Patent Publication Number: US-2022231396-A1

Title: Building antenna

Description:
INCORPORATION BY REFERENCE 
     A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in its entirety and for all purposes. 
     BACKGROUND 
     Certain disclosed embodiments provide antenna systems and/or window structures that allow high bandwidth wireless communication across windows in a building. These window antenna systems may provide through-glass wireless communication. Thus, individuals and/or systems outside a building can have wireless access via antenna systems inside a nearby building. In some cases, the antenna and window systems work in concert with, or as a partial replacement of, the infrastructure of cellular carriers. Examples of components sometimes included with the antenna systems include physical antennas, transceivers or radios, and casings configured to mount with mullions or other building structures that abut windows. In some cases, when mounted, the casings hold the antennas near or against windows. In some cases, the antenna systems work in concert with electrically switchable windows and/or windows with low emissivity coatings. In some cases, such windows are modified to facilitate transmission of electromagnetic energy from or to an antenna, and through the window. 
     The disclosed antenna systems may provide additional coverage (beyond that provided by the cellular carrier itself) in the interior of the building and/or provide or supplement the cellular carrier&#39;s ability to provide coverage and capacity outside the building, typically near to the building, e.g., within about one hundred meters of the building, sometimes within a line of sight. In some cases, a building outfitted with antenna systems as described herein can serve as a cellular tower. In some cases, a building outfitted with antenna systems as described herein can serve as a wireless relay or link to another building, such as a building that does not have a backhaul or other wired link to a cellular system. 
     High speed, high frequency communications protocols such as 5G face numerous challenges before they can be widely accepted and deployed. For example, compared to lower frequency communications bands, high frequency bands require more antennas and higher density of antennas. For example, it is estimated that to deploy a 5G cellular service in a given area will require over twice as many antennas as are required to provide the same level of cellular service for 4G. Some cellular antennas as described herein may be provided in a building or a portion of a building. One of the challenges is that higher frequency communications, e.g. 5G spectrum, although able to carry much more data and at higher rates, are often line of site because they are blocked or otherwise attenuated by physical obstructions. 
     For example, providing 5G coverage in an urban canyon, such as a street in major metropolitan area such as Manhattan, NY or Singapore may be contemplated; 5G service will require many antennas to provide adequate coverage and adequate capacity. There is insufficient public space such as telephone poles where a carrier could deploy antennas to provide adequate 5G coverage and capacity. Moreover, garnering access to so many disparate publicly deployed structures may be extremely expensive and/or difficult to achieve. Further, so many antennas deployed on so many exterior structures can be unsightly. 
     Using private buildings that line an urban canyon to provide locations for 5G antennas solves many of these challenges. But remaining issues include finding a location for the 5G antennas in and on such buildings. One option would be on the exterior of buildings, but this may present logistical barriers and aesthetic issues. Even within buildings placement and aesthetics are an issue, not to mention all the technical barriers to develop such technology. 
     Unfortunately, 5G and other high frequency protocols are susceptible to attenuation. A 5G communications protocol, particularly due to it use of high frequency bands such as in the range of about 6 to 30 GHz, may be particularly susceptible to attenuation. The attenuation may result from structures such as reinforced concrete in walls, aluminum coated thermal insulation in building walls and floors, low-E films on glass, and other passive or active layers on glass such as thermochromic, photochromic and electrochromic coatings on glass. Such coatings commonly include metals and metal oxides which may exhibit a high attenuation in wireless communication bands. With 4G, this is already a problem, and with the advent of 5G higher frequency bands, the problem is even worse. To address the attenuation issue, active elements such as repeaters may be provided in a building. For example, cellular repeaters may be disposed on or proximate to the walls, windows, floors, and/or ceilings that attenuate wireless signals. However, such repeaters are often relatively large and/or aesthetically unpleasing. They may also require undue modifications to building structural elements, making them difficult to deploy on a large scale. 
     SUMMARY 
     To address such issues, an antenna system may be employed to transceive (i.e., to transmit and/or receive) electromagnetic communications signals across a window with relatively little attenuation, even when implementing high frequency protocols such as 5G cellular. In some cases, this is accomplished, in part, by disposing antennas on or close to windows through which the electromagnetic signal will pass. In some cases, communication is further facilitated by selectively removing attenuating layers or materials on a window such as portions of a low emissivity coating and/or an optically switchable device such as an electrochromic device. The coating removal may be done via laser ablation, and e.g., after the window is installed. The resulting window may have attenuating coating removed only in a certain location of the window, such as at the edge of a window. In some cases, the material is removed to create a pattern of removed and unremoved material that allows passive modification of the electromagnetic energy passing through the window. For example, such pattern may be structured to focus, spread, direct, polarize, etc. the electromagnetic energy. As should be clear, the material selectively removed from the window is often an electrical conductor such as silver or indium tin oxide. Thus, the resulting pattern provides regions of uncoated insulator (glass, polymer, or other dielectric) through which electromagnetic signals can more easily pass. 
     Note that when describing the cellular protocols disclosed herein, 5G is frequently used as an example. However, the disclosed embodiments may pertain to any wireless communications protocol or combination of protocols. 
     In various aspects, the antenna systems and associated structures described herein are used with eletrochromic windows such as described in U.S. Provisional Patent Application No. 62/850,993, filed May 21, 2019, which is incorporated herein by reference in its entirety. In various aspects, the antenna systems and associated structures described herein are used with integrated glass units (IGUs), communications networks, power distribution systems, ancillary building services (e.g., heating ventilation and air condition (HVAC_, lighting, and/or security systems), wireless communications systems, and/or occupant comfort systems such as also described in U.S. Provisional Patent Application No. 62/850,993. 
     According to some embodiments, a system for transceiving radio frequency (RF) signals includes (a) a window having a first surface facing, when installed in the building, an interior of the building and (b) an antenna arrangement configured to attach to a structure proximate to the first surface; wherein the antenna arrangement comprises one or more radiating elements configured to transceive the RF signals through the window. 
     In some examples, the window may include a coating disposed on the first surface and/or on a surface parallel to the first surface. In some examples, the coating may be an electrochromic device. In some examples, the coating may be a low emissivity coating or antireflective coating. In some examples, the coating may exclude a region proximate to the radiating elements. In some examples, the region may be less than about 2% of the area of the first surface. In some examples, the region may be formed by removing a portion of the coating from the region. In some examples, the removing may be configured to create a pattern of removed and unremoved material that allows passive modification of electromagnetic energy passing through the window. In some examples, the pattern may be structured to focus, spread, direct, and/or polarize the electromagnetic energy. In some examples, the removing may be configured for facilitating reception of a cellular signal. In some examples, facilitating reception of a cellular signal may include tuning reception properties of a radio receiver, and/or defining the shape, size, and/or location of the region. In some examples, the removing may reduce attenuation by selectively removing material proximate to the radiating elements. In some examples, the coating may be removed from an S 1 , S 2 , S 3  and/or S 4  surface of a double pane integrated glass unit. In some examples, the coating may include electrically conductive, semi-conductive, dielectric and/or insulating materials. In some examples, the material removed may include transparent metal oxides and/or a conductive polymer or gel. In some examples, the removing may include one or more of optical techniques, mechanical techniques, thermal techniques, chemical techniques or exposing the region to a plasma. In some examples, the optical techniques may include laser ablation. In some examples, the chemical techniques may include etching, dissolving, reacting, oxidizing or reducing. In some examples, the removing may be executed after the window is installed using a portable device. In some examples, the portable device may employ focused laser ablation to selectively remove the material. In some examples, the removing may be performed after the window is installed in the building. 
     In some examples, the antenna arrangement may be attached after the window is installed in the building. In some examples, a retrofit of the building with the antenna arrangement may enable cellular coverage outside and/or inside the building. In some examples, the cellular coverage may include a 5G cellular coverage. 
     In some examples, the building structure may be a window frame structure. 
     In some examples, the building structure may be a mullion. In some examples, a mullion cap may be disposed with the mullion, the mullion cap including a mullion cap body and at least one antenna wing. In some examples, the mullion cap may be configured to be fixedly attached to the vertical mullion. In some examples, the mullion cap may be configured to include one or more gripping portions for fixedly attaching the mullion cap to the vertical mullion. In some examples, the one or more gripping portions may include a snap fit mechanism. In some examples, the mullion cap body may be substantially elongate, extending, along an axis parallel to a longitudinal axis of the mullion. In some examples, the mullion cap body may be substantially L-shaped in cross-section in a plane perpendicular to the longitudinal axis of the mullion. In some examples, the mullion cap may support two or more antenna wings. In some examples, a longitudinal length of the at least one antenna wing may be greater than a transverse width of the at least one antenna wing. In some examples, the ratio between the longitudinal length and transverse width of the at least one antenna wing may be greater than 2. In some examples, the ratio between the longitudinal length and transverse width of the at least one antenna wing may be greater than 5. In some examples, a longitudinal length of the at least one antenna wing may be less than a transverse width of the at least one antenna wing. In some examples, a ratio between the longitudinal length and transverse width of the at least one antenna wing may be less than 0.5. In some examples, the ratio between the longitudinal length and transverse width of the at least one antenna wing may be less than 0.2. In some examples, the at least one antenna wing may include a glass substrate with one or more radiating elements formed thereon. In some examples, the at least one antenna wing may be substantially transparent. In some examples, the at least one antenna wing may be formed using a glass configured from a low alkali thin glass or a fusion drawn glass. In some examples, the glass may be configured as a first glass substrate for the at least one antenna wing. In some examples, the antenna wing may include a second glass substrate. In some examples, the first glass substrate and the second glass substrate may be laminated together. In some examples, the radiating elements may be disposed between the first glass substrate and the second glass substrate. In some examples, the radiating elements may be etched on one of first glass substrate and the second glass substrate and/or buried in a lamination adhesive used to mate the first glass substrate and the second glass substrate. In some examples, the radiating elements may be laser etched from one or more transparent coatings on the glass. In some examples, the transparent coatings may include conductive metal oxide coatings. In some examples, the at least one antenna wing may be configured to avoid contrasting with the window glass. In some examples, the at least one antenna wing may be opaque. In some examples, the at least one antenna wing may be configured to include a generally opaque obscuration material, paint, ink or other material substantially transparent to radio frequency (RF) signals. In some examples, the obscuration material may be applied only where the antenna wings footprint resides. In some examples, the obscuration material may be applied along an entire side of the glass substrate or around all four sides of the glass substrate so as to mask the visual impact of the mullion cap and or the at least one antenna wing. In some examples, the mullion cap may include vents extending from a proximal portion of the mullion cap body to a distal portion of the mullion cap body. In some examples, at least some vents may not extend through the entire length of the mullion cap body. In some examples, at the proximal portion of the mullion cap body, the vents may be configured to provide for air intake to cool the mullion cap and/or communications electronics housed therein and include an exit at the distal portion of the mullion cap body to facilitate air exhaust. In some examples, at least some vents may be configured to include force air cooling provisions. 
     In some examples, the antenna arrangement may further comprise a radio in electrical communication with the radiating elements. In some examples, the antenna arrangement may be configured transceive radiofrequency signals in two polarization states. In some examples, a single conductive radiating element may provide the two orthogonal polarization states and the antenna arrangement includes two ports and two transceivers to provide signals with two different polarization states. In some examples, the antenna arrangement may have a substantially flat surface registered with the region of the window where the coating was removed. In some examples, the substantially flat surface may be substantially parallel to the first surface. 
     In some examples, the antenna arrangement may have a multiple-input multiple-output (MIMO) configuration. 
     According to some implementations, a method of transceiving radio frequency (RF) signals includes (a) disposing a window in a building, the window having a first surface facing an interior of the building; and (b) attaching an antenna arrangement to a building structure adjacent the first surface; wherein the antenna arrangement comprises one or more radiating elements configured to transceive the RF signals through the window. 
     In some examples, the window may include a coating disposed on the first surface and/or on a surface parallel to the first surface. In some examples, the coating may be an electrochromic device. In some examples, the coating may be a low emissivity coating. In some examples, the coating may exclude a region proximate to the radiating elements. 
     In some examples, the antenna may be configured to provide cellular coverage outside the building. In some examples, the cellular coverage may include a 5G cellular coverage. 
     In some examples, the structure may be a window frame structure. 
     In some examples, the structure may be a mullion. 
     In some examples, the antenna may further comprise a radio connected to the radiating elements. 
     In some examples, the antenna may have a multiple-input multiple-output (MIMO) configuration. 
     According to some implementations, a system includes a plurality of window antennas, each configured to transceive wireless radio frequency (RF) signals through a respective window to or from particular locations, using spatial filtering and/or other beamforming techniques. Each respective window has a first surface facing, when installed in the building, an interior of the building, each window antenna is configured to attach to a structure adjacent the first surface and the window antenna comprises one or more radiating elements configured to transceive RF signals through the window. 
     In some examples, the beamforming techniques may employ active interference, null forming, and/or other techniques. 
     In some examples, the beamforming techniques may form complex signal peaks and null regions tailored to locations of user equipment. In some examples, the signal peaks may be formed at locations of devices that need to communicate over a channel having the signal peak and/or null regions are formed at locations where other devices are located that are not communicating over the channel In some examples, signal adjustments required to provide peaks and null regions may be made in the digital and/or the analog domain. In some examples, adjustments in the analog domain may be made to the phase, amplitude, and/or other characteristic(s) of the RF signals transmitted from individual antennas. 
     According to some embodiments, a window antenna system includes (a) a window; (b) an electrically conductive antenna radiating element disposed proximate to the window; (c) a transceiver; and (d) compensation circuitry electrically coupled with the transceiver that adjusts for interactions between the window and the conductive antenna radiating element. 
     In some examples, the radiating element may include a patch antenna element. 
     In some examples, the compensation circuitry may facilitate transmission through the window. 
     In some examples, the compensation circuitry may be incorporated into the transceiver. 
     In some examples, the compensation circuitry may be separate from the transceiver. 
     In some examples, the compensation circuitry may be flexibly or tunably configurable for deployment on windows having a variety of physical parameters. In some examples, the physical parameters may include a separation distance between the antenna radiating element and at least one reflective surface of the window. In some examples, the physical parameters may include physical properties of the glass coating that influence a magnitude of a reflected signal. 
     In some examples, the compensation circuitry may be configured to tune the compensating signal it applies to the conductive antenna element to account for differences in time-of-flight of reflected signals for different distances between the conductive antenna element and the at least one reflective surface. 
     In some examples, the window may include an indicator of the physical parameters, the indicator configured to be read by the compensating circuitry or associated processing module. In some examples, the indicator may include one or more of a barcode, a QR code, or an RFID. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a portion of a building&#39;s window structure including a first lite and a second lite joined along adjacent edges by a mullion including a mullion cap, according to an embodiment. 
         FIGS. 2-4  illustrate example features of the mullion cap, according to various embodiments. 
         FIG. 5  shows the mullion cap, the mullion and a portion of the first and second lites schematically in cross-section. 
         FIGS. 6 and 7  show a mullion cap according to another embodiment. 
         FIGS. 8 and 9  show a mullion cap according to a yet further embodiment. 
         FIGS. 10 and 11  show a mullion cap according to a yet further embodiment. 
         FIG. 12  shows a mullion cap according to another embodiment. 
         FIGS. 13A and 13B  show cross-sectional shapes of a mullion cap according to further embodiments. 
         FIG. 14  shows an embodiment in which a mullion cap, mounted to a mullion, includes a mullion cap body including integrated antennas. 
         FIG. 15  shows examples of shapes of an uncoated region. 
         FIG. 16  shows a window antenna system in which a patch antenna element  1605  located proximate to and substantially parallel with a dual pane window. 
         FIG. 17  shows a window antenna system disposed on a mullion and including a dual pane window and a patch antenna element disposed on an antenna housing. 
         FIG. 18  is a simplified view of a portion of a framing structure providing several mullions to support windows on a façade or other building exterior structure. 
     
    
    
     DETAILED DESCRIPTION 
     In some embodiments, an antenna system may be configured to hold an antenna against a window or in close proximity to a window, e.g., within one centimeter. The antenna may be on a glass substrate which is substantially flat, or curved. Close proximity of the antenna and window may be combined with a modification the window, that reduces attenuation of electromagnetic energy passing through the window, facilitates an antenna&#39;s ability to provide wireless communications coverage outside the window, such as in a region outside a building housing the window. As explained, the antenna system may have various configurations and may be installed in the building in various locations. It may also be attached to building structures in various ways. Some of these are described below. In certain embodiments, the antenna system is provided as a mullion cap. 
       FIG. 1  shows a portion  100  of a building&#39;s window structure including a first window lite  101  and a second window lite  102 . Lites  101  and  102  are adjacent each other, e.g. installed in a framing system, held in place along adjacent edges by a vertical mullion  103 . The vertical mullion  103  provides structural support for the first and second lites  101  and  102 . In a typical framing system, there are series of such vertical and horizontal mullions; antenna systems described herein may be installed on vertical or horizontal mullions. In  FIG. 1 , only a portion of a vertical mullion is depicted, for simplicity. In some embodiments, the vertical mullion  103  forms part of a frame which surrounds the first and second lites  101  and  102 . For example, such a frame may be made up of multiple such vertical mullions and multiple horizontal mullions. In some embodiments, the vertical mullion  103  also functions as a conduit or channel in which power supply and/or data communications wiring or cabling may be provided, e.g. for the antenna systems described herein and/or electrochromic windows and/or transparent displays as and/or for a building network as described in U.S. Pat. Pub. 2020-0150508, entitled “BUILDING NETWORK”, filed Oct. 25, 2019, assigned to the assignee of the present invention and hereby incorporated by reference in its entirety into the present application. 
     In the embodiment shown in  FIG. 1 , the first lite  101  and the second lite  102  may be perceived as single panes of glass. However, one or both of the first and second lites may be the inboard lite of insulated glass units (IGUs). Referring to View A-A of  FIG. 1 , an IGU may include a first pane having a first (outboard) surface S 1  and a second (inboard) surface S 2 . In some implementations, the first surface S 1  faces an exterior environment, such as an outdoors or outside environment. The IGU also includes a second pane having an outboard surface S 3  and an inboard surface S 4 . In some implementations, the second surface S 4  of the second pane faces an interior environment, such as an inside environment of a home, building or vehicle, or a room or compartment within a home, building or vehicle. 
     They may be part of a laminate that is a stand-alone lite or a lite (e.g. the inboard lite) of an IGU. In some embodiments, the first lite  101  and the second lite  102  (or one or more panes of the corresponding IGUs) have one or more attenuating coatings thereon, such as functional coatings. For example, in some embodiments, the glass is coated with a low-emissivity material, such that the glass can be referred to as low-emissivity (i.e. low-e) glass. In some embodiments, the glass is coated with a functional device coating, such as an electrochromic device coating, in addition to, or as an alternative to, the low-emissivity material. In IGUs, such coatings may be on one or more surfaces of the IGU glass lites. 
     As shown in  FIG. 1 , a mullion cap  104  is mounted on the vertical mullion  103 , in the interior of the building. The surface of glass lites  101  and  102 , facing the interior of the building, would be surface  4  of a double pane IGU, using window industry recognized nomenclature described hereinabove. Example features of exemplary mullion caps  104  are shown in more detail in  FIGS. 2, 3, 4 and 5  in which it may be observed that mullion cap  104  includes a mullion cap body  105  and antenna wings  106  and  107 . The mullion cap body  105  may be substantially elongate, extending, along an axis parallel to the longitudinal axis of the vertical mullion  103 . The mullion cap may have only one antenna wing, e.g. when only one is needed, and/or a mullion on the edge of a window that abuts a wall may only be able to accommodate an antenna wing on one side of the mullion. 
       FIG. 5  shows the mullion cap  104 , the vertical mullion  103  and a portion of the first and second lites  101  and  102  schematically in cross-section in a horizontal plane (i.e. a plane perpendicular to the longitudinal axis of the vertical mullion  103 ) through a region of the mullion cap  104  including the antenna wings  106  and  107 . In  FIG. 5 , it can be seen that the mullion cap body  105  is substantially U-shaped in cross-section. That is to say, the mullion cap body  105  has three principal mullion cap body portions  108 A,  108 B and  108 C, each arranged to lie flush against corresponding portions of three faces of the vertical mullion  103 . 
     In the embodiment shown in  FIGS. 1, 2, 3, 4 and 5 , the antenna wings  106  and  107  extend away from the mullion cap body  105  on opposing sides. The antenna wings  106  and  107  in these examples are substantially planar and rectangular in shape (when viewed perpendicular to the vertical plane of the lites  101  and  102 ). In the illustrated example, antenna wings  106  and  107  are arranged to lie against adjoining surfaces of the respective lites  101  and  102 . As can be seen in  FIG. 4 , a plurality of antenna elements  109 A and  109 B may be disposed on lite-facing surfaces of, respectively the antenna wings  106  and  107 . The antenna wings  106  and  107  may therefore function as respective supports for the antenna elements  109 A and  109 B. The antenna elements  109 A and  109 B of the antenna wings  106  and  107 , together with communications components (such as transceivers or radios) housed in the mullion cap body  105  (which functions as a protective casing for the communications components), may constitute the antenna system. In alternative embodiments, the antenna wings have a glass substrate with one or more antennas formed thereon; the antenna wing may be substantially transparent. In one embodiment the antennas are laser etched from one or more transparent coatings on the glass, e.g. transparent conductive metal oxide coatings. In such embodiments, it is desirable to have the antenna wings have as little contrast as possible to the window glass, so as not to be noticeable to building occupants or those outside the building looking in the window. 
     As can be seen in  FIGS. 2 and 3 , the mullion cap body  105  may include a plurality of vents  111  extending in a direction parallel to the longitudinal axis of the mullion  103 . The illustrated plurality of vents may extend from a proximal portion of the mullion cap body  105  (foreground of  FIGS. 2 and 3 ) to a distal portion (background of  FIG. 2 or 3 , respectively). Alternatively or in addition, at least some vents  111  may not extend through the entire length of the mullion cap body  105 . In the embodiment depicted in  FIGS. 2 and 3 , the vents  111  at the proximal portion of the mullion cap body  105  may be configured to provide for air intake to cool the mullion cap (for example, to cool communications components, such as transceivers or radios housed therein) and include an exit at the distal portion of the mullion cap body  105  (vents not shown) to facilitate air exhaust. In some embodiments, the mullion cap is cooled by passive convective air flow, with air entering a vent  111  at a lower portion of the mullion cap body  105  and rising naturally as the air absorbs heat from the communications and escaping through the vent at an upper portion of the mullion cap body  105 , thereby causing cooler air to be drawn into the mullion cap through the lowermost vents. Nevertheless, the positioning of vents may be different in other embodiments. For example, in some embodiments, air intake and air exhaust may take place at the same end of the mullion cap body. In some embodiments, the mullion cap may not be exclusively passive, i.e. an active device such as a fan may be configured to drive movement of air through the mullion cap body  105 . 
     As can be seen in  FIGS. 1 to 5 , mullion cap  104  is attached to the vertical mullion  103 . Different methods of attachment are possible. In some embodiments, the mullion cap  104  grips the vertical mullion  103 . For example, in some embodiments, the mullion cap  104  is mounted to the vertical mullion  103  by an interference fit. Accordingly, in some embodiments, the mullion cap  104  is configured (i.e. dimensioned) for an interference fit with a particular design of vertical mullion  103 . In some embodiments, the mullion cap  104  includes one or more gripping portions for gripping the vertical mullion  103 . In some embodiments, the one or more gripping portions are adjustable to enable gripping of the vertical mullion  103 . In some embodiments, the one or more gripping portions include a biasing mechanism (such as a spring mechanism) to enable gripping of the vertical mullion  103 . In some embodiments, the one or more gripping portions include flexible, deformable and/or resilient elements which enable gripping of the vertical mullion  103 . A gripping portion may include a snap fit mechanism, e.g. the U-shape of a mullion cap body may fit snugly over a mullion, and may include specific protrusions that fit into grooves of the mullion, or vice versa 
     In some embodiments, the mullion cap  104  is fixedly attached to the vertical mullion  103 . For example, the mullion cap  104  may be bolted or screwed or riveted to the vertical mullion  103 . In some embodiments, the mullion cap is adhesively attached to the mullion. Such attachments can be made without puncturing the hermetic seal that a curtain wall makes for a building, i.e. only small holes in the interior-disposed mullion are made to accommodate the bolt, screw or rivet. In other embodiments, the mullion cap  104  is welded to the vertical mullion  103 . In some embodiments, the mullion is made of PVC or other polymeric material, for example that is extruded. Ultrasonic welding may be used to attach the mullion cap to such a PVC or polymeric material mullion. 
     The attachment means for the mullion cap may include positioning elements, e.g. to align or otherwise configure the antenna wings appropriately for their intended transmission and reception characteristics. Positioning elements can be, e.g., sliding, rotating or other adjustable stages or elements that can be positioned and then locked into place, e.g. by a set screw or other clamping mechanism. This may allow precise positioning of the antenna wings and also repositioning and/or replacement of the antenna wings e.g. if the transmission/reception characteristics change. That is, the antenna wings may be moveable and removable and the antenna portions of the wings may be moveable and removable. In certain embodiments the antenna wings may be configured so as not to be substantially parallel to the window lite. 
     In some embodiments, the mullion cap is integrated (i.e., integrally formed) with the mullion, for example the mullion cap and the mullion are configured as a unitary component. In some embodiments, the mullion cap and the mullion are distinct components, but the mullion cap and the mullion are installed in the building together, for example where the mullion cap is attached to the mullion before the mullion is installed in the building. Alternatively, the mullion cap may be attached to the mullion during construction of the building, after installation of the mullion itself. 
     In the embodiment shown in  FIGS. 1 to 5 , the antenna wings  106  and  107  are substantially elongate in the vertical direction (i.e. parallel to the longitudinal axis of the vertical mullion  103 ). That is to say, a vertical length of each of the antenna wings  106  and  107  is greater than the corresponding horizontal width. In some embodiments, the ratio between the vertical length and horizontal width of each antenna wing is greater than 1, for example, greater than 2, or greater than 3, or greater than 4, or greater than 5. 
     In the embodiment shown in  FIGS. 1 to 4 , the antenna wings  106  and  107  do not extend along the entirety of the longitudinal length of the mullion cap body  105 , although the said antenna wings do extend along a substantial proportion of the longitudinal length of the mullion cap body  105 . Instead, in the embodiment shown in  FIGS. 1 to 4 , the antenna wings extend along approximately two thirds of the longitudinal length of the mullion cap body  105 . Additionally, in the illustrated examples, the antenna wings are arranged such that they extend longitudinally to an end of the mullion cap body  105 . Accordingly, there is a region of the mullion cap body  105  to which the antenna wings  106  and  107  do not extend. 
     In other embodiments, however, the antenna wings take different shapes and/or arrangements. For example,  FIGS. 6 and 7  illustrate a mullion cap  204  including a mullion cap body  205 , which has substantially the same shape as mullion cap body  105 , and antenna wings  206  and  207 , which are substantially elongate in a direction transverse to the longitudinal axis of the vertical mullion  203 .  FIG. 6  depicts mullion cap  204  from a perspective interior to a building and  FIG. 7  depicts mullion cap  203  from the perspective outside of a building. In the illustrated example, a longitudinal length of each of the antenna wings  206  and  207  is less than the corresponding transverse length. In some embodiments, the ratio between the longitudinal and transverse lengths of each antenna wing is less than 1, for example, less than 0.5, or less than 0.3, or less than 0.25, or less than 0.2. 
     In the embodiment showing in  FIGS. 6 and 7 , the antenna wings  206  and  207  do not extend along the entirety of the longitudinal length of the mullion cap body  205 . Rather, the antenna wings  206  and  207  extend vertically along approximately one quarter of the longitudinal length of the mullion cap body  205 . The antenna wings  206  and  207  are arranged such that they extend longitudinally to an end of the mullion cap body  205 . Accordingly, there is a region of the mullion cap body  205  which is not framed by antenna wings. 
       FIGS. 8 and 9  illustrate a further exemplary mullion cap  304  which includes a mullion cap body  305 , which has substantially the same shape as mullion cap body  105 , and antenna wings  306  and  307 , which are substantially elongate in the longitudinal direction of mullion  303 . In the illustrated example, the longitudinal length of each of the antenna wings  306  and  307  is greater than the corresponding horizontal width. For example, in the embodiment shown in  FIGS. 8 and 9 , the ratio between the vertical length and horizontal width of each antenna wing is approximately ten. Moreover, the antenna wings  306  and  307  of  FIGS. 8 and 9  extend along substantially the entirety of the longitudinal length of the mullion cap body  305 , save for a small region of the mullion cap body  305  near the lower end which is not framed by antenna wings. The antenna wings  306  and  307  are arranged such that they extend longitudinally to the upper end of the mullion cap body  305 . 
     In the embodiments of  FIGS. 1 to 9 , the antenna wings  106 ,  107 ,  206 ,  207 ,  306  and  307  may be opaque because, for example, they include at least opaque materials such as opaque metals and/or polymers. An obscuration material, paint, ink or other material substantially transparent to radio frequency (RF) signals, but generally opaque to visible light may be used to obscure the antenna wings. The obscuration material may be applied only where the antenna wings footprint resides or along an entire side of the glass or, for example, around all four sides of the glass so as to mask the visual impact of the mullion cap and particularly the antenna wings. 
     In some embodiments, however, at least portions of antenna wings may be translucent or transparent, for example, because they include translucent or transparent materials, such as glass or transparent polymers. 
     For example,  FIGS. 10 and 11  illustrate a mullion cap  404  including a mullion cap body  405 , which has substantially the same shape as mullion cap body  305 , and antenna wings  406  and  407 , which have substantially the same shape as antenna wings  306  and  307 . Antenna wings  406  and  407 , however, differ from antenna wings  306  and  307  in that antenna wings  406  and  407  are include transparent materials, such as glass, so that the antenna wings  406  and  407  are substantially transparent. As a result, the antenna wings may be substantially less noticeable than opaque antenna wings. Transparent antenna wings may be functionally invisible when the mullion cap is mounted to a mullion, such that a casual observer would not ordinarily notice the presence of the transparent antenna wings unless the observer&#39;s focus is drawn directly to the antenna wings. 
     Transparent antenna wings may be formed using e.g. low alkali thin glass, such Eagle XG™ or similar fusion drawn glass, commercially available from Corning, Inc. of Corning, N.Y., U.S.A. Such glass may be used as a substrate for the antenna wing, with one or more substantially transparent antennas formed thereon. The antenna wing may include an additional glass substrate, where the two substrates are laminated to each other. In such embodiments, the antennas in the wing may be between the two glass substrates, e.g. etched on one of the substrates and/or buried in a lamination adhesive used to mate the two substrates. 
       FIG. 12  illustrates a further alternative mullion cap  504  including a mullion cap body  505 , which has substantially the same shape as mullion cap body  405 , and antenna wings  506  and  507 , which have substantially the same shape as antenna wings  406  and  407 . Antenna wings  506  and  507  are substantially transparent because they are made of transparent materials, such as glass. Antenna wings  506  and  507  are again substantially less noticeable than opaque antenna wings. The antenna wings  506  and  507 , however, may be moderately more visible than antenna wings  406  and  407  due to a discernable antenna pattern etched onto the antenna wings  506  and  507 . 
     In some embodiments, mullion caps take different shapes from those illustrated in  FIGS. 1 to 12 . For example,  FIG. 13A  illustrates the cross-sectional shape of a mullion cap  604  mounted on a vertical mullion  603 . The mullion cap  604  includes a mullion cap body  605  and a single antenna wing  606 . The mullion cap body  605  is substantially L-shaped in cross-section in a horizontal plane (i.e. perpendicular to the longitudinal axis of the mullion  603 ). More specifically, in the illustrated example, the mullion cap body  605  has two principal mullion cap body portions  607 A and  607 B, configured adjacent to corresponding portions of two faces of the vertical mullion  603 , such that the mullion cap body  605  fits around an edge of the vertical mullion  603  (corresponding to a vertex of the vertical mullion  603  in cross-section in  FIG. 13 ). The antenna wing  606  extends away from the mullion cap body  605  on one side, flush against the surface of the respective lite  601 . As can be seen in  FIG. 13A , a plurality of antenna elements  608  are provided on the lite-facing surface of the antenna wing  606 . A second mullion cap  704 , which may be an approximate mirror-image of mullion cap  604 , may be mounted on the opposing side of the vertical mullion  603 . L-shaped mullion caps may be used alone, e.g. at a mullion at the edge of a wall, where there is no adjoining window on the other side or the other side of the mullion is not exposed. 
     As a further example,  FIG. 13B  illustrates a cross-sectional shape of a rectangular mullion cap  604  mounted on a vertical mullion  603 . The mullion cap  604  includes a mullion cap body  605  and a single antenna wing  606 . The mullion cap body  605  is substantially rectangular in cross-section in a horizontal plane (i.e. perpendicular to the longitudinal axis of the mullion  603 ). More specifically, in the illustrated example, the mullion cap body  605  has a first surface adjacent to a corresponding portion of a face of the vertical mullion  603  that is orthogonal to the lite  601 , and a second surface adjacent to the light  601 . The antenna wing  606  extends away from the mullion cap body  605  on one side, flush against the surface of the respective lite  601 . A plurality of antenna elements  608  may be provided on the lite-facing surface of the antenna wing  606 . A second mullion cap  704 , which may be an approximate mirror-image of mullion cap  604 , may be mounted on the opposing side of the vertical mullion  603 . 
     In some embodiments, mullion caps do not include antenna wings. In some embodiments, antennas are instead attached to or integrated into the mullion cap body. For example,  FIG. 14  shows an embodiment in which a mullion cap  804 , mounted to a mullion  803 , includes a mullion cap body  805  including integrated antennas  806 A and  806 B. The antennas  806 A and  806 B are located on faces of the mullion cap body  805  which are adjacent, or contact, the lites  801  and  802  of the window when the mullion cap  804  is mounted on the mullion  803 . The antennas are therefore hidden from view. view from the perspective of a building occupant. Antennas  806  may be visible to those outside the building, or, an obscuration material, transparent to RF frequencies but translucent or opaque, may obscure antennas  806 . In other embodiments, antennas  806  are colored to match the mullion cap so that no distinct antenna structures are discernable against the portion of the mullion cap visible to those outside the building. 
     It is contemplated that antennas may be attached to or integrated with any portions or faces of the mullion cap (e.g., of the mullion cap body), and in particular portions or faces which are adjacent to, face or contact lites when the mullion cap is mounted on a mullion. In some embodiments, mullion caps include both antennas attached to or integrated with antenna wings and antennas attached to or integrated with the mullion cap body. Yet further different mullion cap shapes are possible. For example, the cross-sectional shape and dimensions of the mullion cap body can be configured or selected for mounting to a particular shape and/or size of mullion. For example, in some embodiments, one or more surfaces of the mullion cap are curved to accommodate curvature of a mullion. In some embodiments, the cross-sectional shape of the mullion body varies along a longitudinal length of the mullion body to accommodate variation in cross-sectional mullion shape. 
     Although the antenna wings shown in  FIGS. 1 to 13  are substantially rectangular in shape (when viewed perpendicular to the vertical plane of the window lites), it will be appreciated that other antenna wing shapes are possible. For example, antenna wings may have straight or curved sides and may be regular or irregular in shape. Antenna wings may be triangular, quadrilateral, pentagonal, or hexagonal in shape, or have any other number of sides. Quadrilateral antenna wings may be rectangular (e.g. oblong or square), trapezial, trapezoidal or rhomboid in shape. 
     In certain embodiments, the antenna wings are oriented parallel to the mullion cap&#39;s long axis (i.e., the longitudinal axis). In certain embodiments, the antenna wings are oriented orthogonal to the mullion cap&#39;s long axis (i.e., the longitudinal axis). In yet further embodiments, the antenna wings are inclined with respect to the mullion cap&#39;s long axis (i.e., the longitudinal axis). 
     In some embodiments, the antenna wings do not have a longer (i.e., major) axis, e.g. they are square. Generally speaking it is desirable to minimize the footprint of the antenna wings, since they are configured (e.g., arranged) in the viewable area of the window. In certain embodiments the antenna wings have a length that is at least 5 or at least 10 times their width, so as to minimize their visual impact. In such embodiments, the antenna wings may be configured (e.g., arranged) along a substantial portion of the edge of the lite, vertical or horizontal, in line with the mullion cap or orthogonal to it. 
     In some embodiments, such as those shown in  FIGS. 1 to 13 , the antenna wings are substantially planar. However, the profile of the antenna wings perpendicular to the plane of the lites may also be non-planar. 
     The dimensions of each antenna wing are typically small relative to the dimensions of the lite across part of which the antenna wing extends. In particular, the surface area of each antenna wing (when viewed perpendicular to the plane of the lite) is typically small relative to the surface area of the lite. For example, the surface area of the lite may be at least 50, or at least 100, times the surface area of the antenna wing. 
     It will be appreciated that the scale of one dimension of an antenna wing may be comparable to the scale of a corresponding dimension of the lite across part of which the antenna wing extends. For example, in some embodiments, an antenna wing may extend along the majority of (for example, the entirety of) the length of a first side of the lite. However, in such embodiments, the width of the antenna wing may advantageously be small relative to the length of a second side of the lite, the second side extending substantially perpendicular to the first side, such that the total surface area of the antenna wing remains small relative to the total surface area of the lite. 
     In some embodiments, antenna wings are removably or adjustably mounted to mullion cap bodies. For example, antenna wings and mullion cap bodies may be manufactured as separate components and antenna wings may be attached to mullion cap bodies prior to, or after, mounting the mullion cap bodies to mullions. 
     In some embodiments, the antenna wings are attached to the mullion cap body by a clamp. The clamp may provide for electrical connection between the antenna wings and the mullion cap body for transfer of signals between antennas in the antenna wings and electronics in the mullion cap body. For example, clamps may include electrical connectivity posts or pogo-pins configured to connect with antenna wings. Removable antenna wings may permit replacement or maintenance of antennas without requiring removal of the entire mullion cap and/or conform with positioning elements, if present, as described hereinabove. 
     In some embodiments, the antenna wings are arranged to lie against (i.e. in direct contact with) the corresponding lites when the mullion cap is mounted on a mullion. In other embodiments, the antenna wings are spaced apart from the surfaces of the lites (such that there is an air gap between the antenna wings and the lite surfaces), for example by a small distance such as at least 1 mm, or at least 5 mm, or at least 1 cm. The spacing between the antenna wings and the lite surfaces may be determined by the mullion cap body, for example by the shape and dimensions of the mullion cap body. In some embodiments, the spacing between the antenna wings and the lite surfaces is adjustable. 
     In some embodiments, each mullion cap supports two or more antenna wings. For example, in some embodiments, each mullion cap supports two or more antenna wings spaced vertically (i.e. longitudinally) apart from one another. In some embodiments, each mullion cap supports two or more antenna wings spaced apart from one another along a single (i.e. the same) edge of a lite. In other embodiments, multiple mullion caps may be installed on a single mullion to enable placement of multiple antenna wings along a single (i.e. the same) edge of a lite. 
     It will be appreciated that, although the discussion hereinabove relates primarily to the mounting of mullion caps to vertical mullions, all such mullion caps could also be mounted to horizontal mullions in order to arrange antenna wings along horizontal edges of lites. Accordingly, it will be understood that all references to ‘vertical’ and ‘vertically’ can be replaced by ‘horizonal’ and ‘horizontally’, and vice-versa. Indeed, all mullion caps disclosed herein could be mounted to mullions inclined at any angle with respect to the horizontal or vertical. 
     The mullion caps disclosed herein enable antennas (by way of the antenna wings) to be mounted to window structures via mullions. The placement of the antennas in the antenna wings, which each extend across a respective portion of the corresponding lite, enable signals to be transmitted and/or received wirelessly across (i.e. through) the window lites. In some embodiments, this enables communications signals, such as cellular network signals, to be transceived across (i.e. through) the window lites. By mounting the mullion caps, and therefore the corresponding antenna wings, on the mullions in the interior of the building, the antennas are also are protected against exposure to the elements (i.e. the weather) outside the building. Moreover, the use of mullion caps to mount the antennas to the windows enables antennas, in some embodiments, to be retrofitted to existing window structures with minimal or no structural modifications required. For example, use of mullion caps to mount antennas to existing window structures enables communications to be transmitted between the interior and the exterior of a building while avoiding a need to drill holes through existing walls or mullions between the interior and the exterior of the building. 
     In the embodiments shown in  FIGS. 1 to 13 , the mullion cap bodies house communications components, such as transceivers or radios, for transmitting or receiving communications signals by way of the antennas in the respective antenna wing(s). In some embodiments, the radio is configurable such as a VRAN (virtual radio access network) transceiver such as described in described in Patent Application No. PCT/US20/32269. 
     Buildings in which mullion caps described herein are installed may include a communications infrastructure into which the mullion caps are integrated. For example, the communications infrastructure may include a high-speed optical fiber building communications network including multiple network switches, control panels, and/or building devices. Details of such communications infrastructures are described in Patent Application No. PCT/US20/32269, entitled “ANTENNA SYSTEMS FOR CONTRLLED COVERAGE IN BUILDINGS”, filed May 21, 2020 and U.S. Provisional Patent Application Nos. 62/977,001, 62/978,755 and 63/027,452, the disclosures of which are hereby incorporated in their entirety into the present application. 
     In some embodiments, the communications infrastructure of the building is connected to an external network, for example by a backhaul such as high-speed fiber optic line. The external network may be an external cellular network such as a 3G, 4G or 5G network. Accordingly, by integration into the communications infrastructure of the building, the mullion caps may also be connected to the external network. In some embodiments, the antennas of the mullion caps are used to wirelessly extend connection to the external network, through the windows, to the exterior of the building. For example, the antennas of the mullion caps may be used to extend 5G cellular network coverage, provided by the backhaul, to areas surrounding the exterior of the building. 
     While the embodiments described above contemplated attaching an antenna structure to a mullion, other building structural components may be used in place of mullions. Generally such a building structural component abuts or is proximate to a window. In some cases, such a structural component is a permanent element of a building such as an element provided during construction. Examples include walls, partitions (e.g., office space partitions), doors, beams, stairs, façades, moldings, and transoms, etc. In various examples, the building structural elements are located on a building or room perimeter. In some cases, an antenna is installed on a fixture, which may be a post construction building installation. Examples include some types of lighting, work area structures such as cubicles, ceiling tiles, and the like. In some cases, an antenna is installed on an unfixed element such as an item of furniture. Examples of furniture on which an antenna may be installed includes desks, chairs, cabinets, artwork, and the like. 
     Examples of window components and associated building structural elements on which an antenna structure may be installed include: Frames, the framework that surrounds and supports the entire window system including a head, jambs and a sill, where the head is a horizontal part forming the top of the window frame; jambs are vertical parts forming the sides of a window frame, abutting or forming a part of a fixed part of the building (i.e., generally not contacted by windows on two sides); and the sill being a horizontal part forming the bottom of the frame of a window; jambliners, a strip which goes on the sides of a window frame that provides a snug fit for the window sash; grilles, decorative pieces that visually divide window panels, giving the glass the appearance of multiple glass panes; muttons, thin pieces of wood or other material that subdivide windows (e.g., multiple small windows in a door); and mullions, a major structural vertical or horizontal piece that separates two or more windows while supporting them. 
     Muttons are usually decorative rather than structural and may be oriented either horizontally or vertically. A mullion is a vertical or horizontal element that forms a division between units of a window or screen, and/or is used decoratively. When dividing adjacent window units, a mullion may provide a rigid support to the glazing of the window. It may also provide structural support to an arch or lintel above the window opening. Horizontal elements separating the head of a door from a window above are both a head jamb and horizontal mullion and are sometimes called “transoms.” An example of a framing structure providing several mullions to support windows on a façade or other building exterior structure is depicted in  FIG. 18 . The illustrated network of mullions may provide pathways for electrical and/or light carrying lines and fibers, in the illustrated framing structure, pathway  1810 , for example. They may also provide attachment points for mounting antennas, radios, controllers, sensors, and the like. 
     In some embodiments, the antenna system is bolted or clipped to a mullion or other building structure by including a hole in the mullion or other building structure to facilitate attachment to the building structure. 
     Antennas of the antenna structures may be oriented horizontally, vertically, or diagonally in a building. These directions may refer to not only the physical orientation of an antenna along its primary axis but additionally or alternatively to the orientation of a signal intensity or polarization (transmitted or received by an antenna). In certain embodiments, an antenna is mounted to a building structural element or other building feature that is vertically oriented. For example, an antenna may be mounted to a vertically oriented element that extends up to the ceiling. In certain embodiments, an antenna is mounted horizontally and provides a horizontally directed radiation pattern. 
     While much of the foregoing disclosure described windows on the edge or outer wall of a building, the present techniques are not limited to this. The concepts disclosed herein, including the antenna designs, supporting structures for antennas, and window modifications, apply to interior windows as well. Interior windows may be located in interior offices, inner walls, etc. 
     The window or other medium through which the antenna transceives electromagnetic signal may be transparent, translucent, opaque, etc. in the visible spectrum. In some embodiments, the medium is a window through which building occupants may view the outside world. In some embodiments, the medium is a window that allows diffuse solar radiation to enter the building. In some embodiments, the medium is spandrel glass or a spandrel window. 
     In some embodiments, the antenna is not actually attached to a mullion cap or other structure affixed to a building structural element. In some such embodiments, the antenna is disposed on the window itself as by adhesive or as a coating or etching. For example, a patch antenna, a strip antenna, a fractal antenna, etc. may be fabricated on the window itself. In such cases, an attenuating layer on the same or a different lite is selectively removed in the vicinity of the antenna as described herein. 
     Multiple Polarization Embodiments 
     In some embodiments, the window antenna system is designed or configured to transmit and/or receive radiofrequency signals in two polarization states (e.g., two orthogonal polarization states). In some cases, a single conductive antenna element provides the two orthogonal polarization states. In such cases, the window antenna system may have two ports and two transceivers to provide signals with two different polarization states. 
     In some cases, two conductive antenna elements are provided, one for each orthogonal polarization state. In some examples, one patch antenna is provided on each side of a mullion, with one antenna element on one window to provide communications in a first polarization state and a different antenna element on another window to provide communications in a second polarization state. In this example, the windows straddle a mullion. 
     Communication between Antenna System and Building Exterior 
     As explained, the antenna system may be designed and installed to facilitate transmission of electromagnetic signals such as gigahertz range communication signals between a building&#39;s interior and exterior, particularly through a window such as a window having a low emissivity coating and/or an optically switchable device. In certain aspects, the communications signals are transmitted on a frequency band of at least 2 GHz, or on a frequency band of between about 2 GHz and 20 GHz. To facilitate such transmission, a window may be modified in a way that physically affects the transmission of electromagnetic waves across the window, e.g., between the interior and exterior of a building. In some aspects, such modification passively or actively effect transmission of electromagnetic waves through the window. 
     In particular embodiments, an antenna or array of antennas are placed in close proximity to or touching surface  4  of an insulated glass unit, so that communications to and from the antenna(s) can pass through the IGU. In particular embodiments, described in more detail herein, coatings on S 1 , S 2 , S 3  and/or S 4  that otherwise would inhibit or impede communications (an “RF attenuating” coating) through the IGU are ablated in the area where the antenna(s) are situated on or near the window at S 4 . In particular embodiments, an RF attenuating coating (e.g. a low emmissivity, photochromic, electrochromic or other coating) from S 2  is first removed, patterned or otherwise ablated with a portable laser ablation tool, in order to retrofit the window to facilitate communication signals to and from the antenna(s). The removal may be a bulk removal, e.g. from a defined area approximating the area and registered with the antenna(s), or in some cases a particular pattern to allow communications through without having to remove the entirety of the RF attenuating coating in that area. In some cases, the RF attenuating coating is patterned for the specific purpose of aiding, shaping or focusing the communications coming to and from the antenna(s). The synergy of the antenna(s) placement in close proximity to or on S 4 , along with ablation of the coating(s) on S 1 -S 4  as needed to allow and/or modify the communications through the IGU is an important feature of certain embodiments. One embodiment is a method of configuring a building to transmit and receive cellular communications, e.g. 5G communications, including 1) removing one or more coatings on one or more surfaces of an IGU,  2 ) configuring one or more antennas on or proximate surface  4  of the IGU and registered with the area in which the one or more coatings were removed in  1 ), wherein the removal of the one or more coatings allows and/or modifies transmission or reception of the cellular communications. 
     In various aspects, the antenna systems described herein may be deployed on the ground floor and/or lower floors of a building (e.g., on the 10 th  or lower floors or on the 5 th  or lower floors). This may facilitate good cellular coverage on the street outside a building. For an additional description of building antennas and their uses, see Patent Application No. PCT/US20/3226962, incorporated, hereinabove, by reference into the present application. 
     Window Antenna Systems for Receiving Exterior Wireless Signals 
     In some embodiments, components of the window antenna system are designed or tuned to optimize reception of cellular communication signals transmitted from a source outside the building. In the absence of the presently disclosed embodiments, reception of such cell signals inside the building may be relatively poor. If one or more cellular towers is located in the vicinity of a building that would otherwise have poor interior cellular reception, window antenna elements and/or RF coating ablation methods may be designed or tuned to facilitate reception of the cellular signal in the region of the building closest to the source of external cellular signals. In some cases, designing or tuning of the elements of the window antenna involves (a) locating antennas on a particular region of the building (e.g., an east facing side of the building that is within the line of sight of a cell tower), (b) tuning reception properties of the radio receiver, and/or (c) defining the shape, size, and/or location of the uncoated region. In the case of the latter item, a cross -shaped uncoated region may be employed, for example. 
     Arrays of Building Antenna Systems 
     Antennas from multiple window antenna systems may be configured to work together to transceive wireless radio frequency signals to or from particular locations, optionally using spatial filtering and/or other beamforming techniques. Such techniques may have various applications. In some cases, the antennas work together to define wireless coverage to users within a building, when a cell tower or other external cellular signal source provides coverage in the vicinity of the building. In some cases, the antenna systems as described herein may be configured to work together to define wireless coverage to users outside, but near, a building, such as at street level or in an adjacent building (e.g., across the street). In such cases, the building&#39;s internal communications infrastructure (e.g., wiring, switches, processing logic, memory, and antennas) may serve as an extension or component of the cellular carrier&#39;s service. In some cases, the antenna systems work together to create a high power, high capacity source of cellular coverage, e.g., in the manner of a cellular tower. 
     In certain embodiments, antenna systems, e.g. mullion caps, located at two or more windows are employed to form antenna arrays. Some embodiments employ 2×2 antenna arrays, or 4×4 antenna arrays, or 16×16 antenna arrays, or 32×32 antenna arrays, or 64×64 antenna arrays, or 128×128 antenna arrays, etc. Any of these can be configured in a (multiple-input multiple-output) (MIMO) configuration, e.g., a massive MIMO configuration. Antenna wings as described herein may themselves employ MIMO antennas, and in addition or in the alternative, antenna arrays formed from multiple such antenna wings. 
     Beamforming techniques may employ active interference, null forming, and other techniques. Such techniques can form complex signal peaks and null regions tailored to locations of user equipment. The signal peaks can be formed at locations of devices that need to communicate over a channel having the signal peak. Signal null regions can be formed at locations where other devices are located that are not communicating over the channel. The null regions may appear as a low level signal or noise, so that devices in the vicinity ignore or suppress it. One embodiment is beamforming using mullion caps as described herein. 
     Signal adjustments required to provide such peaks and null regions may be made in the digital and/or the analog domain. Adjustments in the analog domain may be made to the phase, amplitude, and/or other characteristic(s) of the signals transmitted from individual antennas of the array. 
     Adjustments in the digital domain may be made to define locations of signal beam foci and null areas. The digital cellular communications logic may dynamically update maps of where user equipment is located. Digital parameters are adjusted to steer the signal where desired. For example, in a multi-user MIMO scenario where there are, for example, three user devices handled by a MIMO array at any given time, the digital control logic may define, for one channel, a region of constructive maximum signal near a known location of a device communicating on that channel, and define null regions at known locations of other users on other channels. The digital information defining such locations may be pushed to the analog domain where the mullion cap antennas launch the signals with appropriate beamforming parameters. 
     Uncoated Region of a Window 
     As explained above, conductive window coatings can strongly attenuate high frequency electromagnetic signals such as those used in 5G cellular protocol. Some prior approaches to address this issue employed large repeater designs that, while moderately effective for relatively low frequency transmissions, are relatively ineffective for high frequency transmissions. Other prior approaches employed modifications to building structural components such as holes that might compromise the integrity and/or weather proofing of the building. Unlike such approaches, aspects of this disclosure employ a modified window structure that selectively removes conductive layers on one or more window surfaces. Such modifications reduce the attenuation of electromagnetic signal passing through the window, to or from an antenna system. One aspect is to remove as small a portion of the coating as possible, and to configure analogously small antenna arrays (e.g. in antenna wings of mullion caps) so as to maximize coverage and signal, while minimizing physical footprint and impact to aesthetic features of the window and mullion. 
     For example, a window proximate to an antenna system may be modified locally, e.g. laser ablated, to reduce attenuation by selectively removing material in the vicinity of an antenna, for example an antenna wing of a mullion cap. The material removed may be in the form of a coating on the window. Examples of such coatings include low emissivity coatings, antireflective coatings, optically switchable devices such as electrochromic devices, and the like. The coating or coatings may be on  51 , S 2 , S 3  and/or S 4  of a double pane IGU. The material removed may include electrically conductive, semiconductive, dielectric and/or insulating materials. Examples include metals such as silver, gold, aluminum, and combinations thereof including, e.g., alloys and mixtures. Other materials include transparent metal oxides such as indium tin oxide, titanium oxide, fluorine doped tin oxide, and combinations thereof. In some cases, the material is a conductive polymer or gel. 
     In some cases, material of a window coating is removed in the vicinity of the antenna&#39;s installed location. The area of removal may correspond to the area of an antenna wing or only correspond to radiating elements of the antenna wing. For example, when the antenna is located at the edge of a window, the removed material may also be at that edge of the window, optionally touching the edge of the viewable area of the window. In some cases, the material removed is in a first region that overlaps with or is encompassed by a region of the antenna&#39;s installed location (a second region). In some cases, the first region falls within the second region and extends beyond it. In some cases, not all material within the first region is removed. For example, a pattern of removed material may exist within the first region such as the case where the first region has a generally rectangular shape but regions of removed material within the first region have a serpentine, random, or crosshatched pattern. In some examples, less than the full thickness of a coating material is removed. In other words, the coating material is thinned rather than completely removed. In some cases, only a portion of an electrochromic device is removed. For example, the material of the device may be removed down to, but not including, a lower transparent conductive layer. In other embodiments, all coatings are removed 
     The material removed may exist on one or more surfaces of a window, e.g. an IGU. In the case of a multi-pane window such as a double or triple pane IGU, the material may be removed from any surface or combination of surfaces of the IGU where a coating has been applied. In some cases, a portion of a coating is removed from S 2  of a double pane IGU, where S 1  is an exterior facing surface of the IGU and S 4  is the interior facing surface of the IGU. In some cases, a portion of an electrochromic device is removed from S 2  of a double pane IGU. In certain embodiments of antenna systems described, e.g. mullion caps, a low-E coating is selectively ablated as described herein in order to facilitate a transceiver of the antenna system to pass and receive signals through the window. These methods are particularly useful in retrofit applications where low-E windows are installed, and antenna systems as described are desired. 
     Window antenna systems may employ various shapes, sizes, and/or locations of uncoated regions on a window surface. These features of the uncoated region may be chosen to facilitate transmission of RF energy from the window antenna system to the exterior of the building. 
     In certain embodiments, the uncoated region has a generally annular shape. In some such cases, the annular region overlaps, at least to some degree, with the location of the conductive antenna element. The overlap may be defined in the x,y plane (where the z direction is normal to the face of a window&#39;s surface). 
     In certain embodiments, the uncoated region has a primary region such as, for example, an annular region or a polygonal region, and an ancillary or secondary region. In some cases, the ancillary region includes meander lines that are not part of the primary region but extend therefrom. In one example, an annular region of material removal has meander lines that extend into the inner region of conductive material that is surrounded by the annular region of uncoated region. 
     As shown in of  FIG. 15 , examples of the region&#39;s shape include polygonal areas where the coating or coatings are fully removed, ring shaped areas where only the perimeter is removed, intersecting lines such as cross-shaped areas, etc. Again, this removal may be from one or multiple surfaces, e.g. in  FIG. 15 , the rectangular area in the left-most depiction may represent removal of coating from one, two, three or four surfaces (of S 1 -S 4 ) of e.g. a double-pane IGU, where two- and three-surface removal may be from any combination of surfaces of that number, e.g. removal from S 1  and S 2 , or from S 1  and S 3 , or S 1  and S 4 , or S 2  and S 3 , or S 2  and S 4 , or S 3  and S 4  for two-surface removal. 
     Note that in certain embodiments, the area of the uncoated region of the window is relatively small, e.g., less than about  5 % of the area of the coated region. In certain embodiments, the area of the uncoated region of the window is relatively small, e.g., less than about 2% of the area of the coated region. 
     Process of Modifying Windows to Selectively Reduce Attenuation 
     Attenuating material may be removed from a window before, during, and/or after installation of the window in a building. In some cases, the material is removed during fabrication of an IGU or other window structure used for installation in a building. In some cases, the material is removed after installation of a window or even during retrofit of a window and/or an antenna. In some aspects, a window modified to remove attenuating material includes an optically switchable device such as an electrochromic device. In other cases, a window does not have an optically switchable device. In certain embodiments, low-E, photochromic, thermochromic, electrochromic or other signal attenuating coatings are selectively applied so as to accommodate mullion caps as described herein. For example, masks may be used, corresponding to the footprint and location of the antenna wings, to prevent such coatings from being applied to those areas of the glass. In other embodiments, the coatings are selectively applied to the area of the glass except where antenna wings will be registered with the glass. 
     In some cases, an optically switchable device is included in a window but the device is modified in a manner that remove some of the device or some of the device&#39;s material in the vicinity where an antenna structure will be disposed when a building is constructed. In one approach, an optically switchable device is fabricated on a window in a conventional manner, but after the fabrication is complete, a portion of the device is removed. The portion of the device may be removed by various techniques such as optical techniques, mechanical techniques, thermal techniques, or chemical techniques. Examples of optical techniques include laser ablation and the like. Examples of mechanical techniques include grinding, scraping, and the like. Examples of chemical techniques include etching, dissolving, reacting (e.g., oxidizing or reducing), and the like. Other examples involve exposure to a plasma. 
     In another approach, rather than removing a portion of an optically switchable device after fabrication is complete, the optically switchable device is fabricated on a window in a manner that does not create the device in a region or regions selected to be free of the device in order to facilitate transmission of electromagnetic energy. For example, a mask may be employed to block fabrication of the device in such region or regions. 
     In some cases, an optically switchable device is included in a window as fabricated, and the device is modified only after installation. As in other cases, the modification involves removing some of the device or some of the device&#39;s material in the vicinity of where an antenna structure is to be deployed, but here the material removal is accomplished only after the window is installed. In other words, the window is fabricated with the device covering the region where it could unduly attenuate transmission of electromagnetic signals unless removed. In some approaches, an optically switchable device on an installed window is selectively removed using a portable device. An example of such portable device is a portable laser ablation device as described below. The optically switchable device may be modified at any time after installation. For example, it may be modified at a time when a building&#39;s owner decides to retrofit the building with antennas of the types described herein. 
     In some cases, an optically switchable device is not included in a window, but the window has a different type of attenuating coating such as a passive coating. One common example so such coating is a low emissivity coating which may include, e.g., a thin layer of silver. Prior to installation, the window is modified or fabricated in a manner that removes some of the attenuating material in the vicinity of where an antenna structure will be disposed when a building is constructed. In one approach, the window is fabricated in a conventional manner, but after the fabrication is complete, the portion of the attenuating coating is removed. The portion of the coating may be removed by various techniques such as those described for removing an optically switchable device. In some cases, the window is fabricated in a way that does not provide the attenuating coating in a region selected for it to be absent. This may be accomplished in various ways such as by applying a mask to the region prior to application of the coating. 
     In some cases, a passive coating, such as a low emissivity coating, is included in a window as fabricated, and the coating is modified only after installation. The modification involves removing some of the coating in the vicinity of where an antenna structure is to be located. In this case, the window is fabricated with the coating covering the region where it would unduly attenuate transmission of electromagnetic signals unless removed. In some approaches, the passive coating is selectively removed using a portable device. An example of such portable device is a portable laser ablation device as described below. The passive coating may be selectively removed at any time after installation. For example, it may be modified at a time when a building&#39;s owner decides to retrofit the building with antennas of the types described herein. 
     In some embodiments, lites of a window are laminates, each laminate comprising two or more panes adhered to one another, for example with functional (e.g. electrochromic) device layers provided thereon or therebetween. In some embodiments, the presence of a lamination adhesive between panes is taken into account when focusing a laser and/or ablating coatings from laminate lites. In some embodiments, the presence of the lamination adhesive is taken into account during the ablation process so as not to occlude or otherwise interfere with the transmission of radio signals through the lite. 
     In some embodiments, when a window&#39;s passive or active material is modified after the window is installed, the modification may be accomplished using a portable device such as one that employs focused laser ablation to selectively remove the material. Examples of such portable devices include devices similar or identical to laser ablation devices described in U.S. Pat. No. 9,885,934, which is incorporated herein by reference in its entirety. 
     In some cases, the portable device is positioned to remove a portion of a coating using a flying device such as an aerial drone or other unmanned vehicle. Such approach is particularly useful when removing material on windows above ground level in a building. The drone may temporarily attach itself to the window and/or framing during ablation processing, or not. In one embodiment, a clamping mechanism attaches to the mullion on the exterior of the building. The drone mitigation device uses the mullion and window surfaces to register and align its ablation components appropriately. The ablation process is undertaken. In certain embodiments, when attached to the building, the drone propulsion mechanism is turned off during ablation processing. In such cases, the propulsion system is turned back on prior to detachment from the building. In some cases, during material removal, a beam blocking element is employed to prevent the laser from passing significantly beyond the window to regions where it could injure people or property. Examples of types of beam blocking element are presented in in US Pat. No. 9,885,934, and previously incorporated herein by reference in its entirety. In some cases, the beam blocking element is positioned by drones or other unmanned flying vehicles. 
     Window Antenna Systems Utilizing Window Reflective Surface(s) 
     Introduction and Overview 
     In certain embodiments, a conductive antenna element such as a patch antenna works in concert with a nearby window to form a single antenna unit, sometimes referred to herein as a window antenna system. Windows, even those with regions where some conductive coating is removed, may reflect electromagnetic radiation back toward the conductive antenna element where it can interfere with the propagation of radio frequency energy (and associated electromagnetic communications). By designing the antenna to account for such reflections, the conductive antenna element and the window work together to transceive electromagnetic communications through the window. In such designs, the conductive antenna element is an active element and the window is a passive element. The conductive antenna element is electrically coupled to a radio or transceiver. 
     As explained elsewhere herein, windows often have conductive coatings, a portion of which is removed, or not formed, in order to facilitate transmission of electromagnetic radiation outside the window. In some window antenna systems, the location, size, shape, and/or pattern of the uncoated region is selected to facilitate operation of the overall antenna system that includes the window and coating. 
     Further, in certain embodiments, the window antenna system has compensation circuitry to counteract and/or work together with the effects of the window. In certain embodiments, the electrically conductive antenna element and the uncoated regions of a window are designed in conjunction with compensation circuitry to account for the reflections and/or attenuation caused by the window and its coating(s). 
     Thus, in some cases, the window antenna system includes the following components: (a) a transmitter and/or a receiver, (b) an electrically conductive antenna element (such as a patch), (c) one or more windows, at least one of which has coated and uncoated regions of an electrically conductive coating, and (d) compensation circuitry that accounts for the interaction of the window with the conductive antenna element. The compensation circuitry facilitates transmission outside the window. In certain embodiments, the compensation circuitry is incorporated into the transmitter and/or receiver. In other embodiments, the compensation circuitry is separate from the transmitter and/or receiver. 
     A conductive coating such as a low emissivity coating may reflect the vast majority of incident radio frequency energy and it may also absorb a portion of such energy. For example, in some cases, as a result of reflection and/or attenuation a window with a low emissivity coating may permit transmission of less than 1/1000 th  of incident RF energy (i.e. transmission loss of at least - 30 dB). Reflection is the portion of the electromagnetic energy that bounces off the window. Attenuation is the portion of the wave energy that is absorbed by the medium. Attenuation of a wave involves an interaction in which the wave oscillates in a medium where its energy tends to dissipate as the heat rather than providing propagation through space. In certain embodiments, a window antenna system, and particularly the compensating circuitry, is designed to account for both reflection and attenuation. 
     As indicated above, a conductive antenna radiating element such as a patch radiating element may be disposed flush with or close to a window in a window antenna system. For example, the window surface closest to the antenna element may be substantially parallel to a planar face of the radiating element and be separated therefrom, on average, by less than about ten centimeters. At such separation distances, the reflection and attenuation caused by the window have near-field interactions (evanescent), which are different from plane wave interactions. Antenna system designs, advantageously, account for these nearfield interactions because coating free regions that pass energy emitted from an antenna far from the glass regions will behave differently when passing energy from an antenna that is near the window. 
     In certain cases, window antenna designs utilize reflection off of windows to create and maintain a standing wave between or near the conductive antenna element and the window. The standing wave may be localized between the conductive antenna element and the reflective surface(s) of the one or more windows. A certain fraction of energy of the standing wave is transmitted into space in the direction outside of or through the window. 
     To accomplish an appropriate interaction between the conductive antenna element and the window and its patterned conductive surface, compensating circuitry may be configured to account for reflections back toward the conductive antenna element. In some cases, the compensating circuitry produces a signal that is approximately 180° out of phase with the reflected electromagnetic signal that returns to the antenna element from the window surface(s). This effectively cancels the reflected component of the signal that would otherwise be coupled back into the window conductive antenna element and toward the radio. 
     To effectively set the desired resonating conditions in the window antenna system, the compensating circuitry must account for the time it takes a signal from the antenna element to reach a reflective window surface and reflect back to the antenna element. It may also account for the magnitude of the reflected signal, which is a function of the reflectivity of the window surface. Further, it may account for these considerations for each of multiple reflective surfaces provided by the window. 
       FIG. 16  shows a window antenna system in which a patch antenna element  1605  is located proximate to and substantially parallel with a dual pane window  1603 , which has an exterior surface  1607  (sometimes referred to as S 1 ), an interior surface  1613  (sometimes referred to as S 4 ), and internal surfaces  1609  (sometimes referred to as S 2 ) and  1611  (sometimes referred to as S 3 ). In this example, surface  1609  has a conductive coating such as a low emissivity coating or an electrochromic device that is selectively removed to produce an uncoated region. Reflections of RF energy from surfaces  1609  and  1613  are illustrated by arrows  1615  and  1617 , respectively. Both of these reflections reach patch antenna element  1605 , but very little of the reflected signal is transmitted back toward a radio (not shown) because tunable matching circuit (compensating circuitry)  1619  applies compensating signals to patch antenna element  1605 . 
       FIG. 17  shows window antenna system  1701  disposed on a mullion  1703  and including a dual pane window  1705  and a patch antenna element  1707  disposed on an antenna housing  1709 . Dual pane window  1705  has four surfaces, S 1 -S 4 , with a conductive coating  1711  on surface S 2 . S 1  is on the building exterior. Surface S 2  has an uncoated region  1713  that extends under and beyond patch antenna element  1707 . The radio and compensating circuitry of window antenna system  1701  are not shown. In some cases, they are disposed within mullion  1703 . In other cases, they be disposed on the back of the conductive patch antenna element  1707 . 
     Design Variations for Different Types of Window 
     If every window was configured identically, then a single compensating circuit could be deployed. However, windows have many different properties. For example, integrated glass units (IGUs) may have different thicknesses of glass and different separation distances between the inner surfaces of the two or more glass panes. These different distances produce different times-of-flight of RF signals propagated by the conductive antenna element and reflected off one or more glass surfaces back to the antenna element. Additionally, different windows have different types of coating, with different electrical properties that affect the amplitude of signal that is reflected back to the antenna element. 
     Therefore, in some cases, the compensating circuitry is flexible or tunable to allow it to be deployed on different types of windows. In certain embodiments, the compensating circuitry is configured to tune the compensating signal it applies to the conductive antenna element to account for differences in time-of-flight of reflected signals for different distances between the conductive antenna element and the reflective surface(s) of a window. It may also be tuned to account for different magnitudes of the reflected signal, which are a function of, inter alia, the reflectivity of the surface that is reflecting the signal. 
     In some cases, the window uncoated region is also chosen to account for different window designs. In other words, the shape, dimensions, and location of the uncoated region may be selected to account for the particular types of window for which the window antenna system is designed. 
     In certain embodiments, to account for different separation distances between window surfaces, the compensating circuitry employs a variable capacitor (e.g., a varactor) to tune its response. In certain embodiments, to account for different separation distances between window surfaces, the compensating circuitry employs a micro-electromechanical system (MEMS) device in which a cantilever or other oscillating structure is varied to implement the tuning. 
     As an adjunct to the compensating circuitry or as part of the compensating circuitry, a mechanism is provided for determining parameters for the window in which the window antenna is deployed. As indicated above, these parameters may include the separation distance between the conductive antenna element and one or more reflective surfaces of the window, and optionally the physical properties of the glass coating, which properties influence the magnitude of the reflected signal. When these parameters are known, the compensating circuitry can be appropriately tuned. 
     In some embodiments, a mechanism associated with the compensating circuitry is able to probe the windows and measure reflected signal in order to determine how to appropriately tune the compensating circuitry. In other embodiments, an IGU or other window, as provided by a supplier, contains information that provides these parameters. As an example, an IGU may include a barcode, a QR code, an RFID, or other in appropriate indicator of the parameters that can be read by the compensating circuitry or associated processing module. In yet another embodiment, a laser ablation tool or other tool used to selectively remove the conductive coating may be configured to provide information about some parameters such as the relative positions of the reflective surface(s), and hence the separation distance between the conductive antenna element and the reflective surfaces. 
     Active Interference Cancelling using Window Antenna Systems 
     In certain embodiments, a window antenna system or associated circuitry is configured to perform or participate in active interference cancelling. In current technology, cell phones and cell towers both participate in interference cancelling. The goal is to allow user devices such as mobile phones to preferentially receive the strongest signal and ignore or suppress weaker, interfering, signals. 
     The need for active interference cancelling arises for various reasons such as because wireless signals can reflect off various structures including walls, windows, etc., and because cell towers may compete to connect to a phone or other user device. Internal reflections cause time of flight differences for the same communication reaching the device, leading to interference. And signals from multiple external sources such as multiple cell towers likewise produce interference. 
     To implement active interference cancelling, user equipment is sometimes configured with software or other logic that allows it to detect the strongest inbound signal and to block weaker signals by transmitting blocking signals or otherwise suppressing the weaker signals. As the user equipment moves around, this relationship changes, so the user equipment may be configured to dynamically perform the analysis and blocking. In other words, the user equipment must, at times, switch between signals in order to receive the best signal. Also, as the incoming signal&#39;s strength varies over time, the user equipment may similarly identify new “best” signals and block weak signals. 
     In some cases, wireless modems, base stations, and/or cell towers are configured to determine where a user device is currently located. It may do this by, for example, sending and receiving a training sequence. Regardless of how the current location is determined, the model, base station, or tower employs digital and/or analog signal propagation logic to direct the wireless signal intensity peaks to the current location of the user device. For example, in a MIMO (multiple-input multiple-output) antenna configuration, the phase and amplitude of transmissions from various component antennas may be tuned to launch wireless signal with the determined beamforming characteristics. The wireless infrastructure may also be configured to shape the transmitted wireless signal to cause null or low signal strength regions where other user devices are known to be currently located. In some cases, the window antenna system is configured to apply the inverse of wireless signals identified for suppression and thereby spare the user device from this effort. 
     Regardless of how the transmitted signal is defined and controlled, at least a portion of the effort to identify the strongest signal and to cancel the weaker signals is performed by the mobile device or other user equipment. This consumes power at the local device, which accelerates battery discharge, and may, over the long term, reduce the battery&#39;s lifetime. 
     In certain embodiments, a window antenna system or associated circuitry is configured to perform some or all of this function, i.e., identify the strongest signal and cancel the weaker signals. This reduces the burden on the user equipment and extends the battery&#39;s charge time. The window antenna system may be hard wired to a power source, which provides a reliable source of power to perform these functions. 
     Participation of the window antenna systems in active interference cancellation may be particularly useful in controlling signals from outside a building to user equipment inside the building. In certain embodiments, a window antenna system is configured to (a) determine which of many incoming wireless signals is most appropriate for one or more user equipment devices in the vicinity of the system, and (b) selectively transmit that signal to the local device(s). In some embodiments, the window antenna system accomplishes this by cancelling or suppressing undesirable incoming signals. In some embodiments, the window antenna system accomplishes this by beamforming techniques so that desired signals are focused in at or near a mobile user device and/or undesirable signals directed to locations away for the device (possibly toward a different device that can use such signals). In some cases, the window antenna system operates as a relay to receive and then retransmit only signals needed by the local user equipment devices. In some cases, the window antenna system works in concert with passive or active window devices or coatings that selectively block and transmit particular regions of the radio frequency spectrum. 
     In certain embodiments, the active interference cancellation logic is deployed in a building network locally, e.g. in the window antenna system. In certain embodiments, the active interference cancellation logic is deployed remotely such as on a server in the building (e.g., a master controller) or even outside the building, such as on a geographically distant server connected by a network, e.g., a public network 
     Conclusion 
     It should be understood that the certain embodiments described herein can be implemented in the form of control logic using computer software in a modular or integrated manner Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will know and appreciate other ways and/or methods to implement the present invention using hardware and a combination of hardware and software. 
     Any of the software components or functions described in this application, may be implemented as software code to be executed by a processor using any suitable computer language such as, for example, Java, C++or Python using, for example, conventional or object-oriented techniques. The software code may be stored as a series of instructions, or commands on a computer-readable medium, such as a random-access memory (RAM), a read-only memory (ROM), a magnetic medium such as a hard-drive or a floppy disk, or an optical medium such as a CD-ROM. Any such computer readable medium may reside on or within a single computational apparatus, and may be present on or within different computational apparatuses within a system or network. 
     Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Additionally, one or more features from any embodiment may be combined with one or more features of any other embodiment without departing from the scope of the disclosure. Further, modifications, additions, or omissions may be made to any embodiment without departing from the scope of the disclosure. The components of any embodiment may be integrated or separated according to particular needs without departing from the scope of the disclosure. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.