Patent Publication Number: US-2022231708-A1

Title: Wideband antenna system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial No. 110102392, filed on Jan. 21, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The disclosure relates to a wideband antenna system. 
     Description of the Related Art 
     In the existing antenna design of consumer electronic products, 2G/3G/4G/sub-6G communication systems having an operating frequency of 617 MHz to 5000 MHz may be supported. Generally, the frequency range is divided into a low band (617 MHz to 960 MHz), a medium band (1475 MHz to 2200 MHz), a high band (2300 MHz to 2690 MHz), and an ultra-high band (3300 MHz to 5000 MHz). Conventionally, if all of the bands are designed in the same antenna system, the antenna efficiency of all bands cannot be guaranteed simultaneously. As a result, the efficiency of some bands may be impact. 
     For example, due to the bandwidth supported by the antenna is increased, an antenna tuner is usually applied switch the antenna frequency. The antenna tuner may be sorted into an aperture tuner and an impedance tuner. In the antenna design, one aperture tuner is used with one impedance tuner, or two aperture tuners are used. However, such manners only support the low band, the medium band, and the ultra-high band, but the efficiency of the high band under the configuration is not good. For the instance that when the configuration supports the low band, the high band, and the ultra-high band, the efficiency of the medium band is not good. Therefore, the conventional configurations cannot simultaneously guarantee the efficiency of all bands. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an aspect of the disclosure, a wideband antenna system is provided. The wideband antenna system includes a metal radiating portion, an aperture contact, a feed contact, an aperture tuner, an impedance tuner, a first switch, and a second switch. Two ends of the metal radiating portion respectively include a first contact and a second contact. The aperture contact is electrically connected to the metal radiating portion and is located between the first contact and the second contact. The feed contact is electrically connected to the metal radiating portion and is located between the first contact and the aperture contact. The aperture tuner is electrically connected to the aperture contact, and the impedance tuner is electrically connected to the feed contact. The first switch is electrically connected between the first contact and a zero-ohm resistor to selectively effect connection of the first contact to the zero-ohm resistor. The second switch is electrically connected between the first contact and the impedance tuner to selectively effect connection of the first contact to the impedance tuner. 
     To sum up, the wideband antenna system provided in the disclosure can simultaneously support antenna operating bands such as a low band, a medium band, a high band, and an ultra-high band, which achieves good antenna efficiency. 
     The purposes, the technical content, and the effects achieved in the disclosure are easier to understand by means of specific embodiments, accompanying drawings, and detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an architecture of a wideband antenna system according to an embodiment of the disclosure. 
         FIG. 2A  to  FIG. 2D  are each a schematic diagram of a circuit of an aperture tuner according to an embodiment of the disclosure. 
         FIG. 3  is a schematic diagram of a circuit of an impedance tuner according to an embodiment of the disclosure. 
         FIG. 4  is a schematic block diagram of a central processing unit controlling operations according to an embodiment of the disclosure. 
         FIG. 5  is a schematic diagram of a circuit of a wideband antenna system in a first operating status according to an embodiment of the disclosure. 
         FIG. 6  is a schematic diagram of a circuit of a wideband antenna system in a second operating status according to an embodiment of the disclosure. 
         FIG. 7  is a schematic diagram of a circuit of a wideband antenna system in a third operating status according to an embodiment of the disclosure. 
         FIG. 8  is a schematic diagram of a circuit of a wideband antenna system in a fourth operating status according to an embodiment of the disclosure. 
         FIG. 9  is a schematic diagram of S-parameter simulation of a wideband antenna system according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1 , a wideband antenna system  10  includes a metal radiating portion  12 , an aperture contact  18 , a feed contact  20 , an aperture tuner  22 , an impedance tuner  24 , a first switch  26 , and a second switch  28 . Two ends of the metal radiating portion  12  respectively include a first contact  14  and a second contact  16 . The aperture contact  18  is electrically connected to the metal radiating portion  12  and is located at a position close to the second contact  16  between the first contact  14  and the second contact  16 . The feed contact  20  is also electrically connected to the metal radiating portion  12  and is located between the first contact  14  and the aperture contact  18 . The aperture tuner  22  is electrically connected to the aperture contact  18  for switching a grounding path. The impedance tuner  24  is electrically connected to the feed contact  20  to transmit a radio frequency signal transmitted from a cable  30  or transmit a received radio frequency signal to a back end via the cable  30 . The first switch  26  is electrically connected between the first contact  14  and a zero-ohm resistor  32 , and an other end of the zero-ohm resistor  32  is connected to a ground terminal GND, so that the first switch  26  can selectively effect connection of the first contact  14  to the zero-ohm resistor  32 . The second switch  28  is electrically connected between the first contact  14  and the impedance tuner  24  to selectively effect connection of the first contact  14  to the impedance tuner  24 . 
     In an embodiment, if the metal radiating portion  12  has a length L, a first distance D 1  between the first contact  14  and the feed contact  20  is L/10-L/4, and a second distance D 2  between the second contact  16  and the aperture contact  18  is L/10-2L/3. 
     In an embodiment, the aperture tuner  22  further includes a switch module and a plurality of grounding paths, so as to switch and select one of the grounding paths by means of the switch module. In addition, the grounding path includes at least one of an open grounding path and at least one passive element grounding path, and a zero-ohm resistor grounding path. Referring to  FIG. 2A , the switch module in the aperture tuner  22  is a single-pole four-throw (SP4T) switch  34 , and four grounding paths  36  are connected to the SP4T switch  34 . Each of the grounding paths  36  comprises a passive element, an open circuit, or a zero-ohm resistor connected to the ground terminal, so as to form a passive element grounding path, an open circuit grounding path, or a zero-ohm resistor grounding path. In this embodiment, the four grounding paths  36  may include an open circuit grounding path, two passive element grounding paths, and a zero-ohm resistor grounding path. Referring to  FIG. 2B , the switch module in the aperture tuner  22  is at least one single-pole double-throw (SPDT) switch  38 , and two grounding paths  36  are connected to the SPDT switch  38 . Each of the grounding paths  36  comprises a passive element, an open circuit, or a zero-ohm resistor connected to the ground terminal, so as to form a passive element grounding path, an open circuit grounding path, or a zero-ohm resistor grounding path. In this embodiment, the two grounding paths  36  may include an open circuit grounding path, or one passive element grounding path, and a zero-ohm resistor grounding path. 
     In an embodiment, the aperture tuner  22  further use switches the grounding path  36  through a plurality of single-pole single-throw (SPST) switches  40 . Referring to  FIG. 2C , the switch module in the aperture tuner  22  is four SPST switches  40 , and each of the SPST switches  40  is connected to one grounding path  36 . Each of the grounding paths  36  comprises a passive element, an open circuit, or a zero-ohm resistor connected to the ground terminal by the SPST switches  40 , so as to form a passive element grounding path, an open circuit grounding path, or a zero-ohm resistor grounding path. In this embodiment, the four grounding paths  36  may include an open circuit grounding path, two passive element grounding paths, and a zero-ohm resistor grounding path. Referring to  FIG. 2D , the switch module in the aperture tuner  22  is two SPST switches  40 , and one grounding path  36  is connected to each of the SPST switches  40 . Each of the grounding paths  36  comprises a passive element, an open circuit, or a zero-ohm resistor connected to the ground terminal by the SPST switches  40 , so as to form a passive element grounding path, an open circuit grounding path, or a zero-ohm resistor grounding path. In this embodiment, the two grounding paths  36  includes an open circuit grounding path, or one passive element grounding path, and a zero-ohm resistor grounding path. 
     In an embodiment, the passive element path may be a capacitor grounding path, an inductor grounding path, or a resistor grounding path. 
     In an embodiment, a circuit structure of the impedance tuner  24  is shown in  FIG. 3 . The impedance tuner  24  usually includes a variable capacitor  42  connected to a plurality of switches  44  connected in parallel. Each of the switches  44  is electrically connected to a passive element  46 , and an other end of the passive element  46  is connected to the ground terminal GND. The variable capacitor  42  is connected in parallel to a bypass switch  48  to select passive elements  46  having different values by means of a plurality of switches  44  for switching different antenna bands. The passive element  46  may be a capacitor, an inductor, or a resistor. 
     In an embodiment, referring to  FIG. 1 , the above metal radiation portion  12  may be a metal frame or a metal back cover of an electronic device, or a metal plane attached to an electronic device. For example, the metal radiation portion  12  may be a metal case of an electronic device or a metal portion or a metal plate inside a plastic case of an electronic device, which is not limited thereto. The metal radiating portion  12  may be different with the application of the wideband antenna system  10 . 
     In an embodiment, referring to  FIG. 1  and  FIG. 4  together, the aperture tuner  22 , the impedance tuner  24 , the first switch  26 , and the second switch  28  are controlled by a central processing unit (CPU)  50 . The CPU  50  generates a corresponding mobile industry processor interface (MIPI) control signal according to a requirement of an antenna band. The MIPI control signal is transmitted to the aperture tuner  22 , the impedance tuner  24 , the first switch  26 , and the second switch  28  via a modem  52  to control operations of all switches (ON and OFF). 
     Detailed operations of the wideband antenna system continue to be described. The aperture tuner  22  in the wideband antenna system  10  uses the SP4T switch  34 . Referring to  FIG. 1  and  FIG. 5  together, the four grounding paths  36  connected to the single-pole four-throw switch  34  are respectively an open grounding path  361 , two passive element grounding paths  362  and  363 , and a zero-ohm resistor grounding path  364 . In a first operating status of the wideband antenna system  10 , the first switch  26  is in an ON state, and the second switch  28  is in an OFF state. The SP4T switch  34  in the aperture tuner  22  switches the grounding path  36  to the open grounding path  361  or the passive element grounding paths  362 ,  363 . In this embodiment, the passive element grounding path  362  is connected, for example. In this case, the aperture contact  18  is connected to the ground terminal GND through the passive element grounding path  362 , the first contact  14  is connected to the ground terminal GND through the first switch  26  and the zero-ohm resistor  32 , and the radio frequency signal transmitted via the cable  30  is fed to the feed contact  20  by the impedance tuner  24 . In the first operating status, the wideband antenna system  10  can support a low band, a high band, and an ultra-high band, and can achieve good antenna efficiency. 
     In a second operating status of the wideband antenna system  10 , referring to  FIG. 1  and  FIG. 6  together, the first switch  26  is in an OFF state, and the second switch  28  is in an OFF state. The SP4T switch  34  in the aperture tuner  22  switches the grounding path  36  to the zero-ohm resistor grounding path  364 . In this embodiment, the passive element grounding path  364  is connected, for example. In this case, the aperture contact  18  is connected to the ground terminal GND through the zero-ohm resistor grounding path  364 , the first contact  14  is not connected, and the radio frequency signal transmitted via the cable  30  is fed to the feed contact  20  by the impedance tuner  24 . In the second operating status, the wideband antenna system  10  can support a medium band, the high band, and the ultra-high band, and can achieve good antenna efficiency. 
     In a third operating status of the wideband antenna system  10 , referring to  FIG. 1  and  FIG. 7  together, the first switch  26  is in an OFF state, and the second switch  28  is in an OFF state. The SP4T switch  34  in the aperture tuner  22  switches the grounding path  36  to the open grounding path  361  or the passive element grounding paths  362 ,  363 . In this embodiment, the passive element grounding path  362  is connected, the aperture contact  18  is connected to the ground terminal GND through the passive element grounding path  362 , the first contact  14  is not connected, and the radio frequency signal transmitted via the cable  30  is fed to the feed contact  20  by using the impedance tuner  24 . In the third operating status, the wideband antenna system  10  can support the low band and the medium band, or support the low band and the high band, and can achieve good antenna efficiency. 
     In a fourth operating status of the wideband antenna system  10 , referring to  FIG. 1  and  FIG. 8  together, the first switch  26  is in an OFF state, and the second switch  28  is in an ON state. The SP4T switch  34  in the aperture tuner  22  switches the grounding path  36  to the open grounding path  361  or the passive element grounding paths  362 ,  363 . In this embodiment, the open grounding path  361  is connected, the aperture contact  18  is open through the open grounding path  361 , the first contact  14  is connected to the impedance tuner  24  through the second switch  28 , and the radio frequency signal transmitted via the cable  30  is simultaneously fed to the feed contact  20  and the first contact  14  by the impedance tuner  24  and the second switch  28 , so as to achieve the effect of dual feed. In the fourth operating status, the wideband antenna system  10  can support the low band, the medium band, the high band, and the ultra-high band, and can achieve good antenna efficiency. 
     Therefore, suitable distances of the first distance D 1  and the second distance D 2  are selected, and through the adjustment of the impedance tuner  24  and the aperture tuner  22  and the switching of the first switch  26  and the second switch  28 , the wideband antenna system  10  can select an applicable operating status according to different antenna bands to simultaneously support the low band, the medium band, the high band, and the ultra-high band, thereby optimizing the antenna performance. 
     Referring to  FIG. 1 ,  FIG. 5 , and  FIG. 7  to  FIG. 9  together, during transmission of the radio frequency signal (700 MHz used as an example) in the wideband antenna system  10  in the first operating status in  FIG. 5 , the wideband antenna system  10  in the third operating status in  FIG. 7 , and the wideband antenna system  10  in the fourth operating status in  FIG. 8 , S-parameter simulation is performed. In the operating bands of the low band LB, the medium band MB, and the high band HB, S-parameter simulation results are shown in  FIG. 9  and Table 1 below. The wideband antenna system  10  in the first operating status performs well in the low band LB and the high band HB, the wideband antenna system  10  in the third operating status also performs well in the low band LB and the medium band MB, and the wideband antenna system  10  in the fourth operating status (dual feed) performs the best and performs well in the low band LB, the medium band MB, and the high band HB. Therefore, it may be learned from the foregoing experimental results that the wideband antenna system  10  of the disclosure indeed has good antenna efficiency, and the wideband antenna system  10  (shown in  FIG. 8 ) in the fourth operating status (dual feed) may further greatly improve the antenna efficiency and increase design dimensions. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Frequency (MHz) 
                   
               
            
           
           
               
               
               
               
            
               
                 Gain (dBi) 
                 754 (LB) 
                 1805 (MB) 
                 2600 (HB) 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 First operating status 
                 −7.4 
                 −12.3 
                 −6.4 
               
               
                 Third operating status 
                 −10.7 
                 −8.8 
                 −19.2 
               
               
                 Fourth operating status 
                 −9.4 
                 −6.4 
                 −6.8 
               
               
                   
               
            
           
         
       
     
     Based on the above, the wideband antenna system of the disclosure can simultaneously support antenna operating bands such as the low band, the medium band, the high band, and an ultra-high band, so as to achieve a wide band effect and good antenna efficiency. 
     The above embodiments are merely to describe the technical ideas and features of the disclosure, which are intended to enable those who are familiar with the technology to understand the content of the disclosure and implement them accordingly. Equivalent changes or modifications made to the spirit of the disclosure should still shall fall within the scope of the patent application in the disclosure.