Patent Publication Number: US-2013241777-A1

Title: Multi-band antenna structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The instant disclosure relates to an antenna structure; more particularly, to a multi-band antenna structure having a hairpin tuning portion for increased antenna efficiency. 
     2. Descriptions of Related Art 
     Majority of the wireless communication devices, such as mobile phones, laptops, and tablets, in the market today are equipped with antenna structures. These antenna structures serve as a medium for sending and receiving electromagnetic signals. The antennas are often disposed within the limited space inside the wireless communication devices as a built-in component. 
     A conventional antenna structure is shown in  FIG. 6 . Structurally, the antenna structure comprises a grounding portion  1   a , a linear radiating portion  2   a , and a connecting portion  3   a  normally connected to the ground portion  1   a  and the radiating portion  2   a  on opposite ends. The radiating portion  2   a  is defined by a high frequency segment  21   a  and a low frequency segment  22   a . The connecting portion  3   a  is connected between the high and low frequency segments  21   a  and  22   a . The interconnecting location between the connecting portion  3   a  and the radiating portion  2   a  is defined as a feeding point O for a feed signal. 
     Furthermore, the connecting portion  3   a  has a feeding segment  31   a , a connecting segment  32   a , and a grounding segment  33   a  connected in sequence. One end of the feeding segment  31   a  is perpendicularly connected between the high and low frequency segments  21   a  and  22   a . The opposite ends of the connecting segment  32   a  are perpendicularly connected to the other end of the feeding segment  31   a  and one end of the grounding segment  33   a . Whereas the other end of the grounding segment  33   a  is perpendicularly connected to the grounding portion  1   a . The perpendicular arrangements between various segments of the connecting portion  3   a  are used for adjusting the antenna efficiency. 
     The test results of the high frequency performance for the conventional antenna structure are shown in  FIG. 4  by the broken line A. For the low frequency test, the results are shown in  FIG. 5  by the broken line A′. Since the efficiency value is an important parameter in the design of antenna structures, the measured data suggest the conventional antenna still has rooms for improvement. 
     To address the above issues, the inventors strive via industrial experience and academic research to present the instant disclosure, which can effectively improve the limitations described above. 
     SUMMARY OF THE INVENTION 
     The instant disclosure provides a multi-band antenna structure, which utilizes a tuning portion to increase the antenna efficiency in both high and low frequency operations. 
     Embodiments of the instant disclosure provides a multi-band antenna structure that comprises a grounding portion; a radiating portion spaced apart from the grounding portion and arranged on one side thereof; and a tuning portion arranged between and connecting the grounding and the radiating portions. The radiating portion comprises a first radiating segment and a second radiating segment. One portion of the first radiating segment is arranged pointing toward the grounding portion. The second radiating segment, being a structural extension of the first radiating segment, extends perpendicularly from the first radiating segment. The tuning portion bridges the first radiating segment of the radiating portion and the grounding portion. The tuning portion has a hairpin segment and a grounding segment. The hairpin segment is substantially U-shaped. One end of the hairpin segment is connected to the portion of the first radiating segment that points toward the grounding portion, while the other end thereof bendingly extends to form the grounding segment, which in turn connects the grounding portion. The interconnecting portion between the first radiating segment and the hairpin segment defines a feed point. 
     Preferably, the hairpin segment has a first arm, a connecting arm, and a second arm sequentially connected in the above mentioned order. The first arm is connected by one end of first radiating segment proximate to the grounding portion. The second arm is arranged between the first arm and the grounding portion, where the second arm is connected to the grounding segment. 
     Preferably, the first and second arms are substantially parallel to each other. 
     Preferably, the first radiating segment and the first arm cooperatively form a substantially U-shaped structure. 
     Preferably, the second radiating segment is connected by one end of the first radiating segment proximate to the grounding portion. The second radiating segment and the first arm are connected to the same location on the first radiating segment but directed toward opposite directions. 
     Preferably, the second arm is dimensionally shorter than the first arm. 
     Preferably, in a direction away from the grounding portion, the second radiating segment is connected by one end of the first radiating segment, where the second radiating segment is arranged between the first radiating segment and the first arm. 
     Preferably, the first and second radiating segments cooperatively define an L-shaped structure. 
     Preferably, the second radiating segment extends from the first radiating segment toward the first arm and bends to extend in parallel with the first arm. 
     Preferably, the multi-band antenna structure further has a coupling portion for coupling to the radiating portion by extending from the grounding portion toward the first radiating segment. 
     Based on the above, the multi-band antenna structure utilizes the signal feed point, the hairpin segment of the tuning portion, and the positions of the first and second radiating segments relative to each other to increase the antenna efficiency for high and low frequency operations. 
     In order to further appreciate the characteristics and technical contents of the instant disclosure, references are hereunder made to the detailed descriptions and appended drawings in connection with the instant disclosure. However, the appended drawings are merely shown for exemplary purposes, rather than being used to restrict the scope of the instant disclosure. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         FIG. 1  shows a schematic view of a multi-band antenna structure for a first embodiment of the instant disclosure. 
         FIG. 2  shows a schematic view of a multi-band antenna structure for a second embodiment of the instant disclosure. 
         FIG. 3  shows a schematic view for a variant of the multi-band antenna structure for the second embodiment of the instant disclosure. 
         FIG. 4  shows a plot comparing the efficiencies between the multi-band antenna structure of the instant disclosure and a conventional antenna structure for high frequency operation. 
         FIG. 5  shows a plot comparing the efficiencies between the multi-band antenna structure of the instant disclosure and the conventional antenna structure for low frequency operation. 
         FIG. 6  shows a schematic view of the conventional antenna structure. 
     
    
    
     DETAILED DESCRIPTIONS OF EMBODIMENTS 
     First Embodiment 
     For a first embodiment of the instant disclosure, please refer to  FIG. 1  in conjunction with  FIGS. 4 and 5 .  FIG. 1  is a schematic view of the instant embodiment, while  FIGS. 4 and 5  show the measured data of the instant embodiment. 
     As shown in  FIG. 1 , a multi-band antenna structure is formed on a substrate  5  for accepting a feed signal. The antenna structure has a grounding portion  1 , a radiating portion  2  spaced apart from the grounding portion  1  and arranged on one side thereof, and a tuning portion  3  arranged between and bridging the grounding and the radiating portions. 
     The substrate  5  has a first surface  51  and a second surface  52 . The first and second surfaces  51  and  52  are opposite surfaces of the substrate  5 . For the instant embodiment, the antenna structure is formed on the first surface  51  of the substrate  5 . Alternatively, the antenna structure may also be formed on the second surface  52  instead. Also, for the instant embodiment, the substrate  5  has a plate-like shape. However, in practice, the shape of the substrate  5  is not restricted. For example, the substrate  5  may have an arc-like shape. 
     For practical applications, the multi-band antenna structure may be adapted in tablet computers, laptops, mobile phones, or other wireless communication devices. Moreover, for the instant embodiment, the structural features of the antenna structure are illustrated by the referenced figures. However, in practice, based on the user&#39;s requirements, the structural configurations can be adjusted to meet the needs. For example, any segment of the antenna structure can be widened or display a wave-like shape. 
     The radiating portion  2  is bridged by the tuning portion  3  to the grounding portion  1 . The radiating portion  2  has a first radiating segment  21  and a second radiating segment  22 . The first radiating segment  21  has a portion thereof (for example, segment  211 ) bendingly arranged toward the grounding portion ( 1 ). The second radiating segment  22 , being an extension structure of the first radiating segment  21 , extends perpendicularly from the first radiating segment  21 . 
     The tuning portion  3  is disposed between the first radiating segment  21  of the radiating portion  2  and the grounding portion  1 . The tuning portion  3  has a hairpin segment  31  and a grounding segment  32 . The hairpin segment  31  is substantially U-shaped. One end of the hairpin segment  31  is connected by one end of the first radiating segment  21  proximate to the grounding portion  1 . The opposite ends of the grounding segment  32  are connected by the other end of the hairpin segment  31  and the grounding portion  1 . 
     In greater detail, the hairpin segment  31  has a first arm  311 , a connecting arm  312 , and a second arm  313  formed in sequence. One end of the first arm  311  is connected by one end of the first radiating segment  21  proximate to the grounding portion  1 . The opposite ends of the connecting arm  312  are connected by the other end of the first arm  311  and one end of the second arm  313 . The second arm  313  is disposed between the first arm  311  and the grounding portion  1 , where the other end of the second arm  313  is connected to the grounding segment  32 . 
     For the instant embodiment, the first and second arms  311  and  313  are substantially parallel to one another. The connecting arm  312  is dimensionally shorter than the first arm  311 . However, in practice, the structural configurations of the tuning portion  3  are not restricted. 
     Through the dimensional adjustment of the first and second arms  311  and  313  of the hairpin segment  31 , the multi-band antenna structure is capable of increasing its frequency bandwidth, thus increasing the antenna efficiency. 
     The radiating portion  2  that functions cooperatively with the tuning portion  3  is described in more details hereinbelow. The first radiating segment  21  is substantially L-shaped. Namely, the first radiating segment  21  has a short arm  211  and a long arm  212  perpendicularly connected to each other. The first radiating segment  21  and the first arm  311  form a substantially U-shaped structure. The short arm  211  of the first radiating segment  21  is perpendicularly connected to the first arm  311 . The long arm  212  of the first radiating segment  21  is parallel to the first arm  311 . 
     In particular, the connecting location between the first radiating segment  21  and the hairpin segment  31  is defined as a feed point P for accepting the feed signal. More specifically, the location of the feed point P is defined on the short arm  211  of the first radiating segment  21  proximate to the hairpin segment  31 . 
     Meanwhile, the relative locations between the short and long arms  211  and  212  of the first radiating segment  21  and their dimensions can be adjusted according to the user&#39;s needs, rather than being restricted by  FIG. 1 . 
     The second radiating segment  22  is connected to one end of the first radiating segment  21  proximate to the grounding portion  1 . Namely, the second radiating segment  22  and the hairpin segment  31  share the same connecting location on the short arm  211  of the first radiating segment  21  pointing toward opposite directions. In other words, the second radiating segment  22  and the first arm  311  split from the first radiating segment  21  toward opposite directions. 
     In practice, the first radiating segment  21  can be used for low frequency operation, while the second radiating segment  22  is applicable for high frequency operation. The structural configurations of the multi-band antenna structure, such as the feed point P location, the length adjustment of the hairpin segment  31  for the tuning portion  3 , and the relative position between the first and second radiating segments  21  and  22  of the radiating portion  2 , enable the antenna structure to achieve higher efficiency for high and low frequency operations. 
     For the high frequency operation, the test results of the antenna structure of the instant disclosure are presented by the broken line B in  FIG. 4 . The measure data for the conventional antenna structure (as shown in  FIG. 6 ) is presented by the broken line A. The comparison clearly shows significant improvement in efficiency for the antenna structure of the instant disclosure. 
     Similarly, for low frequency operation, the test results of the antenna structure of the instant disclosure are presented by the broken line B′ in  FIG. 5 . The measure data for the conventional antenna structure (as shown in  FIG. 6 ) is presented by the broken line A′. The comparison clearly shows significant improvement in efficiency for the antenna structure of the instant disclosure. 
     The plots shown in  FIGS. 4 and 5  verify the multi-band antenna structure of the instant embodiment can indeed provide better efficiency for both low and high frequency operations versus the conventional antenna. 
     Second Embodiment 
     For a second embodiment of the instant disclosure, please refer to  FIGS. 2˜5 .  FIGS. 2 and 3  are schematic views of the instant embodiment, while  FIGS. 4 and 5  show the actual test results for the instant embodiment. 
     The instant embodiment is similar to the previous embodiment. Therefore, identical features are not described again hereinafter. Only the differences are explained hereinbelow. 
     As shown in  FIG. 2 , the first and second radiating segments  21  and  22  are both substantially L-shaped. In other words, the second radiating segment  22  also has a short arm  221  and a long arm  222  perpendicularly connected to each other. 
     The second radiating segment  22  is connected to one end of the first radiating segment  21  away from the grounding portion  1 , and the second radiating segment  22  is disposed between the first radiating segment  21  and the first arm  311 . 
     More specifically, the second radiating segment  22  extends from one end of the long arm  212  of the first radiating segment  21  toward the first arm  311 . Then, the second radiating segment  22  is bent and extends toward the first radiating segment  21  parallel to the first arm  311 . In other words, the short arm  221  of the second radiating segment  22  extends perpendicularly from the end of the long arm  212  of the first radiating segment  21  away from its short arm  211  toward the first arm  311 . Then, the short arm  221  of the second radiating segment  22  is bent and extended toward the short arm  211  of the first radiating segment  21  parallel to the first arm  311  in forming the long arm  222  of the second radiating segment  22 . 
     Meanwhile, the distance between the long arm  222  of the second radiating segment  22  and the long arm  212  of the first radiating segment  21  is less than the distance between the long arm  222  of the second radiating segment  22  and the first arm  311  of the hairpin segment  31 . However, in practice, the structural configurations of the radiating portion  2  are not restricted by  FIG. 2 . For example, the relative positions between the short and long arms  211  and  212  of the first radiating segment  21  and their respective lengths can be adjusted based on the requirements of the user, and same principle is applied to the second radiating segment  22 . 
     In practice, the first radiating segment  21  is used for high frequency operation, while the first and second radiating segments  21  and  22  work cooperatively to perform low frequency operation. Based on the structural configurations of the multi-band antenna structure of the instant embodiment, such as the location of the feed point P, the dimensional adjustment of the hairpin segment  31  of the tuning portion  3 , and the relative positions between the first and second radiating segments  21  and  22  of the radiating portion  2 , the antenna efficiency can be increased for high and low frequency operations. Moreover, the relative positions between the second radiating segment  22  and the hairpin segment  31  shown by the instant embodiment are favorable in generating a resonant frequency of 5 GHz. The structural characteristics of the instant embodiment also enable the antenna to occupy less space. 
     The antenna structure of the instant embodiment further has a coupling portion  4  for coupling to the high frequency segment (i.e., first radiating segment  21 ). The purpose is to increase the efficiency for high frequency operation. The coupling portion  4  extends from the grounding portion  1  in a direction toward the first radiating segment  21 . More specifically, the coupling portion  4  extends from the grounding portion  1  across from the short arm  211  of the first radiating segment  21  in a direction toward the short arm  211  of the first radiating segment  21 . The extended length of the coupling portion  4  is less than or equal to the distance between the short arm  211  of the first radiating segment  21  and the grounding portion  1 , but is not restricted thereto. 
     However, in practice, the coupling portion  4  may also be omitted in constructing the antenna structure, as shown in  FIG. 3 . 
     The actual test results of the antenna structure for the instant embodiment at high frequency operation are shown in  FIG. 4  by the broken line C. The measured data for the conventional antenna structure (as shown in  FIG. 6 ) is represented by the broken line A. The comparison clearly shows a significant improvement in efficiency achieved by the antenna structure of the instant embodiment. 
     Similarly, for low frequency operation, the test results of the antenna structure of the instant disclosure are presented by the broken line C′ in  FIG. 5 . The measure data for the conventional antenna structure (as shown in  FIG. 6 ) is presented by the broken line A′. The comparison clearly shows significant improvement in efficiency for the antenna structure of the instant disclosure. 
     The plots shown in  FIGS. 4 and 5  verify the multi-band antenna structure of the instant embodiment can indeed provide better efficiency for both low and high frequency operations versus the conventional antenna. 
     [Capabilities of the Embodiments] 
     Based on the above embodiments, the multi-band antenna structure of the instant disclosure can increase the efficiency for high and low frequency operations through the following: adjusting the location of the feed point P; adjusting the length of the hairpin segment  31  of the tuning portion  3 ; and adjusting the relative positions between the first and second radiating segments  21  and  22  of the radiating portion  2 . Furthermore, the inclusion of the coupling portion  4  for coupling with the high frequency segment can also increase the antenna efficiency. 
     In addition, the increase in efficiency is verified by the test results in comparing to the conventional antenna, where significant improvement is achieved by the instant disclosure. 
     The descriptions illustrated supra set forth simply the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims.