Abstract:
This disclosure relates to antennas for wearable devices. In an aspect, the antenna includes an active portion that includes conductive traces that send and receive radiofrequency communication signals. The antenna also includes a ground plane. The antenna includes a spacer that provides separation between the active portion and the ground plane portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of International Patent Application No. PCT/US2013/020326, the disclosure of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     Devices capable of wireless communication have become pervasive in society. “Smart” portable devices such as smartphones and tablet computers are nearly ubiquitous. These devices are typically able to connect to wireless networks using a variety of radiofrequency standards, such as Wi-Fi, cellular, and Bluetooth. 
     There have been attempts to develop wearable devices that can offer much of the utility of these smart devices in a package that can be worn on the body. Such attempts have fallen short of the connectivity and performance that purchasers seek. Accordingly, there is a need in the art for a wearable wireless device that provides this desired performance and connectivity. 
     SUMMARY 
     It is to be understood that both the following general description and the following detailed description are exemplary and explanatory only and are not restrictive, as claimed. Provided is an antenna for a wearable device. 
     In one aspect, an antenna for a wearable device is described. The antenna can include an active portion that can include conductive traces that can send and receive radiofrequency communication signals. The antenna can also include a ground plane portion. The antenna can also include a spacer between the active portion and the ground plane portion. The spacer can provide separation between the active portion and the ground plane portion. The antenna can be a flexible printed circuit. 
     The spacer can be made from a dielectric material. The spacer can also include a cavity that can be filled with air. The spacer can have an inside surface that is generally disposed toward a body. The spacer can also have an outside surface that is generally disposed away from a body. The active portion of the antenna can be generally disposed on the outside surface of the spacer. The ground plane portion can be substantially disposed on the inside surface of the spacer. 
     The wearable device can include a band that can be worn on a body. The band can include active portion, the ground plane portion, and the spacer. In an aspect, the wearable device can be worn on a wrist. 
     In another aspect, a wearable radiofrequency device is described. The wearable radiofrequency device can include a band that allows the device to be worn. The wearable device can be configured to be worn on a wrist. The band can include an antenna. The antenna can include an active portion that includes conductive traces that are configured to send and receive radiofrequency communication signals. The antenna can also include a ground plane portion. The antenna can also include a spacer between the active portion and the ground plane portion that provides separation between the active portion and the ground plane portion. 
     The spacer can include an inside surface and an outside surface. The inside surface can be disposed toward a body. The outside surface can be disposed away from a body. The antenna can be mounted on the spacer such that the active portion is substantially disposed on the outside surface of the spacer and the around plane portion is substantially disposed on the inside surface of the spacer. The spacer can be made from a dielectric material. The spacer can also include a cavity. The cavity can include air. 
     In yet another aspect, an antenna assembly for a wearable radiofrequency device is described. The antenna assembly can include a flexible printed circuit antenna. The flexible printed circuit antenna can include an active portion that can include conductive traces that are configured to send and receive radiofrequency communication signals. The flexible printed circuit antenna can also include a ground plane portion. 
     The antenna assembly can also include a spacer that provides separation between the active portion and the ground plane portion. The spacer can include an inside surface that can be disposed toward a body when the wearable device is worn. The spacer can also include an outside surface that can be disposed away from a body when the wearable device is worn. The spacer can be made from a dielectric material. The flexible printed circuit antenna can be coupled to the spacer such that the active portion is substantially disposed on the outside surface and the ground plane portion is substantially disposed on the inside surface. 
     The antenna assembly can include a band that can be worn around a portion of a body. The band can be configured to be worn around a wrist. 
     Additional advantages will be set forth in part in the description which follows or may be learned by practice. The advantages will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments and together with the description, serve to explain the principles of the apparatus: 
         FIG. 1  is a perspective view of a wearable device in accordance with an exemplary embodiment of the apparatus described herein; 
         FIG. 2  is a diagram of an antenna in accordance with an exemplary embodiment of the apparatus described herein; 
         FIG. 3  is a perspective view of an antenna and antenna support in accordance with an exemplary embodiment of the apparatus described herein; and 
         FIG. 4  is a perspective view of an antenna support in accordance with an exemplary embodiment of the apparatus described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Before the present apparatus is disclosed and described, it is to be understood that the claimed apparatus is not limited to specific components, configurations, or to particular implementations described herein. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. 
     As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the distribution points of each of the ranges are significant both in relation to the other distribution point, and independently of the other distribution point. 
     “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. 
     Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other components, integers or steps. “Exemplary” means “an example of” and is not intended to convey an indication of a preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes. 
     Disclosed are components that can be used to make the described apparatus. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all apparatuses. This applies to all aspects of this application. 
     The present apparatus may be understood more readily by reference to the following detailed description of preferred embodiments and the examples included therein and to the Figures and their previous and following description. 
     Turning now to  FIG. 1 , a perspective view of a wearable device in accordance with an exemplary embodiment of the apparatus described herein is shown. In an exemplary embodiment, the wearable device  100  is a wrist-borne device. In alternative exemplary embodiments, the apparatus may be worn on other areas of the body, such as the ankle, waist, neck, or around other parts of the legs and/or torso. As one of skill in the art would understand, modifying the wearable device  100  to fit various parts of the body involves modifying the size and configuration of the band  110  so as to be the appropriate size and have the appropriate rigidity for a given application. Such modifications are within the scope of the present disclosure. 
     The wearable device  100  includes a band  110  and a housing  105 . The band  110  can be made from a suitable material and configured such that it can hold the wearable device  100  in place on the wrist. By way of example, the band  110  can be made from a thermoplastic elastomer (TPE). In alternative exemplary embodiments, the band  110  can be made from other suitable materials, such as, but not limited to, cloth, canvas, rubber, or silicone. The band  110  in the exemplary embodiment can be configured as a solid, moderately flexible band that is approximately C-shaped as shown in  FIG. 1 , however, alternative configurations of the band  110  are contemplated in this disclosure. For example, the band  110  can form a complete loop so long as the loop is either sufficiently flexible or detachable so as to be able to be put in place on the wrist. International Patent Application No. PCT/US2013/020326, which is incorporated by reference in its entirety, describes one such alternative configuration for the band  110 . In accordance with an exemplary embodiment, the band  110  is also configured to contain an antenna. The configuration of the antenna within the band  110  will be discussed in greater detail with respect to  FIGS. 2-4 . 
     The band  110  is coupled to a housing  105 . The housing  105  is configured to hold a communication device. By way of example, the communication device can be a device such as the device disclosed in International Patent Application No. PCT/US2013/020326. In an alternative exemplary embodiment, however, the communication device can be any type of communication device, such as a miniaturized smartphone, fitness monitor, pedometer, GPS device, biometric sensor, or any other device that can take advantage of the antenna in the band  110 . The size and shape of the housing  105  shown in  FIG. 1  is for illustrative purposes only and may be modified so as to suitably hold the chosen device. 
     Turning now to  FIG. 2 , an antenna  200  in accordance with an exemplary embodiment of the present invention is shown. The exemplary antenna  200  is configured to fit within the band  110  of the device, such that the band  110  completely envelopes at least the conductive portions of the antenna  200 . In alternative exemplary embodiments, certain conductive portions of the antenna  200  may be external to the band  110 . 
     In the exemplary embodiment, the antenna  200  is a flexible printed circuit (FPC). In alternative exemplary embodiments, the antenna  200  can be formed from stamped metal, plating over plastic, or other antenna creation techniques. The antenna  200  can include an active portion  205  that includes the radiating portions of the antenna  200 . The antenna  200  can also include a ground plane portion  210  that contains a ground plane  240 . 
     The active portion  205  of the exemplary antenna  200  can include conductive traces consistent with the wireless application for which the antenna  200  is to be used. By way of example, the antenna  200  shown in  FIG. 2  is designed to operate on a GSM (Global System for Mobile Communications) network in the United States. The exemplary antenna  200  shown in  FIG. 2  includes a first trace  215  that is connected to the transmitter and receiver. The first trace  215  emanates from a connection point  220  and splits into two portions. The first branch  225  of the first trace  215  splits off with a trace that is approximately as wide as the first trace  215 , and then ends in a trapezoidal trace. The second branch  230  of the first trace  215  remains approximately the same width as the first trace  215  and extends much of the length of the top portion of the antenna  200 . The second branch  230  then turns and runs substantially parallel to the top of the antenna  200 . The second branch  230  then turns again and runs substantially parallel with the side of the antenna  200 . In the exemplary embodiment, the first trace  215  is electrically isolated from the second trace and the ground plane  240 . 
     The exemplary antenna  200  includes a parasitic trace  235  that is electrically coupled to a ground plane  240 . The exemplary parasitic trace  235  extends upward from the ground plane  240  and turns away from the first trace  215 . The parasitic trace  235  then expands and terminates in a trapezoidal shape. 
     The ground plane portion  210  of the exemplary antenna  200  can include a ground plane  240 . The ground plane  240  is coupled to a ground line from the communication device (not shown). The antenna  200  can be configured so that it is bendable, and so that it can be folded along a fold line  245  that generally distinguishes the ground plane portion  210  of the antenna  200  from the radiating portion of the antenna  200 . The antenna  200  is also configured with several notches  255  and holes  250  that can be used to align the antenna  200  when mounting it in the wearable device  100 . 
     At the time of this application filing, GSM networks in the United States operate in frequency ranges from 824-849 MHz, 869-864 MHz, 1,850-1,910 MHz, and 1,930-1,990 MHz. However, one of skill in the art would understand that other types of wireless networks (such as CDMA networks), and networks in other countries, operate at different frequencies. One of ordinary skill in the art would be able to modify the conductive traces shown in the antenna  200  in  FIG. 2  to optimize antenna  200  performance for networks that operate at different frequencies. 
     Turning now to  FIG. 3 , the exemplary antenna  200  described in  FIG. 2  is shown installed on an exemplary band core  300 . In an exemplary embodiment, the antenna  200  would be mounted on the band core  300 , although in alternative exemplary embodiments, the conductive portions of the antenna can be stamped directly onto the band core. This assembly would then be inside the band  110  (described with respect to  FIG. 1 ). The band core  300 , in conjunction with the antenna  200 , provides certain functional advantages with respect to the wearable device  100 . For example, the core can provide rigidity that can support the antenna  200 . In addition, the core provides spacing between the ground plane  240  and the active portion  205 . This spacing both reduces the heat generated by the antenna  200 , and improves the antenna&#39;s  200  performance. In an exemplary embodiment, the core also includes posts  320  that can be inserted into holes in the antenna  200  so as to align the antenna  200  with the core. 
     In an exemplary embodiment, the ground plane  240  is located on the inside surface  305  of the core (body side of the band  110 ) while the active portion  205  of the antenna  200  is located on the outside surface  310  of the core (non-body side of the band  110 ). The fold line  245  is aligned with the top portion  315  of the core that marks the transition between the inside and the outside. This exemplary configuration, in combination with the spacing provided by the core, directs the antenna&#39;s  200  radiation pattern away from the body, while still providing sufficient performance to be able to allow the communication device to operate in conjunction with wireless networks. 
     Orienting the ground plane portion  210  and the active portion  205  of the antenna  200  as described herein also allows for the use of a larger ground plane  240  with respect to the active portion  205  of the antenna  200 . Conventional ground planes can generate a significant amount of heat, which, in some applications, is not a problem. However, in the context of a wearable device  100 , generating a significant amount of heat in a ground plane that is worn close to the body is not desirable, and may even be dangerous. A larger ground plane has improved ability to dissipate current generated in the ground plane by radiation from the active portion  205  of the antenna  200 , and therefore the larger ground plane  240  generates less heat. Further, because of the increased surface area, any heat generated is dissipated more quickly, and over a greater area, further reducing the amount of heat available to be transferred to the wearer of the device. Because the disclosed embodiments allow for the use of a larger ground plane  240  less heat is generated in the ground plane  240 , thus improving the performance of the antenna  200  for use in a wearable device  100 . 
     Turning now to  FIG. 4 , a perspective view of an exemplary embodiment of the band core  300  is shown.  FIG. 4  provides an additional view of the top portion  315 , inside surface  305 , outside surface  310 , and posts  320  for the exemplary embodiment, as set forth in  FIG. 3 . The exemplary embodiment of the band core  300  can also include a spacer  405  that provides separation between the active portion  205  of the antenna  200  and the ground plane portion  210 . The spacer  405  can also provide additional structural support to the band  110 . Because the spacer  405  provides insulation between the radiation emanating from the active portion  205  of the antenna  200  and the ground plane  240 . This separation further reduces the amount of heat generated in the ground plane  240 , as discussed above. 
     In an exemplary embodiment, the spacer  405  is made from injection-molded plastic, although in alternative exemplary embodiments, the spacer  405  may be made from any material having dielectric properties. The exemplary spacer  405  forms a cavity  410  between the inside surface  305  and the outside surface  310 , and in the exemplary embodiment, that cavity  410  can be filled with air, although in alternative embodiments the cavity  410  may be filled with any material that is not detrimental to the performance of the antenna  200 . The cavity  410  may also be a solid piece made from the same material as the band core  300 . 
     While the methods and systems have been described in connection with preferred embodiments and specific examples, it is not intended that the scope be limited to the particular embodiments set forth, as the embodiments herein are intended in all respects to be illustrative rather than restrictive. 
     Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification. 
     It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope or spirit. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit being indicated by the following claims.