Patent Publication Number: US-8970436-B2

Title: Surface mount device multi-frequency antenna module

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an antenna module, and especially relates to a high-gain multi-frequency antenna module. 
     2. Description of the Related Art 
     The wireless communication technology is progressing every day. Many portable electronic apparatuses, such as notebooks, smart phones, and tablet PCs, are slim and light. Therefore, the antennas for the portable electronic apparatuses are small, too. Or, the structures of the antennas have to be modified, so that the antennas can be arranged into the portable electronic apparatuses. 
     The planar inverted-f antenna (PIFA) is the most common multi-frequency antenna. The PIFA is designed in two-dimension and is made of copper printed on the printed circuit board. Or the PIFA is designed in three-dimension and is made of foil stamped with the stamping technology. 
     The structure of the PIFA mentioned above (both designed in two-dimension and three-dimension) can be modified, so that the PIFA can receive dual-band and tri-band wireless signals. In order to maintain the performance of the antenna, the volume of the PIFA is usually not small, so that the space for arranging the PIFA into the portable electronic apparatus is not small. However, if the space for arranging the PIFA into the portable electronic apparatus is not small, the portable electronic apparatus will not be slim and light. 
     SUMMARY OF THE INVENTION 
     In order to solve the above-mentioned problems, an object of the present invention is to provide a surface mount device multi-frequency antenna module which is slim and light. The surface mount device multi-frequency antenna module includes a carrier which is made of ceramic with high dielectric constant. 
     In order to achieve the object of the present invention mentioned above, the surface mount device multi-frequency antenna module includes a base plate, the carrier, a first ground layer, a first signal feed-in line, a first gap, a second signal feed-in line, a second gap, a third signal feed-in line, and a third gap. The base plate includes a first surface and a second surface. The first ground layer and the first signal feed-in line are arranged on the first surface. The first gap is formed between the first signal feed-in line and the first ground layer. The second signal feed-in line is electrically connected to the first ground layer and is on a left side of the first signal feed-in line. The second gap is formed between the second signal feed-in line and the first signal feed-in line. The third signal feed-in line is electrically connected to the first ground layer and is on a right side of the first signal feed-in line. The third gap is formed between the third signal feed-in line and the first signal feed-in line. 
     The carrier includes a first radiator, a second radiator, a third radiator, and a fourth radiator. The first radiator is electrically connected to the second radiator. The first radiator is not electrically connected to the third radiator and the fourth radiator. 
     A contact connecting the first radiator and the second radiator is electrically connected to the first signal feed-in line when the carrier is electrically connected to the base plate. The third radiator is electrically connected to the second signal feed-in line. The fourth radiator is electrically connected to the third signal feed-in line. 
     Moreover, the first signal feed-in line includes a front segment, a rear segment, and a perforation. The perforation is at the front segment. The front segment is prolonged forward to the first ground layer. The first gap is formed between the front segment and the first ground layer. A width of the second gap formed between the rear segment and the second signal feed-in line is adjusted for adjusting a coupling capacitance, so that the first ground layer provides a resonance point of high frequency. A width of the third gap formed between the rear segment and the third signal feed-in line is adjusted for adjusting the coupling capacitance, so that the first ground layer provides the resonance point of high frequency. The surface mount device multi-frequency antenna module further includes two fixed contacts mounted on the first surface and opposite to each other. The fixed contacts are electrically connected to the first radiator and the second radiator. The surface mount device multi-frequency antenna module further includes a second ground layer arranged on the second surface. The carrier is made of cuboid ceramic with high dielectric constant. The first radiator, the second radiator, the third radiator, and the fourth radiator are made of different rectangle metal patterns and line metal patterns arranged on at least one surface of the carrier. The surface mount device multi-frequency antenna module further includes a connecting unit. The connecting unit includes a connector and a signal feed-in probe. The signal feed-in probe is arranged inside the connector. The signal feed-in probe is electrically connected to the first signal feed-in line through the perforation. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING 
         FIG. 1  shows an exploded view of the multi-frequency antenna module of the present invention. 
         FIG. 2  shows another exploded view of the multi-frequency antenna module of the present invention. 
         FIG. 3  shows still another exploded view of the multi-frequency antenna module of the present invention. 
         FIG. 4  shows an assembly drawing of the multi-frequency antenna module of the present invention. 
         FIG. 5  shows a circuit diagram of the multi-frequency antenna module of the present invention. 
         FIG. 6  shows a diagram showing how the multi-frequency antenna module of the present invention is used. 
         FIG. 7  shows a side cross-sectional view of  FIG. 6 . 
         FIG. 8A  shows a frequency response curve of the present invention. 
         FIG. 8B  shows a frequency response curve of the present invention. 
         FIG. 8C  shows a table for  FIG. 8B . 
         FIG. 9  shows a table for long-term evolution antenna peak gain parameters of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an exploded view of the multi-frequency antenna module of the present invention.  FIG. 2  shows another exploded view of the multi-frequency antenna module of the present invention.  FIG. 3  shows still another exploded view of the multi-frequency antenna module of the present invention.  FIG. 4  shows an assembly drawing of the multi-frequency antenna module of the present invention. A surface mount device (SMD) multi-frequency antenna module includes a base plate  1 , a carrier  2 , a first ground layer  13 , a first signal feed-in line  14 , a first gap  15 , a second signal feed-in line  16 , a second gap  17 , a third signal feed-in line  18 , and a third gap  19 . 
     The base plate  1  includes a first surface  11  and a second surface  12 . The first ground layer  13  and the first signal feed-in line  14  are arranged on the first surface  11 . The first signal feed-in line  14  includes a front segment  141 , a rear segment  142 , and a perforation  143 . The perforation  143  is at the front segment  141 . The front segment  141  is prolonged forward to the first ground layer  13 . The first gap  15  is formed between the front segment  141  and the first ground layer  13 . The second signal feed-in line  16  is electrically connected to the first ground layer  13  and is on a left side of the rear segment  142 . The second gap  17  is formed between the second signal feed-in line  16  and the rear segment  142 . A width of the second gap  17  formed between the rear segment  142  and the second signal feed-in line  16  is adjusted for adjusting a coupling capacitance, so that the first ground layer  13  provides a resonance point of high frequency. Therefore, the bandwidth is increased. The third signal feed-in line  18  is electrically connected to the first ground layer  13  and is on a right side of the rear segment  142 . The third gap  19  is formed between the third signal feed-in line  18  and the rear segment  142 . A width of the third gap  19  formed between the rear segment  142  and the third signal feed-in line  18  is adjusted for adjusting the coupling capacitance, so that the first ground layer  13  provides the resonance point of high frequency. Therefore, the bandwidth is increased. Moreover, the surface mount device multi-frequency antenna module further includes two fixed contacts  101  mounted on the first surface  11  and opposite to each other. The carrier  2  is fixedly mounted on the fixed contacts  101 . The surface mount device multi-frequency antenna module further includes a second ground layer  102  arranged on the second surface  12 . Moreover, a ground part of a coaxial cable connector of a coaxial cable (not shown in  FIGS. 1 ,  2 ,  3 , and  4 ) is electrically connected to the second ground layer  102 . 
     The carrier  2  is of cubic shape and made of ceramic with high dielectric constant. The carrier  2  includes a first radiator  21 , a second radiator  22 , a third radiator  23 , and a fourth radiator  24 . The first radiator  21 , the second radiator  22 , the third radiator  23 , and the fourth radiator  24  are made of different rectangle metal patterns and line metal patterns arranged on at least one surface of the carrier  2 . Therefore, the volume of the antenna is minimized. The first radiator  21  is electrically connected to the second radiator  22 . The first radiator  21  is not electrically connected to the third radiator  23  and the fourth radiator  24 . The fixed contacts  101  are electrically connected to the first radiator  21  and the second radiator  22  when the carrier  2  is electrically connected to the base plate  1 . Therefore, the carrier  2  is fixedly connected to the first surface  11 . Moreover, a contact connecting the first radiator  21  and the second radiator  22  is electrically connected to the first signal feed-in line  14 . The third radiator  23  is electrically connected to the second signal feed-in line  16 . The fourth radiator  24  is electrically connected to the third signal feed-in line  18 .  FIG. 5  shows a circuit diagram of the multi-frequency antenna module of the present invention. The first radiator  21  and the second radiator  22  are electrically connected to the first signal feed-in line  14 . Therefore, the first radiator  21  is a first antenna, and the second radiator  22  is a second antenna. The third radiator  23  is electrically connected to the second signal feed-in line  16 . Therefore, the third radiator  23  is a third antenna. The third signal feed-in line  18  is electrically connected to the fourth radiator  24 . Therefore, the fourth radiator  24  is a fourth antenna. 
     A signal source  3  is transmitted to the first radiator  21  and the second radiator  22  through the first signal feed-in line  14  to form the high frequency resonance structure and the low frequency resonance structure. The width of the second gap  17  formed between the first signal feed-in line  14  and the second signal feed-in line  16  is adjusted for adjusting the coupling capacitance, so that the first ground layer  13  provides the resonance point of high frequency. Therefore, the bandwidth is increased. Similarly, the width of the third gap  19  formed between the first signal feed-in line  14  and the third signal feed-in line  18  is adjusted for adjusting the coupling capacitance, so that the first ground layer  13  provides the resonance point of high frequency. Therefore, the bandwidth is increased. 
       FIG. 6  shows a diagram showing how the multi-frequency antenna module of the present invention is used.  FIG. 7  shows a side cross-sectional view of  FIG. 6 . A signal feed-in probe  41  of a connecting unit  4  connected to a coaxial cable  5  is electrically connected to the first signal feed-in line  14  through the perforation  143 . A connector  42  of the connecting unit  4  is electrically connected to the second ground layer  102 . 
     A coaxial cable connector  51  of the coaxial cable  5  is screwed to a thread  43  of the connector  42 . The first radiator  21 , the second radiator  22 , the third radiator  23 , and the fourth radiator  24  receive wireless signals with different bands. Therefore, the antenna module of the present invention is used as a multi-frequency antenna module. 
       FIG. 8A  shows a frequency response curve of the present invention.  FIG. 8B  shows a frequency response curve of the present invention.  FIG. 8C  shows a table for  FIG. 8A  and  FIG. 8B . The return loss is −3.98 and the standing wave ratio (SWR) is 4.20 when the frequency of the multi-frequency antenna module is 700 MHz. 
     The return loss is −11.66 and the SWR is 1.73 when the frequency of the multi-frequency antenna module is 824 MHz. The return loss is −5.57 and the SWR is 3.02 when the frequency of the multi-frequency antenna module is 960 MHz. The return loss is −10.39 and the SWR is 1.76 when the frequency of the multi-frequency antenna module is 1710 MHz. The return loss is −6.38 and the SWR is 2.88 when the frequency of the multi-frequency antenna module is 2170 MHz. 
       FIG. 9  shows a table for long-term evolution antenna peak gain parameters of the present invention. The surface mount device multi-frequency antenna module of the present invention is slim, light, high efficiency, and suitable for long-term evolution (LTE) and fourth-generation communication systems. The bands of the present invention include 700˜960 MHz, 1710˜2170 MHz, and so on, for LTE, global system for mobile communications (GSM), digital communications system (DCS), personal communication system (PCS), and wideband code division multiple access (WCDMA). 
     Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.