Abstract:
The present invention relates to a porous magnetic antenna, comprising: an antenna; an insulating layer, having one side next to said antenna; and a magnetic layer, placed next to the other side of the insulating layer, separated from said antenna with a distance, and having at least one hole. The porous magnetic antenna has the advantages of shaping the field pattern, lowering the sensitivity, improving the gain value and possessing stable directionality.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention follows what is disclosed in a TIPO paten application with application number 098110021. The present invention relates to a magnetic antenna, especially to a porous magnetic antenna, of which a magnetic layer comprising at least one hole for altering the original field pattern and the gain value of an antenna, so that the antenna can possess stable directionality. 
         [0003]    The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
         [0004]    2. Description of the Related Art 
         [0005]    In recent years, due to the practical applications of wireless communication and the popularization of hi-tech products, the communication industry has had new breakthroughs and achievements. As a variety of electronic communication products and wireless communication equipments have been applied in our daily life, the antenna, especially the planar antenna, broadly found in the wireless communication systems, is gaining a lot of attention due to its simple manufacture process and small form factor. Common planar antenna includes microstrip antenna, printed antenna, planar inverted-F antenna, etc. 
         [0006]    However, the common antenna has fixed characteristics, no matter of what type it is—for example, the EM wave field pattern radiated from an antenna is usually of omni-direction type and can not be changed—while there are occasions where EM wave intensity needs to be enhanced in some specific direction. For example, when using a mobile phone in a tunnel, it is desirable to enhance the antenna&#39;s EM wave in the direction towards the exits of the tunnel, or alter the EM field pattern to a directional one directing towards the exits of the tunnel to improve the mobile phone communication quality in the tunnel. 
         [0007]    It is found that the Taiwan TW466,799 patent has disclosed an antenna comprising an EMI snubber, which utilizes a magnetic means having soft magnetic powder to cover the antenna for controlling the field pattern to reduce the antenna&#39;s EM radiation against human body. However, the magnetic means is mainly for shielding or inhibiting EMI, and the field pattern still does not possess directionality though part of the field pattern is altered. 
         [0008]    It is also found that the U.S. Pat. No. 6,768,476 patent “Capacitively-loaded bent-wire monopole on an artificial magnetic conductor” has disclosed an antenna consisting of a thin strip bent-wire monopole disposed on an artificial magnetic conductor (AMC), to achieve an electrically small antenna for use in handheld wireless devices without suffering a substantial loss of efficiency. However, the antenna disposed on an artificial magnetic conductor can not change the antenna&#39;s field pattern to enhance the gain in some specific direction, though it can reduce the substantial loss. 
         [0009]    Further, it is found that the Taiwan TW466,799 patent “Directional antenna” has disclosed a directional antenna, which utilizes a hybrid magnetic means having soft magnetic powder and an oxide film layer to cover the antenna for shielding or inhibiting EMI, but it still can not change the antenna&#39;s field pattern to enhance the gain in some specific direction. 
         [0010]    To conquer the disadvantages of the prior art antennas mentioned above, the present invention proposes a porous magnetic antenna. 
       SUMMARY OF THE INVENTION 
       [0011]    One objective of the present invention is to provide a porous magnetic antenna, of which a magnetic layer has at least one hole to alter the original field pattern of the antenna. 
         [0012]    Another objective of the present invention is to provide a porous magnetic antenna, of which a magnetic layer has at least one hole to enhance the gain value of the antenna. 
         [0013]    Another objective of the present invention is to provide a porous magnetic antenna, of which a magnetic layer has at least one hole to induce directionality of the antenna. 
         [0014]    Still another objective of the present invention is to provide a porous magnetic antenna, of which a magnetic layer has at least one hole to reduce the sensitivity of the antenna. 
         [0015]    To achieve the foregoing objectives, the present invention provides a porous field pattern shaping device to alter a field pattern of an antenna, at least comprising: a magnetic layer, having at least one hole, placed beside said antenna, and separated from said antenna with a distance. 
         [0016]    To make it easier for our examiner to understand the objective of the invention, its structure, innovative features, and performance, we use a preferred embodiment together with the accompanying drawings for the detailed description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a breakdown diagram of a porous magnetic antenna according to a preferred embodiment of the present invention. 
           [0018]      FIG. 2   a  is a front view of a porous magnetic antenna according to a preferred embodiment of the present invention. 
           [0019]      FIG. 2   b  is a left side view of a porous magnetic antenna according to a preferred embodiment of the present invention. 
           [0020]      FIG. 3  shows the field patterns of a porous magnetic antenna according to a preferred embodiment of the present invention. 
           [0021]      FIG. 4  shows a gain vs. distance profile of a porous magnetic antenna according to a preferred embodiment of the present invention. 
           [0022]      FIG. 5  is a breakdown diagram of another porous magnetic antenna according to a preferred embodiment of the present invention. 
           [0023]      FIG. 6  is a breakdown diagram of another porous magnetic antenna according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    The present invention will be described in more detail hereinafter with reference to the accompanying drawings that show the preferred embodiment of the invention. 
         [0025]    Please refer to  FIG. 1-4 , wherein  FIG. 1  shows a breakdown diagram of a porous magnetic antenna according to a preferred embodiment of the present invention;  FIG. 2   a  shows a front view of a porous magnetic antenna according to a preferred embodiment of the present invention;  FIG. 2   b  shows a left side view of a porous magnetic antenna according to a preferred embodiment of the present invention;  FIG. 3  shows the field patterns of a porous magnetic antenna according to a preferred embodiment of the present invention;  FIG. 4  shows a gain vs. distance profile of a porous magnetic antenna according to a preferred embodiment of the present invention. 
         [0026]    As shown in the figures, the porous magnetic antenna  1  comprises an antenna  10 , an insulating layer  20  and a magnetic layer  30 . 
         [0027]    In the structure, the antenna  10  is a monopole microstrip antenna fixed on a substrate  13 , having a line structure  11   a , a feed line  11   b  and a ground contact  11   c.  The line structure  11   a  mainly acts as a cavity for 2.4 GHz resonant frequency to contribute the most part of radiation. The feed line  11   b  is used to feed a radiation signal to the line structure  11   a.  The back side of the feed line  11   b  is the ground contact  11   c.  The contact point of the line structure  11   a  and the feed line  11   b  is presumed as the origin of a Cartesian coordinate system having x-axis, y-axis and z-axis. The substrate  13  is in parallel with x-axis and perpendicular to y-axis, and the angle θ shown in the figures is the angle of a vector on xy plane relative to y-axis. 
         [0028]    The insulating layer  20 , placed at one side—for example but not limited to left side—of the antenna  10 , comprises preferably but not limited to expanded polystyrene with a thickness around 3 mm. The porous magnetic antenna  1  can have the antenna  10  separated from the magnetic layer  30  with a distance controlled by the number of the insulating layer  20 . 
         [0029]    The magnetic layer  30 , having at least one hole  31 , is located at the other side—for example but not limited to left side—of the insulating layer  20  in a parallel manner, and separated from the antenna  10  with a distance d. The magnetic layer  30  has a thickness of t, and the relative permeability μ r  of which is higher than 10. The magnetic layer  30  can be viewed as an absorber—a flexible laminate constructed by uniting a magnetic material and a plastic material—originally used to shield an EMI of some specific frequency, of which the absorption effect is dependent on the thickness and the density of the magnetic material, i.e. dependent closely on the permeability. Besides, the present invention sets the ratio of the distance d relative to the thickness of the magnetic layer  30  to be, for example but not limited to, between 14 and 15. 
         [0030]    The hole  31  is formed on the magnetic layer  30  at a place corresponding to the maximal current intensity location on the antenna  10 . The magnetic layer  30  having the hole  31  influences the transmission of the EM waves emitted by the antenna  10  in a way that it allows part of the EM waves pass through freely and part of them be effected, so it can change the field pattern. In regards to performance, the magnetic layer  30  having holes of certain shape, size and number, can provide much more the effect of field pattern stabilization and gain value enhancement (when shielding distance d≧4 mm, the gain value is always greater than that of the original field pattern) than the magnetic layer having no hole, and as the enhanced gain is insensitive to the shielding distance variation, the field pattern is stabilized. When the antenna  10  is installed without the magnetic layer  30  having the hole  31 , it possesses an original field pattern; when the magnetic layer  30  having the hole  31  is added in, the antenna  1  is formed and the field pattern is changed. The field pattern is therefore can be switched between two patterns. 
         [0031]    As shown in  FIG. 3 , it indicates an E-plane diagram of the radiated field pattern when the magnetic layer  30  having a round hole  31  is installed. With the magnetic layer  30  having a round hole  31  installed, the field pattern of the magnetic antenna can be altered by adjusting the distance d. When the magnetic layer  30  having the hole  31  is not added in, the field pattern of the antenna  10  is near to the omni-direction type; when the magnetic layer  30  having the hole  31  is installed with the insulating layer  20  controlling its distance from the antenna  10 , the field pattern will gradually change to be directional as the distance increases, and becomes obviously north-south oriented when the distance is 35 mm. Therefore, by forming a round hole  31  on the magnetic layer  30 , and by changing the distance d between the antenna  10  and the magnetic layer  30 , the field pattern can be changed from omni-directional to directional, and a function of field patterns switching is proposed. 
         [0032]    As shown in  FIG. 4 , it indicates a gain vs. distance profile when the magnetic layer  30  having a round hole  31  is installed. With the thickness t of the magnetic layer  30  being 1 unit, the magnetic layer  30  being in parallel with the antenna  10 , θ=180°, the profile of antenna gain vs. distance d of the antenna installed with the magnetic layer  30  not having the hole  31 , and the profile of antenna gain vs. distance d of the antenna installed with the magnetic layer  30  having the hole  31  are measured. There are two gain profiles in  FIG. 4 , including a gain profile O corresponding to θ=180° and the magnetic layer  30  not having the hole  31 , and a profile G corresponding to θ=180° and the magnetic layer  30  having the hole  31 . As can be seen in  FIG. 4 , when the distance d is 13.4 mm, the gain of the gain profile G is up to 3.7 dB, the gain of the gain profile O is around 0 dB, the gain profile G has positive gain values over all the settings of the distance d, and the gain profile O has zero gain value over all the settings of the distance d. As the magnetic layer  30  having the hole  31  can increase the gain value of the antenna  10 , the volume of the insulating layer  20  can be reduced to cut the production cost with a gain value requirement still being met.  FIG. 4  is drew under θ=180°, but it is not intended to be limited thereof. For example, when θ=0°, the resulted effect is similar. 
         [0033]    Please refer to  FIG. 5 , which shows a breakdown diagram of another porous magnetic antenna according to a preferred embodiment of the present invention. As shown in the figure, the magnetic layer  30  has a plurality of holes  31 , and it can also attain the effects mentioned in the above embodiment. Since the principle is disclosed above, it will not be addressed here. 
         [0034]    Please refer to  FIG. 6 , which shows a breakdown diagram of another porous magnetic antenna according to a preferred embodiment of the present invention. As shown in the figure, the magnetic layer  30  has a rectangle hole  31 , and it can also attain the effects mentioned in the above embodiment. Since the principle is disclosed above, it will not be addressed here. As a result, the porous magnetic antenna of the present invention has gained improvement relative to the prior art. 
         [0035]    In summary, through the implement of the porous magnetic antenna of the present invention, of which a magnetic layer comprising at least a hole, a variety of advantages can be offered: 1. the original field pattern of the antenna can be changed; 2. the gain value of the antenna can be increased; 3. the antenna can become less sensitive to distance variation, so the porous magnetic antenna of the present invention has indeed conquer the disadvantages of the prior art. 
         [0036]    While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures. 
         [0037]    In summation of the above description, the present invention herein enhances the performance than the conventional structure and further complies with the patent application requirements and is submitted to the Patent and Trademark Office for review and granting of the commensurate patent rights.