Patent Publication Number: US-2015084833-A1

Title: Embedded antenna

Description:
This application claims the benefit of Taiwan application Serial No. 102134595, filed Sep. 25, 2013, the subject matter of which is incorporated herein by reference. 
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The disclosure relates in general to an embedded antenna, and more particularly to a multi-band embedded antenna. 
     2. Description of the Related Art 
     In the contemporary information society, personal mobile communication products have become popular and brought to the market a lot of commercial opportunities. As to versatile electronic communication devices such as laptops, tablet computers, All-in-one PCs, these electronic communication devices have different antenna design. Moreover, the antenna designer is required to take environmental factors into consideration, so as to achieve the desired characteristic and performance of antennas. Even under the same RF specification, the antenna may be needed to be adjusted according to the environment, and thus can meet the requirement of RF specification for versatile electronic communication devices. 
     For a personal mobile communication product, a build-in antenna (embedded antenna) is usually located on a place around a display screen (such as an LCD), so that the radiator of the embedded antenna is designed according to the available space surrounding the display screen. For use in the personal mobile communication product, the antenna is required to have powerful function. In view of the current antenna, the lower the operation frequency of the antenna, the larger the antenna. On the other hand, the higher the operation frequency of the antenna, the smaller the antenna. 
     Thus, it is an issue worthy of being discussed to provide an antenna design that can be used in versatile mobile communication products. 
     SUMMARY OF THE DISCLOSURE 
     The disclosure is directed to a multi-band embedded antenna, wherein a length of an exposed core and/or a gap between the core and a metal protrusion portion may be adjusted for resonance frequency tuning and/or matching. 
     The disclosure is directed to an embedded antenna for multi-band, wherein a feed position of the core can be adjusted so as to achieve resonance frequency tuning and/or matching of the antenna. 
     According to an example of the present disclosure, an embedded antenna is provided. The embedded antenna includes: a metal protrusion portion for providing a first resonance frequency; a co-axial cable for providing a second resonance frequency; and a ground portion. The co-axial cable is fixed and electrically connected to the ground portion. The ground portion is fixed and electrically connected to a system ground plane. The ground portion is electrically connected to the metal protrusion portion. 
     According to another example of the present disclosure, an embedded antenna is provided. The embedded antenna includes: a metal protrusion portion for providing a first resonance frequency; a coupled metal stub for providing a second resonance frequency; a co-axial cable fed into the coupled metal stub, wherein a feed position where the co-axial cable is fed into the coupled metal stub is relative to the first resonance frequency and the second resonance frequency; and a ground portion. The co-axial cable is fixed and electrically connected to the ground portion. The ground portion is fixed and electrically connected to a system ground plane. The ground portion is electrically connected to the metal protrusion portion. 
     The above and other contents of the disclosure will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing a portion of a co-axial cable of an embedded antenna according to the embodiments of the disclosure. 
         FIG. 2  is a schematic diagram showing an embedded antenna according to a first embodiment of the disclosure. 
         FIGS. 3A˜3C  are schematic diagrams showing an example of an embedded antenna according to a second embodiment of the disclosure. 
         FIG. 4  is a schematic diagram showing another example of the embedded antenna according to the second embodiment of the disclosure. 
         FIGS. 5A˜5D  are schematic diagrams showing the field pattern and the efficiency of the embedded embodiment according to the embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The disclosure adopts technical terms which are commonly used by those skilled in the art. If specifically described or defined in the disclosure, some terms should be referred to their description or definition in the disclosure. Technology principles, which are known in the art, are thus omitted for sake of brevity. In addition, elements shown in the figures are provided for exemplary illustration without any intention of limitation to their shape, dimension, and/or scale, and figures are provided for those skilled in the art to understand the disclosure. Thus, the disclosure is not limited thereto. 
     Embodiments of the disclosure each have one or more technical features. In practice, some or all of the technical features described in any embodiment may be selectively used by those skilled in the art. Alternatively, some of all of the technical features described in these embodiments may be selectively combined by those skilled in the art. 
     In the following embodiments of the disclosure, the embedded antenna includes a co-axial cable. In convention, the co-axial cable is mainly used for power transmission. However, in the following embodiments of the disclosure, the co-axial cable is not only used for power transmission but also used to affect resonance frequencies of the antenna. 
       FIG. 1  is a schematic diagram showing a portion of a co-axial cable of an embedded antenna according to an embodiment of the disclosure. The co-axial cable  11  includes a core  112 , an insulation layer  113 , an outer woven shield  114  (which can be made of metal materials), and a plastic cover  115 . The core  112  is exposed outside the insulation layer  113 . The core  112  can affect the resonance frequencies of the embedded antenna. 
     The insulation layer  113  covers the core  112 , but does not completely cover the core  112 . The insulation layer  113  may be made of Teflon. The outer woven shield  114  covers the insulation layer  113  and the core  112  inside the insulation layer  113 . But, the outer woven shield  114  does not completely cover the insulation layer  113 . 
     The plastic cover  115  of the co-axial cable  11  does not completely cover the outer woven shield  114 . The exposed outer woven shield  114  may be fixed to and electrically connected to a system ground plane (not shown) of a mobile communication product. The co-axial cable  11  is electrically connected to the system ground plane of the mobile communication product through the outer woven shield  114 . 
     The system ground plane of the mobile communication product can be electrically connected to the outer woven shield  114 . Specifically, the outer woven shield  114  of the co-axial cable  11  is connected to the system ground plane of the mobile communication product through, for example, a ground connector (not shown) which may be made of a copper foil tape. 
     First Embodiment 
       FIG. 2  is a schematic diagram showing an embedded antenna  20  according to a first embodiment of the disclosure. As shown in  FIG. 2 , the embedded antenna  20  includes: a co-axial cable  11  (details of which can be referred to the co-axial cable in  FIG. 1 ), a metal protrusion portion  22 , and a ground portion  24 . 
     The ground portion  24  of the embedded antenna  20  may be fixed to and electrically connected to the system ground plane G. For example, a part of the ground portion  24  of the embedded antenna  20  may be fixed to and electrically connected to the system ground plane G, so that both of them are fixed and electrically connected to each other. Similarly, the metal protrusion portion  22  may be electrically connected to the system ground plane G and the ground portion  24 . In fact, the metal protrusion portion  22  and the ground portion  24  are integrated together, while they are described as two separate components here for the sake of explanation. 
     In addition, as is described above, the outer woven shield of the co-axial cable is fixed to the ground portion  24 , thus to be fixed to and electrically connected to the system ground plane G. 
     The metal protrusion portion  22  is for the resonance of the first frequency band (e.g. 2.4 GHz), i.e. for providing a first resonance frequency. The metal protrusion portion  22  is, for example, as an inverted L-shape. In the first embodiment of the disclosure, by adjusting the pattern of the metal protrusion portion  22 , the metal protrusion portion  22  may be resonated at around 2.4 GHz. Adjusting the parameters “a” and “b” may achieve tuning of the resonance frequency (or pattern) in the first frequency band and/or matching. 
     The parameter “a” is indicative of a portion of the core  112  of the co-axial cable which is extended towards the metal protrusion portion  22  in a horizontal direction. That is, the parameter “a” is the length of the core  112  exposes/protrudes from the insulation layer  113 . 
     The parameter “b” is indicative of a gap between the core  112  of the co-axial cable and the metal protrusion portion  22  in a vertical direction. 
     In the first embodiment of the disclosure, adjusting the parameter “c” may achieve tuning of the lowest resonance frequency and the pattern in the second frequency band. The parameter “c” is indicative of a sum of the length of the exposed core  112  and the exposed insulation layer  113 . That is, the core  112  has a portion (having a length represented by the parameter “c”) extended from the outer woven shield  114 , and this portion can affect the resonance frequency of the second frequency band. Slightly adjusting the parameters “c” and “b” may achieve tuning of the resonance frequency in the second frequency band and matching. 
     Thus, in the first embodiment of the disclosure, by controlling the length (the parameter “a”) of the core (i.e., the length of the exposed portion of the core), the gap (the parameter “b”) between the core and the metal protrusion portion  22 , and the length (the parameter “c”) of the core exposed from the outer woven shield, the coupling of the embedded antenna  20  can be controlled, so as to achieve resonance at two frequency bands (e.g. 2.4 GHz and 5 GHz). 
     As can be seen from  FIG. 1  and  FIG. 2 , the embedded antenna in the first embodiment of the disclosure can be modularized. In this way, mass production is convenient and possible. In addition, the embedded antenna in the first embodiment of the disclosure can be used in different situations. In other words, if the antenna is required to be tuned for different situations, the parameters “a” and/or “b” and/or “c” can be slightly adjusted. Therefore, the embedded antenna in the first embodiment of the disclosure is helpful in mass production, thus reducing the manufacturing cost. 
     Second Embodiment 
     As to the embedded antenna of a second embodiment of the disclosure, adjusting a feed position of the core may tune resonance frequency of two frequency bands and/or matching. 
       FIGS. 3A˜3C  are schematic diagrams showing an example of an embedded antenna according to the second embodiment of the disclosure. As shown in  FIGS. 3A˜3C , in tuning, the parameters “a”˜“c” are not adjusted in principle, but rather the feed position of the core of the co-axial cable is adjusted. Detailed description is provided below. 
     In the second embodiment of the disclosure, the embedded antenna  30  further includes a coupled metal stub  35 . In the second embodiment of the disclosure, adjusting the position where the core  112  is fed into the coupled metal stub  35  can tune the resonance frequency of two frequency bands and/or matching. It is made as an example that the coupled metal stub  35  is of an inverted L-shape. The coupled metal stub  35  can be formed on a substrate (not shown). 
     It is made as an example that, in  FIG. 3A , the core  112  is fed into the coupled metal stub  35  at the right angle corner of the coupled metal stub  35 . In this way, two current paths I 1  and I 2  are formed in the embedded antenna  30 . The current path I 1  is formed in the metal protrusion portion  22 , thus providing the resonance of the first frequency band. The current path I 2  is formed in the coupled metal stub  35 , thus providing the resonance of the second frequency band. 
     Thus, as can be seen from  FIG. 3A , if the feed position of the core  112  is adjusted, the paths I 1  and I 2  will be changed correspondingly. As a result, resonance frequency tuning of the first and the second frequency bands and/or matching can be achieved. 
     Similarly, refer to  FIG. 3B  where the core  112  is fed into an end of the coupled metal stub  35 . In this way, two current paths I 1  and I 2  are formed in the embedded antenna  30 A. The current path I 1  is formed in the metal protrusion portion  22 , thus providing the resonance of the first frequency band. The current path I 2  is formed in the coupled metal stub  35 , thus providing the resonance of the second frequency band. 
     Similarly, refer to  FIG. 3C  where the core  112  is fed into another end of the coupled metal stub  35 . In this way, two current paths I 1  and I 2  are formed in the embedded antenna  30 B. The current path I 1  is formed in the metal protrusion portion  22 , thus providing the resonance of the first frequency band. The current path I 2  is formed in the coupled metal stub  35 , thus providing the resonance of the second frequency band. 
     Thus, as can be seen from  FIGS. 3A˜3C , in the second embodiment of the disclosure, the position of where the core  112  is fed into the coupled metal stub  35  can be properly selected and controlled, so as to achieve the resonance frequency at two frequency bands (2.4 GHz/5 GHz) and match adjustment. In addition, the feed position of the core is not limited to those disclosed in  FIGS. 3A˜3C . Any position on the coupled metal stub  35  can be used as the feed position of the core based on different requirements. 
       FIG. 4  is a schematic diagram showing another example of the embedded antenna according to a second embodiment of the disclosure. The antennas of  FIG. 4  and  FIGS. 3A˜3C  are different in that the coupled metal stub  35  of the embedded antenna in  FIGS. 3A˜3C  is of an inverted L-shape, and the coupled metal stub  45  of the embedded antenna  40  in  FIG. 4  is of an irregular shape. Similarly, the position where the core is fed into the coupled metal stub can be properly selected and controlled, so as to achieve the resonance frequency tuning of multiple frequency bands and matching. 
     Besides, the embedded antennas in  FIGS. 2˜4  are located on the upper part of the system ground plane G, but this disclosure is not limited thereto. For example, the embedded antenna in other practicable embodiments of the disclosure can be located on the center part, the lower part, or two sides of the system ground plane G, which also is within the disclosure. That is, the embedded antenna in the embodiments of the disclosure can be properly located on any position of the system ground plane according to different requirements. 
       FIGS. 5A˜5D  are schematic diagrams showing the field pattern and the efficiency of the embedded antenna according to the embodiments of the disclosure. In  FIG. 5A , the embedded antenna of the embodiment of the disclosure is located on a place around a screen (e.g. a 14-inch LCD), and is not blocked by a metallic shield.  FIG. 5A  shows the field pattern and the efficiency of the embedded antenna which is resonant at a first frequency brand (2.45 GHz). In  FIG. 5B , the embedded antenna of the embodiment of the disclosure is located on a place around the screen, and is blocked by a metallic shield.  FIG. 5B  shows the field pattern and the efficiency of the embedded antenna which is resonant at the first frequency brand (2.45 GHz). In  FIG. 5C , the embedded antenna of the embodiment of the disclosure is located on a place around the screen, and is not blocked by a metallic shield.  FIG. 5C  shows the field pattern and the efficiency of the embedded antenna which is resonant at a second frequency brand (5.5 GHz). In  FIG. 5D , the embedded antenna of the embodiment of the disclosure is located on a place around the screen, and is blocked by a metallic shield.  FIG. 5D  shows the field pattern and the efficiency of the embedded antenna which is resonant at the second frequency brand (5.5 GHz). 
     As can be seen from  FIGS. 5A˜5D , the embedded antenna of the embodiment of the disclosure provides excellent field pattern and efficiency no matter the embedded antenna is operated at either the first or the second frequency bands, and blocked or not blocked by a metallic shield. 
     From the description mentioned above, according to the two embodiments of the disclosure, resonance frequency tuning of two frequency brands and/or matching can be achieved by changing position or length of the core in different ways (e.g. adjusting an exposed length of the core or an length of the core protruding from the outer woven shield in  FIG. 2 , or adjusting a feed position of the core of the co-axial cable in  FIGS. 3A˜3C  or  FIG. 4 ). Thus, the embedded antenna of the embodiments of the disclosure can be used in different environment conditions and/or different mobile communication products (for example, the embedded antenna of the embodiments of the disclosure may be located at a proper position on the system ground plane). In this way, product standardization can be achieved, and manufacturing cost can be reduced because the embedded antenna of the embodiments of the disclosure is suitable for different environment conditions and/or different mobile communication products. 
     On the other hand, in order to adjust the resonance frequency and/or matching of a convention antenna, the shape of the metal (i.e. the radiator) of the conventional antenna is adjusted. In this way, different products are required to have different shapes of metal, thus failing in providing a single antenna design for versatile product requirements. 
     While the disclosure has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.