Patent Publication Number: US-2019181545-A1

Title: Luminaire with radio frequency transparent cavity

Description:
TECHNICAL FIELD 
     The present subject matter relates to technologies that provide improved radio frequency performance of a luminaire equipped with a radio frequency device. 
     BACKGROUND 
     In recent years, the use of wireless communication systems to deliver or exchange data with mobile user devices, such as smartphones and tablet, within indoor locations have become more prevalent. Wireless networks have also been used to provide communications for building management and control functions, such as HVAC systems control, lighting system control, and/or building or area access control, as well as other functions, such as asset and inventory tracking, theft-prevention control functions radio frequency (RF), and the like. 
     Light fixtures within indoor locations are ubiquitous and have become increasingly sophisticated. Lighting fixtures have been equipped with wireless (optical and/or RF) detectors as well as RF receivers and/or transceivers for a number of reasons, such as to control the light sources of the light fixture, provide access to a data communication network, utilize a location determination service or the like. 
     The traditional back-lit, luminaire architecture has a number of elements, such as light sources and associated circuit boards, metalized diffuser elements, internal reflector elements, or the like, that interfere with RF signals emitted by and received by antennas within the luminaire. 
     While some implementations place the antenna in front of the light sources and associated circuit boards in an attempt to improve RF performance, such implementations have typically used antennas that are omnidirectional in which case RF performance is degraded by the presence of interfering materials within the luminaire. In addition, such implementations have to accommodate the illumination occluding effects of the antenna being in front of the light source. 
     SUMMARY 
     Hence, a need exists for a luminaire configuration that is substantially free of RF radiation interfering materials in the RF path to/from the antenna and that outputs light meeting the lighting requirements for the space in which the luminaire is located. 
     By way of an example, a luminaire includes a housing, visible light sources, and an RF antenna. The housing having a back wall and a housing output aperture at a front of the housing. The housing enclosing an RF transparent volume may that may be at least substantially free of RF radiation interfering materials and at least substantially transparent with respect to the RF radiation, and the RF transparent volume being at least substantially transmissive with respect to visible light. The visible light sources may be mounted within the housing along at least a portion of the perimeter of the housing output aperture, and oriented to direct substantial emissions of visible light from the light sources into the RF transmission volume for combination and output of combined light from the light sources via the housing output aperture. The RF antenna may be mounted near a back wall of the housing opposite the aperture and coupled to the volume for transmission and/or reception of RF radiation through the aperture and the volume. 
     By way of another example, a luminaire includes radio frequency circuitry, an antenna, a housing and a light source. The radio frequency circuitry may be configured to emit or receive radio frequency signals. The antenna may be coupled to the radio frequency circuitry. The housing may have a back wall opposite a housing output aperture, and the housing may contain the antenna affixed to the back wall. The housing includes an RF radiation transparent volume substantially free of RF radiation interfering materials. The volume extends from the antenna at the housing back wall to an RF radiation transparent aperture in the housing output aperture. The light source may be configured to emit light for general illumination of a space in which the luminaire is located. The light source may be located at a perimeter of the housing in closer proximity to the housing output aperture than to the back wall. 
     Additional objects, advantages and novel features of the examples will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples. The objects and advantages of the present subject matter may be realized and attained by means of the methodologies, instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawing figures depict one or more implementations in accordance with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1A  is a high-level cross sectional view of an example of a luminaire having a volume that is at least substantially free of radio frequency (RF) radiation interfering materials and at least substantially transparent with respect to radio frequency RF energy going to or coming from an antenna of the luminaire coupled to the volume. 
         FIG. 1B  is a high-level plan view through a diffuser of an example of the luminaire of  FIG. 1 . 
         FIG. 2  is a high-level cross sectional view of another example of a luminaire having a volume that is at least substantially free of RF radiation interfering materials, and has a lower cross-sectional profile than the luminaire example shown in  FIG. 1A . 
         FIG. 3  is a high-level cross sectional view of another example of a luminaire that includes radio frequency components external to a reflector within the luminaire, and having a volume that is at least substantially free of RF radiation interfering materials and at least substantially transparent with respect to radio frequency RF. 
         FIG. 4  is a high-level cross sectional view of another example of a luminaire that includes radio frequency components external to a reflector within the luminaire, and having a volume that is at least substantially free of RF radiation interfering materials and at least substantially transparent with respect to radio frequency RF. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent that the present teachings might be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. 
     A luminaire implementation disclosed herein provides a substantially unobstructed radio frequency signal pathway from or to a radio frequency antenna installed within the luminaire to or from an RF-enabled device near the luminaire. 
     In the example light fixture type luminaires, the antenna for RF applications is mounted inside the luminaire housing at a location opposite an output aperture of the housing that is intended for light output and for wireless RF signal input or output. The interior volume of the fixture between the antenna and the output aperture is as clear as practical of materials that otherwise might substantially interfere with wireless RF signals. If there are materials between the antenna and the exterior space to be illuminated by the luminaire, such as a diffuser or light guide at or near the aperture, the materials are chosen for such components that are substantially non-interfering relative to wireless RF signals. The interior volume having the non-interfering materials that is produced by the location of the antenna inside the housing with respect to the housing output aperture may also be referred to as an RF transparent volume. The RF transparent volume has a boundary that is substantially coplanar with the output aperture of the housing. 
     The housing aperture may be a physical opening through a wall of the housing. In some examples, however, the housing aperture is solid or covered by a solid that is transmissive with respect to illumination light and RF radiation, e.g. a suitable material forming a diffuser or a light guide. 
     The adverb “substantially” is intended to indicate that the words being modified are not absolute in their definitions. For example, “substantially transparent” means transparent to a particular degree, such as greater than approximately 85 percent, of transparency. More specifically, an RF transparent volume and aperture may be greater than approximately 85 percent transparent to RF radiation, and, in such a case, the RF transparent volume may be considered to contain “substantially non-interfering” materials or be “substantially free of RF radiation interfering” materials. In addition, terms such as “transparent” are also intended to mean “less than completely transparent.” Alternatively, “substantially RF transparent” may also mean that RF signals are not noticeably attenuated by material within the RF transparent volume or by components that may be within the RF volume, such as a light guide and/or diffuser, to diminish or adversely affect antenna or radio system performance. 
     In the illustrated examples, there may be ambient air filling the RF transparent volume. If free of conductive contaminants or the like, air is sufficiently non-interfering to be considered transparent with respect to RF radiation and sufficiently transmissive with respect to visible light for purposes of this discussion. Some other materials that may be in the RF transparent volume or within the housing but in or adjacent to the RF transparent volume also may be sufficiently non-interfering to be considered transparent with respect to RF radiation and sufficiently transmissive with respect to visible light. Examples of such materials include glass, or acrylic or other non-conductive plastic materials like those used to form a diffuser or light guide. 
     The term “luminaire,” as used herein, is intended to encompass essentially any type of device that processes energy to generate or supply artificial light, for example, for general illumination of a space intended for occupancy or observation, typically by a living organism typically a human that can take advantage of or be affected in some desired manner by the light emitted from the device. However, a luminaire may provide light for use by automated equipment, such as sensors/monitors, robots, etc. that may occupy or observe the illuminated space, instead of or in addition to light provided for an organism. However, it is also possible that one or more luminaires in or on a particular premises have other lighting purposes, such as signage for an entrance or to indicate an exit. In most examples, the luminaire(s) illuminate a space or area of a premises to a level useful for a human in or passing through the space, e.g. general illumination of a room or corridor in a building or of an outdoor space such as a street, sidewalk, parking lot or performance venue. The actual source of illumination light in or supplying the light for a luminaire may be any type of artificial light emitting device having suitable light emission characteristics. 
     The illumination light output of a luminaire, for example, may have an intensity and/or other characteristic(s) that satisfy an industry acceptable performance standard for a general lighting application. The performance standard may vary for different uses or applications of the illuminated space, for example, as between residential, office, manufacturing, warehouse, or retail spaces. 
     In several illustrated examples, such a luminaire may take the form of a light fixture, such as a pendant or drop light or a downlight, or wall wash light or the like. Other fixture type luminaire mounting arrangements are possible. For example, at least some implementations of the luminaire may be surface mounted on or recess mounted in a wall, ceiling or floor. Orientation of the example luminaires and components thereof are shown in some of the drawings and described below by way of non-limiting examples only. The luminaire with the lighting component(s) may take other forms, such as lamps (e.g. table or floor lamps or street lamps) or the like. Additional devices, such as fixed or controllable optical elements, may be included in the luminaire, e.g. to distribute light output from the light source in a particular manner. 
     The term “coupled” as used herein refers to any logical, physical or electrical connection, link or the like by which signals produced by one element are imparted to another “coupled” element. Unless described otherwise, coupled components, elements or devices are not necessarily directly connected to one another and may be separated by intermediate components, elements, devices or communication media that may modify, manipulate or carry the signals. 
     Reference now is made in detail to the examples illustrated in the accompanying drawings and discussed below. 
       FIG. 1A  is a high-level cross-sectional view of an example of a luminaire having a volume that is at least substantially free of radio frequency (RF) radiation interfering materials and at least substantially transparent with respect to radio frequency RF. 
     As shown in the cross-sectional view of  FIG. 1A , the luminaire  100  includes a housing  110 , visible light sources  132 A and  132 B, and a radio frequency antenna  120 . The luminaire includes RF electronic circuitry  125 , power supply  127  and RF antenna  120 . 
     The housing  110  may be configured to form an enclosed RF transparent volume  188  that may extend from in front of the antenna  120  to the housing output aperture  115 . The housing output aperture  115  may be located at the end of the housing sides  117  and  119  or substantially between the light guide  133  and diffuser  145 . As such, the light guide  133  may be positioned inside the volume  188  adjacent to the housing output aperture  115 . 
     The light guide  133  may be configured to receive and combine the substantial emissions of visible light from the light sources and direct the output of combined light from the light sources via the housing output aperture  115 . The volume  188 , for example, is at least substantially free of RF radiation interfering materials and at least substantially transparent with respect to RF radiation. The volume  188  is also at least substantially transmissive with respect to visible light such as the light emitted by the light sources  132 A and  132 B. 
     The housing  110 , for example, has a mechanical design suitable for integrating a large radio frequency antenna  120  into the luminaire  100 , and that creates enough volume inside the luminaire  110  to house components without impacting the illumination output from the luminaire  100 . The housing  110  forms an interior space that includes the substantially RF transparent volume  188  that is free of RF interfering materials. The housing  110  may have a region or portion  112  adjacent to the housing output aperture  115  and an opposite region, or portion  111  adjacent to the back wall  113 . The housing  110  may contain the RF antenna  120 . For example, the RF antenna  120  may be located at or mounted near the back wall  113  of the housing  110  opposite the housing output aperture  115  and coupled to the volume  188  for transmission and/or reception of RF radiation through the housing output aperture  115  and the volume  188 . The housing  110  may, for example, have sides  117 ,  119  coupled to the housing back wall  113  and housing output aperture  115 . The housing back wall  113  may be a wall of the housing  110  at which the RF antenna  120  is located, while the housing output aperture  115  is a part of the housing  110  from which the illumination light and signals are output from the luminaire  100 . In the example of  FIG. 1A , the housing sides  117 ,  119  may be configured to extend perpendicularly from the housing back wall  113  to the housing output aperture  115 . The housing sides  117 ,  119  may be coupled to the housing back wall  113  and housing output aperture  115  using a number of different techniques and/or coupling devices, such as welding, screws, interconnecting tabs and slots, or the like. 
     The visible light sources  132 A and  132 B may respectively be coupled to a light source (LS) printed circuit board assembly (PCBA)  131 A and  131 B. The LS PCBA  131 A and  131 B may control the operation of the light sources  132 A and  132 B. The light sources  132 A and  132 B emit light into a light guide  133  for general illumination of a space  190  in which the luminaire  100  is located. The light sources  132 A and  132 B may be located at a perimeter of the housing  110  in proximity closer to the housing exterior portion  112  than the housing interior portion  111 . For example, the light source  132 A may be located approximately at an interior intersection of the housing output aperture  115  and housing sides  117 ,  119 . 
       FIGS. 1A and 1B  relate to an edge lit type lighting device. This type of lighting device is colloquially referred to as “edge” lit or as an “edge light” in that the source of illumination light is coupled to a periphery, e.g. around an edge, of a light guide  133  that outputs the illumination light. In actual implementations, such as that shown, one or more light sources that together form the source of illumination light are coupled to one or more lateral surfaces along the periphery of the light guide  133 , for example, formed between peripheral edges of longitudinal surfaces of the light guide  133 . The illumination light sources  132 A and  132 A in the example includes a number of lighting LEDs, supported along the periphery of the light guide  133 . 
     Light waveguides, also sometimes referred to as “light guides” or “light pipes,” are known in the lighting arts. For example, a light guide, such as  133 , may utilize internal reflections governed by Snell&#39;s Law. The light guide  133  may, for example, be fabricated of a clear light and RF transmitting material, such as clear polycarbonate, polymethyl methacrylate (PMMA), silicone, glass, acrylic, or other clear plastic having opposing surfaces (top and bottom surfaces in the drawing) between which the light is internally guided. The light guide  133  also includes one or more lateral surfaces through which light can be introduced into the guide from one or more light sources coupled to the ‘edge’ surface(s). Because of the high angle of incidence (angle from an axis perpendicular to the respective surface) of light rays at the longitudinal surfaces of the light guide body, the light rays will internally reflect off of these surfaces and consequently will not escape the guide. In this way, the internal reflections, at longitudinal surfaces of the guide structure, channel or guide light introduced at one or more lateral or peripheral surfaces along the light guide  133 , often without emerging from the guide&#39;s lateral surfaces except at desired specially configured output locations. 
     In the illustrated example, a body of the light guide  133  is at least substantially planar. In the specific example shown, a longitudinal output surface and a longitudinal opposite surface of the guide  133  are planar surfaces that are actually parallel to each other, although there may be some minor deviation due to the process of forming those surfaces of the material forming the body of the light guide  133 . There may also be applications in which either one or both surfaces on the body of the light guide  133  has a non-planar contour, such as concave, convex or exhibiting a recurring light form (e.g. sinusoidal or sawtooth). The light guide  133  as described herein is intended to output the light emitted by the light sources  132 A and  132 B out of the luminaire  100  to illuminate the space  190  up to a level that satisfies governmental (e.g., Occupational Safety and Health Administration (OSHA)) and industry standards (e.g., American National Standards Institute)). 
     Also, the plan view ( FIG. 1B ) shows a luminaire  100  having a rectangular shape, of course, the luminaire  100  and appropriate components thereof may have other shapes, e.g. circular, oval square, hexagonal, or the like. The drawings also show some representative examples of scale and spatial relationships, although implementations of the luminaire may exhibit other sizes/relationships. 
     As shown in  FIG. 1B , the light sources  132 A and  132 B as well as light sources  132 C and  132 D are located beyond a perimeter of the RF radiation transparent volume  188  and housing output aperture  115 . The RF radiation transparent volume  188  being at least substantially free of radio frequency (RF) radiation interfering materials meaning that materials, if any, in the volume do not substantially interfere with the transmission of, or noticeably attenuate, RF signals passing through the volume  188 . In the example shown in  FIG. 1A , the RF radiation transparent volume  188  may extend from the antenna  120  to the housing output aperture  115  in a first direction, and may extend in a second direction between the light sources  132 A and  132 B. 
     The light guide  133  may be configured to receive and combine the substantial emissions of visible light from the light sources  132 A and  132 B, and direct the output of combined light from the sources via the housing output aperture  115  (shown in  FIG. 1A ). The light guide  133  may be mounted in the RF radiation transparent volume  188  adjacent to or across the housing output aperture  115 . The light guide  133  may also be described as being located near the exterior portion  112  of the housing  110 , or above the diffuser  145 . In some examples, the diffuser  145  is substantially transparent to RF radiation meaning that the diffuser  145  is formed of a light diffusing material that does not substantially interfere with the transmission of, or noticeably attenuate, RF signals passing through the diffuser  145 . In an example, the diffuser  145  as well as the light guide  133  may be within the RF radiation transparent volume  188 . 
     As shown in  FIG. 1B , the light sources  132 A- 132 D may be mounted within the housing  110  along at least a portion of the perimeter of the aperture (such as  189  of  FIG. 1 , but not shown in this example) and oriented to direct substantial emissions of visible light from the sources  132 A- 132 D into the volume via the light guide  133  for combination and output of combined light from the sources via the aperture. The light guide  133  may, for example, facilitate the use of light emitting diode (LED) light sources, such as  132 A-D, to provide the general illumination lighting into the space, such as  190  shown in  FIG. 1A , in which the luminaire  100  is located. Each of the light sources  132 A,  132 B,  132 C and  132 D are shown in  FIG. 1A  as being located in the corners of housing  110 . However, the light sources  132 A- 132 D may be positioned elsewhere to facilitate a desired distribution of light for general illumination or task lighting. 
     The luminaire  100  may also include a diffuser  145  formed from a light diffusing material that is transparent to RF radiation. The diffuser  145  may be supported by the bottom  115  of the housing  110 . As shown in the example of  FIG. 1B , the diffuser  145  may extend across all or at least a substantial portion of the housing output aperture  115 . Alternatively, the diffuser  145 , depending upon the desired aesthetics for the luminaire  100 , may extend a part or parts of the housing output aperture  115  thereby leaving the volume  188  open to the space  190 . 
     Returning to the example of  FIG. 1A , the luminaire  100  may also include radio frequency (RF) circuitry  125 . The RF antenna  120  may be coupled to the RF circuitry  125 . A power supply  127  may provide electrical power to the RF circuitry  125 . For example, the power supply  127  may be coupled to AC mains or other form of power supply, such as battery, solar cell, or the like. The RF circuitry  125  may be configured to emit or receive radio frequency signals via the RF antenna  120 . For example, the RF circuitry  125  and the RF antenna may be configured to transmit/receive in frequencies associated with radio frequency identification (RFID), Bluetooth®, ZigBee®, Wi-Fi, or ultra wideband (UWB) radio or radar and the like. For example, the luminaire  100  may include a radio frequency identifier (RFID) reader circuit (not shown), which may include an RFID transceiver (not shown). The RF transceiver, for example, may supply RF signals to and/or obtain RF signals via the RF antenna  120 . The details of an RF transceiver are unnecessary for the understanding of the present subject matter. However, examples of an RF transceiver suitable for use in the luminaire  100  and other luminaire examples include RF transceivers provided by Texas Instruments®, Analog Devices®, Maxim®, Renesas®, Hittite® or Broadcom®. In addition, the RF circuitry  125  may be configured to couple to a lighting control network for RFID data transmission, and/or may use a common power supply, such as  127 , to power RFID and lighting components. 
     As shown in  FIG. 1A , the RF antenna  120  may be affixed to a back wall  113  of the housing  110  opposite the housing output aperture  115  and coupled to the volume  188  for transmission and/or reception of RF radiation through the volume  188  and the housing output aperture  115 . In some examples, the RF antenna  120  may not substantially protrude into the volume  188 . In an example, the light source(s)  131 A,  131 B and the radio frequency identifier reader circuitry  125  are located outside the RF radiation transparent volume  188 . By positioning the RF antenna  120  in the housing and the RF circuitry  125  outside the housing  110 , potential sources of RF interference (e.g. circuit boards, radio frequency sources and the like) may be moved farther from the RF antenna. The RF antenna  120  may be enclosed with an RF transparent antenna enclosure (not shown) having a form factor such as an approximately 6 inch to 8 inch square, other polygon or another shape, such as circular or elliptical. More specific examples of an antenna may include a patch antenna, dipole antenna, chip antenna, or arrays thereof. The RF transparent enclosure containing the RF antenna  120  may be affixed to the housing  110  via any known method or device(s). 
     The housing  110  may be formed of an RF transparent material, such as rigid or structurally molded (e.g., honey-combed, diamond-shaped) plastics or the like, that replaces a metallic frame typically included with light fixtures. In addition, areas about the center of the luminaire  110  may contain electrically non-conductive materials to further eliminate possible sources of interference. 
     By arranging the associated RF circuitry  125  outside of the housing  110  and positioning the LEDs  132 A,  132 B and related LED PCBA  131 A,  131 B around the interior perimeter of the luminaire housing LEDs, an RF transparent volume  188  substantially in the center of the luminaire housing  110  is provided. The RF transparent volume  188  allows RF signals to pass through (e.g., in and out of the RF transparent volume) without minimal interfering structures present while also passing visible light for illumination of a space in which the luminaire  100  is located. The RF antenna  120  that is located at the housing back wall  113  and the volume  188  is intended to be large enough to allow for adequate dispersion of the RF signals emitted by the RF antenna  120 . The configuration of the luminaire  100  as shown in  FIGS. 1A and 1B  and described herein provides improved transmission and reception performance of the RF antenna  120  within the luminaire  100 . 
     The visible light output from the luminaire  100  in intended to provide illumination that conforms to governmental and industry standards for illumination suitable for the particular space in which the luminaire is located. For example, if the luminaire  100  is installed in a warehouse setting, the illumination provided by the luminaire conforms to the governmental and industry standards for a warehouse. 
     While luminaire configurations as described with reference to  FIGS. 1A and 1B  may be appropriate for some installations having high ceilings, deep walls, large wall-mounted lighting fixtures, or drop ceilings with expansive voids, other configurations of the housing  110  that accommodate installation locations with limited area are also envisioned. For example,  FIG. 2  provides a high-level cross sectional view of an example of a luminaire having a volume being substantially free of RF radiation interfering materials and substantially transparent with respect to RF radiation, and has a lower cross-sectional profile than the luminaire example shown in  FIG. 1A . 
     The luminaire  200  of  FIG. 2  has substantially similar features as the luminaire of  100  of  FIG. 1 . The luminaire  200  may be configured in the form of a trougher-type light fixture having dimensions such as 4 feet×4 feet, 2 feet×2 feet, 1 foot×4 feet, or the like. The luminaire  200  includes a housing  210 , an RF antenna  220 , a light guide  234 , light sources (LS)  232 A and  232 B, light source printed circuit board assembly (LS PCBA)  231 A and  231 B, and a light guide  234 . 
     The light guide  234  may be mounted outside the RF radiation transparent volume  288 . Alternatively, the RF radiation transparent volume  288  may extend to include the light guide  234 . The light guide  234  may be configured to receive and combine the substantial emissions of visible light from the light sources  231 A and  231 B, and direct the output of combined light from the light sources  232 A and  232 B via the housing output aperture  201 . The light sources  232 A and  232 B may be located beyond a perimeter of the RF radiation transparent volume  288 , and therefore, do not interfere with RF signals within the volume  288 . 
     A luminaire configuration as shown in  FIGS. 1A-2  utilizes a type of light engine (e.g., LS PCBA, such as  131 A, and LS, such as  132 A) located along a perimeter around the luminaire housing of the luminaire enables the integration of a type of RF or other radiation electromagnetic antenna, such as  120  or  220 , that is larger than a thin wire antenna or the like into the luminaire. 
     The housing  210  may have a housing output aperture  201  and a housing back wall  213  that is coupled to housing sides  215 A and  215 B. Unlike housing  110  of  FIG. 1  that has sides  117  and  119  that are perpendicular to the housing back wall  213 , the housing sides  215 A and  215 B of luminaire  200  are at obtuse angles with respect to the housing back wall  213 . Or, said differently, the respective sides  215 A and  215 B of the housing  210  form acute angles with respect to the light guide  234 . In general, the housing sides  215 A and  215 B are coupled to the housing top  213  at obtuse angles and to a point on the housing  210  at about the light sources  232 A and  232 B at which the respective sides  215 A and  215 B of the housing form acute angles with respect to the light guide  234 . A benefit of this housing configuration enables the housing height, shown as dimension H, to be reduced as compared to, for example, a height (not shown) of the housing  110  of  FIG. 1 . As a result, the housing  210  configuration of  FIG. 2  allows for installation of RF transparent luminaire in locations with reduced void spacing, such as a wall or low ceiling heights. 
     The RF antenna  210  may be configured to emit frequencies in the ranges compatible with RFID, BLE, Wi-Fi or other electromagnetic radiation that may be emitted from an RF antenna  220  is physically located in the luminaire  200 . The RF antenna  220  may be located at the center of the luminaire  200 . The RF antenna  220  coupled to the housing back wall  213  and opposite the housing output aperture  201 . The diffuser  245  is positioned at the housing output aperture  201  to diffuse light output from the housing output aperture  201 . 
     In the luminaire  200  example of  FIG. 2 , the RF circuitry  225  may be positioned on the exterior of the housing  210  at either side  215 A or  215 B of the luminaire. Similarly, the power supply  227  may also be positioned at the exterior of the housing  210  at either side  215 A or  215 B of the luminaire. Alternatively, the power supply  227  and the RF circuitry  225  may be located at the same side, such as  215 A or  215 B. The RF circuitry  225  may be radio frequency identifier reader circuitry is located outside the housing  210 . 
     The diffuser  245  may be made from a light diffusing material that is transparent to RF radiation such that the diffuser  245  does not substantially interfere with, or noticeably attenuate, the passage of RF signals through the diffuser  245 . The diffuser  245  may be supported by the housing  210  and may extend across at least a substantial portion of the housing output aperture  201 . As such, the view of the interior of the luminaire housing  210  through the housing output aperture  201  of luminaire  200  may be similar to that of luminaire  100  shown in  FIG. 1B . 
     In addition to the different configurations of housings, such as  110  and  210 , examples of a luminaire may incorporate additional structure that enhances the RF transparent volume already present and enhances the output of the general illumination light from the luminaire. The examples of  FIGS. 3 and 4  illustrate the use of a reflector to enhance the RF capabilities as well as the illumination output capabilities of a luminaire. 
       FIG. 3  is a high-level cross sectional view of another example of a luminaire that includes radio frequency components external to a reflector within the luminaire, and having a volume being at least substantially free of RF radiation interfering materials and at least substantially transparent with respect to radio frequency RF. 
     The luminaire  300  includes radio frequency circuitry  325 , an antenna  320 , light sources  332 A and  332 B, a power supply  327 , and reflector  315 . The antenna  320  may be coupled to the radio frequency circuitry  325 . The antenna  320  may be affixed to a back wall  313  of the housing  310 . 
     In the example, the light sources  332 A and  332 B are coupled to a light source (LS) printed circuit board assembly (PCBA)  331 A and  331 B. The LS PCBA  331 A and  331 B are configured to supply power and control the supply of power to the light sources  332 A and  332 B. A discussion of the detailed operation of the LS PCBA  331 A and  331 B is unnecessary for an understanding of the luminaires as described herein, and will therefore be omitted. The light source  332 A or  332 B is located at a perimeter of the housing  310  in proximity close to an output aperture  314  of the housing  310 . The light source  332 A or  332 B is configured to emit light for general illumination of a space  390  in which the luminaire  300  is located. The light sources  332 A and  332 B are further configured, from their respective positions beyond the perimeter of the RF radiation transparent volume  388  to emit light toward the reflector  315 . The housing output aperture  314  encompasses an open space in the housing  310  through which the light emitted by the light source  332 A or  332 B and reflected by the reflector  315  is output as general illumination light to the space  390 . The housing output aperture  314  also enables RF signals to pass into and out of the housing  310  substantially without interference. The light source  332 A or  332 B is located beyond a perimeter of the RF radiation transparent volume  388  as well as beyond the perimeter of the housing aperture  314 . 
     The reflector  315  may be an internal reflector that may, for example, be mounted within the housing  310  to diffusely reflect the substantial emissions of visible light from the light source(s)  332 A and/or  332 B within the RF transparent volume  388  for the output of combined light from the sources  332 A and  332 B via the housing output aperture  314 . The configuration of the reflector  315  may be such that the combined light is distributed substantially uniformly for emission from the housing output aperture  314  into the space  390  as general illumination or specific task lighting. For example, when the luminaire  300  is implemented as general illumination lighting the outputted light conforms to governmental and industry standards, while if selected for task lighting, the outputted light may have an intensity appropriate for the selected task. In an example, the reflector  315  is a non-specular and non-metallic reflector (e.g. diffusely reflective) configured to minimize interference, or attenuation, RF signals within the field of view of antenna  320 . The antenna  320  may be affixed to the top of the reflector  315  substantially adjacent to the housing back wall  313 . In other examples, when the reflector is mounted within the housing, the reflector may be positioned in front of the antenna, while in other examples, the reflector, when mounted within the housing, may be positioned closer to the back wall of the housing than the antenna. The reflector may also be partially within the RF transparent volume when mounted within the housing, or may be around the RF transparent volume. 
     The RF circuitry  325  may be coupled to a power supply  327  that is configured to supply electrical power to the RF circuitry  325 . For example, the power supply  327  may receive power from AC mains (not shown) that supply electrical power to space  390 , a battery, or other source of electricity. The power supply  327  may be located within the housing  310  in an area, such as any location substantially out of the field of view of the antenna  320 . Alternatively, the power supply  327  may be located outside the housing  310 , for example, as in the example of  FIG. 2 . 
     One benefit of the luminaire structure in the example of  FIG. 3  is that such a configuration allows for integration of the antenna  320  in a luminaire  300  without substantially diminishing the performance of the antenna  320  or the illumination output of the luminaire  300 . Examples of antennas suitable for use as antenna  320  may include antennas configured to communicate in frequencies associated with radio frequency identification (RFID), Bluetooth®, ZigBee®, Wi-Fi and the like. The antenna  320  is coupled to the radio frequency circuitry  325 . 
     The radio frequency circuitry  325  is configured to emit or receive radio frequency signals, such as those associated with radio frequency identification (RFID), Bluetooth®, ZigBee®, Wi-Fi and the like. For example, the radio frequency circuitry  325  may include radio frequency identifier (RFID) reader circuitry. When the radio frequency circuitry  325  is configured as RFID reader circuitry, the RFID reader circuitry may include an RF transceiver (not shown). The RF transceiver supplies RF signals to and/or obtains RF signals via the antenna  320 . The radio frequency identifier reader circuitry  325  is located outside the housing  310 . 
     The housing  310  may include an RF radiation transparent volume  388  substantially free of RF radiation interfering materials. In the example of  FIG. 3 , the RF radiation transparent volume  388  extends from beneath the antenna  320  contained within the housing  310  to an RF radiation transparent aperture  389  at the housing output aperture  314 . The housing output aperture  314  may be a substantially unimpeded pathway for RF signals into and out of the RF radiation transparent volume  388 . In other examples, the RF radiation transparent volume  388  may include part of the antenna  320  and may or may not extend into the diffuser  345  below the housing output aperture  314 . The housing output aperture  314  may be a point where the housing sides  318  and  319  end nearest to the housing output aperture  314 . 
     The RF radiation transparent volume  388  is configured to pass RF signals substantially unattentuated or without radio frequency interference and in addition, is configured to pass the light reflected by reflector  315 , the light initially being emitted by the light source(s)  332 A or  332 B for general illumination. 
     The housing output aperture  314  may be completely, or partially, covered by a diffuser  345 . The diffuser  345  may include a light diffusing material, such as acrylic film or substrate, polycarbonate film or substrate, or the like, that is substantially transparent to RF radiation. In an example, the light source(s)  332 A or  332 B and the radio frequency identifier reader circuitry  325  are located outside the RF radiation transparent volume  388 . 
     An RF device  393  may exchange signals with the RF circuitry  325  via antenna  320 . The RF device  393  may, for example, be an RFID communication tag, a smartphone, a short-range handheld device, a computer peripheral device, such as a printer, copier, facsimile machine or the like, or any other wireless device that operates at a frequency compatible with the RF circuitry  325 . Depending upon the configuration of the space  390 , the RF signals to and from the RF device  393  may be interfered with, or attenuated, due to objects nearby the RF device  393 . For example, if the RF device is a smart phone in a purse or pocket and thereby positioned closer to the floor of the space  390 , a greater number of structures (e.g. metallic shelves, drop ceilings and the like) and objects (e.g. shopping carts, machinery, other RF sources, and the like) may interfere or attenuate the signals By providing an RF transparent volume in the luminaires, communication with the RF device  393  may be improved as the antenna field of view is greater in the disclosed luminaire examples. 
     In the example of  FIG. 3 , the reflector  315  extends from the housing output aperture  314  to the housing back wall  313 . However, other reflector configurations within luminaires are also contemplated. 
     In the example of  FIG. 4 , the reflector  415  does not extend to the back wall  413  of the housing  410 . Instead, the reflector  415  extends to a surface  421  of the antenna  420 . The luminaire example of  FIG. 4  includes elements similar to those shown in the luminaire  300  of  FIG. 3 . For example, the luminaire  400  includes radio frequency circuitry  425 , an antenna  420 , light sources  432 A and  432 B, a power supply  427 , and the reflector  415 . The antenna  420  and the power supply  427  may be coupled to the radio frequency circuitry  425 . The light sources  432 A and  432 B may be configured in a similar manner as light sources  332 A and  332 B. In an example, the light source(s)  432 A or  432 B and the radio frequency identifier reader circuitry  425  are located outside the RF radiation transparent volume  488 . 
     The RF radiation transparent aperture  489  is also configured to permit passage of the light emitted by the light source(s)  432 A or  432 B for general illumination. The luminaire  400  is shown without a diffuser. However, a diffuser, such as diffuser  345 , that is transparent to RF radiation may be included. 
     The reflector  415  extends from one side  418  to the other side  419  of the housing  410 , and is positioned to receive light emitted by the light sources  432 A and  432 B, and disperse the emitted light into the housing  410  and ultimately out of the luminaire  400 . 
     In the example of  FIG. 4 , the RF radiation transparent volume  488  extends from beneath the antenna  420  contained within the housing  410  to the housing output aperture  414 . In the example, the RF radiation transparent aperture  489  is located substantially on the same plane as the light sources  432 A and  432 B. The potential interference that may be caused by the light sources  432 A and  432 B and respective LS PCBAs  431 A and  431 B is minimized because of the light sources  432 A and  432 B and respective LS PCBAs  431 A and  431 B being located beyond a perimeter of the RF radiation transparent aperture  489 . 
     Other than the absence of a diffuser and the configuration of the reflector  415 , the coupling of the RF circuitry  425 , power supply  427  and antenna  420  in luminaire  400  are substantially similar to the coupling of the RF circuitry  325 , power supply  327  and antenna  320  in luminaire  300 , and therefore, a detailed discussion of the coupling of those elements is omitted for the sake of brevity. 
     Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain. For example, unless expressly stated otherwise, a parameter value or the like may vary by as much as ±10% from the stated amount. 
     The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections  101 ,  102 , or  103  of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed. 
     Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims. 
     It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “includes,” “including,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
     The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed examples require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed example. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter. 
     While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all modifications and variations that fall within the true scope of the present concepts.