Abstract:
In one embodiment, the antenna arrangement includes a primary antenna having a conductive sidewall; and a loop antenna disposed in and physically separated from the primary antenna. The loop antenna includes a first conductive loop and a capacitor electrically connected between ends of the first conductive loop.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This U.S. non-provisional application claims the benefit of priority under 35 U.S.C. §119 to U.S. Provisional Application No. 62/117,024 filed on Feb. 17, 2015 in the USPTO, and Korean Patent Application No. 10-2015-0055642 filed on Apr. 21, 2015 in the Korean Intellectual Property Office (KIPO), the entire contents of each of which are incorporated by reference herein in their entireties. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    Example embodiments relate generally to electronic devices and, more particularly, to portable devices, and near field communication chips embedded in the portable devices. 
         [0004]    2. Description of the Related Art 
         [0005]    A portable device, such as a smart phone, has been widely used because of its high portability. Further, as one type of the portable device, there is a wearable electronic device that is used while being worn on a body, such as a wrist, a neck, a head, etc. of a human (or an animal), and the use of the wearable electronic device has been gradually increased. However, a conventional wearable electronic device cannot provide a near field communication (NFC). Thus, a wearable electronic device having an NFC function has been developed. However, the wearable electronic device can perform the near field communication at a back surface of the wearable electronic device opposite to a front surface where a display panel is located, and thus the wearable electronic device should be taken off to perform the near field communication. 
       SUMMARY 
       [0006]    At least one embodiment relates to an antenna arrangement. 
         [0007]    In one embodiment, the antenna arrangement includes a primary antenna having a conductive sidewall; and a loop antenna disposed in and physically separated from the primary antenna. The loop antenna includes a first conductive loop and a capacitor electrically connected between ends of the first conductive loop. 
         [0008]    At least one embodiment relates to a portable device. 
         [0009]    In one embodiment, the portable device includes an NFC chip; a case configured to generate a first magnetic field based on an electrical signal from the NFC chip; and a loop antenna physically separated from the NFC chip and the case. The loop antenna is configured to magnetically couple to the case such that the loop antenna forms a second magnetic field in response to the first magnetic field. 
         [0010]    In another embodiment, the portable device includes a case, a near field communication (NFC) device and a loop antenna. The case includes a conductive material, and has at least a first terminal. The NFC device is electrically connected to the first terminal of the case, and is configured to provide an electrical signal to the case such that the case radiates a first magnetic field based on the electrical signal. The loop antenna is disposed inside the case, and is configured to magnetically couple to the case such that the loop antenna forms a second magnetic field in response to the first magnetic field. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Illustrative, non-limiting example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. 
           [0012]      FIG. 1  is a diagram illustrating an example of a portable device according to some example embodiments. 
           [0013]      FIG. 2  is a diagram for describing a configuration of a portable device according to some example embodiments. 
           [0014]      FIG. 3  is a diagram illustrating an example of a case employed in a portable device according to some example embodiments. 
           [0015]      FIG. 4  is a diagram illustrating an example of a loop antenna employed in a portable device according to some example embodiments. 
           [0016]      FIG. 5  is a diagram illustrating another example of a loop antenna employed in a portable device according to some example embodiments. 
           [0017]      FIGS. 6A through 6D  are diagrams for describing examples of a capacitor included in a loop antenna of a portable device according to some example embodiments. 
           [0018]      FIG. 7  is a diagram illustrating a portable device according to some example embodiments. 
           [0019]      FIG. 8  is a diagram for describing a configuration of a portable device according to some example embodiments. 
           [0020]      FIG. 9  is a diagram illustrating a portable device according to some example embodiments. 
           [0021]      FIG. 10  is a diagram for describing a configuration of a portable device according to some example embodiments. 
           [0022]      FIG. 11  is a diagram illustrating a portable device according to some example embodiments. 
           [0023]      FIG. 12  is a diagram for describing a configuration of a portable device according to some example embodiments. 
           [0024]      FIG. 13A  is a diagram for describing a configuration of a portable device according to some example embodiments, and  FIG. 13B  is a diagram for describing a connection relationship among a case, a loop coil and a near field communication (NFC) chip. 
           [0025]      FIG. 14  is a diagram for describing an example of a connection relationship among an NFC chip, a matching circuit, a case and a loop antenna in a portable device according to some example embodiments. 
           [0026]      FIG. 15  is a diagram for describing another example of a connection relationship among an NFC chip, a matching circuit, a case and a loop antenna in a portable device according to some example embodiments. 
           [0027]      FIG. 16  is a diagram for describing still another example of a connection relationship among an NFC chip, a matching circuit, a case and a loop antenna in a portable device according to some example embodiments. 
           [0028]      FIG. 17  is a diagram for describing a portable device including an inductor between a matching circuit and a case according to some example embodiments. 
           [0029]      FIG. 18  is a diagram for describing a portable device including a low pass filter between a matching circuit and a case according to some example embodiments. 
           [0030]      FIG. 19  is a diagram for describing a portable device that performs a near field communication, wireless charging, and/or a magnetic secure transmission according to some example embodiments. 
           [0031]      FIG. 20  is a diagram for describing a configuration of a portable device according to some example embodiments. 
           [0032]      FIG. 21  is a diagram for describing an example of a portable device performing a near field communication according to some example embodiments. 
           [0033]      FIG. 22  is a diagram for describing another example of a portable device performing a near field communication according to some example embodiments. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0034]    Various example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some example embodiments are shown. The present inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. 
         [0035]    It will be understood that when an element or layer is referred to as being “on,” “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Like numerals refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0036]    It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present inventive concepts. 
         [0037]    Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0038]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present inventive concepts. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0039]    Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized example embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present inventive concepts. 
         [0040]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concepts belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0041]      FIG. 1  is a diagram illustrating an example of a portable device according to some example embodiments,  FIG. 2  is a diagram for describing a configuration of a portable device according to some example embodiments,  FIG. 3  is a diagram illustrating an example of a case employed in a portable device according to some example embodiments,  FIG. 4  is a diagram illustrating an example of a loop antenna employed in a portable device according to some example embodiments,  FIG. 5  is a diagram illustrating another example of a loop antenna employed in a portable device according to some example embodiments, and  FIGS. 6A through 6D  are diagrams for describing examples of a capacitor included in a loop antenna of a portable device according to some example embodiments. 
         [0042]    Referring to  FIG. 1 , a portable device  100  according to some example embodiments may be any electronic device that can be carried by a user. For example, the portable device  100  may be any electronic device, such as a cellular phone, a smart phone, a tablet computer, a laptop computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigation system, etc. 
         [0043]    Further, in some example embodiments, the portable device  100  may be a wearable electronic device that is used while being worn on a body of the user, such as a wrist, a neck, a head, etc. For example, as illustrated in  FIG. 1 , the portable device  100  may be a wrist-worn electronic device  100 , such as a smart watch, a wrist band electronic device, etc. In other examples, the portable device may be any wearable electronic device, such as a necklace type electronic device, a glasses type electronic device, etc. 
         [0044]    In some example embodiments, an appearance of the portable device  100  may be provided by a display panel  120 , a case (or a housing)  140  and a band portion  160 . The display panel  120  may display an image. In some example embodiments, the display panel  120  may be an organic light emitting diode (OLED) display panel or a liquid crystal display (LCD) panel, but not limited thereto. In some example embodiments, the display panel  120  may be a curved display panel having a curved surface or a flat display panel having a flat surface, but not limited thereto. Further, in some example embodiments, the display panel  120  may have any shape, such as a circular shape, a rectangular shape, a polygonal shape having five or more sides, an elliptical shape, or the like. In some example embodiments, the display panel  120  may include any type of touch sensor, such as an add-on type touch sensor, an on-cell type touch sensor, an in-cell type touch sensor, etc. 
         [0045]    The band portion  160  may be formed to be readily worn by the user. In some example embodiments, the band portion  160  may include one or more materials, such as rubber, silicone, plastic, Mylar, vinyl, metal, etc. 
         [0046]    The case (or housing)  140  may support the display panel  120 , and may define an internal space along with the display panel  120 . In some example embodiments, the case  140  may expose a button, a camera lens, an infrared module, etc. The case  140  may include a conductive material. In some example embodiments, the case  140  may be a metal case including a metal material. In this example, at least a portion of the case  140  may be formed of any metal material having a desired strength and a desired electrical conductivity. In some example embodiments, the case  140  may have a side wall portion and a back cover portion. The side wall portion of the case  140  may be formed of the conductive material or the metal material, and the back cover portion of the case  140  may be formed of a nonconductive material. In other example embodiments, both of the side wall portion and the back cover portion of the case  140  may be formed of the conductive material or the metal material. For example, the side wall portion and/or the back cover portion of the case  140  may include at least one of copper (Cu), aluminum (Al), iron (Fe), titanium (Ti), silver (Ag), palladium (Pd), platinum (Pt),  aurum  (Au), nickel (Ni) and the like. In some example embodiments, the case  140  may have a unitary structure where the side wall portion and the back cover portion are integrally formed. In other example embodiments, the side wall portion and the back cover portion may be attached to each other to form the case  140 . Since at least the portion of the case  140  is formed of the metal material, the portable device  100  may have an improved strength and a good appearance. 
         [0047]    A main board may be located in the internal space defined by the case  140 . Various electrical components may be disposed on the main board. For example, a processor controlling an operation of the portable device  100  may be disposed on the main board. In some example embodiments, the processor may be any processor, such as an application processor (AP), a central processing unit (CPU), a microcontroller (MCU), etc. 
         [0048]    A memory may be further disposed on the main board. The memory may store a boot image for booting the portable device  100 , or may store data transmitted/received to/from an external device. For example, the memory may include a volatile memory, such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a mobile DRAM, DDR SDRAM, LPDDR SDRAM, GDDR SDRAM, RDRAM, etc., and/or a nonvolatile memory, such as an electrically erasable programmable read-only memory (EEPROM), a flash memory, a phase change random access memory (PRAM), a resistance random access memory (RRAM), a nano floating gate memory (NFGM), a polymer random access memory (PoRAM), a magnetic random access memory (MRAM), a ferroelectric random access memory (FRAM), etc. 
         [0049]    In some example embodiments, the processor and the memory may be packaged as a package on package (PoP). In other example embodiments, the processor and the memory may be packaged in various forms, such as ball grid arrays (BGAs), chip scale packages (CSPs), plastic leaded chip carrier (PLCC), plastic dual in-line package (PDIP), die in waffle pack (DIWP), die in wafer form (DIWF), chip on board (COB), ceramic dual in-line package (CERDIP), plastic metric quad flat pack (MQFP), thin quad flat pack (TQFP), small outline IC (SOIC), shrink small outline package (SSOP), thin small outline package (TSOP), system in package (SIP), multi-chip package (MCP), wafer-level fabricated package (WFP), or wafer-level processed stack package (WSP). 
         [0050]    In some example embodiments, various components, such as a power management integrated circuit (PMIC), a sensor, an audio codec, a Bluetooth controller, etc., may be further disposed on the main board. For example, the sensor may include an accelerometer, a gyroscope, a heart rate sensor, etc. In some example embodiments, the processor, the memory, the PMIC, the sensor, and the like may be disposed on one surface of the main board. In other example embodiments, the processor, the memory, the PMIC, the sensor, and the like may be disposed on both surfaces of the main board. 
         [0051]    The portable device  100  according to some example embodiments may include a near field communication (NFC) chip connected to the case  140 . In some example embodiments, the NFC chip may be located in the internal space defined by the case  140 . The NFC chip may be located on the main board. In some example embodiments, the NFC chip may be located in any position, such as inside the band portion  160 . The NFC chip may include an NFC controller connected to the case  140 . The NFC controller may perform a near field communication by providing an electrical signal to the case  140 . 
         [0052]    In some example embodiments, the NFC chip may further include a secure storage device connected to the NFC controller. The secure storage device may store information to be transferred to an external device through the near field communication. For example, the secure storage device may store payment information (e.g., credit card information), an encryption key, etc. For example, the secure storage device may be an embedded secure element (eSE). In some example embodiments, the NFC controller and the secure storage device may be packaged as one chip (or one package) using a system in package (SIP) technique. 
         [0053]    The case  140  may have first and second terminals spaced apart from each other, and at least one of the first and second terminals of the case  140  may be connected to the NFC chip. In some example embodiments, the NFC chip may output a differential electrical signal, and the first and second terminals of the case  140  may be connected to the NFC chip to receive the differential electrical signal. In other example embodiments, the NFC chip may output a single-ended electrical signal, one of the first and second terminals of the case  140  may be connected to the NFC chip to receive the singled-ended electrical signal, and the other of the first and second terminals of the case  140  may be grounded. In still other example embodiments, the NFC chip may output a differential electrical signal, the differential electrical signal may be converted into a single-ended electrical signal by a transformer (e.g., a balun (balanced-to-unbalanced) transformer), one of the first and second terminals of the case  140  may be connected to the NFC chip to receive the singled-ended electrical signal, and the other of the first and second terminals of the case  140  may be grounded. 
         [0054]    The NFC chip may provide the electrical signal to the case  140 , and the case  140  may radiate a first magnetic field based on the electrical signal. For example, as illustrated in  FIG. 2 , the case  140  and  240  of the portable device  100  and  200  may have a first terminal T 1  and a second terminal T 2 , and the NFC chip may provide the electrical signal to the first terminal T 1  and/or the second terminal T 2  of the case  140  and  240 . According to some example embodiments, a current path  250  may be formed in a direction from the first terminal T 1  to the second terminal T 2 , or in a direction from the second terminal T 2  to the first terminal T 1 , or the direction of the current path  250  may be dynamically changed. To achieve a sufficient length of the current path  250 , the first terminal T 1  and the second terminal T 2  may be spaced apart from each other. In some example embodiments, as illustrated in  FIG. 2 , the first and second terminals T 1  and T 2  of the case  140  and  240  may be spaced apart from each other such that a loop antenna  280  and a capacitor C are located between the first and second terminals T 1  and T 2  of the case  140  and  240 . For example, the second terminal T 2  may be located near (or substantially on) a straight line  265  connecting the first terminal T 1  and a center point of the internal space  260  defined by the case  140  and  240 . In this case, the current path  250  may be formed at a shorter one (e.g., a lower region of the case  140  and  240  in an example of  FIG. 2 ) of two regions between the first terminal T 1  and the second terminal T 2 . In another example, the second terminal T 2  may be 120 degrees from the first terminal T 1  on the case. When the NFC chip provides the electrical signal to the first terminal T 1  and/or the second terminal T 2 , the electrical signal (e.g., a current) may flow through the current path  250  of the case  140  and  240 , and thus the case  140  and  240  may radiate a first magnetic field. The case  140  and  240  may radiate the first magnetic field not only toward the outside of the portable device  100  and  200 , but also toward the internal space  260 . 
         [0055]    Although  FIG. 2  illustrates an example where the side wall portion of the case  140  and  240  has a circular shape, according to some example embodiments, the side wall portion of the case  140  and  240  may have any shape, such as an elliptical shape, a rectangular shape, a polygonal shape, etc. For example, as illustrated in  FIG. 3 , a side wall portion of a case  240   a  defining an internal space  260   a  may have a rectangular shape. In this case, to achieve a sufficient length of a current path  250   a , the case  240   a  may have first and second terminals T 1  and T 2  that are spaced apart from each other and are located near a straight line  265   a  that bisects the internal space  260   a.    
         [0056]    In a conventional portable device using a case or a side wall portion of the case as an antenna, a slit is formed at the side wall portion of the case, and terminals to which an electrical signal is applied are located adjacent to each other such that the slit (or an insulator filled in the slit) is located between the terminals. However, in the portable device  100  and  200  according to some example embodiments, the case  140  and  240  or the side wall portion of the case  140  and  240  may have a unitary structure with no slit. Accordingly, compared with the conventional portable device where the slit (or the insulator filled in the slit) is formed at the side wall portion of the case, the case  140  and  240  of the portable device  100  and  200  according to some example embodiments may have an improved waterproof function and an improved aesthetic impression. 
         [0057]    As illustrated in  FIG. 2 , a loop antenna  280  and capacitor C may be further located in the internal space  260  defined by the case  140  and  240  of the portable device  100  and  200 . The loop antenna  280  and capacitor C may be spaced apart from the case  140  and  240  such that the loop antenna  280  and capacitor C are not physically connected to the case  140  and  240 . Further, the loop antenna  280  and capacitor C may not be physically connected to the NFC antenna, and may not receive the electrical signal from the NFC chip. However, the loop antenna  280  and capacitor C may be magnetically (or mutual-inductively) coupled to the case  140  and  240 . Thus, based on the first magnetic field radiated by the case  140  and  240 , a current may flow through a current path  290  of the loop antenna  280  and capacitor C in a direction (e.g., a counter-clockwise direction in an example of  FIG. 2 ) the same as a direction of the current path  250  of the case  140  and  240 , and, by this current flow, a second magnetic field may be radiated at the loop antenna  280  and C. 
         [0058]    Thus, the case  140  and  240  of the portable device  100  and  200  according to some example embodiments may have the relatively short current path  250 . And, magnetic field radiation efficiency of the case  140  and  240  may be reduced due to the relatively short current path  250 . However, since the second magnetic field is additionally radiated by the loop antenna  280  and capacitor C that are magnetically coupled to the case  140  and  240 , total magnetic field radiation efficiency of the portable device  100  and  200  may be improved. Accordingly, the portable device  100  and  200  according to some example embodiments may efficiently perform the near field communication using the case  140  and  240  and the loop antenna  280  and C. In some example embodiments, to efficiently receive power based on the first magnetic field radiated by the case  140  and  240 , the loop antenna  280  and capacitor C may have a resonance frequency substantially the same as a resonance frequency of the case  140  and  240 . For example, the case  140  and  240  and the loop antenna  280  and capacitor C may have substantially the same resonance frequency of about 13.56 MHz. 
         [0059]    In some example embodiments, the loop antenna  280  and capacitor C may include a loop coil  280  located inside the case  140  and  240  and a capacitor C connected between a first end E 1  and a second end E 2  of the loop coil  280 . The loop coil  280  may be located in the internal space  260  defined by the case  140  and  240 , and may be spaced apart from the case  140  and  240 . The loop coil  280  may be formed of any metal material having a high conductivity, such as copper, silver, aluminum, etc. Although  FIG. 2  illustrates an example where the loop coil  280  has three turns, the loop coil  280  may have an appropriate number of turns for a desired inductance according to example embodiments. For example, the loop coil  280  may have one or more turns. Further, although  FIG. 2  illustrates an example where the loop coil  280  has a circular shape, according to some example embodiments, the loop coil  280  may have any shape, such as an elliptical shape, a rectangular shape, a polygonal shape, etc. For example, as illustrated in  FIG. 4 , the loop coil  280   a  may have the rectangular shape. In some example embodiments, the loop coil  280  may be formed as a single layer. In other example embodiments, the loop coil  280  may have a multi-layer structure. That is, the loop coil  280  may be formed at two or more layers. For example, as illustrated in  FIG. 5 , a loop antenna  300  may include a loop coil  380   a  and  380   b  having the multi-layer structure. The loop coil  380   a  and  380   b  may include a first loop coil  380   a  formed at a first layer L 1  and a second loop coil  380   b  formed at a second layer L 2 . The loop antenna  300  may further include a capacitor C connected between a first end E 1  and a second end E 2  of the loop coil  380   a  and  380   b  having the multi-layer structure. According to some example embodiments, to form the loop coil  380   a  and  380   b  having the multi-layer structure, the first and second loop coils  380   a  and  380   b  may be disposed on opposite surfaces of the same substrate (or film), or may be disposed on different substrates (or films). 
         [0060]    The capacitor C connected between the first and second ends E 1  and E 2  of the loop coil  280  may have an appropriate capacitance such that the loop antenna  280  and capacitor C has desired resonance frequency (e.g., about 13.56 MHz). According to some example embodiments, the capacitor C may be implemented in various forms. In some example embodiments, as illustrated in  FIG. 6A , the loop antenna  400   a  may include, as the capacitor C, a chip capacitor  490   a  that is implemented as a chip. The chip capacitor  490   a  may be connected between the first and second ends E 1  and E 2  of the loop coil  480   a . In other example embodiments, the capacitor C may be formed by metal patterns extending from the first and second ends E 1  and E 2  of the loop coil  280 . For example, as illustrated in  FIG. 6B , the loop antenna  400   b  may include a metal-insulator-metal (MIM) capacitor  490   b . The MIM capacitor  490   b  may be formed by metal patterns that extend from the first and second ends E 1  and E 2  of the loop coil  480   b  and are formed at different layers. In another example, as illustrated in  FIG. 6C , the loop antenna  400   c  may include an edge-coupled capacitor  490   c . The edge-coupled capacitor  490   c  may be formed by metal patterns that extend from the first and second ends E 1  and E 2  of the loop coil  480   c  and are located adjacent to each other. In still another example, as illustrated in  FIG. 6D , the loop antenna  400   d  may include an interdigital capacitor  490   d . The interdigital capacitor  490   d  may be formed by metal patterns that extend from the first and second ends E 1  and E 2  of the loop coil  480   c  and have a comb shape. 
         [0061]    The portable device  100  and  200  according to some example embodiments may perform the near field communication by radiating the first magnetic field using the case  140  and  240  connected to the NFC chip and by further radiating the second magnetic field using the loop antenna  280  and capacitor C magnetically coupled to the case  140  and  240 . In the portable device  100  and  200  according to some example embodiments, the case  140  and  240  (or the side wall portion of the case  140  and  240 ) may have the unitary structure having no slit, and thus the waterproof function and the aesthetic impression of the case  140  and  240  and the portable device  100  and  200  may be improved. Further, since the loop antenna  280  and capacitor C magnetically coupled to the case  140  and  240  forms the second magnetic field in response to the first magnetic field formed at the case  140  and  240 , the magnetic field radiation efficiency of the portable device according to some example embodiments may be improved. 
         [0062]    Each of the following described embodiments may employ or incorporate any aspect of the foregoing embodiments except for the noted or implied differences. 
         [0063]      FIG. 7  is a diagram illustrating a portable device according to some example embodiments, and  FIG. 8  is a diagram for describing a configuration of a portable device according to some example embodiments. 
         [0064]    Referring to  FIGS. 7 and 8 , a portable device  500  includes a display panel  520 , a case  540  that supports the display panel  520  and defines an internal space, a main board  530  located in the internal space defined by the case  540 , a band portion  560  configured to be worn on a body of a user, and a loop antenna  580  located between the display panel  520  and the main board  530 . 
         [0065]    The main board  530  is located inside the case  540 , and a processor may be disposed on the main board  530 . The processor may control an operation of the portable device  500 . In some example embodiments, a memory, a PMIC, a sensor, etc. may be further disposed on the main board  530 . In some example embodiments, an NFC chip for performing a near field communication may be further disposed on the main board  530 , and the NFC chip may be connected to the case  540 . 
         [0066]    The case  540  may have a side wall portion defining a side surface of the portable device  500  and a back cover portion defining a back surface of the portable device  500 . In some example embodiments, the case  540  may have a unitary structure where the side wall portion and the back cover portion are integrally formed, for example, molded. In other example embodiments, the side wall portion and the back cover portion may be separately formed, and then attached to each other. 
         [0067]    The case  540  may include a conductive material (e.g., a metal material), and may radiate a first magnetic field based on an electrical signal provided by the NFC chip. That is, the portable device  500  may perform the near field communication by radiating the first magnetic field in all directions using the case  540 . The first magnetic field may be radiated not only to the outside, but also to the inside of the case  540 . Accordingly, the first magnetic field radiated by the case  540  may be provided to the loop antenna  580  that is magnetically coupled to the case  540 . 
         [0068]    The loop antenna  580  may be located between the display panel  520  and the main board  530  inside the case  540 . The loop antenna  580  magnetically coupled to the case  540  may form a second magnetic field in response to the first magnetic field formed at the case  540 . For example, when an NFC chip applies the electrical signal to terminals of the case  540 , a current may flow through a region of the case  540  between the terminals, and thus the first magnetic field may be radiated at the case  540 . The first magnetic field radiated at the case  540  may be provided to the loop antenna  580 , and thus, in the loop antenna  580 , a current may be induced in the same direction as the current in the case  540 , which results in the radiation of the second magnetic field. Although the second magnetic field radiated by the loop antenna  580  may be shielded by the main board  530 , the second magnetic field may pass through the display panel  520  since the loop antenna  580  is located between the display panel  520  and the main board  530 . That is, the loop antenna  580  may radiate the second magnetic field in a front direction of the portable device  500 , and thus the portable device  500  may perform the near field communication with an external device located in front of the portable device  500 . 
         [0069]    Accordingly, in a case where the portable device  500  is a wearable electronic device (e.g., a smart watch), the wearable electronic device may perform the near field communication while being worn on a body of a user. 
         [0070]    In some example embodiments, the portable device  500  may further include a magnetic sheet disposed under a back surface of the loop antenna  580 . That is, the magnetic sheet may be located between the loop antenna  580  and the main board  530 . The magnetic sheet may improve magnetic field radiation efficiency of the loop antenna  580  by preventing the magnetic field for the near field communication from being reduced by an eddy current caused by a change of the magnetic field at the main board  530 . For example, the magnetic sheet may be a ferrite sheet or a magneto-dielectric material (MDM) sheet. 
         [0071]      FIG. 9  is a diagram illustrating a portable device according to some example embodiments, and  FIG. 10  is a diagram for describing a configuration of a portable device according to some example embodiments. 
         [0072]    Referring to  FIGS. 9 and 10 , a portable device  600  includes a display panel  620 , a case  640  that supports the display panel  620  and defines an internal space, a main board  630  located in the internal space defined by the case  640 , a band portion  660  configured to be worn on a body of a user, and a loop antenna  680  located between the main board  630  and a back cover portion  640   b  of the case  640 . The portable device  600  of  FIGS. 9 and 10  may have a similar configuration to a portable device  500  of  FIGS. 7 and 8 , except for a location of the loop antenna  680 . 
         [0073]    The case  640  may have a side wall portion  640   a  defining a side surface of the portable device  600  and the back cover portion  640   b  defining a back surface of the portable device  600 . In some example embodiments, the side wall portion  640   a  may be formed of a conductive material (e.g., a metal material), and the back cover portion  640   b  may be formed of a nonconductive material (e.g., a nonmetal material or an insulating material). The side wall portion  640   a  and the back cover portion  640   b  may be attached to each other. 
         [0074]    The side wall portion  640   a  may have first and second terminals spaced apart from each other, and an NFC chip may be connected to at least one of the first and second terminals of the side wall portion  640   a . The side wall portion  640   a  of the case  640  may have a unitary structure with no slit, and thus a waterproof function and an aesthetic impression of the side wall portion  640   a  of the case  640  may be improved. The NFC chip may provide an electrical signal to the case  640  (or the side wall portion  640   a ), and the case  640  (or the side wall portion  640   a ) may radiate a first magnetic field. 
         [0075]    The loop antenna  680  may be located between the main board  630  and the back cover portion  640   b  inside the case  540 . The loop antenna  680  magnetically coupled to the case  640  (or the side wall portion  640   a ) may form a second magnetic field in response to the first magnetic field formed at the case  640  (or the side wall portion  640   a ). Although the second magnetic field radiated by the loop antenna  680  may be shielded by the main board  630 , the second magnetic field may pass through the back cover portion  640   b  formed of the nonconductive material. That is, since the loop antenna  680  is located between the main board  630  and the back cover portion  640   b , the loop antenna  680  may radiate the second magnetic field in a direction passing through the back cover portion  640   b  of the cover  640 . Accordingly, the portable device  600  may perform a near field communication with an external device located in the back of the portable device  600 . 
         [0076]    In some example embodiments, the portable device  600  may further include a magnetic sheet disposed on a surface of the loop antenna  680  opposite to the direction toward the back cover portion  640   b . That is, the magnetic sheet may be located between the main board  630  and the loop antenna  680 . The magnetic sheet may improve magnetic field radiation efficiency of the loop antenna  680 . 
         [0077]      FIG. 11  is a diagram illustrating a portable device according to some example embodiments, and  FIG. 12  is a diagram for describing a configuration of a portable device according to some example embodiments. 
         [0078]    Referring to  FIGS. 11 and 12 , a portable device  700  includes a display panel  720 , a case  740  that supports the display panel  720  and defines an internal space, a main board  730  located in the internal space defined by the case  740 , a band portion  760  configured to be worn on a body of a user, a first loop antenna  780  located between the display panel  720  and the main board  730 , and a second loop antenna  785  located between the main board  730  and a back cover portion  740   b  of the case  740 . The portable device  700  of  FIGS. 11 and 12  may have a similar configuration to a portable device  500  of  FIGS. 7 and 8  or a portable device  600  of  FIGS. 9 and 10 , except the loop antenna  780  and  785 . 
         [0079]    The case  740  may have a side wall portion  740   a  defining a side surface of the portable device  700  and the back cover portion  740   b  defining a back surface of the portable device  700 . In some example embodiments, the side wall portion  740   a  may be formed of a conductive material (e.g., a metal material), and the back cover portion  740   b  may be formed of a nonconductive material (e.g., a nonmetal material or an insulating material). The side wall portion  740   a  may have first and second terminals spaced apart from each other, and an NFC chip may be connected to at least one of the first and second terminals of the side wall portion  740   a . The NFC chip may provide an electrical signal to the case  740  (or the side wall portion  740   a ), and the case  740  (or the side wall portion  740   a ) may radiate a first magnetic field. 
         [0080]    The first loop antenna  780  may be located between the display panel  720  and the main board  730  inside the case  740 , and the second loop antenna  785  may be located between the main board  730  and the back cover portion  740   b  inside the case  740 . Each of the first and second loop antennas  780  and  785  may be magnetically coupled to the case  740  (or the side wall portion  740   a ), and may form a second magnetic field in response to the first magnetic field formed at the case  740  (or the side wall portion  740   a ). The second magnetic field radiated by the first loop antenna  780  may pass through the display panel  720 , and the second magnetic field radiated by the second loop antenna  785  may pass through the back cover portion  740   b  of the case  740 . Thus, the first loop antenna  780  may radiate the second magnetic field in a direction passing through the display panel  720 , and the second loop antenna  785  may radiate the second magnetic field in a direction passing through the back cover portion  740   b  of the case  740 . Accordingly, the portable device  700  according to some example embodiments may perform a near field communication with an external device located at any position. In some example embodiments, the portable device  700  may further include a magnetic sheet located the first loop antenna  780  and the main board  730 , and/or a magnetic sheet located the main board  730  and the second loop antenna  785 . 
         [0081]      FIG. 13A  is a diagram for describing a configuration of a portable device according to some example embodiments, and  FIG. 13B  is a diagram for describing a connection relationship among a case, a loop coil and a near field communication (NFC) chip. 
         [0082]    Referring to  FIGS. 13A and 13B , compared with a portable device  200  illustrated in  FIG. 2 , a portable device  800  may further include a loop coil  830  surrounding a loop antenna  880 . 
         [0083]    A case  840  may have first and second terminals T 1  and T 2  spaced apart from each other, and an NFC chip  870  may be connected to the first and second terminals T 1  and T 2  of the case  840 . The NFC chip  870  may provide an electrical signal to the first and second terminals T 1  and T 2  of the case  840 , and the electrical signal (e.g., a current) may flow through a current path  850  of the case  840  between the first and second terminals T 1  and T 2 . Accordingly, the case  840  may radiate a first magnetic field. 
         [0084]    The loop coil  830  may be connected to the NFC chip  870  in parallel with the case  840 . For example, one end E 3  of the loop coil  830  may be connected to a terminal of the NFC chip  870  to which the first terminal T 1  of the case  840  is connected, and the other end E 4  of the loop coil  830  may be connected to a terminal of the NFC chip  870  to which the second terminal T 2  of the case  840  is connected. Accordingly, the loop coil  830  may receive the electrical signal provided from the NFC chip  870 , and may additionally radiate the first magnetic field based on the electrical signal, which results in strengthening the first magnetic field provided to the loop antenna  880 . In response to the first magnetic field radiated by the case  840  and the loop coil  830 , a current may flow through a current path  890  in the loop antenna  880 , and thus the loop antenna  880  may radiate a second magnetic field. 
         [0085]    As described above, in the portable device  800  according to some example embodiments, the loop coil  830  magnetically coupled to the NFC chip  870  in parallel with the case  840  may be located to surround the loop antenna  880 , and thus the first magnetic field may be sufficiently provided to the loop antenna  880  by the loop coil  830 . Accordingly, even if the loop antenna  880  is distant from the case  840 , or even if the case  840  has low magnetic field radiation efficiency, the first magnetic field may be sufficiently provided to the loop antenna  880 , and the portable device  800  may accurately perform the near field communication. 
         [0086]      FIG. 14  is a diagram for describing an example of a connection relationship among an NFC chip, a matching circuit, a case and a loop antenna in a portable device according to some example embodiments. 
         [0087]    Referring to  FIG. 14 , a portable device  900  according to some example embodiments may include a display panel, a case (e.g., a metal case)  950  that supports the display panel and has first and second terminals T 1  and T 2  spaced apart from each other, and a loop antenna  970  located inside the case  950 . The loop antenna  970  may be spaced apart from the case  950 , and, may be magnetically coupled to the case  950 . Further, an NFC package  910  may be embedded in the portable device  900 . 
         [0088]    The NFC package  910  may include an NFC chip  911  having an NFC controller  912  that performs a near field communication by providing an electrical signal to the case (e.g., the metal case)  950 . The NFC controller  912  may be connected to at least one of first and second terminals T 1  and T 2  of the case  950 , and may apply the electrical signal to the at least one of first and second terminals T 1  and T 2  of the case  950 . Accordingly, the case  950  may radiate a first magnetic field based on the electrical signal, and the loop antenna  970  magnetically coupled to the case  950  may form a second magnetic field in response to the first magnetic field. In some example embodiments, the NFC package  910  may operate in an NFC card mode. In the NFC card mode, the NFC controller  912  may perform a transmitting operation and/or a receiving operation through a first transmission terminal TX 1  and a second transmission terminal TX 2 . In other example embodiments, the NFC package  910  may operate in an NFC reader mode, and may have terminals for transmitting/receiving electrical signal for the NFC reader mode. 
         [0089]    In some example embodiments, the NFC package  910  may further include a secure storage device  914  connected to the NFC controller  912 . The secure storage device  914  may store information to be transferred to an external device through the near field communication using the first and second magnetic fields. For example, the secure storage device  914  may store payment information (e.g., credit card information), an encryption key, etc. In some example embodiments, the secure storage device  914  may be an embedded secure element (eSE). In some example embodiments, the NFC controller  912  and the secure storage device  914  may be packaged as one chip  910  using a system in package (SIP) technique. 
         [0090]    In some example embodiments, the case  950  may be a metal case formed of a metal material. The case  950  may have the first and second terminals T 1  and T 2  spaced apart from each other. The case  950  may be represented by an inductor as an equivalent circuit. 
         [0091]    In some example embodiments, a matching circuit  930  may be connected between the NFC package  910  and the case  950  of the portable device  900 . The matching circuit  930  may perform impedance matching between the NFC package  910  and the case  950 . For example, the matching circuit  930  may include a first capacitor C 1 , a second capacitor C 2 , a third capacitor C 3 , a fourth capacitor C 4 , a first inductor  11  and a second inductor  12 . The first capacitor C 1  may be connected between the first and second terminals T 1  and T 2  of the case  950 . The first capacitor C 1  may have an appropriate capacitance such that the case  950  represented by the inductor L 1  may have a desired resonance frequency (e.g., about 13.56 MHz). The second capacitor C 2  may be connected between the first terminal T 1  of the case  950  and a first node N 1 , a third capacitor C 3  may be connected between the second terminal T 2  of the case  950  and a second node N 2 , and the fourth capacitor C 4  may be connected between the first node N 1  and the second node N 2 . The first inductor  11  may be connected between the first node N 1  and the first transmission terminal TX 1  of the NFC package  910 , and the second inductor  12  may be connected between the second node N 2  and the second transmission terminal TX 2  of the NFC package  910 . However, this configuration of the matching circuit  930  illustrated in  FIG. 14  is only one example, and the matching circuit  930  for impedance matching between the NFC chip  930  and the case  950  may have various configurations according to some example embodiments. 
         [0092]    In some example embodiments, the NFC package  910  (or the NFC controller  912 ) may output a differential electrical signal through the first and second transmission terminals TX 1  and TX 2 , and the first and second terminals T 1  and T 2  of the case  950  may receive the differential electrical signal through the matching circuit  930 . The case  950  may radiate the first magnetic field based on the differential electrical signal. The loop antenna  970  located inside the case  950  may be magnetically coupled to the case  950 , and may be represented, as an equivalent circuit, by an inductor L 2  and a capacitor C that are connected to each other. Since the loop antenna  970  is magnetically coupled to the case  950 , the loop antenna  970  may form the second magnetic field in response to the first magnetic field radiated at the case  950 . Accordingly, magnetic field efficiency of the portable device  900  may be improved, and the portable device  900  may accurately perform the near field communication. 
         [0093]      FIG. 15  is a diagram for describing another example of a connection relationship among an NFC chip, a matching circuit, a case and a loop antenna in a portable device according to some example embodiments. 
         [0094]    Referring to  FIG. 15 , in a portable device  900   a , a matching circuit  930   a  may be connected between an NFC chip  911   a  and a case (e.g., a metal case)  950  of the portable device  900   a . The matching circuit  930  may include a first capacitor C 1  connected between first and second terminals T 1  and T 2  of the case  950 , a second capacitor C 2  connected between the first terminal T 1  of the case  950  and a first node N 1 ′, a fourth capacitor C 4  connected between the first node and a ground voltage, and a first inductor  11  connected between the N 1 ′ first node and at least one transmission terminal TX of the NFC chip  911   a . The portable device  900   a  may have a similar configuration to a portable device  900  of  FIG. 14 , except that the NFC chip  911   a  outputs a single-ended electrical signal and the case  950  receives the single-ended electrical signal. 
         [0095]    The NFC chip  911   a  may output the single-ended electrical signal through at least one transmission terminal TX, and one of the first and second terminals T 1  and T 2  of the case  950  may receive the single-ended electrical signal through the matching circuit  930   a . The other of the first and second terminals T 1  and T 2  of the case  950  may be grounded. The case  950  may radiate a first magnetic field based on the single-ended electrical signal. A loop antenna  970  located inside the case  950  may be magnetically coupled to the case  950 , and may form a second magnetic field in response to the first magnetic field radiated at the case  950 . 
         [0096]      FIG. 16  is a diagram for describing still another example of a connection relationship among an NFC chip, a matching circuit, a case and a loop antenna in a portable device according to some example embodiments. 
         [0097]    Referring to  FIG. 16 , a portable device  900   b  according to some example embodiments may include a display panel, an NFC chip  911   b  that outputs a differential electrical signal, a matching circuit  930   b  connected to the NFC chip  911   b , a case (e.g., a metal case)  950  that supports the display panel and is connected to the matching circuit  930   b , and a loop antenna  970  located inside the case  950 . The loop antenna  970  may be spaced apart from the case  950 , and, however, may be magnetically coupled to the case  950 . The case  950  may include a conductive material. For example, the case  950  may be the metal case  950  including a metal material. The case  950  may have a first terminal T 1  connected to the matching circuit  930   b  and a second terminal T 2  spaced apart from the first terminal T 1  and connected to a ground voltage. 
         [0098]    The matching circuit  930   b  may be connected between the NFC chip  911   b  and the case  950  of the portable device  900   b , and may perform impedance matching between the NFC chip  911   b  and the case  950 . Further, the matching circuit  930   b  may receive the differential electrical signal from the NFC chip  911   b , may convert the differential electrical signal into a single-ended electrical signal, and may transfer the single-ended electrical signal to the case  950 . In some example embodiments, to convert the differential electrical signal into the single-ended electrical signal, the matching circuit  930   b  may include a transformer  940  for converting the differential electrical signal into the single-ended electrical signal. The transformer  940  may have first and second input terminals IN 1  and IN 2  respectively connected to first and second transmission terminals TX 1  and TX 2  of the NFC chip  911   b , a first output terminal OUT 1  connected to the first terminal T 1  of the case  950 , and a second output terminal OUT 2  connected to the ground voltage. For example, the transformer  940  may be a balun (balanced-to-unbalanced) circuit or a balun transformer. 
         [0099]    In some example embodiments, the matching circuit  930   b  may include a first capacitor C 1  connected between the first terminal T 1  of the case  950  and the ground voltage, a second capacitor C 2  connected between the first terminal T 1  of the case  950  and the first output terminal OUT 1  of the transformer  940 , a fourth capacitor C 4  connected between the first and second input terminals IN 1  and IN 2  of the transformer  940 , a first inductor  11  connected between the first input terminal IN 1  of the transformer  940  and the first transmission terminal TX 1  of the NFC chip  911   b , and a second inductor  12  connected between the second input terminal IN 2  of the transformer  940  and the second transmission terminal TX 2  of the NFC chip  911   b . The configurations and connections of the capacitors C 1 , C 2  and C 4  and the inductors  11  and  12  included in the matching circuit  930   b  may be changed or modified according to some example embodiments. 
         [0100]    The NFC chip  911   b  may output the differential electrical signal through the first and second transmission terminals TX 1  and TX 2 , and the differential electrical signal may be converted into the single-ended electrical signal by the transformer  940 . One (e.g., the first terminal T 1 ) of the first and second terminals T 1  and T 2  of the case  950  may receive the single-ended electrical signal from the transformer  940 . The other (e.g., the second terminal T 2 ) of the first and second terminals T 1  and T 2  of the case  950  may be grounded. The case  950  may radiate a first magnetic field based on the single-ended electrical signal. The loop antenna  970  located inside the case  950  may be magnetically coupled to the case  950 , and may form a second magnetic field in response to the first magnetic field radiated at the case  950 . 
         [0101]    As described above, in the portable device  900   b  according to some example embodiments, the differential electrical signal output from the NFC chip  911   b  may be converted into the single-ended electrical signal by the matching circuit  930   b  or the transformer  910 , and the single-ended electrical signal may be provided to the case  950 . Thus, in a case where the NFC chip  911   b  outputs the differential electrical signal and, the matching circuit  930   b  is not readily connected to both terminals T 1  and T 2  of the case  950 , or in a case where it is not easy to form two feeding points at the case  950 , the portable device  900   b  can radiate the first magnetic field using the case  950 . 
         [0102]    Further, the loop antenna  970  magnetically coupled to the case  950  may radiate the second magnetic field in response to the first magnetic field, thereby improving magnetic field radiation efficiency of the portable device  900   b.    
         [0103]      FIG. 17  is a diagram for describing a portable device including an inductor between a matching circuit and a case according to some example embodiments. 
         [0104]    Referring to  FIG. 17 , in a portable device  1000 , a matching circuit  1030  may be connected between an NFC chip  1010  and a case  1050  of the portable device  1000 , and at least one inductor  1040  may be connected between the matching circuit  1030  and at least one terminal of the case  1050 . 
         [0105]    The case  1050  may radiate a first magnetic field MF 1 , and a loop antenna  1070  magnetically coupled to the case  1050  may radiate a second magnetic field MF 2  in response to the first magnetic field MF 1 . Compared with a portable device  900  of  FIG. 14 , the portable device  1000  may further include at least one inductor  1040 . 
         [0106]    The inductor  1040  may located within a current loop formed by the case  1050  and a first capacitor C 1  illustrated in  FIG. 14 . The inductor  1040  may block a signal component having a frequency that is different from an operating frequency (e.g., about 13.56 MHz) of NFC in the current loop. Accordingly, the inductor  1040  may allow the near field communication not to interfere with another wireless communication (e.g., a cellular telephone communication, such as a long term evolution (LTE) communication, a wideband code division multiple access (WCDMA) communication, etc., a wireless local area network (WLAN) communication, a global positioning system (GPS) communication, a Bluetooth communication, or the like) using the case  1050 . 
         [0107]      FIG. 18  is a diagram for describing a portable device including a low pass filter between a matching circuit and a case according to some example embodiments. 
         [0108]    Referring to  FIG. 18 , in a portable device  1100 , a matching circuit  1130  may be connected between an NFC chip  1110  and a case  1150  of the portable device  1100 , and at least one low pass filter  1140  may be connected between the matching circuit  1130  and at least one terminal of the case  1150 . The case  1150  may radiate a first magnetic field MF 1 , and a loop antenna  1170  magnetically coupled to the case  1150  may radiate a second magnetic field MF 2  in response to the first magnetic field MF 1 . Compared with a portable device  1000  of  FIG. 17 , the portable device  1100  may include at least one low pass filter  1140  instead of an inductor  1040  illustrated in  FIG. 17 . 
         [0109]    The low pass filter  1140  may located within a current loop formed by the case  1150  and a first capacitor C 1  illustrated in  FIG. 14 . The low pass filter  1140  may block a signal component having a frequency that is different from an operating frequency (e.g., about 13.56 MHz) of NFC in the current loop. Accordingly, the low pass filter  1140  may allow the near field communication not to interfere with another wireless communication using the case  1150 . For example, the low pass filter  1140  may include an inductor  1142  and a capacitor  1144 . 
         [0110]      FIG. 19  is a diagram for describing a portable device that performs a near field communication, wireless charging, and/or a magnetic secure transmission according to some example embodiments. 
         [0111]    Referring to  FIG. 19 , a portable device according to some example embodiments may include an NFC chip  1210 , a case (or a metal case)  1230  connected to the NFC chip  1210 , and a loop antenna  1250  magnetically coupled to the case  1230 . The NFC chip  1210  may perform a near field communication using the case  1230  and the loop antenna  1250   
         [0112]    In some example embodiments, the portable device may further include a wireless charging circuit  1270  connected to the loop antenna  1250 . The wireless charging circuit  1270  may be wirelessly supplied with power through the loop antenna  1250 , and thus may charge the supplied power for the portable device. Thus, the loop antenna  1250  may be used not only for the near field communication, but also for wireless charging. 
         [0113]    In some example embodiments, the portable device may further include a magnetic secure transmission (MST) circuit  1290  connected to the loop antenna  1250 . The MST circuit  1290  may perform a magnetic secure transmission using the loop antenna  1250 . Thus, the loop antenna  1250  may be used not only for the near field communication, but also for the magnetic secure transmission. 
         [0114]      FIG. 20  is a diagram for describing a configuration of a portable device according to some example embodiments. 
         [0115]    Referring to  FIG. 20 , in a portable device  1300 , a case  1340  defining an internal space and a loop antenna  1380  located in the internal space may be connected in series. For example, a first terminal T 1  of the case  1340  may be connected to a first end E 1  of the loop antenna  1380  (or a loop coil), and an NFC chip  1390  may be connected to a second terminal T 2  of the case  1340  and a second end E 2  of the loop antenna  1380 . Thus, in an NFC antenna including the case  1340  and the loop antenna  1380 , the second terminal T 2  of the case  1340  and the second end E 2  of the loop antenna  1380  may serve as feeding points for the NFC antenna. The NFC chip  1390  may perform a near field communication using the case  1340  and the loop antenna  1380  that are connected in series. In some example embodiments, the case  1340  may have a unitary structure with no slit, and thus a waterproof function and an aesthetic impression of the case  1340  may be improved. 
         [0116]      FIG. 21  is a diagram for describing an example of a portable device performing a near field communication according to some example embodiments, and  FIG. 22  is a diagram for describing another example of a portable device performing a near field communication according to some example embodiments. 
         [0117]    As illustrated in  FIG. 21 , a portable device  1410  according to some example embodiments may be a wearable electronic device  1410 , such as a wrist-worn electronic device. The wearable electronic device  1410  may perform pairing or a data transfer with an external wireless communication device  1430  through a near field communication while the wearable electronic device  1410  is being worn. For example, the wearable electronic device  1410  may perform the pairing with the external wireless communication device  1430  to perform another wireless communication (e.g., a Bluetooth or a Wi-Fi). 
         [0118]    By the pairing, the wearable electronic device  1410  and the wireless communication device  1430  may be paired or bonded by sharing a shared key (or a link key). According to some example embodiments, the wearable electronic device  1410  may perform the data transfer with the wireless communication device  1430  through the near field communication, or may perform the data transfer with the wireless communication device  1430  through the wireless communication (e.g., the Bluetooth or the Wi-Fi) paired through the near field communication. 
         [0119]    As illustrated in  FIG. 22 , a portable device  1510  according to some example embodiments may be a wearable electronic device  1510 , such as a wrist-worn electronic device. The wearable electronic device  1510  may perform an electronic payment by transferring payment information (e.g., credit card information) to a payment terminal  1530  through a near field communication while the wearable electronic device  1510  is being worn. 
         [0120]    The portable device  1410  and  1510  illustrated in  FIGS. 21 and 22  according to some example embodiments may perform the pairing, the data transfer, the electronic payment, etc. through the near field communication using a case of the portable device  1410  and  1510  and a loop antenna that are magnetically coupled to each other. In the portable device  1410  and  1510  according to some example embodiments, no slit may be formed at the case, and thus a waterproof function and an aesthetic impression of the case may be improved. In some example embodiments, the portable device  1410  and  1510  may be the wearable electronic device  1410  and  1510 , and the wearable electronic device  1410  and  1510  may perform the pairing, the data transfer, the electronic payment, etc. through the near field communication while the wearable electronic device  1410  and  1510  is being worn. 
         [0121]    The inventive concepts may be applied to any portable device, such as a smart phone, a tablet computer, or a wearable electronic device, such as a smart watch, a wrist band electronic device, a necklace type electronic device, a glasses type electronic device, etc. 
         [0122]    The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the novel teachings and advantages of the present inventive concepts. For example, the antenna may be coated with a resin or other material such as in the example embodiments shown in  FIGS. 8, 10 and 12 . 
         [0123]    Accordingly, all such modifications are intended to be included within the scope of the present inventive concepts as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and is not to be construed as limited to the specific example embodiments disclosed, and that modifications to the disclosed example embodiments, as well as other example embodiments, are intended to be included within the scope of the appended claims.