Abstract:
A complex antenna apparatus including a base, a circular polarization antenna and a capacitance (inductance) cylinder loading monopole antenna. The base has a central through hole. The circular polarization antenna is disposed on the base and has a hollow feeding portion corresponding to the central through hole. The capacitance (inductance) cylinder loading monopole antenna is fixed on the base by inserting one end of the capacitance (inductance) cylinder loading monopole antenna into the central through hole.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a complex antenna apparatus, and in particular to a complex antenna apparatus that simultaneously receives radio signals from satellites and base stations on earth.  
           [0003]    2. Description of the Related Art  
           [0004]    Referring to FIG. 1A and FIG. 1B, U.S. Pat. No. 6,483,465 discloses a circularly polarized wave antenna  10  which allows the matching of resonant frequencies in a higher order mode to be easily achieved. In this circularly polarized wave antenna  10 , a flat portion  12   a  is provided by flattening a portion of the peripheral side surface of a substrate  11 . Two feeding electrodes  17 ,  18  for use in the higher order mode excitation are formed on the flat portion  12   a.  Additionally, a circular radiation electrode  14  is formed on a main surface  13  of the substrate  11  while a ground electrode  16  is formed on the other main surface  15  of the substrate  11 . The circularly polarized wave antenna  10  simply receives radio signals from satellites.  
           [0005]    Referring to FIG. 2, U.S. Pat. No. 6,483,471 discloses a complex antenna  40  having a quadrifilar helix antenna  49  and a dipole antenna  44 . The quadrifilar helix antenna  49  has a first coaxial cable  46 , and the dipole antenna  44  has a linear polarization portion and a second coaxial cable  42 . The linear polarization portion is external to the quadrifilar helix antenna  49 . Accordingly, the complex antenna  40  can simultaneously receives radio signals from satellites and base stations. Nevertheless, the complex antenna  40  has a large length or height and the volume thereof cannot be reduced, thereby causing inconvenience when carried by an object.  
           [0006]    Referring to FIG. 3, U.S. Pat. No. 6,476,773 discloses an antenna array  120  formed on a deformable dielectric material or substrate  122 . The antenna array  120  has a center element  130  and a plurality of radial elements  126  extending from a center hub  128 . In the operative mode, the radial elements  126  are folded upwardly into an approximately vertical position, with the center element  130  at the center of the center hub  128  and the radial elements  126  circumferentially surrounding the center element  130 . When not in use, the antenna array  120  is deformed into a plane and can therefore be integrated into a housing for compact storage. Accordingly, the structure of the antenna array  120  is complex, such that complex assembly steps are needed.  
           [0007]    Referring to FIG. 4, a conventional monopole antenna  50  is employed to receive the radio signals from the base stations.  
           [0008]    Referring to FIG. 5, a conventional circular polarization antenna  60  is employed to receive the radio signals from the satellites. The circular polarization antenna  60  is disposed on a base  70  having a ground  71  formed thereunder. According to the antenna characteristics, most of the electric current flowing through the circular polarization antenna  60  is aggregated on the peripheral edge thereof. Namely, there is least electric current flowing through the central part of the circular polarization antenna  60 .  
           [0009]    Generally speaking, there are two types of conventional circular polarization antennas, the cross dipole antenna and quadrifilar helix antenna. In addition to the conventional circular polarization antenna, an additional linear antenna is also needed for receiving the radio signals coming from both the satellites and base stations. Nevertheless, the number of antenna elements and the space required is increased.  
           [0010]    Additionally, there are a few drawbacks when the cross dipole antenna or quadrifilar helix antenna is combined with a monopole linear antenna. Additional assembly steps are needed, artificial welding is difficult, and manufacturing costs and time are considerably increased.  
           [0011]    Moreover, it is uneasy to tune the impedance match between the cross dipole antenna and monopole linear antenna to meet designer&#39;s requirement, thereby increasing the development time thereof. It is not easy to reduce the length or height of the quadrifilar helix, thus makes reduction of the total volume of the quadrifilar helix antenna and monopole linear antenna difficult.  
         SUMMARY OF THE INVENTION  
         [0012]    Accordingly, an object of the invention is to provide a complex antenna apparatus to overcome the aforementioned problems. The complex antenna apparatus comprises a base, a circular polarization antenna and a capacitance (inductance) cylinder loading monopole antenna. The base includes a central through hole. The circular polarization antenna is disposed on the base and has a hollow feeding portion corresponding to the central through hole. The capacitance (inductance) cylinder loading monopole antenna is fixed on the base by inserting one end of the capacitance (inductance) cylinder loading monopole antenna into the central through hole.  
           [0013]    Preferably, the capacitance (inductance) cylinder loading monopole antenna further comprises a monopole linear antenna and a conductive element covering the monopole linear antenna.  
           [0014]    Preferably, the capacitance (inductance) cylinder loading monopole antenna further comprises a dielectric disposed between the conductive element and monopole linear antenna.  
           [0015]    Preferably, the base further comprises a ground formed thereunder.  
           [0016]    Preferably, the circular polarization antenna is circular or polygon.  
           [0017]    Preferably, the complex antenna apparatus further comprises an RF module. The RF module is connected to the circular polarization antenna and capacitance (inductance) cylinder loading monopole antenna.  
           [0018]    Preferably, the base further comprises a through hole. The circular polarization antenna and capacitance (inductance) cylinder loading monopole antenna are connected to the RF module passing through the through hole and central through hole of the base, respectively.  
           [0019]    Preferably, the complex antenna apparatus further comprises a demodulator. The demodulator is connected to the RF module.  
           [0020]    Preferably, the base is composed of ceramic or printed circuit board.  
           [0021]    Preferably, the dielectric is composed of Teflon.  
           [0022]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0024]    [0024]FIG. 1A and FIG. 1B show a conventional circular polarization antenna;  
         [0025]    [0025]FIG. 2 shows a conventional complex antenna;  
         [0026]    [0026]FIG. 3 shows a conventional antenna array;  
         [0027]    [0027]FIG. 4 shows a conventional monopole antenna;  
         [0028]    [0028]FIG. 5 shows a conventional circular polarization antenna;  
         [0029]    [0029]FIG. 6 is a schematic perspective view showing a complex antenna apparatus of the invention;  
         [0030]    [0030]FIG. 7 is a schematic cross section according to FIG. 6; and  
         [0031]    [0031]FIG. 8 is a schematic perspective view showing another complex antenna apparatus of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    Referring to FIG. 6, the complex antenna apparatus  200  includes a base  210 , a circular polarization antenna  220  and a capacitance (inductance) cylinder loading monopole antenna  230 . The circular polarization antenna  220  receives radio signals from satellites while the capacitance (inductance) cylinder loading monopole antenna  230  receives radio signals from base stations on earth.  
         [0033]    As shown in FIG. 6 and FIG. 7, a central through hole  211  is formed on the central part of the base  210 . The circular polarization antenna  220  is disposed on the base  210  and has a hollow feeding portion  221 . Specifically, the position of the hollow feeding portion  221  corresponds to that of the central through hole  211  of the base  210 . The capacitance (inductance) cylinder loading monopole antenna  230  is disposed in the central through hole  211  of the base  210  via the hollow feeding portion  221  of the circular polarization antenna  220 . Thus, the capacitance (inductance) cylinder loading monopole antenna  230  protrudes from the circular polarization antenna  220  and base  210 .  
         [0034]    The structure of the capacitance (inductance) cylinder loading monopole antenna  230  is described as follows. As shown in FIG. 6 and FIG. 7, the capacitance (inductance) cylinder loading monopole antenna  230  is composed of a monopole linear antenna  231 , a dielectric  232  and a conductive element  233 . The dielectric  232 , such as Teflon, covers the monopole linear antenna  231 . The conductive element  233  then covers the dielectric  232 . Thus, the dielectric  232  is between the monopole linear antenna  231  and conductive element  233 . As a whole, the conductive element  233  covers the dielectric  232  and monopole linear antenna  231  so that capacitance coupling is generated between the conductive element  233  and monopole linear antenna  231 . The height or length of the monopole linear antenna  231 , diameter of the monopole linear antenna  231  and value of the dielectric  232  may be relatively adjusted according to the Smith chart to achieve impedance match. The resonant frequency or wavelength of the monopole linear antenna  231  is thus reduced. Namely, because the monopole linear antenna  231  is covered by the conductive element  233 , the monopole linear antenna  231  can obtain a higher impedance match value with shorter length. For example, the monopole linear antenna  231  can be designed according to an impedance match value of 50 ohms.  
         [0035]    According to the antenna characteristics, there is least electric current flowing through the central part of the circular polarization antenna  220  when the circular polarization antenna  220  is disposed on the base  210 . The hollow feeding portion  221  formed on the center of the circular polarization antenna  220  does not adversely affect the capability thereof to receive the satellite signals. Thus, when the capacitance (inductance) cylinder loading monopole antenna  230  is disposed in the central through hole  211  of the base  210  via the hollow feeding portion  221  of the circular polarization antenna  220 , the circular polarization antenna  220  and capacitance (inductance) cylinder loading monopole antenna  230  respectively have different electric current routes and do not interfere with each other.  
         [0036]    Additionally, the base  210  is composed of ceramic and a ground  212  is formed thereunder. Meanwhile, an RF module  240  and a demodulator  250  are connected to the circular polarization antenna  220  and capacitance (inductance) cylinder loading monopole antenna  230 .  
         [0037]    Additionally, as shown in FIG. 7, a through hole  213  is formed in the base  210 . The through hole  213  may correspond to any part of the circular polarization antenna  220 , such that the circular polarization antenna  220  can be connected to the RF module  240  by means of a wire  222  and via the through hole  213 . The capacitance (inductance) cylinder loading monopole antenna  230  is connected to the RF module  240  by means of a wire  234  and via the central through hole  211 . The RF module  240  is then connected to the demodulator  250  by means of a wire  260 .  
         [0038]    In addition, the complex antenna apparatus  200  of the invention is not limited to employing the capacitance (inductance) cylinder loading monopole antenna  230  having the monopole linear antenna  231 , dielectric  232  and conductive element  233 . In other words, the monopole linear antenna  231  or other linear antennas can be directly disposed in the central through hole  211  of the base  210  to simultaneously receive the radio signals from the satellites and base stations with the circular polarization antenna  220 .  
         [0039]    Moreover, the circular polarization antenna  220  of the invention is not limited to a round shape. For example, the complex antenna apparatus  200 ′ has a rectangular circular polarization antenna  220 ′ as shown in FIG. 8. The capability of the circular polarization antenna  220 ′ to receive radio signals from satellites is the same as that of the circular polarization antenna  220 .  
         [0040]    Specifically, the central through hole  211  is not limited to being formed in the center of the base  210 . That is, even though the central through hole  211  is formed slightly away from the center of the base  210 , the complex antenna apparatus  200  can accomplish the same purpose.  
         [0041]    In conclusion, the complex antenna apparatus  200 ,  200 ′ have the following advantages. The development of the complex antenna apparatus  200 ,  200 ′ is simplified. The ideal dimensions of the complex, antenna apparatus can be readily determined by electromagnetic analysis software, such as IE3D or Ansoft, without complicated design or modification. Since the capacitance (inductance) cylinder loading monopole antenna is disposed in the hollow feeding portion of the circular polarization antenna, the height and total volume of the complex antenna apparatus are effectively reduced. The complex antenna apparatus presents an aesthetically pleasing appearance especially when the complex antenna apparatus is carried by a movable object (such as a vehicle) or a building. Because the complex antenna apparatus has fewer components, the manufacturing costs thereof are reduced. The base of the complex antenna apparatus is composed of ceramic, such that the dimensions thereof can be accurately controlled. The stability of the complex antenna apparatus is thereby enhanced. The complex assembly steps and artificial welding of the cross dipole antenna and quadrifilar helix circular polarization antenna are reduced.  
         [0042]    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.