Patent Publication Number: US-2022216596-A1

Title: Antenna structure and display device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY 
     This application claims priority to Korean Patent Application No. 10-2021-0001375 filed on Jan. 6, 2021 in the Korean Intellectual Property Office (KIPO), the entire disclosures of which are incorporated by reference herein. 
     BACKGROUND 
     1. Field 
     The present invention relates to an antenna structure and a display device including the same. More particularly, the present invention relates to an antenna device including a dielectric layer, and a display device including the same. 
     2. Description of the Related Art 
     As information technologies have been developed, a wireless communication technology such as Wi-Fi, Bluetooth, etc., is combined with a display device in, e.g., a smartphone form. In this case, an antenna may be combined with the display device to provide a communication function. 
     As mobile communication technologies have been rapidly developed, an antenna capable of operating a high frequency or ultra-high frequency communication is needed in the display device. 
     Accordingly, developments of an antenna that may be inserted into the thin-type display device in the form of a film or a patch and may provide reliability of radiation properties even in the thin structure. 
     For example, when a feeding is performed to the antenna from a driving integrated circuit (IC) chip, an impedance mismatching of the antenna may occur due to a contact resistance between a pad included in the antenna and an external circuit structure or circuit wiring, and a radiation efficiency of the antenna may be degraded. 
     For example, Korean Published Patent Application No. 2013-0095451 discloses an antenna integrated to a display panel, which may not provide any solution for overcoming the issues. 
     SUMMARY 
     According to an aspect of the present invention, there is provided an antenna structure having improved signaling efficiency and reliability. 
     According to an aspect of the present invention, there is provided a display device including an antenna structure with improved signaling efficiency and reliability. 
     (1) An antenna structure, including: a dielectric layer; a radiator disposed on the dielectric layer; a transmission line branching from the radiator; a signal pad electrically connected to the radiator through the transmission line on the dielectric layer; and an external circuit structure bonded to the signal pad, wherein the signal pad includes a bonding region that is bonded to the external circuit structure and a margin region that is not bonded to the external circuit structure and is adjacent to the bonding region, and an area ratio of the margin region relative to the bonding region in the signal pad is 0.05 or more and less than 0.5. 
     (2) The antenna structure of the above (1), wherein the external circuit structure includes a flexible circuit board that includes a feeding wiring, and a conductive intermediate structure, and the conductive intermediate structure is attached on the bonding region of the signal pad, and the feeding wiring of the flexible circuit board is electrically connected to the signal pad through the conductive intermediate structure. 
     (3) The antenna structure of the above (2), wherein the margin region does not directly contact the conductive intermediate structure. 
     (4) The antenna structure of the above (2), further including a driving integrated circuit chip electrically connected to the flexible circuit board to supply a power to the radiator through the feeding wiring. 
     (5) The antenna structure of the above (4), wherein the radiator is driven at a frequency from 20 GHz to 40 GHz, and a power corresponding to a range of 40Ω to 70Ω is supplied to the radiator through the driving integrated circuit chip. 
     (6) The antenna structure of the above (1), wherein the area ratio of the margin region relative to the bonding region in the signal pad is from 0.1 to 0.3. 
     (7) The antenna structure of the above (1), further including a pair of ground pads spaced apart from the signal pad on the dielectric layer with the signal pad interposed therebetween. 
     (8) The antenna structure of the above (7), wherein each of the pair of the ground pads includes a ground bonding region bonded to the external circuit structure, and a ground margin region adjacent to the ground bonding region, and the ground margin region is not bonded to the external circuit structure. 
     (9) The antenna structure of the above (8), wherein an area ratio of the ground margin region relative to the ground bonding region is the same as the area ratio of the margin region to the bonding region in the signal pad. 
     (10) The antenna structure of the above (1), wherein the bonding region of the signal pad is directly connected to the transmission line. 
     (11) The antenna structure of the above (1), wherein the margin area of the signal pad is directly connected to the transmission line. 
     (12) The antenna structure of the above (1), wherein the margin region has a width greater than a width of the bonding region. 
     (13) The antenna structure of the above (1), wherein the margin region includes: a first portion extending in a length direction to be in contact with the bonding region; and a second portion extending in a width direction from an end of the first portion. 
     (14) The antenna structure of the above (1), wherein the transmission line includes a first transmission line and a second transmission line extending in different directions from the radiator, and the signal pad includes a first signal pad and a second signal pad electrically connected to the radiator through the first transmission line and the second transmission line, respectively. 
     (15) The antenna structure of the above (14), wherein the first signal pad includes a first bonding region that is bonded to the external circuit structure and a first margin region that is not bonded to the external circuit structure and is adjacent to the first bonding region, and an area ratio of the first margin region relative to the first bonding region in the first signal pad is 0.05 or more and less than 0.5, 
     wherein the second signal pad includes a second bonding region that is bonded to the external circuit structure and a second margin region that is not bonded to the external circuit structure and is adjacent to the second bonding region, and an area ratio of the second margin region relative to the second bonding region in the second signal pad is 0.05 or more and less than 0.5. 
     (16) The antenna structure of the above (15), wherein the area ratio of the first margin region relative to the first bonding region is the same as the area ratio of the second margin region relative to the second bonding region. 
     (17) The antenna structure of the above (14), wherein the first transmission line and the second transmission line are symmetrical to each other with respect to a central line of the radiator. 
     (18) A display device including the antenna structure according to embodiments as described above. 
     In an antenna structure according to exemplary embodiments of the present invention, a signal pad electrically connected to a radiator may include a bonding region bonded to an external circuit structure and a margin region that may not be directly bonded to the external circuit structure, and an area ratio of the margin region relative to the bonding region may be 0.05 or more and less than 0.5 
     An adhesion region that may be bonded with the external circuit structure including a different material may be partially allocated, and the area ratio between the bonding region and the margin region may be maintained within the above range, so that an impedance through the signal pad may be maintained in a desired range. 
     Additionally, a radiation amount directed to the external circuit structure may be suppressed by adjusting the area of the bonding region, and an amount of power or radio wave supplied to the radiator through may be increased through the margin region. 
     In some embodiments, the radiator may be electrically connected to a first signal pad and a second signal pad independently supplying an input signal, and the first signal pad and the second signal pad may each have a bonding region and a margin region. 
     Accordingly, a single radiator may implement a plurality of polarization properties, and a first input signal and a second input signal may be alternately supplied, so that a horizontal polarization property and a vertical polarization property may be implemented together through one radiator. 
     In some embodiments, at least a portion of the radiator may be formed in a mesh structure to improve a transmittance of the antenna structure. For example, the antenna structure may be applied to a display device including a mobile communication device for a high frequency or ultra-high frequency band of 3G, 4G, 5G or higher, thereby improving optical properties such as transmittance and radiation properties. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic top planar view and illustrating an antenna structure in accordance with exemplary embodiments. 
         FIG. 2  is a schematic cross-sectional view and illustrating an antenna structure in accordance with exemplary embodiments. 
         FIGS. 3 to 10  are schematic top planar views illustrating antenna structures in accordance with some exemplary embodiments. 
         FIG. 11  is a schematic top planar view illustrating a display device in accordance with exemplary embodiments. 
         FIG. 12  is a graph showing a change of an S-parameter and a gain amount according to a variation of a margin region length in an antenna structure in accordance with exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     According to exemplary embodiments of the present invention, there is provided an antenna structure including a dielectric layer and an antenna unit a radiator and a signal pad that may include a bonding region and a margin region. 
     The antenna structure may be, e.g., a microstrip patch antenna fabricated in the form of a transparent film. The antenna structure may be applied to communication devices for a mobile communication of a high or ultrahigh frequency band corresponding to a mobile communication of, e.g., 3G, 4G, 5G or more. 
     According to exemplary embodiments of the present invention, there is also provided a display device including the antenna structure. An application of the antenna structure is not limited to the display device, and the antenna structure may be applied to various objects or structures such as a vehicle, a home electronic appliance, an architecture, etc. 
     Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that such embodiments described with reference to the accompanying drawings are provided to further understand the spirit of the present invention and do not limit subject matters to be protected as disclosed in the detailed description and appended claims. 
     In the accompanying drawings, two directions parallel to, e.g., a top surface of a dielectric layer  110  to intersect each other are defined as a first direction and a second direction. For example, the first direction and the second direction may be perpendicular to each other. A direction vertical to the top surface of the dielectric layer  110  is defined as a third direction. For example, the first direction may correspond to a length direction of the antenna structure, the second direction may correspond to a width direction of the antenna structure, and the third direction may correspond to a thickness direction of the antenna structure. The definition of the directions may be equally applied to the all accompanying drawings. 
       FIG. 1  is a schematic top planar view and illustrating an antenna structure in accordance with exemplary embodiments. 
     Referring to  FIG. 1 , the antenna structure may include a dielectric layer  110  and an antenna unit disposed on the dielectric layer  110 . The antenna unit may include a radiator  122  and a signal pad  130  electrically connected to the radiator  122 . The radiator  122  and the signal pad  130  may be electrically connected to each other through a transmission line  124 . 
     The dielectric layer  110  may include a polyester-based resin such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; a cellulose-based resin such as diacetyl cellulose and triacetyl cellulose; a polycarbonate-based resin; an acrylic resin such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; a styrene-based resin such as polystyrene and an acrylonitrile-styrene copolymer; a polyolefin-based resin such as polyethylene, polypropylene, a cycloolefin or polyolefin having a norbornene structure and an ethylene-propylene copolymer; a vinyl chloride-based resin; an amide-based resin such as nylon and an aromatic polyamide; an imide-based resin; a polyethersulfone-based resin; a sulfone-based resin; a polyether ether ketone-based resin; a polyphenylene sulfide resin; a vinyl alcohol-based resin; a vinylidene chloride-based resin; a vinyl butyral-based resin; an allylate-based resin; a polyoxymethylene-based resin; an epoxy-based resin; a urethane or acrylic urethane-based resin; a silicone-based resin, etc. These may be used alone or in a combination thereof. 
     An adhesive film such as an optically clear adhesive (OCA), an optically clear resin (OCR), or the like may be included in the dielectric layer  110 . In an embodiment, the dielectric layer  110  may include an inorganic insulating material such as glass, silicon oxide, silicon nitride, silicon oxynitride, etc. 
     In an embodiment, the dielectric layer  110  may be provided as a substantially single layer. In an embodiment, the dielectric layer  110  may have a multi-layered structure of at least two layers. 
     Capacitance or inductance may be generated between the antenna unit and/or an antenna ground layer  160  (see  FIG. 2 ) by the dielectric layer  110 , so that a frequency band at which the antenna structure may be driven or operated may be adjusted. In some embodiments, a dielectric constant of the dielectric layer  110  may be adjusted in a range from about 1.5 to about 12. When the dielectric constant exceeds about 12, a driving frequency may be excessively decreased, so that driving in a desired high frequency band may not be implemented. 
     As described above, the antenna unit may include the radiator  122  and the signal pad  130 , and the radiator  122  and the signal pad  130  may be electrically connected through the transmission line  124 . 
     For example, the transmission line  124  may be branched from a central portion of the radiator  122  to be connected to the signal pad  130 . In an embodiment, the transmission line  124  may be provided as a single member substantially integrally connected with the radiator  122 . In an embodiment, the transmission line  124  may also be provided as a single member substantially integrally connected to the signal pad  130 . 
     The signal pad  130  may receive and transmit a power from an external circuit structure to the radiator  122 . In exemplary embodiments, the signal pad  130  may include a bonding region  132  and a margin region  134 . 
     The bonding region  132  may be a region directly attached or bonded to the external circuit structure. For example, the external circuit structure may include a flexible circuit board (FPCB)  200  and a conductive intermediate structure  150  as will be described later with reference to  FIG. 2 . 
     The margin region  134  may be a region that may not be directly attached or bonded to the external circuit structure. The margin region  134  may include a remaining portion of the signal pad  130  except for the bonding region  132 . 
     For example, while implementing high-frequency communication in a frequency range from about 20 GHz to 40 GHz, a resistance or impedance may be set from about 40Ω to 70Ω, preferably from about 50Ω to 60Ω, more preferably around 50Ω for a resonance without a signal reflection through the driving IC chip  280  (see  FIG. 2 ). 
     As illustrated in  FIG. 1 , the bonding region  132  of the signal pad  130  may be adjacent to the transmission line  124 . In this case, a signal transmission path between the external circuit structure and the radiator  122  may be shortened. For example, a front end portion of the signal pad  130  in the first direction may correspond to the bonding region  132 , and a rear end portion in the first direction may correspond to the margin region  134 . 
     In exemplary embodiments, an area ratio of the margin region  134  relative to the bonding region  132  may be in a range from about 0.05 or more and less than 0.5. Preferably, the area ratio of the margin region  134  relative to the bonding region  132  may be in a range of about 0.1 to 0.3. 
     If the area ratio of the margin region  134  relative to the bonding region  132  is less than 0.05, the impedance value set through the antenna unit may be changed or disturbed by a contact resistance between the external circuit structure and the signal pad  130  to result in a impedance mismatch. If the area ratio of the margin region  134  relative to the bonding region  132  is 0.5 or more, sufficient radiation efficiency and antenna gain may not be obtained and the impedance mismatch may be further increased. 
     The impedance mismatch that may occur in the bonding region  132  may be suppressed or buffered while maintaining a desired impedance through the margin region  134  within the range of the area ratio of the margin region  134  relative to the bonding region  132 . 
     Additionally, a sufficient amount of radiation and power directed to the radiator  122  may be achieved through the margin region  134 . Thus, even when the area of the signal pad  130  is increased, sufficient radiation efficiency and antenna gain may be achieved while suppressing the impedance mismatching. 
     The antenna unit may further include a ground pad  140 . The ground pad  140  may be disposed around the signal pad  130  to be electrically and physically separated from the signal pad  130 . For example, a pair of the ground pads  140  may be disposed to face each other in the second direction with the signal pad  130  interposed therebetween. 
     The ground pad  140  may be disposed at the same layer or the same level as that of the antenna unit (e.g., on the top surface of the dielectric layer  110 ). In this case, a horizontal radiation property may be added from the antenna structure. As will be described later with reference to  FIG. 2 , the antenna structure may further include the antenna ground layer  160  on a bottom surface of the dielectric layer  110 . In this case, a vertical radiation property may be implemented from the antenna structure. 
     As illustrated in  FIG. 1 , a length (a length in the first direction) of the ground pad  140  may cover both the bonding region  132  and the margin region  134 . For example, the length of the ground pad  140  may be equal to or greater than an entire length of the signal pad  130 . 
     The antenna unit may include silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium (Cr), titanium (Ti), tungsten (W), and niobium. (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), tin (Sn), molybdenum (Mo), calcium (Ca) or an alloy containing at least one of the metals. These may be used alone or in combination of two or more therefrom. 
     In an embodiment, the antenna unit may include silver (Ag) or a silver alloy (e.g., silver-palladium-copper (APC)), or copper (Cu) or a copper alloy (e.g., a copper-calcium (CuCa)) to implement a low resistance and a fine line width pattern. 
     The antenna unit may include a transparent conductive oxide such indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnOx), indium zinc tin oxide (IZTO), etc. 
     In some embodiments, the antenna unit may include a stacked structure of a transparent conductive oxide layer and a metal layer. For example, the first and second antenna patterns  110  and  120  may include a double-layered structure of a transparent conductive oxide layer-metal layer, or a triple-layered structure of a transparent conductive oxide layer-metal layer-transparent conductive oxide layer. In this case, flexible property may be improved by the metal layer, and a signal transmission speed may also be improved by a low resistance of the metal layer. Corrosive resistance and transparency may be improved by the transparent conductive oxide layer. 
     The antenna unit may include a blackened portion, so that a reflectance at a surface of the antenna unit may be decreased to suppress a visual recognition of the antenna unit due to a light reflectance. 
     In an embodiment, a surface of the metal layer included in the antenna unit may be converted into a metal oxide or a metal sulfide to form a blackened layer. In an embodiment, a blackened layer such as a black material coating layer or a plating layer may be formed on the antenna unit or the metal layer. The black material or plating layer may include silicon, carbon, copper, molybdenum, tin, chromium, molybdenum, nickel, cobalt, or an oxide, sulfide or alloy containing at least one therefrom. 
     A composition and a thickness of the blackened layer may be adjusted in consideration of a reflectance reduction effect and an antenna radiation property. 
     In some embodiments, the radiator  122  may include a mesh structure. In this case, transmittance of the radiator  122  may be improved, and a visual recognition of the radiator  122  may be prevented to a user when the antenna structure is employed to a display device. In an embodiment, the transmission line  124  may also be patterned together with the radiator  122  to include the mesh structure. 
     In some embodiments, while employing the mesh structure, electrode lines included in the mesh structure may be formed of a low-resistance metal such as copper, silver, an APC alloy, or a CuCa alloy, thereby suppressing a resistance increase. Accordingly, a low-resistance and high-sensitivity transparent antenna device may be effectively implemented 
     In some embodiments, the signal pad  130  may have a solid structure. Accordingly, a contact resistance between the bonding region  132  and the external circuit structure may be reduced to increase an efficiency of radio wave and power transmission to the radiator  122  through the margin region  134 . In an embodiment, the ground pad  140  may also have the solid structure to improve a noise absorption efficiency. 
       FIG. 2  is a schematic cross-sectional view and illustrating an antenna structure in accordance with exemplary embodiments. 
     Referring to  FIG. 2 , the antenna structure may include an antenna device  100  and a flexible circuit board (FPCB)  200 . 
     In some embodiments, the driving integrated circuit (IC) chip  280  electrically connected to the antenna device  100  through the flexible circuit board  200  may be provided on an upper portion of the flexible circuit board  200  by a surface mounting technology (SMT). 
     For example, a circuit or a contact electrically connecting the driving integrated circuit chip  280  and a feeding wiring with each other may be formed in the flexible circuit board  200 . The driving integrated circuit chip  280  may be disposed on the flexible circuit board  200 , so that a signal transmission/reception path may be shortened and a signal loss may be suppressed. 
     In some embodiments, the flexible circuit board  200  may be electrically connected to an intermediate circuit board (not illustrated), and the driving integrated circuit chip  280  may be mounted on the intermediate circuit board. 
     In this case, a feeding and a driving signal may be applied from the driving integrated circuit chip  280  to the antenna unit through a feeding wiring  220  to be described later. For example, a circuit or a contact electrically connecting the driving integrated circuit chip  280  and the feeding wiring  220  may be further included in the intermediate circuit board. 
     For example, the intermediate circuit board may include a main board of an image display device, a rigid printed circuit board, various antenna package boards, etc. For example, if the intermediate circuit board is a rigid printed circuit board, the intermediate circuit board may include a core layer formed of a resin impregnated with an inorganic material such as glass fiber (e.g., a prepreg) and intermediate circuits formed in the core layer. 
     In some embodiments, the flexible circuit board  200  and an intermediate circuit board may be coupled to each other through a connector. 
     As described with reference to  FIG. 1 , the antenna device  100  may include a dielectric layer  110  and an antenna unit disposed on the top surface of the dielectric layer  110 . For example, the antenna device  100  may be provided as a patch antenna or a film antenna. 
     The antenna unit may include the radiator  122 , the transmission line  124  and the signal pad  130 , and the signal pad  130  may include the bonding region  132  and the margin region  134 . The ground pad  140  spaced apart from the signal pad  130  may be further disposed around the signal pad  130 . 
     In some embodiments, the antenna ground layer  160  may be formed on the bottom surface of the dielectric layer  110 . The antenna ground layer  160  may entirely cover the antenna unit in a planar view. 
     In an embodiment, a conductive member of a display device or a display panel in which the antenna structure is disposed may serve as the antenna ground layer  160 . 
     For example, the conductive member may include electrodes or wires such as a gate electrode, a source/drain electrode, a pixel electrode, a common electrode, a data line and a scan line included in a thin film transistor (TFT) array panel. 
     In an embodiment, various structures including a conductive material disposed under the display panel may serve as the antenna ground layer  160 . For example, a metal plate (e.g., a stainless-steel plate such as a SUS plate), a pressure sensor, a fingerprint sensor, an electromagnetic wave shielding layer, a heat dissipation sheet, a digitizer, etc., may serve as the antenna ground layer  160 . 
     The flexible circuit board  200  may be disposed on the antenna unit to be electrically connected to the antenna element  100 . The flexible circuit board  200  may include a core layer  210 , a feeding wiring  220  and a feeding ground  230 . An upper coverlay film  250  and a lower coverlay film  240  for protecting wirings may be formed on the upper and lower surfaces of the core layer  210 , respectively. 
     The core layer  210  may include, e.g., a resin material having flexibility such as polyimide, an epoxy resin, polyester, a cycloolefin polymer (COP), a liquid crystal polymer (LCP), or the like. 
     The feeding wiring  220  may be disposed on the bottom surface of the core layer  210 . The feeding wiring  220  may serve as a wiring for distributing power from the driving integrated circuit (IC) chip  280  to the antenna unit or the radiator  122 . 
     In exemplary embodiments, the feeding wiring  220  may be electrically connected to the signal pad  130  of the antenna unit through the conductive intermediate structure  150 . 
     The conductive intermediate structure  150  may be obtained from, e.g., an anisotropic conductive film (ACF). In this case, the conductive intermediate structure  150  may include conductive particles (e.g., silver particles, copper particles, carbon particles, etc.) dispersed in a resin layer. 
     As described with reference to  FIG. 1 , the conductive intermediate structure  150  may be selectively bonded to or in contact with the bonding region  132  included in the signal pad  130 , and the margin region  134  of the signal pad  130  may remain as a non-bonding region with the conductive intermediate structure  150 . 
     As described above, the conductive intermediate structure  150  may include a material different from the material included in the signal pad  130  such as the resin material and the conductive particles to cause an impedance mismatch in the antenna unit. However, the impedance mismatch may be buffered or suppressed by allocating the margin region  134  that may not be bonded to the conductive intermediate structure  150 . 
     For example, the lower coverlay film  240  may be partially cut or removed to expose a portion of the feeding wiring  220  having a size corresponding to the bonding region  132 . The exposed portion of the feeding wiring  220  and the bonding region  132  may be pressed and bonded to each other through the conductive intermediate structure  150 . 
     In some embodiments, the lower coverlay film  240  may be disposed on the margin region  134 . In some embodiments, the margin region  134  may additionally provide an alignment margin in the bonding process between the flexible circuit board  200  and the conductive intermediate structure  150 . Accordingly, an additional bonding margin may be provided by the margin area  134  when a mis-alignment occurs on the bonding area  132 . 
     A feeding ground  230  may be disposed on the upper surface of the core layer  210 . The feeding ground  230  may have a line shape or a plate shape. The feeding ground  230  may function as a barrier to shield or suppress a noise or a self-radiation generated from the feeding wiring  220 . 
     The feeding wiring  220  and the feeding ground  230  may include the metal and/or the alloy as mentioned in the antenna unit. 
     In some embodiments, the feed ground  230  may be electrically connected to the ground pad  140  (refer to  FIG. 1 ) of the antenna pattern through a ground contact (not shown) penetrating the core layer  210 . 
     The driving IC chip  280  may be disposed on the flexible circuit board  200  or the intermediate circuit board. Power may be supplied from the driving IC chip  280  to the antenna unit through the feeding wiring  220 . For example, the flexible circuit board  200  may further include a circuit or a contact electrically connecting the driving IC chip  280  and the feeding wiring  220  to each other. 
       FIGS. 3 to 10  are schematic top planar views illustrating antenna structures in accordance with some exemplary embodiments. Detailed descriptions on structures and elements substantially the same as or similar to those described with reference to  FIG. 1  will be omitted herein. 
     Referring to  FIG. 3 , the ground pad  140  may include a ground bonding region  142  and a ground margin region  144 . 
     The ground bonding region  142  may be a region directly bonded or bonded to the external circuit structure. For example, the ground bonding region  142  may be formed to have the same length as that of the bonding region  132  of the signal pad  130 . 
     The ground margin region  144  may be a region that may not be directly attached or bonded to the external circuit structure. The ground margin region  144  may include a remaining portion of the ground pad  140  except for the ground bonding region  142 . 
     In some embodiments, an area ratio of the ground margin region  144  relative to the ground bonding region  142  may be substantially the same as the area ratio of the margin region  134  relative to the bonding region  132 . 
     In this case, a separate alignment may not be performed for the bonding process with the flexible circuit board  200  through the conductive intermediate structure  150 , and a process convenience may be improved. 
     Referring to  FIG. 4 , the margin region  134  of the signal pad  130  may be disposed to be closer to the transmission line  124 . For example, a front end portion of the signal pad  130  in the first direction may serve as the margin region  134 , and rear end portion in the first direction of the signal pad  130  may be allocated as the bonding region  132 . In this case, the margin region  134  may be directly connected to the transmission line  124 . 
     In the embodiment of  FIG. 4 , the margin region  134  may be disposed between the bonding region  132  and the transmission line  124 , so that an impedance mismatch may be resolved before radio-wave or power is supplied to the radiator  122 . Further, a directivity of radio-wave power to the radiator  122  may be improved. 
     Referring to  FIG. 5 , the margin region  134   a  may have a width (e.g., a width in the second direction) greater than that of the bonding region  132 . In this case, when misalignment of the flexible circuit board  200  or the conductive intermediate structure  150  to the bonding region  132  occurs, an additional alignment margin from the margin region  134   a  may be more effectively provided. 
     Additionally, a length of the margin region  134   a  may be relatively reduced, and an area occupied by the signal pad  130  may be reduced. 
     Referring to  FIG. 6 , the margin area  136  may include an extension in the width direction (e.g., the second direction). 
     For example, the margin region  136  may include a first portion  136   a  extending in the length direction (e.g., in the first direction) to be in contact with the bonding region  132 , and a second portion  136   b  extending in the width direction from an end of the first portion  136   a.    
     The impedance mismatch may be buffered or suppressed through the first portion  136   a  having a shape substantially similar to that of the bonding region  132 , and a resistance of the signal pad  130  may be further reduced through the second portion  136   b  to improve a supply efficiency of radio-wave or power to the radiator  122 . 
     Referring to  FIG. 7 , the antenna unit may include the radiator  122 , a first signal pad  153  and a second signal pad  157 , and the radiator  122  may be electrically connected to the first signal pad  153  and the second signal pad  157  through a first transmission line  123  and a second transmission line  125 , respectively. 
     For example, the first signal pad  153  and the second signal pad  157  may receive a power from the external circuit structure and transfer the power to the radiator  122 . 
     In exemplary embodiments, the first signal pad  153  may include a first bonding region  152  and a first margin region  154 , and the second signal pad  157  may include a second bonding region  156  and a second margin region  158 . 
     The first bonding region  152  and the second bonding region  156  may be regions directly attached bonded to the external circuit structure, and may have substantially the same structure and function as those of the above-described bonding region  132 . 
     The first margin region  154  and the second margin region  158  may be regions that are not directly attached or bonded to the external circuit structure. Accordingly, the first margin area  154  and the second margin area  158  may include remaining portions of the first signal pad  153  and the second signal pad  157  excluding the bonding regions. The first margin region  154  and the second margin region  158  may have substantially the same structure and function as those of the margin region  134  as described above. 
     The radiator  122  may receive signals from the first and second signal pads  153  and  157  in different directions. Thus, a plurality of polarization property (e.g., a dual polarization) may be implemented in one radiator. 
     In this case, the signal input to the radiator  122  may be distributed and supplied from the first and second signal pads  153  and  157 , so that a total area of the first and second bonding regions  152  and  156  may be sufficiently obtained to stably provide signals. 
     Additionally, the area ratio of the bonding region and the margin region may be adjusted within the rang as described above, so that the impedance mismatch may be suppressed or buffered, and the antenna gain property may be also improved. 
     The radiator  122  may receive an input signal (an electrical signal) from each of the first signal pad  153  and the second signal pad  157  to radiate an electromagnetic wave signal. Further, the electromagnetic wave signal may be received and converted into the electrical signal based on a reciprocal property of the antenna, 
     In some embodiments, the first transmission line  123  and the second transmission line  125  may be connected to two adjacent sides (two adjacent sides of a polygon in a planar view) of the radiator  122  having a polygonal shape. For example, the first transmission line  123  and the second transmission line  125  may be connected to centers of the two sides. 
     An imaginary line passing through a center of the radiator  122  and equally dividing the radiator  122  may be defined as a central line CL. As illustrated in  FIG. 7 , the central line CL may extend in the first direction. 
     In some embodiments, the first transmission line  123  and the second transmission line  125  may extend obliquely with respect to the central line CL of the radiator  122 . 
     For example, if the radiator  122  has a rhombus shape as illustrated in  FIG. 7 , the first transmission line  123  and the second transmission line  125  may extend vertically to the adjacent two sides of the radiator  122 . In this case, the first transmission line  123  and the second transmission line  125  may have the shortest lengths, and a transmission speed and an efficiency of the input signal may be improved. 
     In some embodiments, the first transmission line  123  and the second transmission line  125  may be symmetrical to each other. For example, the first transmission line  123  and the second transmission line  125  may be symmetrical with respect to the center or the central line CL of the radiator  122 . 
     Referring to  FIG. 8 , the first transmission line  123  and the second transmission line  125  may extend along imaginary lines extending from the center of the radiator  122  to two adjacent vertices. 
     For example, the radiator  122  may have a quadrangular (e.g., rectangular or square) shape with one side parallel to the first direction. The quadrangle-shaped radiator  122  may include a first vertex and a second vertex adjacent to the first vertex in the second direction. 
     The first transmission line  123  may extend from the first vertex along an imaginary line connecting the first vertex and the center of the radiator  122 . The second transmission line  125  may extend from the second vertex along an imaginary line connecting the second vertex and the center of the radiator  122 . 
     In this case, signal transmission and reception, and feeding in different directions may be implemented through the first transmission line  123  and the second transmission line  125 , so that a dual polarization property of the antenna may be effectively implemented. 
     Referring to  FIG. 9 , at least one side of the radiator  122  may be parallel to a width direction (e.g., the second direction) of the antenna structure. For example, the radiation pattern  122  may have a square shape, and one side of the square-shape radiator  122  may be parallel to a width direction (e.g., the second direction) of the antenna structure. 
     In some embodiments, the first transmission line  123  and the second transmission line  125  may branch from two adjacent sides of the radiation pattern  122 . The branched first transmission line  123  may be connected to the first signal pad  153  in a straight line, and the second transmission line  125  may be bent to be connected to the second signal pad  157 . 
     Accordingly, a phase difference between the first input signal and the second input signal supplied to the radiator  122  through the first transmission line  123  and the second transmission line  125 , respectively, may be controlled by the driving IC chip  280 . 
     In some embodiments, the first signal pad  153  may supply the first input signal having a first phase to the radiator  122 . The second signal pad  157  may supply the second input signal having a second phase. 
     In some embodiments, the first input signal and the second input signal may be alternately supplied. In this case, a vertical polarization property and a horizontal polarization property may be implemented from one radiator  122 . For example, one of the vertical polarization property and the horizontal polarization property may be implemented through the radiator  122  when the first input signal is supplied, and the other one may be implemented when the second input signal is supplied. 
     In some embodiments, the phase of the first input signal may be different from the phase of the second input signal. The second input signal having the phase different from the phase of the first input signal may be supplied together to implement a circular polarization or elliptical polarization property. The first input signal and the second input signal having the phase difference may be supplied together to the radiator  122 , and a plurality of polarization properties may be implemented through the radiator  122 . 
     For example, the phase difference between the first input signal and the second input signal may be adjusted, or the first input signal and the second input signal may be supplied while switching each other, so that a plurality of the polarization properties may be implemented. The polarization properties may include a horizontal polarization, a vertical polarization, a right rotation polarization, a left rotation polarization, and the like. 
     In some embodiments, when the first input signal and the second input signal are simultaneously supplied, the phase difference between the first input signal and the second input signal may be from about 80° to 100°. In this case, the antenna structure may effectively implement the horizontal polarization, the vertical polarization and the circular polarization properties together. Preferably, the phase difference may be from 85° to 95°, more preferably about 90°. 
     For example, when the phase difference is from about 90° and an axial ratio of the radiator is about 1, the antenna structure may additionally implement the circular polarization (the right rotation polarization and the left rotation polarization) property. 
     Thus, a plurality of the polarization properties may be implemented through one radiator  122 , so that signals of various polarization types may be effectively transmitted and received. Further, a horizontal polarization antenna and a vertical polarization antenna may be integrated, so that a spatial utilization may be improved when the antenna is disposed in a display device, etc. 
     In some embodiments, the phase difference between the first input signal and the second input signal may be controlled by adjusting lengths of the first transmission line  123  and the second transmission line  125 . For example, as illustrated in  FIG. 7 , the lengths of the first transmission line  123  and the second transmission line  125  may be adjusted to be substantially the same. As illustrated in  FIG. 9 , the first transmission line  123  and the length of the second transmission line  125  may be adjusted to be different from each other. 
     For example, if the lengths of the first transmission line  123  and the second transmission line  125  are substantially the same, the input signals having the predetermined phase difference values may be supplied to the first signal pad  153  and the second signal pad  157  from the driving integrated circuit chip while maintaining the phase difference. Accordingly, accurate adjustment of the phase difference between the first input signal and the second input signal may be facilitated. 
     Referring to  FIG. 10 , if the radiator  122  includes a mesh structure, a dummy mesh pattern  126  may be disposed around the radiator  122 . As described with reference to  FIG. 1 , the radiator  122  may include the mesh structure, so that transmittance of the antenna device  100  or the antenna structure may be improved. 
     The dummy mesh pattern  126  may be disposed around the radiator  122 , so that an electrode arrangement around the radiator  122  may become uniform or averaged. 
     Accordingly, a visual recognition of the mesh structure or electrode lines included therein may be prevented to a user of the display device. 
     For example, a metal layer may be formed on the dielectric layer  110 , and the mesh structure may be formed while the metal layer may be etched along a predetermined separation region  129  to electrically and physically separate the dummy mesh pattern  126  from the radiation pattern  122  and the transmission line  124 . 
     As illustrated in  FIG. 10 , if the transmission line  124  also includes the mesh structure, the dummy mesh pattern  126  may also extend around the transmission line  124 . In an embodiment, the signal pad  130  and/or the ground pad  140  may also include the mesh structure. In this case, the dummy mesh pattern  126  may be extended around the signal pad  130  and/or the ground pad  140 . 
       FIG. 11  is a schematic top planar view illustrating a display device in accordance with exemplary embodiments. For example,  FIG. 11  shows an external shape including a window of a display device. 
     Referring to  FIG. 11 , a display device  300  may include a display area  310  and a peripheral area  320 . The peripheral area  320  may be disposed at both lateral portions and/or both end portions of the display area  310 . 
     In some embodiments, the antenna device  100  included in the above-described antenna structure may be inserted into the peripheral area  320  of the display device  300  in the form of a patch. In some embodiments, the signal pad  130  and the ground pad  140  of the antenna device  100  may be disposed to correspond to the peripheral area  320  of the display device  300 . 
     The peripheral area  320  may correspond to, e.g., a light-shielding part or a bezel portion of the image display device. In exemplary embodiments, the flexible circuit board  200  of the antenna structure may be disposed in the peripheral area  320  to prevent an image degradation in the display area  310  of the display device  300 . 
     The flexible circuit board  200  and/or the driving IC chip  280  may be disposed together in the peripheral area  320 . The pads  130  and  135  of the antenna device  100  may be disposed to be adjacent to the flexible circuit board  200  and the driving IC chip  280  in the peripheral area  320 , so that the signal transmission/reception path may be shortened and the signal loss may be suppressed. 
     The radiator  122  of the antenna device  100  may be at least partially disposed in the display area  310 . For example, as illustrated in  FIG. 10 , the visual recognition of the radiator  122  to the user may be prevented by using the mesh structure. 
     Hereinafter, preferred embodiments are proposed to more concretely describe the present invention. However, the following examples are only given for illustrating the present invention and those skilled in the related art will obviously understand that various alterations and modifications are possible within the scope and spirit of the present invention. Such alterations and modifications are duly included in the appended claims. 
     Experimental Example: Measurement of Maximum Gain while Changing Length and Area of Margin Region 
     An antenna unit including a copper-calcium (CuCa) alloy and having a structure as illustrated in  FIG. 7  was formed on a polyimide dielectric layer. Each of the first and second signal pads was formed to have a width of 250 μm. Lengths of the first bonding region included in the first signal pad and the second bonding region included in the second signal pad were each fixed to 500 μm, and the lengths of the margin regions were changed. 
     An ACF layer was formed on the bonding regions, and the copper feeing wiring of a flexible circuit board was exposed and bonded to the ACF layer. A maximum gain was extracted at about 28.5 GHz frequency and an impedance of 50Ω to the flexible circuit board-signal pad connection structure using a radiation chamber (manufactured by C&amp;G Microwave) while increasing the length of the margin region where the ACF layer does not contact. The simulation results were obtained as a graph shown in  FIG. 12 . 
     Referring to  FIG. 12 , as the length of the margin region increased (an area ratio of the margin region increased), the maximum antenna gain decreased. Specifically, the antenna gain decreased from the length of the signal pad was about 650 μm (length of the margin region: 150 μm, area ratio of the margin region to the bonding region: 0.3). When the length of the signal pad exceeded about 750 μm (length of the margin region: 250 μm, area ratio of the margin region to the bonding region: 0.5) such that the area ratio exceeded about 0.5, the reduction of the antenna gain was explicitly detected. Further, when the length of the signal pad was less than about 750 μm (length of the margin region: 25 μm, area ratio of the margin region to the bonding region: 0.05), the antenna gain was decreased and a radiation efficiency was degraded.