deployment of FIGURE 5; and
FIGURES 7 and 8 show alternative embodiment interface members in preferred embodiment deployments.
DETAILED DESCRIPTION
Directing attention to FIGURE 1, a typical prior art planar antenna array is shown generally as antenna array 100. Antenna array 100 includes a plurality of antenna elements, such as dipole antenna elements lOla-1, 101a-2, 101a-3, and 101a-4, disposed above ground plane 110 and arranged in a series of columns, shown as columns 101a, 101b, 101c, and 101 d. Of course, the antenna columns maybe comprised of other forms of antenna elements (e.g., patch, dipole, helical coil, etcetera) and/or in differing numbers of antenna elements and/or antenna columns than those illustrated.
Antenna array 100, depending upon the feed network coupled thereto, may be utilized as a phased array antenna. For example, a Butler matrix may be coupled to the antenna columns to provide a multiple beam phased array antenna. Additionally or alternatively, adjustable feed networks, such as may include variable phase shifters, variable attenuators, or digital signal processors, may be coupled to the antenna columns to provide an adaptive array providing steerable antenna beams. Irrespective of the particular feed networks coupled to the antenna array, an antenna feed system is generally provided to couple the individual antenna elements to other portions of the signal communication system. Directing attention to FIGURE 2, a cross, sectional view of antenna 100 is shown wherein a portion of an antenna feed system for coupling antenna elements 101a- through 101a-4 to communication circuitry, such as cellular telephony base transceiver station circuitry, is visible. Specifically, each dipole antenna element 101a- 1, 101a-2, 101a-3, and 101a-4 is coupled to air-line bus 210. Air-line bus 210 preferably includes quarter wave shorts 211 disposed at the distal ends of the bus.
The dipole antenna elements shown include an upper and lower dipole half, dipole halves
201 and 202, one of which is coupled to the air-line bus through BALUN 203. It shall be appreciated that the air-line bus, which is a single conductor suspended over the ground plane, is unbalanced and the BALUNs, coupling the dipole antennas thereto, operate to convert the structure from unbalanced to balanced.
Air-line bus 210 is preferably coupled to an antenna feed network, such as the Butler matrix or adaptive array circuitry described above. Accordingly, a plurality of antenna columns may be simultaneously excited by a signal to destructively and beneficially combine in order to
provide a desired radiation pattern. In a preferred embodiment, the air-line bus is coupled to the feed network at a mid point, such as coupler 220 shown between antenna elements 101a-2 and 101a-3. Such a connection aids in providing even power distribution amongst the antenna elements of the column. It shall be appreciated that a 180° phase shift is experienced in the excitation of the antenna elements disposed on the air-line above the air-line/feed network tap as compared to the antenna elements disposed on the air-line below the air-line/feed network tap. Accordingly, antenna elements lOla-1 and 101a-2 are preferably provided with BALUN 203 coupled to upper dipole half 201 whereas antenna elements 2a-3 and a-4 are provided with BALUN 203 coupled to lower dipole half 202. An alternative embodiment of the feed system of FIGURE 2 is shown in FIGURE 3. In the embodiment of FIGURE 3, a dielectric is placed in the space between the air-line bus and the ground plane to alter the transmission properties of the antenna column. By placing a dielectric between the air-line bus and the ground plane, as illustrated by dielectric load 300 in FIGURE 3, the propagation velocity of the electromagnetic energy being distributed along the column is retarded. This retardation of the propagation velocity, and the subsequent compression of the wave length, allows the spacing of the dipoles to be reduced without substantially affecting the grating lobes.
As alluded to with respect to the alternative embodiment of FIGURE 3, in an air-line bus most of the energy communicated via the antenna elements is confined in the space between the air-line bus and the ground plane. Accordingly, the relatively small contact area between BALUN 203 and air-line bus 210 typically experiences high currents.
Antenna elements and/or other components, such as antenna elements lOla-1 through 101 a-4, BALUN 203, and/or air-line bus 210, utilized in antenna systems are often made of aluminum because it is light weight, relatively inexpensive, resistant to corrosion caused by most environmental conditions, and presents an acceptable electrical conductor. However, aluminum is a notoriously soft metal which presents problems with respect to coupling components made thereof to other components of the system. For example, a mechanical fastening system, such as utilizing a screw or rivet, is prone to degradation over time due to the soft nature of the metal. This problem is compounded by the relatively small size of one or more of the components to be connected in an antenna system. Alternative means, such as welding of aluminum parts, are also often ineffective or unavailable.
Additionally, components to be interfaced maybe made of different materials presenting problems with respect to alternative fastening means. For example, a copper BALUN generally cannot be effectively soldered to an aluminum air-line bus. Of course, the aluminum component could be replaced with one made of a compatible material or could be coated with a compatible material to facilitate soldering. However, such solutions have often met with disfavor. As discussed above, aluminum has been utilized for particular advantages associated therewith which are not available with other materials. Additionally, coatings, such as silver, suitable for providing desired connectability, such as through accepting solder, and providing protection against corrosion are often expensive to implement. For example, the air-line bus may be of appreciable size, due to its corresponding to the length of the antenna column to be energized, which may require appreciable material to be fully coated and/or may present a challenge with respect to coating apparatus sized to accommodate the component.
In the past a pressure fit technique has often been utilized in providing coupling between some components of an antenna array. Specifically, it is not uncommon to provide interfacing of components such as BALUN 203 and air-line bus 210 by drilling a hole in the appropriate location of air-line bus 210 and pressing a portion of BALUN 203 therein. However, such a pressure fit of components, although being relatively simple to implement, often results in undesired operation of the antenna array, especially over time.
Antenna systems are typically exposed to the environment and, therefore, a wide range of operating temperatures and conditions. Such conditions can result in repeated expansion and contraction of individual components, corrosive effects, and the like. Moreover, such antenna systems are subject to substantial stresses, such as wind loading, which can result in individual component movement etcetera. Accordingly, a pressure interface such as described above with respect to BALUN 203 and air-line bus 210 is prone to loosen over time, resulting in poor communication between the interfaced components.
Poor communication between components often results in unacceptable transmission characteristics, such as the production of intermodulations of the transmitted signal. Specifically, the metal of the antenna feed system itself produces intermodulations at very high E fields due to the limitations on the rate at which the metal can generate or absorb electrons (i.e., conduct). The relatively small point at which an interface between BALUN 203 and airline bus 210 are pressure fit results in a very high concentration of currents and associated high
E fields. Therefore, any small gaps in this pressure interface result in substantial intermodulations and/or other undesired characteristics.
The present invention provides an interface wherein currents are distributed over a larger surface area to thereby mitigate undesired operational characteristics. Additionally or alternatively, interfaces of the present invention provide an improved, i.e., more permanent, interface between components, mitigating undesired operational characteristics.
Directing attention to FIGURE 4, a preferred embodiment interface member according to the present invention is shown generally as interface member 400. According to the preferred embodiment, by disposing interface member 400 between components to be interfaced, such as the aforementioned BALUN 203 and air-line bus 210, an increased surface area interface is achieved. Preferred embodiment deployments of interface member 400 of FIGURE 4 to interface BALUN 203 and air-line bus 210 according to the present invention are shown in the views of FIGURES 5 and 6.
It should be appreciated that although only a single interface member 400 is shown in FIGURES 5 and 6, multiple ones of the interface member may preferably be utilized according to the present invention. For example, according to a preferred embodiment, an interface member is provided on air-line bus 210 substantially as shown in FIGURES 5 and 6 to correspond with each antenna element of an antenna element column.
Additionally or alternatively, the orientation of deployment of interface member 400 may be different than that shown in FIGURES 5 and 6. For example, rather than being disposed on a surface of air-line bus 210 facing toward ground plane 110, interface member 400 may be disposed on a surface of air-line bus 210 facing away from ground plane 110. Such an embodiment might be preferred to present a substantially smooth or uniform air-line bus surface with respect to the space between the air-line bus and the ground plane wherein most of the energy communicated via the antenna elements is confined. Alternatively, it may be preferred to dispose the interface member of the present invention as shown in FIGURE 6 to accommodate its pressure and subsequent solder connection to BALUN 203 prior to assembly of the components into an antenna array.
It should be appreciated that, in addition or in the alternative to the particular components interfaced using interface member 400 described herein, interface members according to the
present invention may be utilized to interface system components other than those illustrated. For example, an alternative embodiment interface member provides interfacing of air-link 210 and coupler 220.- Similarly, an interface member of the present invention may be utilized to provide interfacing of a ground surface, such as ground plane 110, and a ground strap (not shown).
Preferably, interface member 400 is specifically adapted for proving coupling to the components between which interface member 400 is to be disposed. The preferred embodiment interface member 400 is adapted to provide an interface between components coupled thereto suitable for withstanding expected operating conditions without substantial degradation and without resulting in undesired signal attributes.
For example, interface member 400 of the preferred embodiment of FIGURE 4 includes a plurality of fastener receivers 430 disposed therein to facilitate a good mechanical bond with a component to be interfaced, such as the aforementioned air-line bus 210. It should be appreciated that synergistic advantages are realized through use of the present invention. For example, in addition to providing an increased surface area for use in mitigating undesired signal characteristics, such as to distribute the aforementioned currents at the interface and thereby mitigate intermodulations, the increased surface areaprovides increased area for the deployment of fastening means useful in providing a desired mechanical bond. By providing a plurality of fasteners and/or spreading out the deployment of fasteners degradation associated with their use may be mitigated. Specifically, the increased number of fasteners tends to decrease the severity of loosening or gaps formed over time. Additionally, the spreading apart of the fasteners tends to lessen the effects of any loosening or gaps which do result.
The preferred embodiment fastener receivers 430 illustrated may accommodate such mechanical fastening means as screws, bolts, rivets, staples, wires, and other fasteners suitable for use in providing a mechanical bond sufficient to withstand the stresses associated with antenna array deployment. Directing attention to FIGURE 6, preferred embodiment rivets 510 disposed through fastener receivers 430 are shown. Of course, fastener receivers utilized according to the present invention maybe provided in embodiments alternative to or in addition to those of the illustrated preferred embodiment. For example, fastener receivers useful in attaching interface member 400 to a component, such as air-line bus 210, may include a coating of interface member 400 suitable to accommodate soldering or welding thereto, or other
preparation to accept a conductive adhesive material. Likewise, fastener receivers of interface member 400 may include various structural elements disposed thereon, such as tabs or slots suitable for accepting or providing a mechanical attachment to a desired component.
Interface member 400 also preferably includes fastener receivers to facilitate a good mechanical bond with another component to be interfaced, such as the aforementioned BALUN 203. For example, interface member 400 of FIGURE 4, includes receiver 420 adapted to accept a portion of a component to be interfaced, such as a distal end of BALUN 203 as shown in FIGURE 6. However, as discussed above, a pressure fit connection often results in undesired signal attributes. Therefore, a preferred embodiment interface member 400 is provided with additional fastener receiver adaptation such as a coating adapted to cooperate with a component to be interfaced thereto, e.g. BALUN 203, and provide a desired mechanical bond. According to a most preferred embodiment, interface member 400 is provided with a silver coating suitable for accepting a solder flow as shown by solder 503 of FIGURE 5 and, thus, provide a good mechanical connection with a component adapted accordingly. For example, wherein BALUN 203 is made of copper, such a component may be easily and reliably coupled to interface member 400 using standard soldering techniques. Similarly, where BALUN 203 is made of aluminum which is also coated with an appropriate material, such as the aforementioned silver, coupling to interface member 400 may also be achieved using standard soldering techniques.
It should be appreciated that fasteners utilized according to the present invention to couple another component to be interfaced, such as the above described BALUN 203, may be provided in embodiments other than those described above. For example, fastener receivers, such as discussed above with respect to coupling to air-line bus 210, accommodating such mechanical fastening means as screws, bolts, rivets, staples, and/or wires maybe used to engage interface member 400 and BALUN 203 or various structural elements, such as tabs or slots suitable for accepting or providing a mechanical attachment to a desired component, may be used if desired. Likewise, fastener receivers useful in attaching interface member 400 to BALUN 203 may include a coating or other preparation to accept a conductive adhesive material.
It should be appreciated that, although providing an increased interface surface area as compared to the simple direct interface of components, such as thepressure interface of BALUN
203 and air-line bus 210, interface member 400 is relatively small in size. Specifically, interface
member 400 is substantially smaller than air-line bus 210, as shown in FIGURE 5. Accordingly, the amount of material required to provide a desired coating of interface member 400 is relatively small. Moreover, due to its relatively small size, interface member 400 maybe easily accommodated in a coating apparatus such as an electroplate coater. It should be appreciated that the relatively small size of interface member 400 may be advantageous not only for coating purposes, but also in the use of materials with respect to the making thereof. It maybe desirous to produce interface member 400 of a material different than that of a component to be interfaced thereto, such as air-line bus 210. For example, it may be advantageous to make interface member 400 from a particular type of material well suited for coating with a desired coating material. Alternatively, it may be decided to make interface member 400 from a particular material rather than providing a coating thereon, such as to reduce manufacturing costs and or avoid undesired situations such as delamination. The use of the relatively small interface members of the present invention easily accommodates the use of these alternative materials substantially without the disadvantages of making an entire component to be interfaced from such a material, e.g. weight and cost disadvantages.
Having been suitably coupled with one component, such as BALUN 203, interface member 400 provides an increased surface area for interfacing with another component, such as air-line bus 210. Accordingly, even where imperfections exist at portions of the interface, such as at the points of surface contact between interface member 400 and air-line bus 210, the signal currents are distributed over a relatively large area so as to mitigate their effects. Specifically, spark gaps associated with the distal ends of interface member 400, as current flows between air-line bus 210 and the various antenna elements lOla-1 through 101a-4, enjoy amore disbursed current flow. Accordingly, in addition to providing a superior mechanical bond utilizing fasteners accommodated through the availability of increased surface area, and thereby decreasing the occurrence of interface anomalies such as loose connections etcetera, the affects of anomalies in the interface which still result have a significantly reduced impact on signal quality, e.g. intermodulations and/or echos are reduced in number and/or magnitude.
The preferred embodiment interface member 400 of FIGURE 4 is adapted to enhance the increased interface surface area by including tabs or other surface extensions, such as shown by surface extensions 430, disposed at distal ends of interface member 400, such as to provide the preferred embodiment "bar bell" shaped interface member of FIGURE 4. Accordingly, an
increased surface area where currents are transferred between the components being interfaced is provided for disbursement of signal currents.
The preferred embodiment shown in FIGURE 4 provides squared surface extensions 430. However, the present invention is not limited to such a configuration of surface extensions. For example, an alternative embodiment of surface extensions 430 utilize a curved edge interface member, as shown in FIGURE 7, to further disburse signal currents. Accordingly, an increased distal edge surface area of interface member 400 engages an increased edge surface area of air- link bus 210. Other alternative embodiments of the present invention may also include adaptation to increase corresponding surface areas of the components to be interfaced and/or of the interface member, such as that shown in FIGURE 8. Of course, it should be appreciated that the use of particular edge shapes, such as the curves of FIGURE 7, or orientations, such as that shown in FIGURE 8, may be utilized without the provision of surface extensions, i.e., the "tab" portion of surface extensions 430 extending beyond the edge of air-link bus 210, to provide advantages according to the present invention, if desired. Either or both components to be interfaced may be adapted to cooperate with interface member 400 of the present invention. For example, the preferred embodiment air-line bus includes surface extensions (most easily seen in the alternative embodiments of FIGURES 7 and 8 as surface extensions 730 and 830 respectively) to cooperate with those of the preferred embodiment interface member 400. Additionally or alternatively, a component to be interfaced may be shaped to receive an interface member of the present invention. For example, the preferred embodiment shown in FIGURE 6 includes adaptation of air-line bus 210 to correspond to and cooperate with interface member 400 when interfaced therewith. Specifically, according to the preferred embodiment of FIGURE 6, a portion of air-line bus 210 is relieved to correspond to the shape of interface member 400 to provide a substantially smooth and continuous surface when interface member 400 and air-line bus 210 are fully interfaced. Such an embodiment might be preferred to present a substantially uninterrupted air-line bus surface with respect to the space between the air-line bus and the ground plane wherein most of the energy communicated via the antenna elements is confined. It should be appreciated that the alternative embodiments illustrated in FIGURES 7 and 8 may include adaptation of air-line bus 210 to cooperate with the curved shape of the
alternative embodiment interface member 400 to provide a substantially uninterrupted air-line bus surface having increased edge contact between interface member 400 and air-line bus 210.
According to a preferred embodiment of the present invention, adaptation of either or both of the components to be interfaced in addition or alternative to that discussed above may be utilized to mitigate undesired effects resulting from the use of the interface member of the present invention. For example, where the interface member provides the surface area extensions of the preferred embodiment described above, air-link bus 210 preferably includes corresponding tabs disposed thereon a predetermined fraction of a signal wavelength apart to provide cancellation of undesired effects. Specifically, a preferred embodiment of the present invention disposes surface extensions 530 one half wave length (Vi λ) from surface extensions associated with interface member 400. Accordingly, spurious signals associated with surface extensions 430 and/or surface extensions 730 or 830 are mitigated by destructive combining of corresponding spurious signals associated with surface extensions 530.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.