Patent Publication Number: US-2013237284-A1

Title: Single input/multiple output (simo) or multiple input/single output (miso) or multiple input/multiple output (mimo) antenna module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional of pending U.S. patent application Ser. No. 13/032,713, filed Feb. 23, 2011 and entitled “Single input/multiple output (SIMO) or multiple input/single output (MISO) or multiple input/multiple output (MIMO) antenna module,” the entirety of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a single input/multiple output (SIMO), a multiple input/single output (MISO), or a multiple input/multiple output (MIMO) antenna module, and in particular, relates to a SIMO, MISO, or MIMO antenna module with improved SAR value. 
     2. Description of the Related Art 
     A specific absorption rate (SAR) is a measure of the rate at which radio frequency (RF) energy is absorbed by a human body when exposed to radio-frequency electromagnetic fields. It is defined as the power absorbed per mass of tissue in units of Watts per kilogram. SAR is usually averaged either over a whole body, or over a small sample volume (typically 1 g or 10 g of tissue). The value cited is then the maximum level measured for the body part studied over the stated volume or mass. It may be calculated from the electric field within the tissue as: 
     
       
         
           
             
               SAR 
               = 
               
                 
                   σ 
                    
                   
                     
                        
                       E 
                        
                     
                     2 
                   
                 
                 
                   2 
                    
                   ρ 
                 
               
             
             , 
           
         
       
     
     where σ represents the sample electrical conductivity, |E| represents the magnitude of the electric field and ρ represents the sample density. 
     For a conventional mimo antenna module, decreasing the SAR value of the SIMO, MISO, or MIMO antenna module is difficult due to dimensional restrictions and limited antenna choices. 
     BRIEF SUMMARY OF THE INVENTION 
     An antenna module is provided. The antenna module includes a first slot antenna unit and a second slot antenna unit. The first slot antenna unit is coupled to a radio frequency (RF) unit. The second slot antenna unit is coupled to the RF unit. The first and second slot antenna units are embedded in a wireless communications dongle, and the wireless communications dongle operates as a modem to transmit or receive a wireless signal to or from a wireless telephony communications network for a computer via the first and second slot antenna units when the wireless communication dongle connects to the computer. 
     Utilizing the antenna module of the embodiment with slot antenna units, the SAR value of the antenna module can be improved. Compared to conventional antenna modules with Planar Inverted-F Antenna (PIFA) antenna units, the SAR value of the antenna module of the embodiment is reduced by about 0.4. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1A  is a block diagram of a multiple input/single output (MISO) antenna module of a first embodiment of the invention when the single MISO antenna module is in a receiving mode; 
         FIG. 1B  is a block diagram of the MISO antenna module of the first embodiment of the invention when the MISO antenna module is in a transmitting mode; 
         FIG. 2A  is a perspective view of the first slot antenna unit and the second slot antenna unit for a single input/multiple output (SIMO), a MISO, or a multiple input/multiple output (MIMO) antenna module; 
         FIG. 2B  is a top view of the first slot antenna unit and the second slot antenna unit for the SIMO/MISO/MIMO antenna module; 
         FIGS. 3A-3H  show embodiments of the slot of the slot antenna unit; 
         FIG. 4A  is a block diagram of a MIMO antenna module of a second embodiment of the invention when the MIMO antenna module is in a receiving mode; 
         FIG. 4B  is a block diagram of the MIMO antenna module of the second embodiment of the invention when the MIMO antenna module is in a transmitting mode; and 
         FIG. 5  shows the SIMO/MISO/MIMO antenna module of the embodiment embedded in a portable electronic device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIGS. 1A and 1B  are block diagrams of an electronic apparatus  100  comprising a multiple input/single output (MISO) antenna module of a first embodiment of the invention. The MISO antenna module includes a radio frequency (RF) unit  130 , a first slot antenna unit  110 , a second slot antenna unit  120 , a first switch device  141  and a first power amplifier (PA)  142 . The RF unit  130  may receive an RF wireless signal, convert the received signal to a baseband signal, which is processed by a baseband unit, or receive a baseband signal from a baseband unit and convert the received signal to an RF wireless signal, which are later transmitted. The RF unit  130  may also comprise a plurality of hardware devices to perform radio frequency conversion. For example, the RF unit  130  may comprise a mixer to multiply the baseband signal with a carrier oscillated in a radio frequency of the wireless communications system, wherein the radio frequency may be 900 MHz, 1900 MHz or 2100 MHz utilized in Wideband Code Division Multiple Access (WCDMA) systems, or others depending on which radio access technology (RAT) is being used. The RF unit  130  comprises a first receiving port RX 1 , a second receiving port RX 2  and a transmitting port TX 1 . The first slot antenna unit  110  is coupled to the first switch device  141 , the first switch device  141  is selectively coupled to the first receiving port RX 1  and the transmitting port TX 1 , and the first power amplifier  142  is coupled between the first transmitting port TX 1  and the first switch device  141 . The second slot antenna unit  120  is coupled to the second receiving port RX 2 . In a receiving mode as shown in  FIG. 1A , the first switch device  141  switches the first antenna unit  110  to couple to the first receiving port RX 1 , then, the first slot antenna unit  110  receives a first receiving signal and the first receiving signal is passed to the first receiving port RX 1 , and the second slot antenna unit  120  receives a second receiving signal and the second receiving signal is passed to the second receiving port RX 2 . In a transmitting mode as shown in  FIG. 1B , the first switch device  141  switches the first antenna unit  110  coupled to the transmitting port TX 1 , then, a transmitting signal is transmitted from the transmitting port TX 1 , amplified by the power amplifier  142 , and emitted via the first slot antenna unit  110 . 
       FIGS. 2A and 2B  shows the first slot antenna unit and the second slot antenna unit of an electronic apparatus  100 , wherein the electronic apparatus  100  further comprises a substrate  160  and a ground layer  170 , wherein the RF unit (not shown), the ground layer  170 , the first slot antenna unit  110  and the second slot antenna unit  120  are disposed on the substrate  160 . The substrate  160  comprises a first surface  161  and a second surface  162 , and the first surface  161  is opposite to the second surface  162 , wherein the ground layer  170  is disposed on the second surface  162 . The electronic apparatus  100  is equipped with a single input/multiple output (SIMO), a multiple input/single output (MISO), or a multiple input/multiple output (MIMO) antenna module to improve performance. When two transmitters and two or more receivers are used, two simultaneous data streams may be sent via the antenna module, which double the data rate. Multiple receivers alone with the antenna module allow greater distances between devices. For example, the IEEE 802.11n (Wi-Fi) wireless standard uses MIMO to increase speed to 100 Mbps and beyond, doubling at minimum the 802.11a and 11g rates. The antenna module may also be used in WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long Term Evolution) communications devices. 
     The first slot antenna unit  110  and the second slot antenna unit  120  may have the same structure or different structures. In the embodiment of  FIGS. 2A and 2B , the first slot antenna unit  110  comprises a first feed conductor  111  and a first slot  112 , the first slot  112  is formed in the ground element  170 , the first feed conductor  111  is disposed on the first surface  161  and corresponds to the first slot  112 , the second slot antenna unit  120  comprises a second feed conductor  121  and a second slot  122 , the second slot  122  is formed in the ground element  170 , and the second feed conductor  121  is disposed on the first surface  161  and corresponds to the second slot  122 . 
     Utilizing the antenna module of the embodiment with slot antenna units, the SAR value of the antenna module can be improved. Compared to conventional antenna modules with Planar Inverted-F Antenna (PIFA) antenna units, the SAR value of the antenna module of the embodiment is reduced by about 0.4. 
     The slot patterns of the slot antenna units can be modified. The embodiments of the slots of the invention are described as taking a first slot antenna unit as an example.  FIG. 3A  shows an embodiment of the first slot  112 , wherein the first slot  112  is L shaped.  FIG. 3B  shows another embodiment of the first slot  112 , wherein the first slot  112  comprises a first portion  113  and a second portion  114 , and the first portion  113  is L shaped, the second portion  114  is longitudinal, and the second portion  114  is connected to an end of the first portion  113 . 
       FIG. 3C  shows still another embodiment of the first slot  112 , wherein the first slot comprises a first portion  113 ( 1 ) and a second portion  114 ( 1 ), and the first portion  113 ( 1 ) is L shaped, the second portion  114 ( 1 ) is L shaped. The first portion  113 ( 1 ) comprises a first section  115 ( 1 ) and a second section  116 ( 1 ), and the first section  115 ( 1 ) is connected to the second section  116 ( 1 ) and perpendicular thereto. An end of the first section  115 ( 1 ) is opened at a side  171  of the ground element, and an end of the second portion  114 ( 1 ) is connected to an end of the second section  116 ( 1 ). The second portion  114 ( 1 ) is located between the second section  116 ( 1 ) and the side  171  of the ground element. 
       FIG. 3D  shows still another embodiment of the first slot  112 , wherein the first slot comprises a first portion  113 ( 2 ) and a second portion  114 ( 2 ), and the first portion  113 ( 2 ) is L shaped, the second portion  114 ( 2 ) is L shaped. The first portion  113 ( 2 ) comprises a first section  115 ( 2 ) and a second section  116 ( 2 ), and the first section  115 ( 2 ) is connected to the second section  116 ( 2 ) and perpendicular thereto. An end of the first section  115 ( 2 ) is opened at a side  171  of the ground element, and an end of the second portion  114 ( 2 ) is connected to an end of the second section  116 ( 2 ). The second section  116 ( 2 ) is located between the second portion  114 ( 2 ) and the side  171  of the ground element. 
       FIG. 3E  shows still another embodiment of the first slot  112 , wherein the first slot comprises a first portion  113 ( 3 ) and a second portion  114 ( 3 ), and the first portion  113 ( 3 ) is L shaped, the second portion  114 ( 3 ) is U shaped. The first portion  113 ( 3 ) comprises a first section  115 ( 3 ) and a second section  116 ( 3 ), and the first section  115 ( 3 ) is connected to the second section  116 ( 3 ) and perpendicular thereto. An end of the first section  115 ( 3 ) is opened at a side  171  of the ground element, and an end of the second portion  114 ( 3 ) is connected to an end of the second section  116 ( 3 ). The second portion  114 ( 3 ) is located between the second section  116 ( 3 ) and the side  171  of the ground element. 
       FIG. 3F  shows still another embodiment of the first slot  112 , wherein the first slot comprises a first portion  113 ( 4 ) and a second portion  114 ( 4 ). The first portion  113 ( 4 ) is L shaped, the second portion  114 ( 4 ) is U shaped. The first portion  113 ( 4 ) comprises a first section  115 ( 4 ) and a second section  116 ( 4 ), and the first section  115 ( 4 ) is connected to the second section  116 ( 4 ) and perpendicular thereto. An end of the first section  115 ( 4 ) is opened at a side  171  of the ground element, and an end of the second portion  114 ( 4 ) is connected to an end of the second section  116 ( 4 ). The second section  116 ( 4 ) is located between the second portion  114 ( 4 ) and the side  171  of the ground element. 
       FIG. 3G  shows still another embodiment of the first slot  112 , wherein the first slot comprises a first portion  113 ( 5 ) and a second portion  114 ( 5 ), and the first portion  113 ( 5 ) is U shaped, and the second portion  114 ( 5 ) is U shaped. An end of the first portion  113 ( 5 ) is opened at a side  117  of the ground element, and an end of the second portion  114 ( 5 ) is connected to the other end of the first portion  113  ( 5 ). 
       FIG. 3H  shows still another embodiment of the first slot  112 , wherein the first slot comprises a first portion  113 ( 6 ) and a second portion  114 ( 6 ), and the first portion  113 ( 6 ) is lightning bolt shaped, and the second portion  114 ( 6 ) is U shaped. An end of the first portion  113  ( 6 ) is opened at a side  117  of the ground element, and an end of the second portion  114 ( 6 ) is connected to the other end of the first portion  113  ( 6 ). 
     Note that any of the slot antenna patterns illustrated in  FIGS. 3A to 3H  may be modified to be flipped right to left to form the second slot  122 , and the invention cannot be limited thereto. Those skilled in the art may modify the slot patterns of the embodiments disclosed above to similar but different patterns, and the invention should not be limited thereto. 
       FIGS. 4A and 4B  are block diagrams of an electronic apparatus  100 ′ comprising an MIMO antenna module of a second embodiment of the invention. The electronic apparatus  100 ′ includes an RF unit  130 ′, a first slot antenna unit  110 , a second slot antenna unit  120 , a first switch device  141  a first power amplifier (PA)  142 , a second switch device  151  and a second power amplifier (PA)  152 . The RF unit  130 ′ comprises a first receiving port RX 1 , a second receiving port RX 2 , a first transmitting port TX 1  and a second transmitting port TX 2 . The RF unit  130 ′ operates like the RF unit  130  and detailed reference can be made to description of  FIGS. 1A and 1B . The first slot antenna unit  110  is coupled to the first switch device  141 , the first switch device  141  is selectively coupled to the first receiving port RX 1  and the first transmitting port TX 1 , and the first power amplifier  142  is coupled between the first transmitting port TX 1  and the first switch device  141 . The second slot antenna unit  120  is coupled to the second switch device  151 , the second switch device  151  is selectively coupled to the second receiving port RX 2  and the second transmitting port TX 2 , and the second power amplifier  152  is coupled between the second transmitting port TX 2  and the second switch device  151 . In a receiving mode as shown in  FIG. 4A , the first switch device  141  switches the first antenna unit  110  to couple to the first receiving port RX 1 , the second switch device  151  switches the second antenna unit  120  to couple to the second receiving port RX 2 , such that the first slot antenna unit  110  receives a first receiving signal and the first receiving signal is passed to the first receiving port RX 1 , and the second slot antenna unit  120  receives a second receiving signal and the second receiving signal is passed to the second receiving port RX 2 . In a transmitting mode as shown in  FIG. 4B , the first switch device  141  switches the first antenna unit  110  to couple to the first transmitting port TX 1 , the second switch device  151  switches the second antenna unit  120  to couple to the second transmitting port TX 2 , such that a first transmitting signal is transmitted from the first transmitting port TX 1 , amplified by the first power amplifier  142 , and emitted via the first slot antenna unit  110 , and a second transmitting signal is transmitted from the second transmitting port TX 2 , amplified by the second power amplifier  152 , and emitted via the second slot antenna unit  120 . The data transmitted with the first transmitting signal can be the same or different from the data transmitted with the second transmitting signal. When the data transmitted with the first transmitting signal is the same with the data transmitted with the second transmitting signal, the MIMO antenna module improves output power. When the data transmitted with the first transmitting signal differs from the data transmitted with the second transmitting signal, the MIMO antenna module increases data transmission rate. 
       FIG. 5  shows the antenna module of the embodiments embedded in a portable electronic device  1 . The antenna module of the embodiment may be embedded in a wireless communications dongle, such as a Wi-Fi, WCDMA, WiMAX or LTE dongle, or a similar but different device. The wireless communications dongle may further provide a universal serial bus (USB) interface to connect a personal computer, a notebook or a planar computer, or others. The wireless communications dongle operates as a modem when connecting to any kind of computers via the USB interface, and provides wireless communications services with a base station, a node-B, an advanced node-B, or others, in a wireless telephony communications network. 
     Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.