Abstract:
An antenna device has a dielectric body with a convex surface and a concave surface. The antenna device further has a flexible printed circuit board disposed on the convex surface.

Description:
[0001]     This application is a Continuation of co-pending application Ser. No. 11/099,616 filed on Apr. 4, 2005 and for which priority is claimed under 35 U.S.C. § 120, which claims priority of Application No. 93136269 filed in Taiwan on Nov. 25, 2004 under 35 U.S.C. § 119, the entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to a helix antenna, and in particular to a helix antenna with reduced manufacturing costs.  
         [0004]     2. Brief Description of the Related Art  
         [0005]     Japan Patent. No. 2001-168631 discloses a conventional method for manufacturing a helix antenna providing a frequency of circularly polarized radiation exceeding 200 MHz. As shown in  FIG. 1A , a metal (copper) layer  2  is coated (electroplated) on the outer surface of a solid ceramic cylinder  1  in which a central through hole  3  is formed. The metal (copper) layer  2  of the solid ceramic cylinder  1  is etched by a laser etching system (not shown), thereby providing a specific profile as shown in  FIG. 1B . As shown in  FIG. 1C , a coaxial cable  4  with an exposed copper core  41  is disposed in the central through hole  3  of the solid ceramic cylinder  1 . The copper core  41  is then bent and welded to the metal (copper) layer  2  on the top of the solid ceramic cylinder  1 , thereby achieving electrical connection between the coaxial cable  4  and the metal (copper) layer  2 . At this point, the copper core  41  serves as a feeder. Accordingly, as the solid ceramic cylinder  1  is three-dimensional, the metal (copper) layer  2  cannot be precisely etched to form the specific profile by the laser etching system. Thus, some parameters, such as radio frequency (RF) and impedance matching, of the helix antenna cannot be obtained as required. A test and adjustment device (not shown) must then be applied to fine tune the parameters of the helix antenna.  
         [0006]     The following description is directed to the steps of fine tuning the parameters of the helix antenna.  
         [0007]     The helix antenna shown in  FIG. 1C  is connected to the test and adjustment device. Multiple probes of the test and adjustment device are coupled to the helix antenna, detecting magnitude of relative phases and amplitude of electric currents in some specific positions of the helix antenna. According to the detection of the probes, the laser etching system etches the metal (copper) layer  2  on the top of the solid ceramic cylinder  1 , forming a plurality of openings  21 , as shown in  FIG. 1D . Specifically, to fine tune inductance of the helix antenna, the positions, profiles, and sizes of the openings  21  must be carefully arranged, thereby providing the helix antenna with a frequency of circularly polarized radiation exceeding 200 MHz.  
         [0008]     A few drawbacks, however, exist in the process of manufacturing the aforementioned helix antenna. Bending and welding the copper core  41  to the metal (copper) layer  2  on the top of the solid ceramic cylinder  1  increases manufacturing time and causes inconvenience. Moreover, the laser etching system is very expensive and laser heads thereof must be replaced after 1500 hours, thereby increasing manufacturing costs of the helix antenna. Additionally, the duration for which the metal (copper) layer  2  is etched by the laser etching system is lengthy. Furthermore, as errors occur during etching of the metal (copper) layer  2  with the specific profile by the laser etching system, the helix antenna must be fine tuned by the test and adjustment device and laser etching system. Namely, the metal (copper) layer  2  on the top of the solid ceramic cylinder  1  is etched and the openings  21  are formed thereon. Accordingly, the process of fine tuning the helix antenna increases manufacturing time and costs thereof.  
         [0009]     Hence, there is a need for a helix antenna with reduced manufacturing costs and simplified structure.  
       SUMMARY OF THE INVENTION  
       [0010]     Accordingly, an exemplary embodiment of the invention provides an antenna device comprising a dielectric body and a flexible printed circuit board. The dielectric body comprises a concave surface and a convex surface and the flexible printed circuit board is disposed on the convex surface.  
         [0011]     The dielectric body comprises a cylinder having a through hole therein and the convex surface comprises the circumferential surface of the cylinder and the concave surface comprises an inner surface of the cylinder surrounding the through hole.  
         [0012]     The flexible printed circuit board is swirled and attached to the circumferential surface of the cylinder, wherein a metal feeding strip and a metal grounding strip extend from the flexible printed circuit board and passing through the through hole.  
         [0013]     Furthermore, the flexible printed circuit board further comprises at least one first metal strip and at least one second metal strip parallel thereto, and the first and second metal strips tilt to one side of the flexible printed circuit board at a predetermined angle, wherein the metal feeding strip is connected to the first metal strip and the metal grounding strip is connected to the second metal strip.  
         [0014]     The flexible printed circuit board provides a specific value of impedance matching, whereas the dielectric body comprises ceramic material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The present invention will become more fully understood from the subsequent detailed description and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention and wherein:  
         [0016]      FIG. 1A  is a schematic perspective view showing the manufacturing process of a conventional helix antenna;  
         [0017]      FIG. 1B  is a schematic perspective view showing the manufacturing process of the conventional helix antenna of  FIG. 1A ;  
         [0018]      FIG. 1C  is a schematic perspective view showing the manufacturing process of the conventional helix antenna of  FIG. 1B ;  
         [0019]      FIG. 1D  is a schematic perspective view showing the manufacturing process of the conventional helix antenna of  FIG. 1C ;  
         [0020]      FIG. 2A  is a schematic perspective view of the ceramic cylinder of helix antenna of an embodiment of the invention;  
         [0021]      FIG. 2B  is a schematic plane view of the flexible printed circuit board of helix antenna of an embodiment of the invention;  
         [0022]      FIG. 3  is a schematic view showing assembly of helix antenna of an embodiment of the invention; and  
         [0023]      FIG. 4  is a schematic perspective view of helix antenna of an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Referring to  FIG. 2A , a ceramic cylinder  110  is provided. The ceramic cylinder  110  comprises a central through hole  111 , a first annular surface  112 , and a second annular surface  113 . The first annular surface  112  is opposite the second annular surface  113 . The central through hole  111  is between the first annular surface  112  and the second annular surface  113 .  
         [0025]     Referring to  FIG. 2B , a flexible printed circuit board (FPCB)  120 , the parameters of which are finely tuned, is provided. Namely, some parameters, such as radio frequency (RF) and impedance matching, are finely tuned in the flexible printed circuit board  120 . In this embodiment, the impedance matching of the flexible printed circuit board  120  is 50Ω when the receiving frequency is 1575.42 MHz.  
         [0026]     As shown in  FIG. 2B , the length L of the flexible printed circuit board  120  equals the circumference of the ceramic cylinder  110 , first annular surface  112 , or second annular surface  113 . The width W of the flexible printed circuit board  120  equals the height of the ceramic cylinder  110 .  
         [0027]     The flexible printed circuit board  120  comprises two first metal strips  131 , two second metal strips  132 , a metal feeding strip  133 , and a metal grounding strip  134 . The first metal strips  131  are parallel to the second metal strips  132 . Specifically, the first metal strips  131  and second metal strips  132  tilt to one side of the flexible printed circuit board  120  at a predetermined angle θ. The metal feeding strip  133  is connected to the first metal strips  131  and extends outside the flexible printed circuit board  120 . The metal grounding strip  134  is connected to the second metal strips  132  and extends outside the flexible printed circuit board  120 .  
         [0028]     Referring to  FIG. 3 , the flexible printed circuit board  120  is swirled and attached to the circumferential surface of the ceramic cylinder  110 . At this point, the metal feeding strip  133  and metal grounding strip  134  are above the first annular surface  112  of the ceramic cylinder  110 . As shown in  FIG. 2A  and  FIG. 4 , the metal feeding strip  133  and metal grounding strip  134  pass through the central through hole  111  from the first annular surface  112  to the second annular surface  113 . At this point, assembly of a helix antenna  100  is complete. Specifically, as tilting to one side of the flexible printed circuit board  120  at a predetermined angle θ, the first metal strips  131  and second metal strips  132  helically surround the ceramic cylinder  110  after the flexible printed circuit board  120  is swirled and attached to the circumferential surface of the ceramic cylinder  110 .  
         [0029]     Additionally, the first metal strips  131  and second metal strips  132  can be electroplated or printed on the flexible printed circuit board  120 . Alternatively, the flexible printed circuit board  120  can be formed by electroplating or printing the first metal strips  131  and second metal strips  132  on a substrate.  
         [0030]     In conclusion, the disclosed method for manufacturing the helix antenna  100  has the following advantages. The disclosed method does not require the process of bending and welding the copper core  41  to the metal (copper) layer  2  on the top of the solid ceramic cylinder  1 , as shown in  FIG. 1C  and  FIG. 1D , thus reducing manufacturing time and complexity. Moreover, the laser etching system and test and adjustment device are not required, such that manufacturing costs of the helix antenna  100  are reduced. Additionally, as important parameters in the flexible printed circuit board  120  are finely tuned before the flexible printed circuit board  120  is swirled and attached to the circumferential surface of the ceramic cylinder  110 , fine-tuning operation of the parameters performed by the laser etching system and test and adjustment device is not required, further reducing the manufacturing costs and time of the helix antenna  100 . Furthermore, as unity exists in the flexible printed circuit board(s)  120 , mass production of the helix antenna  100  is available, thereby enhancing productivity.  
         [0031]     While the invention has been described by way of example and in terms of preferred embodiment, 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 (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.