Abstract:
A slot antenna for a portable wireless communication device hides the antenna, which is integrated with the portable wireless communication device. The slot antenna has good communication capabilities, and causes no additional electromagnetic interference to the portable wireless communication device. The slot antenna has multi-polarization capabilities, which can provide better communication functionality.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a slot antenna and, more particularly, to a slot antenna for portable wireless communication devices.  
         [0003]     2. Description of the Related Art  
         [0004]     Tablet PCs and notebook computers not only have the computational power of desktop computers, but also are much smaller than desktop computers. With improvements of wireless communication technology, many users have begun to use wireless data transmission to achieve better mobile functionality. As shown in  FIG. 1 , a tablet computer  10  has a wireless module  12 . When a user uses the wireless module  12  to connect the tablet computer  10  to a wireless network, to obtain good communication and increase the sending/receiving data rate, the wireless module  12  must employ a monopole antenna  14 . However, the monopole antenna  14  has a fragile structure and large dimensions. Consequently, some tablet computers  10  employ a smaller antenna, such as an inverted-F antenna or a microstrip antenna. However, the housing of the tablet computer  10  is usually made of metalic materials. When the antenna  14  is mounted inside the tablet computer  10 , it is difficult for the wireless module  12  to transmit or receive signals, and the signal radiation can cause electronic interference to other elements inside the tablet computer  10  as well.  
         [0005]     Therefore, it is desirable to provide a slot antenna for portable wireless communication devices to mitigate and/or obviate the aforementioned problems.  
       SUMMARY OF THE INVENTION  
       [0006]     A main objective of the present invention is to provide a slot antenna for portable wireless communication devices which can improve wireless communication abilities.  
         [0007]     Another objective of the present invention is to provide a slot antenna for portable wireless communication devices which takes diffraction caused by the portable wireless communication device into account in the design of an antenna radiation field.  
         [0008]     Another objective of the present invention is to provide a slot antenna for portable wireless communication devices which can reduce the manufacturing costs of the antenna.  
         [0009]     Another objective of the present invention is to provide a slot antenna which transmits and receives electromagnetic wave without cutting off the mechanical enclosure of a portable wireless communication device that is compliant its electromagnetic interface design.  
         [0010]     In order to achieve the above-mentioned objectives the slot antenna for portable wireless communication devices includes: at least one metallic resonating chamber, having at least one first slot on at least one side; at least one feeding wire, installed on a side of the metal resonating chamber; at least one excitation section, placed in the metal resonating chamber and connected to the at least one feeding wire; and the portable wireless communication device having at least one second slot on at least one side; wherein the metal resonant chamber is located in the portable wireless communication device and the at least one first slot is coupled to the at least one second slot.  
         [0011]     Since the design of the slot antenna considers the diffraction effect of the computer body, the slot antenna can provide good wireless communications. Furthermore, the slot antenna and a casing of the computer body can be made together to reduce the manufacturing costs. Moreover, the resonating chamber can prevent the slot antenna from electromagnetic interference generated by the other circuits inside portable wireless communications device.  
         [0012]     Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description, when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a schematic drawing of a prior art antenna used in a portable wireless communications device;  
         [0014]      FIG. 2  is a schematic drawing of a slot antenna used in a portable wireless communications device according to the present invention;  
         [0015]      FIG. 3  is a structure drawing of the slot antenna used in a portable wireless communications device according to the present invention; and  
         [0016]      FIG. 4  is a schematic drawing of another slot antenna used in a portable wireless communications device according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     Please refer to  FIG. 2 .  FIG. 2  is a schematic drawing of a slot antenna used in a portable wireless communications device according to the present invention. Several slot antennas  22 ,  24 ,  26  and  28  may be installed in the tablet computer  20 . The slot antennas  22 ,  28  are identical to each other, and are mounted on opposite sides of the tablet computer  20 ; they both receive and transmit wireless data signals (communication signals) from two sides of the tablet computer  20  to achieve a spatial diversity effect. Furthermore, the slot antennas  24 ,  26  both have slots in two directions for receiving and transmitting wireless data signal horizontally and vertically to achieve a polarized diversity effect. Due to the huge body in terms of operating  5  wavelength, the tablet computer  20  has its own diffraction effect. As the slot antennas  22 ,  24 ,  26  and  28  are designed to be mounted in the tablet computer  20 , the diffraction effect of the tablet computer  20  is taken into consideration in the design of radiation field of the slot antennas  22 ,  24 ,  26  and  28 .  
         [0018]      FIG. 3  is a structure drawing of the slot antenna used in the portable wireless communication device according to the present invention. As shown in  FIG. 3 , a chamber body of the slot antenna  22  is made of metal and a resonating chamber is formed inside thereof, and the resonating chamber can provide different resonance by adjusting the size of the chamber body to satisfy different working frequencies (communication signals) for the slot antenna  22 . The internal surface of the resonant chamber may be made from material with high dielectric constants, such as ceramics, so as to provide better resonance results, and the dimensions of the slot antenna  22  can be reduced.  
         [0019]     At least one slot (e.g. slot  221 ) can be placed on the chamber body of the slot antenna  22 . The opening direction decides the radiation polarization direction of the slot antenna. For example, when the opening direction of the slot  221  is in a perpendicular direction, the radiation polarization direction of the slot antenna  22  is in one certain direction, and vice versa. Of course, the opening direction of the slot  221  can be in other directions.  
         [0020]     One end of a feeding wire  223  is connected to a built-in wireless module (not shown) and the other end is connected to an excitation section  222 . Therefore, the communication signals from the built-in wireless module can be sent to the excitation section  222  via the feeding wire  223  for distant transmission, and the distant communication signals can be delivered into the built-in wireless module via the feeding wire  223 . The feeding wire  223  is coupled (wedged or locked) to one side of the slot antenna  22 . The excitation section  222  is located inside the slot antenna  22  and connected to the feeding wire  223 . The excitation section  222  is preferable made of metal, and part of the feeding wire  223 . The length of the excitation section  222  is preferable no longer than one quarter of the wavelength of the communication signal, so does the slot  221 .  
         [0021]     Please refer to  FIG. 4 .  FIG. 4  is a schematic drawing of another slot antenna used in the portable wireless communication device according to the present invention. The slot antennas  22 ,  24 ,  26  and  28  have similar capabilities and characteristics, but have different opening directions.  
         [0022]     The slot antennas  22 ,  24 ,  26  and  28  can be integrated into the mechanism of the tablet computer  20  so that their slots bodies, made of metal, can be placed in the mechanism of the tablet computer  20 , and the slots can be placed on the surface of the tablet computer  20 . Therefore, radio waves generated by the slot antennas  22 ,  24 ,  26  and  28  radiate or diffract from the slots on the surface of the tablet computer  20 . In addition, the sides of the slot can be part of the surface of the tablet computer  20 . Since the slot bodies of the slot antennas  22 ,  24 ,  26  and  28  are made of metal, the radio waves generated by them radiate or diffract only from the slots  221  or  241 , which creates no additional electromagnetic interference and no increased shielding costs. Moreover, the slots on the surface of the tablet computer  20  can be covered by a non-metallic material, such as plastic, to improve the appearance of the surface of the tablet computer.  
         [0023]     The tablet computer  20  can be a notebook computer, a PDA (personal digital assistant), a cellular phone, a smart phone or other wireless communications device.  
         [0024]     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.