Abstract:
Described herein are techniques related to near field coupling (e.g., wireless power transfers (WPF) and near field communications (NFC)) operations among others. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Description:
BACKGROUND 
     Recently, technologies have arisen that allow near field coupling (such as wireless power transfers (WPT) and near field communications (NFC)) between electronic devices in close proximity to each other and more particularly, thin portable electronic devices. Both near field coupling functions use radio frequency (RF) antennas in each of the devices to transmit and receive electromagnetic signals. Because of user desires (and/or for esthetic reasons) many of these portable devices are small, are becoming smaller as markets evolve, and have exaggerated aspect ratios when viewed from the side (i.e., they are “thin”). As a result, many of these thin devices incorporate flat antennas which use coils of conductive material as their radiating (or radiation receiving) antennas for use in near field coupling functions. 
     However, the small form factor of many devices interferes with the ability of the coils to couple. For instance, objects within the devices and near the coils might divert the flux of the magnetic field away from the coils. Notably, metallic objects tend to divert magnetic flux around themselves and, thus, away from the coils. Moreover, it might be the case that users want to transfer power and/or communicate using the devices without generating a strong magnetic field. Instead, users might prefer to use the often-limited onboard power of these devices to affect other functions (for instance, placing phone calls, receiving phone calls, accessing data over RF wide area networks such as the Internet, etc.). 
     In addition, users tend to prefer to hold certain devices and/or to set them down in certain orientations. For instance, some devices provide NFC functions by “bumping” the backs of two devices together. This back-to-back bumping is intended to place the coils in the two devices in close proximity to each other and in such a relative orientation that the coils couple relatively well. In some cases the location, shape, etc. of the two coils correspond to each other relatively closely during back-to-back bumps. Yet, for ergonomic reasons, users holding these devices might find it awkward to hold them in an orientation suitable for back-to-back bumping. In other instances, users might wish to affect WPT between the devices while using (or having available for use) one or both devices. Thus, to perform WPT from a laptop computer to a cellular telephone (for instance) users often do not wish to lay the cellular telephone on top of the keyboard of the laptop device (where the relative orientation and proximity of the coils facilitates their coupling). In many cases, users instead prefer to orient the devices involved in a side-by-side configuration. In other words, users often want to bump one side of one device to a side of another device in NFC scenarios and want to leave one device next to another in lengthier WPT scenarios, which often require some time to occur. 
     Unfortunately, with many small form factor (and, more specifically, “thin”) devices, side-by-side device orientations limit the ability of the coils in the devices to couple. In such relative orientations, the coils might be rather distant from one another and/or one coil might sense only the field generated at the edge of the other coil. Thus, placing such devices side-by-side might limit the rate at which WPT occurs because the portion of the field which the receiving coil happens to be in is so weak (or the relative orientation of the flux is such) as to limit the coupling of the receiving antenna with the magnetic field. In NFC scenarios, the bit rate associated with the communication can be similarly limited by the weak coupling of the coils. Similar considerations also apply to the transmitting coil and its ability to propagate the field in the presence of tightly integrated objects within the transmitting device. Yet users desire WPT and NFC functionality in an increasing number (and variety) of thin devices and they desire those functions with side-by-side operability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  illustrate perspective views of various devices in differing exemplary near field coupling arrangements. 
         FIG. 2  illustrates a top plan view of a partially disassembled device. 
         FIG. 3A  is a top plan view of a pair of devices. 
         FIG. 3B  is a schematic view of transmission and reception coils of a pair of devices. 
         FIG. 4  illustrates a flux pattern associated with a pair of transmitting and receiving coils. 
         FIG. 5  illustrates a flux pattern of another pair of transmitting and receiving coils. 
         FIG. 6  illustrates an interleaved antenna assembly. 
         FIG. 7  illustrates another interleaved antenna assembly. 
         FIG. 8  illustrates an interleaved antenna assembly including a guide extension. 
         FIG. 9  illustrates an interleaved antenna assembly including a pair of receiving coils. 
         FIGS. 10A and 10B  illustrate top plan views of an interleaved antenna assembly. 
         FIG. 11  illustrates an interleaved antenna assembly including a partial “S” shaped flux guide. 
     
    
    
     The following Detailed Description is provided with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number usually identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. 
     DETAILED DESCRIPTION 
     This document discloses one or more systems, apparatuses, methods, etc. for coupling antennas of devices and more particularly for coupling coil antennas of thin portable electronic devices for (among other uses) improving near field coupling capabilities of the devices. In particular, this document discloses an interleaved coil and ferrite configuration to facilitate near field coupling capabilities of the devices. Near field coupling includes (by way of illustration and not limitation) wireless power transfer (WPT) and/or near field communications (NFC) capabilities of the devices. 
       FIGS. 1A and 1B  illustrate perspective views of various devices in differing near field coupling arrangements. More particularly, many users have a desire to operate near field coupling enabled portable electronic devices and/or other devices in certain ergonomically convenient manners. Examples of such device include (but are not limited to) phones, cellular phones, smart phones, personal digital assistants, tablet computers, netbook computers, laptop computers, ultrabook computers, and various potentially wireless devices such as pointing devices (mice), keyboards, wireless disks, and the like. 
     For example,  FIG. 1A  shows a so-called “NFC bump” where two users  100 A and  100 B “bump” their NFC-enabled devices  102 A and  102 B together in an edge-to-edge or head-to-head manner to perform NFC-related information sharing functions. With conventional NFC-enabled devices, the near field coupling would be inefficient or ineffective because of reasons discussed in the Background section. In addition,  FIG. 1B  shows an often desired side-by-side arrangement of devices (such as laptop  102 C and smartphone  102 D) for NFC and/or WPT purposes. However, the mechanical integration of near field coupling components in conventional devices constrains the ability of users to effectively employ these desired arrangements. With reference to at least these constraints and/or others, exemplary implementations described herein free users to operate devices as they desire. 
       FIG. 2  illustrates a top plan view of a partially disassembled device. The emerging technologies related to near field coupling enable many appealing experiences for users of portable electronic devices. Providers of these devices typically include flat coil antennas in their design so that (in part) the devices can possess the thin aspect ratios and small form factors often sought by users. Moreover, these flat coil antennas allow for mechanical integration into these thin devices with comparative ease (when considering mechanical factors in isolation from other considerations such as the ability of the coils of different devices to couple with one another). For instance, integrating a flat printed circuit board (PCB), which incorporates a coil antenna, into a thin device usually minimizes the increase in the thickness of the device  202  due to the antenna itself. 
     With continuing reference to  FIG. 2 , the drawing illustrates a device  202  with its back cover  204  removed (and shown with its inside up). In the current embodiment, the device  202  happens to be a smart phone. However, the device  202  could be any of the variety of available portable electronic devices. With the back cover  204  removed,  FIG. 2  illustrates an antenna of this particular device  202  mounted on, embedded in, or otherwise associated with the back cover  204 . In the current embodiment the antenna happens to include a flat coil  206  and a pair of contacts  208  which are in electrical communication with the coil  206  and which positioned to electrically communicate with a corresponding pair of contacts  210  on a chassis  212  of the device  202  (shown face down). 
       FIG. 2  also illustrates that within the chassis  212  of the device  202 , the device  202  includes a battery  214 , and other metallic components  216  (or components including metallic structures) such as a printed circuit board (PCB)  218 , a camera  220 , etc. As is disclosed further herein with reference to at least  FIG. 3B , when the back cover  204  is placed on the chassis  212 , it places the coil  206  in electrical communication with other functional components of the device  202 . However, it also places the coil  206  in close proximity to some or all of the metallic components  216  (such as the battery  214 ). Of course, other device  202  configurations are within the scope of the disclosure. For instance, the coil  206  could be on the chassis  212  instead of the back cover  204 . In many devices  202  the metallic components  216  deflect the flux of magnetic fields (that might otherwise couple with the coil  206 ) away from the coil  206 . 
     As a result, when users attempt to perform near field coupling (e.g., WPT and/or NFC) functions between conventional devices, the presence of the metallic components  216  and the relative orientation and distance between the coils  206  inhibits the ability of the coils  206  to couple with the coils of the other device. In turn, the inability of the coils  206  to couple efficiently in conventional scenarios limits the ability to perform near field coupling (e.g., WPT and/or NFC) functions with these devices  202 . Accordingly, users cannot use conventional devices in many desired ways or must accept the back-to-back operability limitations of the conventional devices. 
     With reference again to  FIGS. 1A and 1B , the drawing illustrates ways in which the users would like to use the devices  102 . In general, users  100 A and  100 B desire to bump devices  102 A and  102 B along the sides as illustrated by  FIG. 1A . However, due to the constraints imposed on the relative orientation of conventional devices during the bump by the inability of the coils  206  to couple efficiently, users often find that they must bump the conventional devices along their respective backs to enable NFC functions. For some devices such as cellular telephones, this might be ergonomically feasible. However, for other devices (for instance, tablets) it might not be practicable. In contrast, side-to-side bumping (as shown in  FIG. 1A ) of devices  102 A and  102 B allows users  100 A and  100 B to hold the devices  102 A and  102 B in ergonomically desirable manners. 
     Moreover, users often desire to cause WPT functions to occur by placing devices side-by-side with other devices as illustrated in  FIG. 1B . In contrast, the inability of the coils  206  to couple efficiently with conventional devices forces users to place such devices on the top of another device (perhaps a charging mat) to cause a WPT function to occur. In some cases, as with a smart phone, users would find it inconvenient to place one device on top of another device (like a laptop computer). Instead, users often prefer placing devices side-by-side so that their sides (as shown in  FIG. 1B ) are generally proximate to one another. In such situations, the side-by-side placement of devices  102 C and  102 D allow users to use both devices even while WPT functions might be occurring. 
     Various embodiments described herein allow users to bump devices side-to-side and to place devices side-by-side for near field coupling functions (such as NFC and WPT) by improving the coupling between the coils  206  of one or more of such devices. More specifically, embodiments provide devices with strategically shaped, and placed, ferrite materials, which provide for better coupling of coils  206 . Devices of the current embodiment therefore enable new uses of devices  102  in regard to WPT, NFC, and other near field coupling functionality. 
     As disclosed further herein, devices that implement near field coupling-related functions use the coupling achieved by the coils  206  in those devices. Each of these coils  206  has an inductance associated with it, which can be chosen in conjunction with the resistive, capacitive, and other features of devices  202  to enable a common resonant frequency for the devices  202 . In such systems, the transmission efficiency n of power transfers from the transmitting coil  206  to the receiving coil  206  is often described in terms of the quality factors Q of each of the coils and a coupling coefficient k associated with the overall system. 
     More specifically, Equation 1 describes one such relationship: 
     
       
         
           
             
               
                 
                   
                     n 
                     = 
                     
                       
                         ( 
                         
                           1 
                           - 
                           
                             1 
                             kQ 
                           
                         
                         ) 
                       
                       2 
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     Where 
                     ⁢ 
                     
                       : 
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     Q 
                     = 
                     
                       SQRT 
                       ⁡ 
                       
                         ( 
                         
                           
                             Q 
                             TX 
                           
                           ⁢ 
                           
                             Q 
                             RX 
                           
                         
                         ) 
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       Q 
                       
                         TX 
                         , 
                         RX 
                       
                     
                     = 
                     
                       
                         wL 
                         
                           TX 
                           , 
                           RX 
                         
                       
                       / 
                       
                         R 
                         
                           TX 
                           , 
                           RX 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
               
             
           
         
       
         
         
           
             and 
           
         
       
    
     TX indicates the transmitting coil, RX indicates the receiving coil, k is a coupling coefficient, and w is a frequency of interest. 
     Often, in small and/or thin devices  202 , mechanical volume constraints restrict the size, shape, etc. of the transmitting and receiving coils  206 . For instance,  FIG. 2  illustrates that coil  206  deviates from its otherwise generally oblong shape near its upper, left corner. Moreover, the sidebands generated during NFC functions complicate the design of the transmitting and receiving coils  206  further by increasing the range of frequencies associated with those sorts of functions. As a result, the quality factors Q TX  and Q RX  of the transmitting and receiving coils  206 , as well as the system level quality factor Q, might not be optimized for either WPT functions, NFC functions, or both types of functions. Thus, electrical designers of such devices  202  sometimes find that they have little ability to influence the various quality factors Q TX , Q RX , and Q. 
     Nevertheless, embodiments provide systems characterized, in part, by coupling coefficients k designed with WPT and NFC functions in mind. Furthermore, in some embodiments, systems  300  possess coupling coefficients k that enable relatively higher power transmission efficiencies n for WPT functions and frequency ranges sufficiently broad for NFC functions. As is further disclosed herein, these coupling coefficients k depend on how much magnetic flux generated by the transmitting coil  206  penetrates the receiving coil  206  thereby inducing electrical current through that coil. While coupling coefficients k often depend on the geometry of the coils  206 , their relative locations, and the number and location of surrounding objects, embodiments provide flux guides, flux shields, flux wrappers, etc. that influence (and sometimes increase) the coupling coefficients k at frequencies w such as those used in WPT and/or NFC functions. With reference now to  FIGS. 3A and 3B , various considerations are disclosed. 
       FIG. 3A  is a top plan view of a pair of devices. More specifically,  FIG. 3A  illustrates a system  300  which includes two devices  302   TX  and  302   RX . System  300  might arise when a user brings one of the devices  302  into close proximity with the other device  302  as suggested by near field coupling-related protocols. Indeed, one or the other device  302   TX  might reside in a particular location for relatively long periods. In contrast, the other device  302   RX  might be designed to be relatively more mobile and might reside in some location for relatively shorter periods. For instance, device  302   TX  might be a laptop computer and device  302   RX  might be a smart phone as illustrated by  FIG. 3A . 
     Thus, system  300  generally arises as desired by the user or as it might otherwise happen that the devices  302  come into close proximity with each other. In many cases, though, users will want to use both devices  302  while they are in close proximity without constraints imposed by the ability of coils  306  within the devices to couple. Moreover, as is illustrated in  FIG. 3A , the locations, orientations, etc. of transmitting and receiving coils  306   TX  and  306   RX  in the transmitting and receiving devices  302   TX  and  302   RX  might not facilitate use of both devices  302  while near field coupling-related functions are occurring. Indeed, to enable such functions, previously available systems  300  often require that receiving device  302   RX  be place on top of the transmitting device  302   TX  to at least partially align and overlap the coils  306   RX  and  306   TX . 
     In the scenario illustrated by  FIG. 3A , the transmitting device  302   TX  includes the transmitting coil  306   TX  near its bottom and toward its front most, right corner. The receiving device  302   RX  includes a coil  306   RX  situated near its geometric center with portions of the receiving device  302   RX  extending outwardly there from. To align and overlap the coils  306  therefore requires that the receiving device  302   RX  be placed on or near the front, right corner of the transmitting device  302   TX . However, in that position it blocks access to much of the keyboard of the transmitting device  302   TX . It also leaves receiving device  302   RX  prone to slipping off transmitting device  302   TX  and in an awkward location for its use. That being said it might now be beneficial to turn to  FIG. 3B . 
       FIG. 3B  is a schematic view of transmission and reception coils of a pair of devices. Moreover,  FIG. 3B  illustrates that with the smaller of the two devices  302   RX  the coil  306   RX  happens to be positioned in close proximity to various components of the receiving device  302   RX  as is often the case. These components, and particularly metallic components  316  such as batteries, PCBs, etc., can significantly interfere with coupling between the transmitting coil  306   TX  and the receiving coil  306   RX . Moreover, it is noted here that such situations can arise because of the often-felt desire to mechanically integrate the physical components of the devices  302  in small and/or thin housings or chasses. 
       FIG. 4  illustrates a corresponding flux pattern associated with a pair of transmitting and receiving coils.  FIG. 4  also illustrate the results of a simplified simulation of how metallic components  416  (and other objects) can divert flux  408  of a magnetic field  410  away from coils  406  in various devices such as thin electronic devices (not shown). However, it is seen in  FIG. 4  that the corresponding devices are side-by-side each other. In the simplified simulation, transmitting and receiving coils  406   TX  and  406   RX  of typical thin devices were modeled in close enough proximity to one another so that WPT and NFC (non-limiting near field coupling) functions could occur according to the corresponding protocols. In addition, a typical metallic component  416  was modeled as a metallic box at a distance and relative orientation to the receiving coil  406   RX  typically found in thin devices. 
     On the left side of  FIG. 4 , a generally undisturbed pattern of flux  408  is observed near the transmitting coil  406 TX, as those skilled in the art will recognize. However, the presence of the metallic component  416  in the right side of the magnetic field  410  alters the magnetic field  410  and thus the flux in its vicinity. More specifically, near the center of the transmitting coil  406   TX  (and at a relatively large distance from the metallic component  416 ) the flux  408  flows upwardly from the transmitting coil  406  and begins to arc over to the right in a more or less mirror image of the left side of the magnetic field  410 . However, eddy currents (not shown) in the metallic component  416  generate their own magnetic fields (not shown) which influence diverted flux  412  to deviate from that mirror image of the magnetic field  410  associated with the left side of the transmitting coil  406   TX . Indeed, under the influence of these eddy-current-induced magnetic fields, the diverted flux  412  tends to flow around the metallic component  416  until it reaches the far end of the metallic component  416 . Whereupon, the diverted flux  412  arcs downwardly and thence around the surface of the metallic component  416  opposite the transmitting coil  406   TX  until it returns to the vicinity of the transmitting coil  406   TX . At that general location, the influence of the eddy currents in the metallic component  416  begin to fade and the diverted flux  412  returns to the center of the transmitting coil  406   TX  as illustrated. Thus, the metallic component  416  therefore lowers the apparent inductance of the receiving coil  406   RX  and weakens its coupling with the transmitting coil  406   TX . Of course, as with many devices  402 , many metallic components  416  could be in the proximity of either or both coils  406 . 
     In the meantime, the flux  414  of the relatively strong field generated at the edge  418  of the transmitting coil  406   TX  far from the receiving coil  406   RX  (hereinafter “flux  414 ”) follows a similar pattern but on a smaller scale. At the edge  418  of the transmitting coil  406   TX  adjacent to the edge  420  of the receiving coil  406   RX  much of the flux  414  departing the edge  418  encounters the metallic component  416  (or the influence of its eddy currents) and diverts around the same. Thus, the metallic component  416  also blocks and/or limits much of the flux  414  that might have otherwise reached and perhaps have even penetrated the receiving coil  406   RX . 
     As a result, little or no flux  408 , diverted flux  412 , or flux  414  can reach much less penetrate the receiving coil  406   RX . Accordingly, the coupling coefficient k of such an arrangement tends to be low perhaps being as little as 0.016 (or worse) with a correspondingly limited system level quality factor Q. With such a low coupling coefficient k, power transfer efficiencies n drop to such low levels that little if any power can be transferred from the transmitting coil  406   TX  to the receiving coil  406   RX . Likewise, the low-efficiency coupling of these coils  406  (in such situations) creates a correspondingly weak electric signal in the receiving coil  406   RX . Thus, if information was encoded into the electrical current driving the transmitting coil  406   TX  it becomes unlikely and/or difficult to recover that signal and hence the information appearing in the electrical current induced in the receiving coil  406   RX . As mechanically integrated into the receiving device  402   RX , metallic components  416  therefore inhibit both WPT and NFC functions. Embodiments, which improve the coupling coefficients k of various side-by-side systems, are disclosed with reference to  FIG. 5 . Embodiments do so, at least in part, by collecting and concentrating more of the flux emanating from  406 TX in  FIG. 4 . Doing so will likely increase the quality factors Q, coupling coefficients k, and efficiencies n of embodiments. 
       FIG. 5  illustrates another pair of transmitting and receiving coils.  FIG. 5  also illustrates a ferrite wrapper  500  in accordance with various embodiments. As is disclosed further herein, the ferrite wrapper  500  acts as a flux guide to guide flux into the receiving coil  506   RX  (and/or out of transmitting coils  506   TX ) in close proximity to metallic components  516 . Antenna assemblies of the current embodiment capture more of the left-to-right flowing flux discussed with reference to  FIG. 4  thereby increasing pertinent quality factors Q, coupling coefficients k, and effeciencies n. Moreover as flux guides, ferrite wrappers  500  of embodiments need not be made from ferrite. Rather, they can be made of any material having suitable properties such as electrical conductivity/resistivity, magnetic permeability, etc. As a result, embodiments provide devices and systems with coupling coefficients k, efficiencies n, and quality factors Q suitable for side-by-side near field coupling (WPT and NFC) functions. 
     In the current embodiment, the ferrite wrapper  500  defines three portions: a planar portion  504  and shield portions  503  and  505 . In alternative embodiments, the ferrite wrapper  500  may have just two portions, such a planar portion  504  and one of the shield portions  503  or  505 . In some embodiments, the ferrite wrapper  500  is made of one continuous sheet of ferrite and is formed into a channel or bowl shape with the shield portions  503  and  505  forming approximately 90-degree angles with the adjoining planar portion  504 . However, other angles and configurations are envisioned and within the scope of the disclosure. For instance, ferrite wrappers of some embodiments only have one shield portion  503  or  505  although some embodiments provide ferrite wrappers  500  with as many shield portions as might be desired to correspond to the shape of the metallic component(s)  516  with which it will cooperate as disclosed further herein. In some embodiments, the ferrite wrappers  500  are made from discrete, separate shield portions  503  and  505  and planar portions  504 . 
     With continuing reference to  FIG. 5 , in the current embodiment, the receiving coil  506   RX  is illustrated as being positioned toward the bottom or base of the receiving device (not shown). Of course, terms used herein such as “bottom,” “front,” “back,” “right,” left,” “base,” “bottom,” “top,” etc. merely indicate arbitrarily chosen surfaces of the devices and are not intended to limit the disclosure to any particular orientation or orientations of such devices. The surfaces may be two adjoining surfaces, such as the base (or bottom) of the housing and the side of the housing. Moreover, while  FIG. 5  illustrates the ferrite wrapper  500  being positioned in a receiving device, no such limitation is implied. Indeed, ferrite wrappers  500  can be positioned in transmitting devices and such embodiments are within the scope of the disclosure. 
     With reference still to  FIG. 5 , the ferrite wrapper  500  of the current embodiment is generally adjacent to the receiving coil  506   RX . More particularly, the planar portion  504  of the ferrite wrapper  500  is generally adjacent to and aligned with the receiving coil  506   RX  or at least a portion thereof. Moreover, planar portions  504  of some embodiments correspond in shape and size to the shape and size of the receiving coil  506   RX . However, planar portions  504  with shapes, sizes, etc. different from the shapes, sizes, etc. of the receiving coil  506   RX  are envisioned and are within the scope of the disclosure. It is also noted here that the term “generally planar” indicates that the pertinent object is generally flat although it might have some irregularities associated therewith. For instance, an offset of a few millimeters between one portion of a generally planar object and another portion of that same object would not render it non-planar. Nor would a small amount of curvature, surface irregularities, etc. of the sort typically found in available “flat” coils and/or PCBs and particularly as these objects might be mechanically integrated into thin devices. 
     That being said, in the current embodiment, the metallic component  516  is positioned in at least one angle of the ferrite wrapper  500  and can therefore said to be “wrapped” by the same. In accordance therewith, the shield portions  503  and  505  extend at least partially along the corresponding edges of the metallic object. Thus,  FIG. 5  illustrates ferrite wrapper  500  wrapping at least partially around the metallic component  516 . While  FIG. 5  illustrates ferrite wrapper  500  conforming closely to the shape of the metallic component  516 , no such limitation is implied. Instead, embodiments include ferrite wrappers  500  which allow gaps between themselves and metallic components  516  and which do not correspond in shape, or conform to, the metallic components  516 . Even with such deviations, the ferrite wrapper  500  of the current embodiment would “wrap” the metallic component  516  as is meant within the current disclosure. In the current embodiment, though, the metallic component  516  and the receiving coil  506   RX  sandwich the planar portion  504  of the ferrite wrapper  500  between themselves perhaps with some gaps there between. In addition,  FIG. 5  illustrates the resulting assembly positioned in a side-by-side orientation relative to transmitting coil  506   TX . 
     As is disclosed further herein (with reference to  FIG. 4 ), the eddy currents in the metallic component  516  usually do not significantly affect the magnetic field  510  in the volume illustrated on the left side of  FIG. 5 . However, on the side of the transmitting coil  506   TX  toward the receiving coil  506   RX , the magnetic field  510  behaves differently with the ferrite wrapper  500  in place than as disclosed with reference to  FIG. 4 . While some of the diverted flux  512  and/or flux  514  still flows around the metallic component  516 , some of the diverted flux  512  and flux  514  encounter the shield portion  503  on the side of the ferrite wrapper  500  positioned toward the transmitting coil  506   TX . 
     Because of the relatively high magnetic permeability of the ferrite (or other material) from which the ferrite wrapper  500  is made, at least some of the diverted flux  512  and/or flux  514  impinging on the shield portion  503  flows into the shield portion  503  of the ferrite wrapper  500 . Furthermore, once therein, that portion of the diverted flux  512  and/or flux  514  tends to follow the shape of the ferrite wrapper  500  from the shield portion  503  (where it entered) and into the planar portion  504 . Thus, the shield portion  503  of the ferrite wrapper  500  blocks that portion of the diverted flux  512  and/or flux  514  from encountering the metallic component  516  and therefore shields the metallic component(s)  516  behind it. Furthermore, that portion of the diverted flux  512  and/or flux  514  that enters the shield portion  503  (and any flux that enters the planar portion  504  through its edge facing the transmitting coil  506   TX ) becomes concentrated in and flows along the planar portion  504  of the ferrite wrapper  500 . But, it is believed that much more of that flux in the planar portion  504  is able to flow there from in a direction (downwardly) enabling it to penetrate the coil  504   RX  (which is in relatively close proximity to the planar portion  504 ). 
     It is also believed that the foregoing effect is due at least in part to the shape of the ferrite wrapper  500 , which facilitates the concentrated flux flowing in the planar portion  504  penetrating the receiving coil  506   RX . As a result, more of that flux couples with the receiving coil  506   RX  and induces electrical current therein then would otherwise have been the case without the ferrite wrapper  500 . The coupling coefficient k, efficiency n, and system level quality factor Q of the overall system (the transmitting coil  506   TX  and receiving coil  506   RX ) increases accordingly. 
     Moreover, in embodiments with more than one shield portions  503  and  505 , additional coupling can be achieved between the transmitting and receiving coils  506   TX  and  506   RX . For instance, near the shield portion  505  on the side of the ferrite wrapper  500  opposite the transmitting coil  506   TX , additional coupling can be achieved. In this situation, some of the diverted flux  512  will begin to arc downward as it flows passed the corresponding corner of the metallic component  516 . Some of that diverted flux  512  will continue downwardly passed the shield portion  505 . However, some of that diverted flux  512  will continue turning back toward the shield portion  505  and (because of its relatively high magnetic permeability) will enter therein. Again, the ferrite wrapper  500  guides that portion of the diverted flux  512  into the generally planar portion  504  of the ferrite wrapper  500  where it can couple with the receiving coil  506   RX . 
     Embodiments also provide systems in which both the transmitting coils  506   TX  and receiving coils  506   RX  have ferrite wrappers  500  associated therewith. Indeed, in some embodiments, only the transmitting coil  506   TX  has a ferrite wrapper associated with it. Moreover, it is envisioned that instead of a coil antenna being used for the transmitting antenna, a quarter torus antenna may be employed. 
     No matter the type of antenna used as the transmitting antenna, the flux flowing through the portion of the planar portion  504  of the ferrite wrapper  500  nearest the transmitting coil  506   TX  and the flux flowing through the opposite side of the planar portion  504  will have different directions. However, the directions of the flux in each of those portions of the planar portion  504  will (because of the mirrored geometry involved) correspond to the desired flux direction associated with the corresponding side of the receiving coil  506   RX . Accordingly, the effects of having another shield portion  505  of the ferrite wrapper  500  include further increasing the coupling of the coils  506   TX  and  506   RX , the coupling coefficient k, the efficiency n, and the system level quality factor Q. WPT and NFC functions (as well as other near field coupling-related functions) should therefore be facilitated by embodiments. It is noted here that simulations of such systems showed that such effects should result. Indeed, improvements in coupling coefficients k, efficiencies n, and system level quality factors Q ranged by factors between about 2.5 and about 3.0 for typical thin devices  500  with flux guides  500  with thicknesses of between 1 and 3 mm and with coils simulated at center-to-center distances between 45 mm and 65 mm. 
     Some embodiments provide portable devices, which include housings, metallic components, coils, and flux wrappers. Typically, the metallic components are positioned within the housing and define at least two surfaces. The coils define generally planar portions, which are positioned in the housings and in close proximity to the metallic components. In the current embodiment, portions of the flux wrappers are positioned between the metallic components and the generally planar portions of the coils. In addition, the flux wrappers wrap at least partially around each of the two surfaces of the metallic components. 
     In some embodiments, the portable devices are configured to be positioned side-by-side with other devices to perform near field coupling functions including wireless power transfer (WPT), near field communication (NFC), and a combination thereof. These portable devices can be (among others) mobile phones, cellular phones, smartphones, personal digital assistants, tablet computers, netbooks, notebook computers, laptop computers, multimedia playback devices, (digital) music players, (digital) video players, navigational devices, or digital cameras. In addition, the devices can be charging mats. 
     Moreover, in some embodiments, the coils can be configured to receive flux from fields of transmission coils. Alternatively, in some embodiments, the coil can be configured to generate fields (for coupling flux to receiving coils). These coils can be configured to resonate at either 6.78 MHz and 13.56 MHz or other frequencies. Various embodiments provide flux wrappers, which are continuous and/or made of ferrite. In addition, or in the alternative, the flux wrappers can wrap at least partially third surfaces of the metallic components. 
     Some embodiments provide portable devices, which include housings, metallic components, coils, and flux guides. Typically, the metallic components are positioned within the housing and define first and second surfaces. The coils are positioned in the housings and in close proximity to the metallic components and define generally planar portions. Furthermore, the flux guides define generally planar flux guide portions positioned between the generally planar coil portions and the first surfaces of the metallic components. These flux guides also define shield portions positioned adjacent to the second surfaces of the metallic components. 
     Various embodiments therefore provide more user-friendly information and power sharing arrangements. For instance, embodiments improve the ability of electronic devices to perform WPT and NFC functions with fewer data dropouts, with fewer communication interruptions, with increased efficiency, etc. Some embodiments, moreover, allow for side-to-side bumping of devices for communicating information between the devices. For instance, embodiments allow side-to-side bumping for peer-to-peer NFC-based information sharing between tablet computing devices, which would otherwise be ergonomically awkward if users had to comply with back-to-back bumping. In the alternative, or in addition, some embodiments allow for side-by-side power transfers as shown in  FIG. 1B  among other capabilities. For instance, embodiments provide demonstrated side-by-side wireless charging of smart phones from notebook computers. 
       FIG. 6  illustrates an interleaved antenna assembly. As is disclosed further herein with reference to at least  FIG. 4 , inefficient coupling of the coils of conventional devices limits near field coupling related-functions.  FIG. 6  illustrates flux guide  600 , which can improve coupling for such near field coupling related-functions by concentrating flux, and guiding it through the coil along a coherent path. The flux guide  600  includes two generally planar guide portions  604 A and  604 B in addition to an offsetting guide portion  624 . The offsetting guide portion  624  provides an offset h 1  between the planar guide portions  604 A and  604 B. The flux guide  600  interleaves with two generally planar coil portions  606 A and  606 B of a coil  606 . More specifically, the coil  606  mounts to a PCB (not shown) which defines another offset h 2  and an aperture  626 . 
     In the current embodiment, aperture  626  and offsetting guide portion  624  of the flux guide  600  are positioned such that a significant portion of the flux penetrating the coil is confined within the flux guide and routed through the coil along a coherent path. For a planar spiral coil, this means passing through the coil assembly within the innermost turn. By way of example,  FIG. 6  illustrates this with a momentary snapshot of an AC field. The direction of flux in flux guide portion  604 A is substantially from left to right in accordance to the field illustrated by  608 A; the direction of flux in the offsetting guide portion  624  is substantially from bottom to top according to field lines  608 A and  608 B; and the direction of flux in flux guide portion  604 B is substantially left to right according to field line  608 B. In this manner, the flux guide routes flux through coil  606 A and B in coherent direction. Often, the optimal position for the offsetting guide portion of the flux guide happens to be near the center of the coil  606 . But that is not always the case. For instance, coil  606  might have an irregular and/or asymmetric, shape and/or one or more magnetic fields that the coil might encounter might also have irregularities associated therewith (or otherwise be asymmetrical). Nonetheless,  FIG. 6  illustrates a generally symmetric flux guide  600  with generally planar flux guide portions  604 A and  604 B beginning approximately at the centrally located aperture  626  and extending outwardly to either side. Likewise, the planar coil portions  606 A and  606 B also begin at approximately the aperture  626  and extend outwardly there from. 
     Interleaved embodiments (see for instance,  FIGS. 6-11 ) are expected to be relatively effective at preventing eddy currents from being generated in metallic objects  616  since they prevent large currents from circulating in the metal. Since eddy currents in the metallic objects  616  tend to decrease pertinent quality factors Q, coupling coefficients k, and efficiencies w, such embodiments are expected to improve such design/performance criteria. 
     Although the flux guide  600  is described above and illustrated in  FIG. 6  as having two offset planar guide portions  604 A and  604 B with the offsetting guide portion  624  connecting them, other implementations may be shaped differently but yet retain the overall general planar arrangement and functionality. For example, in another implementation, the three portions (e.g., two planar guide portions and offsetting guide portion) may be part of a single sheet where all portions are within the same plane. This solo-plane sheet may be inserted through the aperture  626  between coil portions  606 A and  606 B of the coil  606 . In one implementation, the solo-plane sheet may be arranged horizontally, which would cause the portions  606 A and  606 B to be offset from each other. In another implementation, the solo-plane sheet may be arranged askew from the horizontal, which would allow the portions  606 A and  606 B to be arranged horizontal or nearly so (i.e., without any offset or with little offset). Moreover, the shape of the particular offsetting guide portion  624  shown in  FIG. 6  does not limit the disclosure. While  FIG. 6  illustrates offsetting guide portion  624  having an overall stair shape, it is noted here that it could be “S” shaped and/or continuous (or smooth) without departing from the scope of the disclosure. 
     The coil  606  and flux guide  600  therefore define an interleaved antenna assembly. The interleaved antenna assembly can be positioned adjacent to one or more metallic components  616  in a device so that diverted flux (of one type or another) can be gathered and guided to the planar coil portions  606 A and  606 B by the flux guide  600 . 
       FIG. 7  illustrates another interleaved antenna assembly. As shown, the particular flux guide  700  only includes one generally planar guide portion  704 A and an offsetting guide portion  724 . That guide portion  724  is positioned within an aperture  726  formed between the coil  706 . 
     Partially interleaved antenna assemblies  700  of the current embodiment might find use when some improvement in system-level performance is desired but increasing the thickness of the overall device is not desired. 
     Moreover, as those skilled in the art will appreciate, flux guides  700  and flux guides  500  (see  FIG. 5 ) with only one shield portion  503  or  505  share a common “L” shaped configuration. As such, and depending on the length of the offsetting guide portion  724  and/or shield portion  503  and/or  505 , it is envisioned and within the scope of the disclosure that such flux guides can be used. In either case, flux guides  700  of embodiments might enhance the ability of coils  706  to couple with magnetic fields despite the presence of metallic components  716   
       FIG. 8  illustrates an interleaved antenna assembly including a guide extension. The flux guide  800  of  FIG. 8  includes two planar guide portions  804 A and  804 B and is shown in conjunction with a coil  806  having an offset as in  FIG. 6 . Moreover, flux guide  800  includes a guide extension portion  805 , which serves to gather additional flux from the magnetic field(s) in which the coil  806  is situated and guides it to one or both planar guide portions  804 A and  804 B. As such, it might be desirable for the guide extension portion  805  to cover as much of the side of the metallic object  816  as is practicable within the constraints imposed by mechanically integrating the interleaved antenna assembly of the current embodiment into a housing or chassis of a device. Of course, the guide extension portion  805  could extend across just a portion of the metallic component  816  or even beyond it as might be desired. In any case, the guide extension portion  805  will likely increase the coupling coefficient k, quality factors Q, power transfer efficiencies n, etc. of systems involving such assemblies by more effectively routing flux near the coil, thereby increasing coil-coil coupling, k. 
     Indeed, interleaved antenna assemblies with one guide extension portion  805  were compared against non-interleaved antenna assemblies with one guide shield portion  505  (see  FIG. 5 ). Note that the guide extensions (or shield portions) were both on the side of the respective metallic components  516  and  816  opposite the transmitting antenna. The simulations revealed, that for typical thin device configurations, the interleaved antenna assemblies of  FIG. 8  exhibited approximately 13% to approximately 38% higher power transfer efficiencies, n, than the non-interleaved antenna assemblies of  FIG. 5 . 
     As with the other interleaved embodiments, the current embodiment concentrates flux within the planar guide portion  804 A. That flux  828  then flows through the offsetting guide portion  824 , the other planar guide portion  804 B and then up through the extension  805  and out there from and away from the metallic component  816 . As a result, the metallic component  816  senses less current in its vicinity and the eddy currents there in are expected to decrease in a corresponding manner. Accordingly, it is believed that interleaved antenna assemblies according to embodiments of the current disclosure will likely improve the coupling of coils  806  to various magnetic fields. Moreover, they can do so even in the presence of metallic components  816 . Indeed, simulations have revealed that significant increases in power transfer efficiencies can be expected with interleaved antenna assemblies of the current embodiment over conventional antennas. 
       FIG. 9  illustrates an interleaved antenna assembly including a pair of receiving coils. Antenna assemblies of the current embodiment also increase concentrate the flux flowing through each of the coil elements  906  A, B, C, and D, improving the pertinent quality factors Q, coupling coefficients k, and efficiencies n of systems built in accordance therewith. More specifically, the device of the current embodiment includes a pair of planar coil portions  906 A and  906 B (forming one coil or sub-coil) on one side of a metallic component  916 . Adjacent to an adjoining side of the metallic component  916 , the interleaved coil assembly includes another pair of planar coil portions  906 C and  906 D (forming another coil or sub-coil). These additional planar coil portions  906 C and  906 D communicate with the other planar coil portions  906 A and  906 B and serve to couple with flux near the adjoining side of the metallic component  916 . Together, planar coil portions  906 A,  906 B,  906 C, and  906 D can be considered as one coil if desired since they all electrically communicate with one another. Thus, the coil of the current embodiment will couple better with other coils than if it only had planar coil portions  906 A and  906 B. Interleaved antenna assemblies of the current embodiment can be employed in devices with space alongside their metallic components  916  and/or those devices in which the device envelope can be expanded in a corresponding direction. In the alternative, or in addition, the size of the coil  906  could be reduced to accommodate the interleaved flux guide  904  while still achieving overall improved coupling. 
     In addition to the additional planar coil portions  906 C and  906 D, devices of the current embodiment further includes planar guide portions  904 C and  904 D interleaved with these planar coil portions  906 C and  906 D. Again, an offsetting guide portion  924 B (in addition to offsetting guide portion  924 A) provides continuity between the planar guide portions  904 C and  904 D such that they can guide flux to the planar coil portions  906 C and  906 D. It is noted here that planar guide portions  904 A,  904 B,  904 C, and  904 D can be formed integrally with each other or can be bonded together in such a manner that flux can flow through the flux guide  900 . For instance, flux guide  900  could be formed from a continuous sheet of ferrite. Of course, the current embodiment also provides an aperture  926 B (in addition to aperture  926 A) in the coil  906  through which offsetting guide portion  924 B passes. While  FIG. 9  illustrates a one-to-one correspondence between the various planar portions of the coil  906  and the various planar portions of the flux guide  900 , no such correspondence is required for the practice of embodiments. For instance, embodiments include differing numbers of these planar portions are within the scope of the disclosure. 
     As noted previously, planar coil portions  906 C and  906 D and planar coil portions  906 A and  906 B electrically communicate with each other. However, in the current embodiment, these pairs of planar coil portions have an orthogonal relative orientation. As a result, according to the “right-hand rule” relationship between current and flux direction, the flux that might couple with one pair of planar coil portions  906 A and  906 B will induce current in the overall coil  906 , which opposes the current induced in the other pair of planar coil portions  906 C and  906 B in some configurations. Moreover, the coupling between antennas might be low for a number of reasons such as their overall orientation, nearby metallic components, etc. However, as is disclosed further herein,  FIGS. 10A and 10B  illustrate embodiments that alleviate such situations. Again, compared to conventional devices, interleaved antenna assemblies such as those illustrated by  FIGS. 9 and 10  will likely increase system-level coupling coefficients k, quality factors Q, and power transfer efficiencies n in a variety of situations. 
       FIGS. 10A and 10B  illustrate top plan views of an interleaved antenna assembly. The interleaved antenna assembly of  FIGS. 10A and 10B  illustrates that the coil  1006  of the current embodiment is configured in a “figure 8” shape. More specifically, planar coil portions  1006 A and  1006 B form one of the lobes of the figure 8 shape while planar coil portions  1006 C and  1006 D form the other lobe. As a result, despite the orthogonal orientation of the pairs of planar coil portions  1006 A and  1006 B and  1006 C and  1006 D (when folded around a metallic component  916  as shown in  FIG. 9 ), the induced currents therein will superimpose constructively rather than destructively. 
     Moreover,  FIG. 10A  shows that the flat coil  1006  (or rather the PCB or other structure which carries it) defines two apertures  1026 A and  1026 B through which corresponding offsetting guide portions  1024 A and  1024 B pass when the flux guide  1000  and coil  1006  are assembled as shown by  FIG. 10B . The flux guide  1000  of the current embodiment therefore defines four planar guide portions  1004 A,  1004 B,  1004 C, and  1004 D. These planar guide portions  1004 A,  1004 B,  1004 C and  1004 C interleave with the four planar coil portions  1006 A,  1006 B,  1006 C, and  1006 D as follows. For instance, in the current embodiment, the most proximal planar guide portion  1004 A lies under or adjacent to one side of the coil  1006  (or planar coil portion  1006 A). Offsetting guide portion  1024 A is positioned in aperture  1026 A so that both planar guide portions  1004 B and  1004 C lie on top of or adjacent to the other side of coil  1006  (or planar coil portions  1006 B and  1006 C respectively). Offsetting guide portion  1024 B passes through aperture  1026 B so that planar guide portion  1004 D lies under or adjacent to planer coil portion  1006 D. Thus, the flux guide  1000  and coil  1006  form an interleaved antenna assembly with some planar guide portions  1004 A and  1004 D on one side of the coil  1006  while other planar guide portions  1004 B and  1004 B are on the other side of the coil  1006 . 
     The interleaving of the coil  906  and flux guide  900  can be accomplished by sliding one end of the flux guide  1000  through one of the apertures  1026 A,  1026 B and then sliding the other end of the flux guide  1000  through the other aperture  1026 A or  1026 B. Furthermore, as a comparison of  FIGS. 9 and 10  reveals, the interleaved flux guide  1004  and coil  1006  can be folded through an appropriate angle (as shown approximately 90 degrees) to form an angled or “L” shaped structure. The interleaved antenna assembly (as configured into such an angled shape) can be positioned adjacent to adjoining sides of metallic components  1016 . One of the effects of interleaved antenna assemblies of the current embodiment is that planar guide portions  1004 A,  1004 B,  1004 C, and  1004 D guide flux to corresponding planar coil portions  1006 A,  1006 B,  1006 C, and  1006 D thereby enhancing coupling between coil  1006  and various magnetic fields. 
       FIG. 11  illustrates an interleaved antenna assembly including a partial “S” shaped flux guide. More specifically, the interleaved antenna assembly  1100  of  FIG. 11  includes a pair of planar coil portions  1106 A and  1106 B as well as interleaved planar guide portions  1104 A and  1104 B. The interleaved antenna assembly  1100  also includes a guide extension  1105  and an offsetting guide portion  1124 . However, it also includes planar guide portions  1104 C and  1104 D which, together with planar guide portion  1104 A and offsetting guide portion  1124  generally enclose planar coil portion  1106 A. Moreover, as illustrated by  FIG. 11 , the planar guide portions  1104 A,  1104 B,  1104 C and  1104 D and the offsetting guide portion  1124  form a partial “S” shape. The current interleaved antenna assembly  1100  is expected to capture and route most, if not, all of the left-to-right flowing flux from the left set of coil turns to the right set of coil turns thereby improving the amount of that flux captured as compared to conventional systems. Accordingly, improved quality factors Q, coupling coefficients k, and efficiencies n are expected to flow from the current embodiment. 
     Thus, embodiments provide devices exhibiting increased coupling coefficients k, quality factors Q, power transfer efficiencies n, etc. These features enable improve near field coupled-related functionality even when devices are bumped or placed in side-by-side orientations. Indeed, even compared to conventional systems using high volume antennas, illustrative embodiments improve power transfer efficiencies by between approximately 13% and approximately 38%. Furthermore, embodiments provide such enhanced functionality while mechanically integrating with small form factor and/or thin devices. Moreover, depending on the fabrication techniques employed, embodiments can be built into integrated circuits (ICs) and/or micro-machined electro-mechanical (MEMS) devices. Indeed, it is envisioned and within the scope of the current disclosure that interleaved antenna assemblies of various embodiments can be fabricated using semi-conductor fabrication techniques currently available as well as those yet to be developed. 
     Some embodiments provide antenna assemblies, which include interleaved coils and flux guides. More particularly, in the current embodiment, the coils are mounted on a printed circuit board and define a location where the flux associated with the coil reverses direction. In addition, the coils define two generally planar coil portions and an aperture located approximately at the location of the flux reversal. These planar coil portions are offset from one another in a direction generally perpendicular to themselves. Moreover, they begin at approximately the location of the flux reversal. The flux guides are made from a sheet of ferrite and define two generally planar guide portions and an offsetting portion. The offsetting portion is between the planar guide portions and is positioned in the aperture at the flux reversal location. Each planar guide portion is adjacent to one of the planar coil portions while the offsetting portion is generally perpendicular to the planar guide portions and the planar coil portions. 
     Various embodiments provide antenna assemblies with coils and flux guides. The coils define generally planar coil portions and locations where the flux associated with the coils reverses directions. The flux guides define generally planar guide portions and are interleaved with the coil at the location of the flux reversal. In some embodiments, the flux guide is made from a continuous sheet of ferrite. In some embodiments, the coil and the flux guide each define second generally planar portions, which are adjacent to each other. Moreover, these second planar portions can be on opposite sides of the coil from one another. 
     Antenna assemblies of some embodiments also include extensions of the coil and of the flux guide. In the case of the guide extension, it can extend beyond an edge of the coil, can be perpendicular to the coil (or a portion thereof), and can serve as a flux shield (or portion thereof) to gather flux and guide it to one or more of the guide planar portions. These extensions can be interleaved with each other at a second location where the flux associated with the antenna reverses directions. In addition, or in the alternative, the coil can be configured as a “figure 8.” In some embodiments, the coil resonates at either 6.78 MHz and 13.56 MHz. 
     Moreover, some embodiments provide portable electronic devices with such interleaved antennas therein. Additionally these devices include housings and metallic components within those housings. Interleaved coils and flux guides are adjacent to the first surface of the metallic component in the current embodiment. Moreover, when the antenna includes second planar coil and guide portions, those second planar coil and guide portions can be adjacent to a second surface of the metallic object. Some embodiments provide guide extensions, which are adjacent to the second surface of the metallic object. Furthermore, the devices can be mobile phones, cellular phones, smartphones, personal digital assistants, tablet computers, netbooks, notebook computers, laptop computers, multimedia playback devices, digital music players, digital video players, navigational devices, digital cameras, charging mats, ultrabooks, mouses, keyboards, mobile hotspot producing devices, wireless hard drives, and/or wireless docking stations. 
     Various embodiments provide antenna assemblies, which include coils and flux guides. More specifically, in some embodiments, the coils each define at least one generally planar coil portion and a location where flux, which is (or will be) associated with the coil reverses directions. Additionally, the flux guide defines a generally planar portion and an offsetting portion. The generally planar guide and coil portions are generally adjacent to each other. In some embodiments, the planar guide and planar coil portions are interleaved at the offsetting portion whereas in some embodiments the offsetting portion extends away from the planar coil portion. 
     Although the subject matter has been disclosed in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts disclosed above. Rather, the specific features and acts described herein are disclosed as illustrative implementations of the claims.