Abstract:
A multi-frequency antenna includes a microwave substrate, a first antenna unit, a second antenna unit, a third antenna unit and a grounding unit. The first antenna unit, the second antenna unit, and the third antenna unit are disposed on the microwave substrate surface. The grounding unit is disposed at an edge on the surface of the microwave substrate. The grounding unit is in connection with the second antenna unit. The second antenna unit and the third antenna unit are bent to form perpendicular structures to the microwave substrate. The compact arrangement reduces the physical footprint of the antenna module to enable fitment in a wide range of products having tight special constraint.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The instant disclosure relates to a multi-band antenna, and more particularly, to a multi-band antenna for wireless communication signal receiving and transmitting. 
         [0003]    2. Description of Related Art 
         [0004]    Antenna is an important component of modern wireless-communication devices. The main function of an antenna is to provide signal reception and transmission. Antennas of different shapes and sizes can be found in the entire range of 3C products, including laptop computers, mobile phones, GPS (global positioning system) navigators, digital TVs and many other applications. Different communication standards often require antennas having different operating frequency bands. Moreover, as modern wireless-communication devices grow lighter and smaller, the research for wide-band miniaturized antennas receive much attention. 
         [0005]    Multi-band antenna designs encounter a technical challenge of antenna size miniaturization because the negative effects of coupling interference between nearby antenna components may become more influential as the antenna&#39;s physical dimensions are reduced. The coupling interference between each component on a miniature multi-band antenna in close proximity may cause serious of impedance bandwidth, antenna gain and efficiency. 
         [0006]    Conventional multi-band antennas often include a substrate, a plurality of antenna radiation portions, a grounding portion, and a feeding portion. The multi-band operations can be achieved by incorporating several compositions that support different resonant frequency bands on a single antenna unit. 
         [0007]    However, the conventional multi-band antenna cannot fully support the Wi-Fi (2.4 GHz), Bluetooth (2.4-2.5 GHz), WiMAX (2.5 GHz), GSM900/1800 and GPS (1.57 GHz) operations. Consequently, it is difficult to concurrently integrate the operating bandwidths for wireless networks, mobile phones, and global positioning systems into a wireless-communication device having only a single antenna unit. 
         [0008]    Based on research and related industrial experience, the inventor proposes the following solution for addressing the above issues. 
       SUMMARY OF THE INVENTION 
       [0009]    The object of the instant disclosure is to provide a multi-band antenna, which has multiple operating bandwidths and covers bandwidths from low-frequency to high-frequency Particularly, the instant disclosure provides a multi-band antenna, which includes a microwave substrate, a first antenna unit, a second antenna unit, a third antenna unit and a grounding unit. The first antenna unit, the second antenna unit and the third antenna unit are printed on the surface of the microwave substrate. The grounding unit, connecting to the second antenna unit can be made by metallic foil arranged at an edge of the microwave substrate. The constructions of the second antenna unit and the third antenna unit can be divided into two parts that are perpendicular to each other, which can reduce the size of the proposed antenna. 
         [0010]    The multi-band antenna can cover the frequencies of 670˜800 MHz, 800˜960 MHz and 1570˜3000 MHz. Also, by adjusting the spacing between the three antenna units, the electromagnetic coupling may be altered for fine tuning the resonant frequency of the antenna to meet the requirement of various wireless standards with different operating frequencies. 
         [0011]    In order to further realize the characteristics and technical contents of the instant disclosure, figures of measured results and detailed descriptions of the instant disclosure are presented in the following. However, the abovementioned figures and descriptions are merely shown for exemplary purposes, rather than being used to restrict the scope of the instant disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a plane diagram of the first embodiment of the instant disclosure; 
           [0013]      FIG. 2  shows a stereogram of the first embodiment of the instant disclosure; 
           [0014]      FIG. 3  shows the measured return loss of the first embodiment of the instant disclosure; 
           [0015]      FIG. 4  shows a plane diagram of the second embodiment of the instant disclosure; 
           [0016]      FIG. 5  shows a stereogram of the second embodiment of the instant disclosure; and 
           [0017]      FIG. 6  shows the measured return loss of the second embodiment according to the instant disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    Please refer to  FIG. 1  and  FIG. 2 , which show the configurations of the first embodiment of the instant disclosure for a multi-band antenna M. The multi-band antenna M includes a microwave substrate  1 , a first antenna unit  2 , a second antenna unit  3 , a third antenna unit  4  and a grounding unit  6 . 
         [0019]    The first antenna unit  2  includes a first extended segment  21  and a first distal segment  22 . The first distal segment  22  is connected to the terminal portion of the first extended segment  21 . The first distal segment  22  is perpendicular to the first extended segment  21 . The feeding point  5  of the first antenna unit  2  can be connected to a 50 Ω coaxial cable. 
         [0020]    The second antenna unit  3  includes a second extended segment  31 , a second bent segment  32 , a second straight segment  33 , and a second distal segment  34 . The second bent segment  32  is connected to the terminal portion of the second extended segment  31 . The second bent segment  32  is perpendicular to the second extended segment  31 , and the second extended segment  31  is parallel to the first distal segment  22 . The gap between the second extended segment  31  and the first distal segment  22  can be 1 mm. The second straight segment  33  is connected to the terminal portion of the second bent segment  32 . The second straight segment  33  is perpendicular to the second bent segment  32 , and the straight segment  33  is parallel to the first distal segment  22 . The second distal segment  34  is connected to the terminal portion of the second straight segment  33 . The second distal segment  34  is perpendicular to the second straight segment  33 , and the second distal segment  34  is parallel to the first extended segment  21 . 
         [0021]    The third antenna unit  4  includes a third extended segment  41 , a third bent segment  42 , and a third distal segment  43 . The third bent segment  42  is connected to the terminal portion of the third extended segment  41 . The third bent segment  42  is perpendicular to the third extended segment  41 , and the third bent segment  42  is parallel to the first extended segment  21 . The third distal segment  43  is connected to the terminal portion of the third bent segment  42 . The third distal segment  43  is perpendicular to the third bent segment  42 , and the third distal segment  43  is parallel to the second straight segment  33 . The third extended segment  41  is perpendicular to the first extended segment  21 . 
         [0022]    As shown in  FIG. 1 , the constructions of the second antenna unit  3  and the third antenna unit  4  can be bent along the dash line A-A on the microwave substrate  1  and divided into two parts. One part is perpendicular to the other (show in  FIG. 2 ). This arrangement may help reducing the physical dimensions of the proposed antenna on the microwave substrate. Thus, the instant disclosure of the multi-band antenna can be placed in a 55*8*4 mm 3  volume of space, which can obtain the optimal use of space. 
         [0023]    Please refer to  FIG. 3 , which shows the measured return-loss curve for the first embodiment of the multi-band antenna M. This curve shows that multi-band antenna M can obtain four resonant modes exciting at lower and higher frequencies ranged from 670 to 960 MHz and from 1570 to 3000 MHz, respectively, within the definition of 6-dB return loss. The first antenna unit  2  can stimulate the resonant mode excited at frequencies from 1570 to 3000 MHz. The first antenna unit  2  and the second antenna unit  3  can couple each other to generate two resonant modes excited at frequencies from 670 to 800 MHz and 1570 to 3000 MHz, respectively. The second antenna unit  3  and the third antenna unit  4  can couple each other to generate a resonance ranged from 800 to 960 MHz. Furthermore, the impedance matching of the lower frequency band and the higher band can be improved by adjusting the strip width of the third extended segment  41  and the structure parameters of the third antenna unit  4 , respectively. 
         [0024]    Please refer to  FIG. 4  and  FIG. 5 , which show a multi-band antenna M in accordance with the second embodiment of the instant disclosure. The multi-band antenna M includes a microwave substrate  1 , a first antenna unit  2 , a second antenna unit  3 , a third antenna unit  4 , and a grounding unit  6 . The first antenna unit  2  and the second antenna unit  3  in the second embodiment share similar structural arrangements with the first embodiment. However, in the second embodiment, portions of the second and the third antenna units may be constructed without a bent portion. The flexibility of structural layout allows the instant antenna units to be adjusted to suit particular operational or spatial requirements. 
         [0025]    The third antenna unit  4  is disposed on the surface of the microwave substrate  1 , and includes a third extended segment  41 , a third bent segment  42 , and a third distal segment  43 . The third extended segment  41  comprises a first section  411 , a second section  412 , a third section  413 , a fourth section  414 , and a fifth section  415 . The second section  412  is connected to the terminal portion of the first section  411 . The second section  412  is perpendicular to the first section  411 , and the second section  412  is arranged substantially parallel to the first extended segment  21 . The third section  413  is connected to the terminal portion of the second section  412 . The third section  413  is substantially perpendicular to the second section  412 , and the third section  413  is substantially parallel to the second straight segment  33 . The fourth section  414  is connected to the terminal portion of the third section  413 . The fourth section  414  is substantially perpendicular to the third section  413 , and the fourth section  414  is substantially parallel to the first extended segment  21 . The fifth section  415  is connected to the terminal portion of the fourth section  414 . The fifth section  415  is substantially perpendicular to the fourth section  414 , and the fifth section  415  is substantially parallel to the second straight segment  33 . The third bent segment  42  is connected to the terminal portion of the fifth section  415 . The third bent segment  42  is substantially perpendicular to the fifth section  415 , and the third bent segment  42  is substantially parallel to the first extended segment  21 . The third distal segment  43  includes a sixth section  431 , a seventh section  432 , a eighth section  433 , and a ninth section  434 . The sixth section  431  is connected to the terminal portion of the third bent segment  42 . The sixth section  431  is arranged substantially perpendicular to the third bent segment  42 , and the sixth section  431  is substantially parallel to the second straight segment  33 . The seventh section  432  is connected to the terminal portion of the sixth section  431 . The seventh section  432  is perpendicular to the sixth section  431 , and the seventh section  432  is substantially parallel to the first extended segment  21 . The eighth section  433  is connected to the terminal portion of the seventh section  432 . The eighth section  433  is perpendicular to the seventh section  432 , and the eighth section  433  will be parallel to the second straight segment  33 . The ninth section  434  is connected to the terminal portion of the eighth section  433 . The ninth section  434  is substantially perpendicular to the eighth section  433 . 
         [0026]    The first antenna unit  2  can be a L-shaped metallic micro-strip. The second antenna unit  3  can be the metallic micro-strip. The third antenna unit  4  can be an U-shaped metallic micro-strip. The grounding unit  6  can be the metallic foil, which is set on the surface of the microwave substrate  1 . The one edge of the grounding unit connected with the second antenna unit. 
         [0027]    In the instant embodiment, portions of the second antenna unit  3  may be folded to reduce physical dimension alone a specific direction, thus increasing the adaptability of the antenna unit. For example, the broken line B-B across the second antenna unit  3  as shown in  FIG. 4  may be folded to form a substantially perpendicular structure with respect to the microwave substrate  1 , as show in  FIG. 5 . The folded structure of the instant antenna makes it particularly suitable for fitting around tight corners inside a miniature electronic device. 
         [0028]    The difference between the first embodiment and the second embodiment is the width of metallic micro-strips. We can adjust the width of metallic micro-strips for differential impedance matching of the operating bandwidth. Thus, it can increase the efficient use of antenna and achieve greater efficiency. 
         [0029]    In the second embodiment, the width of metallic micro-strip of the second straight segment  33  can be 3 mm. The width of metallic micro-strip of the first section  411 , the second section  412 , the third section  413 , the fourth Section  414 , and the fifth section  415  can be 0.3 mm. The width of metallic micro-strip of the third bent segment  42 , the sixth section  431 , and the seventh section  432  can be 1 mm. The width of metallic micro-strip of the eighth section  433  can be 0.5 mm. The square measure of metallic piece of the ninth section  434  can be 4*2 mm 2 . 
         [0030]    Finally, please refer to  FIG. 6 , which shows the measured return-loss curve according to the second embodiment. The favorable results shown in  FIG. 6  are similar to that of  FIG. 3 . Specifically, not only we can adjust the metallic micro-strip of the third extended segment  41  of the third antenna unit  4  to enhance the impedance matching of the low-frequency bandwidth, but also can adjust the structure of the third antenna unit  4  to enhance the impedance matching of the high-frequency. 
         [0031]    Based on the above discussions, the instant disclosure has the following advantages. Mainly, the multi-band antenna reach the resonance mode for 670˜800 MHz, 800˜960 MHz and 1570˜3000 MHz. We can adjust the spacing between antenna units to control the electromagnetic coupling. Then, tune the resonant frequency up to reach the various wireless standards of the operating bandwidth. Otherwise, parts of the second and the third antenna units are perpendicular to the microwave substrate, which can reduce the planer area of the microwave substrate. 
         [0032]    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.