Note: Descriptions are shown in the official language in which they were submitted.
CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 VOLUMETRIC ELECTROMAGNETIC COMPONENTS RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. Application No. 14/629,032, titled "Method and Apparatus for Folded Antenna Components," filed 23 February 2015. This application claims priority to and the benefit of U.S. Provisional Application No. 61/996,347 filed February 22, 2014 and entitled "Method and Apparatus for Folded Antenna Components"; this application also claims priority to U.S. Provisional Patent Application No. 62/123,579, titled "Structure Embedded Electromagnetic Absorbers," filed 20 November 2014; this application also claims priority to and the benefit of U.S. Provisional Patent Application No. 62/123,581, titled "Method and Apparatus for Folded Volumetric Electromagnetic Components," filed 20 November 2014; the entire contents of all of which applications are incorporated herein by reference. BACKGROUND [0002] Antennas are used to typically radiate and/or receive electromagnetic signals, preferably with antenna gain, directivity, and efficiency. Practical antenna design traditionally involves trade-offs between various parameters, including antenna gain, size, efficiency, and bandwidth. [0003] Antenna design has historically been dominated by Euclidean geometry. In such designs, the closed area of the antenna is directly proportional to the antenna perimeter. For example, if one doubles the length of a Euclidean square (or "quad") antenna, the enclosed area of the antenna quadruples. Classical antenna design has dealt with planes, circles, triangles, squares, ellipses, rectangles, hemispheres, paraboloids, and the like. [0004] With respect to antennas, prior art design philosophy has been to pick a Euclidean geometric construction, e.g., a quad, and to explore its radiation characteristics, especially with emphasis on frequency resonance and power patterns. Unfortunately antenna design has concentrated on the ease of antenna construction, rather than on the underlying electromagnetics, which can cause a reduction in antenna performance. 1 CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 [0005] Practical antenna design traditionally involves trade-offs between various parameters, including antenna gain, size, efficiency, and bandwidth. Antenna size is also traded off during antenna design that typically reduces frequency bandwidth. Being held to particular size constraints, the bandwidth performance for antenna designs such as discone and bicone antennas is sacrificed resulted in reduced bandwidth. [0006] Dipole-like antenna have used a bicone or discone shape to afford the performance desired over a large pass band. For example, some pass bands desired exceed 3:1 as a ratio of lowest to highest frequencies of operation, and typically ratios of 20:1 to 100:1 are desired. Some prior art discone antennas have included a sub-element shaped as a cone whose apex is attached to one side of a feed system at location. A second sub-element can be attached to the other side of the feed system, such as the braid of a coaxial feed system. This sub-element is a flat disk meant to act as a counterpoise. [0007] Both discone and bicone antennas afford wideband performance often over a large ratio of frequencies of operation; in some arrangements more than 10:1. However, such antennas are often 1/4 wavelength across, as provided by the longest operational wavelength of use, or the lowest operating frequency. In height, the discone is typically 1/4 wavelength and the bicone almost 1/2 wavelength of the longest operational wavelength. Typically, when the lowest operational frequency corresponds to a relatively long wavelength, the size and form factor of these antenna becomes cumbersome and often prohibitive for many applications. [0008] Antenna systems that incorporate a Euclidean geometry include roof- mounted antennas that extend from objects such as residential homes or automobiles. Such extendable antennas can be susceptible to wind and other weather conditions and may be limited in bandwidth and frequency range. Additionally, by implementing a Euclidean geometry into these conformal antennas, antenna performance is degraded. -2- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 SUMMARY [0009] This disclosure relates to systems, apparatus, and methods using three- dimensional, or volumetric, components to interact with energy in a desired manner, e.g., absorb, guide, transmit, and/or receive. [0010] In accordance with an aspect of the disclosure, methods are disclosed for making antenna apparatus, components, and related or ancillary components suitable for wideband transmission and reception. An example of such an antenna apparatus can include a bicone antenna portion (bicone antenna) including two cone-shaped elements (e.g., an accordioned bicone antenna) or a reverse bi- cone antenna, have a general shape where the two open ends of the cones are joined (directly or via an intermediate shape). The physical shape of at least one of the two cone-shaped elements may be at least partially defined by one or more folds (e.g., a series) that extend about a portion of the cone. Other shapes and configurations such as those including self-similar features can be included for the antennas or components. [0011] Exemplary embodiments include a novel system and method for producing such antenna parts and antennas made by same, is also disclosed. The system may utilize a material accretion device, such as a three-dimensional (3D) printer, to make volumetric plastic components that incorporate one or more folds and/or have self- similar structure (fractal in finite iterations for at least a portion) for at least part of the component. The component may be constructed out of conductive plastic, or non- conductive plastic. [0012] If non-conductive plastic is used, the component may be coated, plated, painted or gilded with a conductor (such as conductive paint) after printing so the component then conducts and can act as an antenna component. These components may be actual radiators, filters, counterpoises ground planes, or loads. Dipoles, monopoles, dielectric resonators, leaky antennas, metamaterial antennas, metasurface antennas, slot antennas, cavity antennas, and many other kinds of antennas may be made in this system. The antennas may have smaller size and or better gain and or greater bandwidths than antennas of conventional design. They may be used from 50-6000 MHz or any fraction of same bandwidth. They may be -3- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 used in telematics; wireless, cell phone communication, WIFI, Wimax, UWB, and other systems. [0013] A further aspect of the present disclosure is directed to systems and methods for producing volumetric electromagnetic components, and volumetric electromagnetic components made by same. Such volumetric electromagnetic components can take function as waveguides, absorbers, attenuators and/or other electromagnetic components. In exemplary embodiments, such volumetric electromagnetic components can be embedded within a suitable dielectric material as a system, and together the system may function as electromagnetic absorbers. [0014] Additional advantages and aspects of the present disclosure will become readily apparent to those skilled in the art from the following detailed description, wherein embodiments of the present invention are shown and described, simply by way of illustration of the best mode contemplated for practicing the present invention. As will be described, the present disclosure is capable of other and different embodiments, and its several details are susceptible of modification in various obvious respects, all without departing from the spirit of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as limitative. BRIEF DESCRIPTION OF THE DRAWINGS [0015] Aspects of the disclosure may be more fully understood from the following description when read together with the accompanying drawings, which are to be regarded as illustrative in nature, and not as limiting. The drawings are not necessarily to scale, emphasis instead being placed on the principles of the disclosure. In the drawings: [0016] FIG. 1 depicts an antenna component after being printed by a 3D printer, in accordance with an embodiment of the present disclosure; [0017] FIG. 2 shows the antenna component of FIG. 1 painted with conductive paint and made into a monopole antenna element. ; [0018] FIG. 3 depicts a discone antenna including a folded cone and a disk according to an embodiment of the present disclosure; -4- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 [0019] FIG. 4 depicts a bicone antenna with two folded cones according to an embodiment of the present disclosure; and [0020] FIG. 5 depicts a method of making an antenna component in accordance with the present disclosure. [0021] FIG. 6 shows an example of two representative structures next to dielectric foam in which they are to be embedded. [0022] FIG. 7 shows an example of several volumetric electromagnetic components printed on a 3D printer. [0023] FIG. 8 shows an example of volumetric electromagnetic components as painted with conductive paint. [0024] While certain embodiments are shown in the drawings, one skilled in the art will appreciate that the embodiments depicted in the drawings are illustrative and that variations of those shown, as well as other embodiments described herein, may be envisioned and practiced within the scope of the present disclosure. DETAILED DESCRIPTION [0025] Embodiments of the present disclosure are directed to wideband antennas and related systems and techniques. Such antennas can include an accordioned bicone antenna, e.g., for frequencies from VHF to microwave, and a fractalized dipole, e.g., for lower frequencies. In exemplary embodiments, the fractalized dipole can include a circuit board with a trace at least a portion of which is self similar for at least two iterations. The circuit board can be conformal inside of a tube or mast structure, which can be a cylinder, and/or may be applied to or supported by the outside surface of the mast. The tube structure can act as a mast for the accordioned bicone, which can be located at the top. Exemplary embodiments can provide operation across a 100:1 passband or greater (e.g., in terms of -3dB power), e.g., from HF (or MF) frequencies through microwave. [0026] An aspect of the present disclosure is directed to novel systems for producing antenna parts and antennas made by same. The system uses a three dimensional printer to make volumetric plastic components that incorporate one or more folds and/or have self-similar structure (fractal in finite iterations for at least a -5- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 portion) for at least part of the component. The component may be constructed out of conductive plastic, or non-conductive plastic. [0027] If non-conductive plastic is used, the component may be plated or gilded with a conductor (such as conductive paint) after printing so the component then conducts and can act as an antenna component. These components may be actual radiators, filters, counterpoises ground planes, or loads. Dipoles, monopoles, dielectric resonators, leaky antennas, metamaterial antennas, metasurface antennas, slot antennas, cavity antennas, and many other kinds of antennas may be made in this system. The antennas may have smaller size and or better gain and or greater bandwidths than antennas of conventional design. They may be used from 50-6000 MHz or any fraction of same bandwidth. They may be used in telematics; wireless, cell phone communication, WIFI, Wimax, UWB, and other systems. [0028] FIG. 1 shows an antenna component 100 after being made by a material accreting (or accretion) device, e.g., a three-dimensional (3D) printer. An example of a suitable 3D printer is a MakerBot Replicator Z18 3D printer made available by the MakerBot Industries LLC. [0029] FIG. 2 shows the antenna component 100 of FIG. 1 painted with conductive paint and made into a monopole antenna element. [0030] Examples of suitable fractal shapes for use in one or more antenna systems and antenna components according to the present disclosure include, but are not limited to, fractal shapes described in one or more of the following patents, owned by the assignee of the present disclosure, the entire contents of all of which are incorporated herein by reference: U.S. Patent No. 6,452,553; U.S. Patent No. 6,104,349; U.S. Patent No.6,140,975; U.S. Patent No. 7,145,513; U.S. Patent No., 7,256,751; U.S. Patent No. 6,127,977; U.S. Patent No. 6,476,766; U.S. Patent No. 7,019,695; U.S. Patent No. 7,215,290; U.S. Patent No. 6,445,352; U.S. Patent No. 7,126,537; U.S. Patent No.7,190,318; U.S. Patent No. 6,985,122; U.S. Patent No. 7,345,642; and, U.S. Patent No. 7,456,799. Further examples are disclosed in U.S. Application Serial No. 11/716,909 filed March 12, 2007; U.S. Application Serial No. 10/812,276, filed March 29, 2004; U.S. Provisional Application Number: 60/458,333, filed March 29, 2003; U.S. Provisional Application No. 60/802,498 filed 22 May 2006; U.S. Application No. 10/868,858, filed June 17, 2004, now issued as U.S. Patent No. -6- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 7,126,531; and U.S. Application No. 09/700,005, filed November 7, 2000, now issued as U.S. 6,445,352; the contents of all of which applications and patents are incorporated herein by reference in their entireties. [0031] Other suitable fractal or folded shapes for antenna systems and antenna components (e.g., a resonator or resonant structures) can include any of the following: a Koch fractal, a Minkowski fractal, a Cantor fractal, a torn square fractal, a Mandelbrot, a Caley tree fractal, a monkey's swing fractal, a Sierpinski gasket, and a Julia fractal, a contour set fractal, a Sierpinski triangle fractal, a Menger sponge fractal, a dragon curve fractal, a space-filling curve fractal, a Koch curve fractal, a Lypanov fractal, and a Kleinian group fractal. [0032] Other features produced by or for embodiments of the present disclosure can include metamaterials, which are materials with negative permittivity and permeability leading to negative index of refraction were theorized by Russian noted physicist Victor Veselago in his seminal paper in Soviet Physics USPEKHI, 10, 509 (1968). Since that time, metamaterials have been developed that produce negative index of refraction, subject to various constraints. Such materials are artificially engineered micro/nanostructures that, at given frequencies, show negative permeability and permittivity. Metamaterials have been shown to produce narrow band, e.g., typically less than 5%, response such as bent-back lensing. Such metamaterials produce such a negative-index effect by utilizing a closely- spaced periodic lattice of resonators, such as split-ring resonators, that all resonate. Previous metamaterials provide a negative index of refraction when a sub- wavelength spacing is used for the resonators. Metamaterials are typically engineered by arranging a set of small scatterers or apertures in a regular array throughout a region of space, thus obtaining some desirable bulk electromagnetic behavior. The desired property is often one that is not normally found naturally (negative refractive index, near-zero index, etc.). Three-dimensional metamaterials can be extended by arranging electrically small scatterers or holes into a two- dimensional pattern at a surface or interface. This surface version of a metamaterial has been given the name metasurface (the term metafilm has also been employed for certain structures). For many applications, metasurfaces can be used in place of metamaterials. Metasurfaces have the advantage of taking up less physical space -7- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 than do full three-dimensional metamaterial structures; consequently, metasurfaces offer the possibility of less-lossy structures. [0033] Such features when used in or for antenna systems and components can provide increased performance relative to antennas and antenna components not employing those fractal or folded features, e.g., improved bandwidth characteristics in terms of 3 dB bandwidth, etc. [0034] FIG. 3 depicts a discone antenna 75 including a folded cone and a disk. Antenna 75 is another example of an antenna component that can be made in accordance with the present disclosure. Referring to FIG. 3, to provide wider bandwidth performance, while allowing for reduced size and form factors, shaping techniques are incorporated into the components of the antenna. For example, a discone antenna 75 includes a conical portion 80 that includes folds that extend about a circumference 85 of the conical portion. Along with incorporating folds into the conical portion of the discone antenna 75, to further improve bandwidth performance while allowing for relative size reductions based on operating frequencies, shaping techniques are incorporation into the disc element of the antenna. In this example, a disc element 90 of the discone antenna 75 is defined by a fractal geometry, such as the fractal geometries described in United States Patent 6,140,975, filed November 7, 1997, which is herein incorporated by reference. By incorporating the folds into the conical portion and the fractal (i.e., self- similar) disc design, the size of the discone antenna 74 is approximately one half of the size of the discone antenna 5 (shown in FIG. 1) while providing similar frequency coverage and performance. [0035] Referring to FIG. 4, a bicone antenna 100 is shown that includes two conical portions 110, 120. Each of the two conical portions 110, 120 are respectively defined by folds that extend about the respective circumferences 130, 140 of the two portions. By incorporating the folded-shaping or folded shape(s) into the conical portions 110, 120, the bicone antenna 100 provides the frequency and beam- pattern performance of a larger sized bicone antenna that does not include shaping. [0036] While the shaping techniques implemented in the discone antenna 75 (shown in FIG. 3) and the bicone antenna 100 (shown in FIG. 4) utilized a folded- -8- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 shape in the conical portions and a fractal shape in the disc portion, other geometric shapes, including one or more holes, can be incorporated into the antenna designs. [0037] By incorporating these shaping techniques, for example, into a discone antenna, such as the discone antenna 75 (shown in FIG. 3), the standing wave ratio (SWR) of the antenna demonstrates the performance improvement. For example, such a structure can exhibit a wideband 50 ohm match of a discone antenna across a preferred frequency band (e.g., 100 MHz ¨3000 MHz). [0038] FIG. 5 depicts a method 500 of making an antenna component in accordance with the present disclosure. As shown at 502, a material accreting device can be used for accreting material in layers, wherein each layer defines a predetermined shape of an antenna feature. The antenna component can accordingly be formed having a predetermined three-dimensional (3D) shape, as shown at 504. The antenna component includes a folded or self-similar shape for at least a portion of the component, as shown at 506. As further shown at 508, the method 500 can include coating the component with a conductive medium as a thin layer, for at least a portion of the component. [0039] An aspect of the present disclosure is directed to novel systems and components for electromagnetic absorption over a band of frequencies using fractal and or folded and or spiked structures embedded in an absorbing dielectric material. Fig. 6 shows an example 600 of two representative structures 602, 604 next to foam 606 in which they are to be embedded. The absorber structures 602-604 scatter, diffract and/or reflect the waves in the dielectric material, e.g., carbon- based foam or other type of microwave-absorbing foam. Accordingly, these structures can allow for (i.e., provide) greater absorption with a thinner thickness compared to conventional absorbers (e.g., prior art wedge absorbers). These structures (e.g., 602-604 as embedded in 606) can also provide a flat form factor rather than wedge shaped ones. Such absorbers can be made by suitable techniques, including by use of 3D printing, such as described in further detail below. [0040] These absorption systems and components can operate at or across desired frequency bands. Examples of such frequency bands can include, but are not limited to, one or more of L, S, C, X, Ku, K Ka, V, and W bands in the microwave regime. Attenuation of electromagnetic waves is facilitated via electromagnetic -9- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 energy absorbing structures such as shown in Fig. 6 (as 602, 604). Such EM absorbing structures (or, absorbers) can overcome prior art limitations of impractical thickness and limited bandwidth. Use of such EM absorbing structures, e.g., 602, 604, can provide a method of absorbing that allows a wide bandwidth of absorption while maintaining suitable thinness of the absorbers. While exemplary embodiments of an absorbing system can be used at radio (RF) frequencies, other embodiments can be used at other frequencies, e.g., with appropriate scaling of structures. [0041] Exemplary embodiments of EM absorbers can include an absorber that incorporates fractal structures or features. Such fractal structures or features can provide, facilitate and/or enhance the ability to diffuse RF waves. Such fractal structures or features may produce additional paths within the absorbing dielectric material, thus producing broadband (or, wideband) absorption. [0042] Any suitable type of dielectric material may be used. An example of such a dielectric material can be, but is not limited to, a carbon-based foam. A commercially available example of a suitable dielectric foam is C-FOAM PK-2, made available by PPG Aerospace Cuming Microwave Corporation of 264 Bodwell Street, Avon, MA 02322 USA; other suitable foams and/or other types of dielectric materials may be used instead or in addition. Other examples include suitable microwave- absorbing elastomers (elastomeric absorbers) and films, as well as magnetic absorbers. [0043] In exemplary embodiments, 3D printing using a suitable 3D printer can be used to make the structures. Any suitable technique(s) may be used for embedding the structures within the dielectric material, e.g., foam. In some embodiments, an electromagnetic absorption component, e.g., 602, after being formed by a 3D printer, can be placed on a support surface or hung over a support surface while foam is poured around it. [0044] A further aspect of the present disclosure is directed to systems capable of producing electromagnetic parts or components¨those that are designed to propagate, guide, duct, radiate, absorb, reflect, diffract refract, resonate and/or re- propagate electromagnetic waves themselves or as components of a larger system¨and parts made by same. Fig. 7 shows an example 700 of several components 702-706 after being printed on a 3D printer (not shown). -10- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 [0045] Such a system can use a three-dimensional (3D) printer to make volumetric electromagnetic components (or, parts) that incorporate one or more folds and/or bends and/or have self-similar structure (e.g., fractal in finite iterations for at least a portion of the structure) for at least part of the component. The component may be constructed out of conductive plastic or non-conductive plastic or other non- conductive material. Alternatively, such systems can use a three-dimensional printer to make volumetric metal or metal coated components that incorporate one or more folds and/or have self-similar structure (e.g., fractal in finite iterations for at least a portion of the structure) for at least part of the component. [0046] If non-conductive material is used, the component may be plated or gilded with a conductor (such as conductive paint) after printing so the component then conducts and can act as an electromagnetic component. Alternatively, the component may only be partially plated and the non-conductive material will act as a dielectric. These components may be actual radiators, filters, counterpoises ground planes, or loads, absorbers, diffusers, reflectors, directors (lenses), waveguides, etc., and the like. Dipoles, monopoles, dielectric resonators, leaky antennas, metamaterial antennas, metasurface antennas, slot antennas, cavity antennas, and many other kinds of antennas can be made by such systems. The antennas or components may have smaller size and or better gain and or greater bandwidths than antennas of conventional design. They may be used, e.g., from 50-60,000 MHz or any fraction of same bandwidth or multiple bands within. They may be used, e.g., in telematics, wireless, cell phone communication, WIFI, public safety, Wimax, UWB, and other systems similar systems. [0047] Fig. 8 shows an example 800 of EM components 802-816 painted with conductive paint, after having been printed with a 3D printer. Any suitable 3D printer may be used. An example of a suitable 3D printer is the Makerbot Replicator Fifth Generation made commercially available by MakerBot' industries, LLC, One MetroTech Center, 21st Fl, Brooklyn, NY 11201 USA; other suitable 3D printers may be used, [0048] In some implementations/embodiments, an accordioned bicone antenna apparatus according to an embodiment of the present disclosure can include an accordioned bicone and a fractalized circuit board, which can be conformal to a -11- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 given surface, e.g., a cylinder. The conformal circuit board can be configured to act as a fractalized dipole. The circuit board can include one or more conductive portions or traces that include self-similar structure such as various suitable fractal shapes. Such an antenna can be fed by a main feed, which may be configured as splitting to (i) a bicone feed leading to the center of the accord ioned bicone, and (ii) a dipole feed feeding the fractalized dipole section. RLC matching circuitry may be used in exemplary embodiments. [0049] While the shaping techniques implemented in or for a bicone antenna (or other shape or configuration of antenna such as disclosed in the patents and applications incorporated herein) can utilize a folded-shape in the conical portions and a fractal shape in/or the conformal portion, other geometric shapes, including one or more holes, can be incorporated into the antenna designs. By incorporating the folded-shaping into the conical portions, the bicone antenna can provides the frequency and beam-pattern performance of a larger sized bicone antenna that does not include such shaping. [0050] Each folded, e.g., of a bicone portion, can include two faces joined at a vertex having an included angle of less than 180 degrees as directed away from a principal axis of the cone-shaped element and/or antenna. In exemplary embodiments, the two faces of a folded do not substantially overlap one another in a direction transverse to a bisector of the included angle. For certain embodiments, the faces and included angle for a folded can be symmetrical; in other embodiments, the faces and includes angle are not symmetrical (e.g., can lie along the two sides of a non-Isosceles triangle.) [0051] The self-similar shape of the circuit board can be defined as a fractal geometry. In general, fractal geometry may be grouped into random fractals (which can also be referred to as chaotic or Brownian fractals, and include a random noise component) or deterministic fractals. Fractals typically have a statistical self- similarity at all resolutions and are generated by an infinitely recursive process. For example, a so-called Koch fractal may be produced with N iterations (e.g., N=1, N=2, etc.). One or more other types of fractal geometries may also be incorporated into the design to produce antenna. Non-fractal portion(s) (such as sawtooth patterns) -12- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 can be utilized in conjunction with fractal portion(s). Such patterns can be utilized, e.g., as a counterpoise. [0001] Antenna components can also be made or formed to include metamaterials. Representative frequencies of operation can include, but are not limited to, those over a range of 500 MHz to 1.3 GHz, though others may of course be realized. Operation at other frequencies, including for example those of visible light, infrared, ultraviolet, and as well as microwave EM radiation, e.g., K, Ka, X- bands, etc. may be realized, e.g., by appropriate scaling of dimensions and selection of shape of the resonator elements. [0002] The resonators can be in groups of uniform size and/or configuration (shape) or of several different sizes and/or geometries. The relative spacing and arrangement of groupings (at least one for each specific frequency range) can be defined by self-similarity and origin symmetry, where the "origin" arises at the center of a structure (or part of the structure) individually designed to have the wideband metamaterial property. [0052] By incorporating the fractal geometry into the electrically conductive and non-conductive portions of circuit board, the length and width (e.g., and consequently, electrical size) of the conductive and non-conductive portions of the antenna is increased due to the nature of the fractal pattern. While the lengths and widths increase, however, the overall footprint area of circuit board (fractalized dipole) is relatively small. By providing longer conductive paths, dipole (and, consequently, the related antenna) can perform over a broad frequency band. [0053] In exemplary embodiments, matching circuitry/components can be utilized, e.g., capacitors, RLC circuit(s), etc. Additional tuning can optionally be augmented/facilitated by placement of tuning elements, e.g., capacitors, inductors, and/or RLC circuitry, across the circuit board trace(s), forming a partial electrical trap. [0054] While certain embodiments have been described herein, it will be understood by one skilled in the art that the methods, systems, and apparatus of the present disclosure may be embodied in other specific forms without departing from -13- CA 02968375 2017-05-18 WO 2016/081775 PCT/US2015/061690 the spirit thereof. Accordingly, the embodiments described herein are to be considered in all respects as illustrative of the present disclosure and not restrictive. -14-
