Patent Publication Number: US-6911943-B2

Title: Antenna for portable wireless communication apparatuses

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to an antenna for portable wireless communication apparatuses, and more particularly to an improved antenna for the prevention of harm to users by electromagnetic waves generated by portable wireless communication apparatuses. 
   2. Description of the Prior Art 
   Today, mobile phones and other wireless apparatuses have been widely used due to the development of the communication service, and such communication apparatuses can be used everywhere by means of wireless communication technology. 
   In general, communication can mainly be classified into wire communication and wireless communication. In the case of wireless communication, there are needed a transmitter for transmitting electromagnetic waves, an antenna for receiving the electromagnetic waves transmitted from the transmitter, and a receiver for receiving the electromagnetic waves from the antenna. 
   The transmitter-receiver and the antenna are installed on the body of the communication apparatus. Since these devices, such as the transmitter-receiver and the antenna, have become smaller and lighter, the communication apparatuses including these device have been miniaturized. 
   The antenna can be classified according to the operation method of a linear radiator and a helical antenna part in which the radiating directions of the electromagnetic waves are non-directional. That is, the antennas are mainly classified into three types, that is, a retractable type, a fixed type and a top mounted-helical type. In the retractable type of antenna, the helical antenna part  100  is fixed to the housing and the linear radiator  200  can move up and down in the helical antenna part  100 , as shown in  FIG. 10   a . In the fixed type of antenna, both helical antenna part  100  and linear radiator  200  are fixed to the housing, as shown in  FIG. 10   b . In the top mount-helical type of antenna, the helical antenna part  100  is installed on top of the linear radiator  200 , as shown in  FIG. 10   c.    
   As described above, if the helical antenna part in which the radiating directions of electromagnetic waves are non-directional is used, the antenna has direct harmful effects on the user of the wireless communication apparatuses. The electromagnetic waves of the antenna include direct waves, reflected waves and diffracted waves. All these waves do harm to people, and above all the direct waves are the most harmful. 
   A conventional electromagnetic waves intercepting system encloses a circuit substrate mounted in the communication apparatus so as to prevent the electromagnetic waves from leaking to the outside. This conventional electromagnetic waves intercepting system has a problem in that the electromagnetic waves leak to the outside through an antenna connecting hole which is formed in the electromagnetic waves intercepting system. 
   That is, this conventional electromagnetic waves intercepting system includes the hole in which the antenna connector is installed so as to ground the antenna exposed to the outside on the circuit substrate of the communication apparatuses. When the antenna connector is connected to the hole, the hole is not completely sealed due to the tolerance of the hole. 
   According to another conventional method for intercepting electromagnetic waves, a filter material for intercepting the electromagnetic waves is coated onto the inside of the casing so as to intercept the electromagnetic waves. 
   However, since the conventional wireless antenna is positioned on the upper side of the casing of the communication apparatuses and is pulled from a guide protrusion to make a phone call, the electromagnetic waves radiated when using the communication apparatuses are directly transmitted to the head of the user. Thus, the health of the user becomes worse because the direct waves, the reflected waves and the diffracted waves have a direct negative influence upon the head of the user. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an antenna for portable wireless communication apparatuses, which is comprised of an antenna element for providing electromagnetic waves directional properties, replacing the conventional helical antenna part for generating non-directional electromagnetic waves, and a linear radiator supplied with power and connected in parallel with the antenna element, thereby preventing the electromagnetic waves generated by portable wireless communication apparatuses from doing harm to people, and increasing the efficiency of the antenna. 
   In order to accomplish the above object, there is provided an antenna for portable wireless communication apparatuses including an antenna element, which is provided on its outer surface with a conductor on which a plurality of openings are formed, provided on the inner portion of the conductor with a dielectric material, and connected in parallel with a linear radiator in an insulated state, thereby radiating electromagnetic waves and at the same time being capable of adjusting the radiated amount and direction of the electromagnetic waves. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a perspective view showing an antenna element of the present invention; 
       FIG. 2  is a longitudinal section of the antenna element of  FIG. 1 ; 
       FIG. 3  is a perspective view showing the installation of the antenna element; 
       FIG. 4   a  is a cross section showing a powered linear radiator retracted into the housing through the antenna element; 
       FIG. 4   b  is a cross section showing the powered linear radiator extended from the housing through the antenna element; 
       FIGS. 5   a  to  5   e  are perspective views showing the variations of the antenna element; 
       FIG. 6  is a view showing an example of the radiating directions of electromagnetic waves of the antenna with the antenna element of the present invention; 
       FIGS. 7   a  and  7   b  are views showing two openings having different areas; 
       FIGS. 7   c  and  7   d  are views showing the directional characteristics of two openings having different areas, shown in  FIGS. 7   a  and  7   b;    
       FIGS. 8   a  and  8   b  are views showing the openings equal to each other in length and width but different from each other in form; 
       FIGS. 8   c  and  8   d  are views showing the directional characteristics of the openings having different shapes, shown in  FIGS. 8   a  and  8   b;    
       FIGS. 8   e  and  8   f  are graphs showing the band widths of the openings having different shapes, shown in  FIGS. 8   a  and  8   b;    
       FIGS. 9   a  and  9   b  are views showing the openings similar to each other in form and different from each other in number and area; 
       FIGS. 9   c  and  9   d  are views showing the directional characteristics of the openings shown in  FIGS. 9   a  and  9   b; and    
       FIGS. 10   a  to  10   c  are views showing three kinds of antennas classified according to the structure of the antenna. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. 
   As shown in  FIGS. 1 and 2 , an antenna element  3  of the present invention is cylindrical-shaped and includes on its outer surface a conductor  32  in which a plurality of openings  32   a  are formed at desired intervals. The outer portion of the interior of the conductor  32  is filled with a dielectric material  31 . A hollow portion  31   a  surrounded with the dielectric material  31  includes a stepped portion  31   b  on the bottom portion thereof, with the stepped portion  31   b  being provided with a hole to supply a linear radiator  2  with power. The antenna element  3  is installed at the position where a helical antenna part is conventionally installed. 
   As shown in  FIGS. 3 and 4 , the linear radiator  2  includes the first radiator part  20  and the second radiator part  22  linked together in a row in a capacitive connecting manner. The first radiator part  20  is relatively short in length and inserted into the antenna element  3  longitudinally. The first radiator part  20  consists of a dielectric cap  20   b  on its top portion, a power supply terminal  20   a  on its bottom portion and a rod  21  connecting the dielectric cap  20   b  with the power supply terminal  20   a , with the rod  21  being made of a conductive material. The second radiator part  22  is longer than the first radiator part  20 . This second radiator part  22  consists of a rod  23  covered with a dielectric material  24  and the power supply terminal  22   a . The rod  23  is a conductor as a rod  21  of the first radiator part  20 , and is aligned with the rod  21 . 
   Although in this embodiment there is employed the linear radiator  2  consisting of a plurality of rods, there can be employed a linear radiator  2  in which a plurality of rods are integrated into a single body. In the meantime, the linear radiator  2  and the antenna element  3  are fixedly attached to the housing while the linear radiator  2  can be inserted into the antenna element  3 , or the antenna element  3  can be fixedly attached to the upper portion of the linear radiator  2 . 
   In this present embodiment, the dielectric material  31  is surrounded with the conductor  32 . Preferably, the dielectric material  31  can be plated with metal or coated with a printed circuit substrate in place of the conductor  32 , thereby being capable of reducing the weight and size of the antenna, being convenient to manufacture and reducing the manufacturing cost of the antenna. 
   The openings  32   a  may be rectangular-shaped, as shown in FIG.  1 . However, the openings  32   a  having one of the elongated-shape and triangular-shape may be formed at desired intervals around the antenna element  3 , as shown in  FIGS. 5   a  and  5   b . Also, each opening  32   a  may be divided into a plurality of parts each having one of elongated, rectangular or triangular-shape, with a plurality of openings  32   a  being formed around the antenna element  3  at desired intervals, as shown in  FIG. 5   c.    
   The openings  32   a  may be butterfly-shaped, as shown in  FIG. 5   e , and may have two or more different shapes regularly spaced apart from each other, as shown in  FIG. 5   d.  In this way, the openings  32   a  can be varied in form so as to adjust the electrical characteristics of the antenna. 
   The operation and effect of the antenna of the present invention will be described with reference to the retractable-type antenna shown in  FIGS. 4   a  and  4   b.    
   The operation of the antenna of the present invention is described in the following when the linear radiator  2  moves up and down in the antenna element  3 , a principal element of the present invention. 
   When the Linear Radiator is Retracted (refer to  FIG. 4   a ) 
   When the linear radiator  2  passing through the antenna element  3  fixed to the housing is retracted into the housing, the linear radiator  2  is inserted into the housing and is extended through the antenna element  3 . 
   At this time, the first radiator part  20  is supplied with power and resonated with the antenna element  3 . Specifically, the power supply terminal  20   a  formed on the bottom of the rod  21  of the first radiator part  20  is inserted into the hole of the stepped portion  31   b  to be supplied with power through the supply power terminals  20   a ,  22   a  of the linear radiator  2 . Thus the first radiator part  20  is electrified and resonated. In this case, the radiated electromagnetic waves have directional properties by means of the openings  32   a  formed on the conductor  32 , as shown in FIG.  6 . 
   When the Linear Radiator is Extended (refer to  FIG. 4   b ) 
   When the linear radiator  2  is extended out of the housing, the first radiator part  20  is separated from the antenna element  3 , and at the same time the rod  23  covered with the dielectric material  24  of the second radiator part  22 , which is connected with the first radiator part  20  in a capacitive coupling manner, is partially vertically extended from the antenna element  3  through the hollow portion  31   a  of the antenna element  3 . 
   At this time, the power supply terminal  22   a  formed on the bottom of the rod  23  of the second radiator part  22  is inserted into the hole of the stepped portion  31   b  to be supplied with power through the supply power terminals  20   a ,  22   a  of the linear radiator  2 . Thus the second radiator part  22  is electrified and resonated. In this case, the radiated electromagnetic waves have directional properties by means of the openings  32   a  formed on the conductor  32 , as shown in FIG.  6 . 
   Therefore, the linear radiator  2  is always grounded with the stepped portion  31   b  of the dielectric material  31  through the power supply terminals  20   a  and  22   a  of the first and second radiator parts  20  and  22  passing through the stepped portion  31   b  of the dielectric material  31 , when retracted and extended. Though the stepped portion  31   b  of the dielectric material  31  is grounded with the power supply terminals  20   a  and  22   a  of the linear radiator  2 , there is not a power supply point between the antenna element  3  and the linear radiator  2 , that is, power is not supplied between the antenna element  3  and the linear radiator  2 . 
   When the radiated electromagnetic waves have directional properties as shown in  FIG. 6 , the width W of the beam can be adjusted by the area, shape, position and number of the openings  32   a.    
   The relation between the adjustment of the width W of the beam and the gain due to its adjustment is described in the following. As shown in  FIGS. 7   a  and  7   b , two openings  32   a  are equal to each other in terms of the shape and position but different from each other in terms of area. That is, when the length of the opening  32   a  is represented by S and its width is represented by L, the lengths S 1  and S 2  of two openings  32   a  are equal to each other and the width L 1  of one opening  32   a  shown in  FIG. 7   a  is longer than L 2  of the other opening  32   a  shown in  FIG. 7   b , the width W of the beam gets smaller, as the area of the opening  32   a  gets larger, as shown in  FIGS. 7   c  and  7   d , thereby allowing the electromagnetic waves to have directional properties. 
   The case where the openings  32   a  are equal to each other in terms of area and position but different from each other in terms of shape, will be described in the following with reference to  FIGS. 8   a  and  8   b . When the height of the opening  32   a  is represented by H and its width is represented by P, the height H 1  of the opening  32   a  of  FIG. 8   a  is equal to the height H 2  of the opening  FIG. 8   b  and further the width P 1  of the opening of  FIG. 8   a  is equal to the width P 2  of the opening  FIG. 8   b , the shape of the beam of the rectangular opening of  FIG. 8   a  is shown in  FIG. 8   c  and the shape of the beam of the triangular opening of  FIG. 8   b  is shown in  FIG. 8   d.    
   As shown in  FIGS. 8   c  and  8   d , the widths W of the beams are equal or similar to each other on the x-y line, whereas the shapes thereof are different from to each other on the x-z line. In this manner, the shape of the beam can be varied. The width of the band is narrow when the opening  32   a  is rectangular in shape, as shown in  FIG. 8   e , whereas the width of the band is wide when the opening  32   a  is triangular in shape as shown in  FIG. 8   f . Accordingly the width of the band can be adjusted, and thus problems due to polarized wave synchronization and the reflected waves of the antenna can be solved. 
   By changing the position of the opening  32   a , the radiating direction of the beam can be adjusted in the desired direction. For example, in the case where the electromagnetic waves are non-directional, the electromagnetic waves are transmitted to the user of the wireless communication apparatuses, even though the upper portion of the antenna is modified. However, when the direction of the electromagnetic waves are changed by moving the passive antenna or the openings  32   a  according to the present invention, the direction of the radiation of the electromagnetic waves transmitted to the user of the wireless communication apparatuses can be changed and/or adjusted. 
   The shape of the beam according to the number of openings  32   a  is illustrated in  FIGS. 9   a  to  9   d . Taking the rectangular opening  32   a  as an example, when the length of the opening  32   a  is represented by S and the width thereof is represented by L, the S 3  of  FIG. 9   a  is equal to the S 4  of  FIG. 9   b , and L 3  of  FIG. 9   a  is longer than L 4  of  FIG. 9   b . As shown in  FIG. 9   a , the adjustment of the width W of the beam with one wider opening  32   a  is restricted within a limited range. On the contrary, when the width W of the beam is adjusted with divided openings  32   a  having the width L 4  respectively, as shown in  FIG. 9   b , the width W of the beam can be adjusted to be narrower than that when using one wider opening  32   a . The butterfly-shaped opening  32   a  of  FIG. 5   e  is an example to which this principle is applied. 
   Since the gain and the radiating characteristics of the antenna are varied depending on the shape, area, position and number of the openings  32   a , the radiating direction and radiating amount of the electromagnetic waves are adjusted by varying the shape, area, position and number of the openings  32   a.    
   In the present embodiment, the antenna element  3  is fixed to the housing and the radiator  2  moves up and down through the antenna element  3  to be resonated, thereby adjusting the radiating direction and radiating amount of the electromagnetic waves. However, the present invention is not limited to this embodiment and can be widely applied to the various antennas for the portable wireless communication apparatuses. For example, in the antenna structure where the helical antenna part is installed as shown in  FIGS. 10   a  to  10   c,  when the antenna element is used in place of the helical antenna part, the antenna has directional properties. 
   Further, for the antenna structure in which the antenna element  3  and the linear radiator  2  are fixedly attached to the housing in parallel and the structure in which the antenna element  3  is attached to the upper portion of the linear radiator  2  moving up and down and is connected in parallel with the linear radiator  2 , the antenna element  3  is resonated as described above, so the gain and radiating characteristics of the antenna are varied depending on the shape, area, position and number of the opening  32   a . Therefore, the radiating direction and radiating amount of the electromagnetic waves can be adjusted by varying the shape, area, position and number of the openings  32   a.    
   As described above, the present invention is directed to provide an antenna for portable wireless communication apparatuses, which is comprised of an antenna element for providing electromagnetic waves with directional properties in place of the conventional helical antenna part for generating non-directional electromagnetic waves, and a linear radiator supplied with power and connected in parallel with the antenna element, thereby preventing the electromagnetic waves generated by portable wireless communication apparatuses from doing harm to users, and increasing the efficiency of the antenna. 
   Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.