Abstract:
A beamwidth adjustment device, which is used for a feedhorn comprising an opening and a ring encircling the opening, comprises a conductor used for adjusting beamwidth formed by the feedhorn according to a characteristic of a dish of a satellite antenna corresponding to the feedhorn, and a fixing element used for fixing the conductor to the feedhorn, wherein the satellite antenna is used for receiving signals from the feedhorn.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a beamwidth adjustment device, and more particularly, to a beamwidth adjustment device for adjusting a beamwidth formed by a feedhorn. 
         [0003]    2. Description of the Prior Art 
         [0004]    Satellite communication is distinguished in wide coverage and terrestrial interference avoidance, and is widely used in military, probe, and commercial communication services, such as satellite navigation, satellite voice broadcasting, and satellite television broadcasting. A conventional satellite communication receiving device consists of a dish reflector and a low noise block down-converter with feedhorn (LNBF). The LNBF is disposed on the focus of the dish reflector, and is used for receiving radio signals reflected via the dish reflector, down-converting the radio signals to middle band, and then transmitting the radio signals to a backend satellite signal processor for signal processing, thereby enabling the playing of satellite television programs. 
         [0005]    The LNBF is composed of a feedhorn, a waveguide and a low noise block down-converter (LNB). The feedhorn is used for collecting signals reflected by a satellite antenna to the waveguide, to output to the LNB. Except receiving satellite signals, the feedhorn can transmit signals (reflected via the dish reflector) to the satellite for different applications. 
         [0006]    The reception quality of the satellite antenna is significant related to the placed position of the feedhorn. For example, the feedhorn radiates electromagnetic waves from a focal position of the satellite antenna, and thereby the electromagnetic waves are reflected to the satellite via the dish reflector. A number of signals that can be received by the satellite antenna is decreased when the feedhorn is deviated from the focal position. In practice, the focal position is represented by a focal length to diameter ratio (F/D) of the dish. Note that, the reception efficiency of the satellite antenna is affected by whether the focal length to diameter ratio (hereafter called F/D value) of the dish matches a beamwidth formed by the feedhorn. In other words, different F/D design requires different values of the beamwidth, so that the beams emitted from the feedhorn can be efficiently received by the satellite antenna. For example, a dish with F/D=0.6 requires a narrower beamwidth compared to a dish with F/D=0.4. If the beamwidth does not conform the F/D design of the dish (e.g. too wide or too narrow), reception efficiency of the satellite antenna is affected, thereby lowering the reception quality of the satellite antenna. 
         [0007]    However, a device for adjusting the beamwidth formed by the feedhorn has never been provided in the current market, so that the beamwidth formed by the feedhorn may not match the dish perfectly. In addition, in the beginning of product design, manufacture companies take much effort to reduce size of products, toward compact products and low cost. Therefore, under reduction of an opening size of the feedhorn, how to match the beamwidth and the dish is a topic for discussion. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, the present invention provides a beamwidth adjustment device for a feedhorn, for adjusting a beamwidth formed by the feedhorn, so as to perfectly match the beamwidth with a dish of a satellite antenna. 
         [0009]    The present invention discloses a beamwidth adjustment device for a feedhorn comprising an opening and a ring encircling the opening. The beamwidth adjustment device comprises a conductor for adjusting beamwidth formed by the feedhorn according to a characteristic of a dish of a satellite antenna corresponding to the feedhorn, and a fixing element for fixing the conductor to the feedhorn, wherein the satellite antenna is used for receiving signals from the feedhorn. 
         [0010]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram of a beamwidth adjustment device used for a feedhorn according to an embodiment of the present invention. 
           [0012]      FIG. 2-FIG .  5  are schematic diagrams of beamwidth adjustment devices according to embodiments of the present invention. 
           [0013]      FIG. 6  is a schematic diagram of a waterproof component with the beamwidth adjustment device of  FIG. 1 . 
           [0014]      FIG. 7  is a schematic diagram of a beam emitted from the feedhorn without a beamwidth adjustment device according to an embodiment of the present invention. 
           [0015]      FIG. 8  is a schematic diagram of a beam emitted from the feedhorn of  FIG. 1 . 
           [0016]      FIG. 9  is a schematic diagram of a beam emitted from the feedhorn of  FIG. 3 . 
           [0017]      FIG. 10  is a comparison table of beamwidths in  FIG. 7-FIG .  9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Please refer to  FIG. 1 , which is a schematic diagram of a beamwidth adjustment device  10  according to an embodiment of the present invention. The beamwidth adjustment device  10  is used in a feedhorn  100 . The feedhorn  100  includes an opening  102  and a ring  104  encircling the opening  102 . In  FIG. 1 , the beamwidth adjustment device  10  is composed of a conductor used for adjusting beamwidth formed by the feedhorn  100  according to a characteristic of a dish of a satellite antenna (not shown in  FIG. 1 ) corresponding to the feedhorn  100 . The characteristic of the dish is a focal length to diameter radio (F/D). Note that, a shape of the conductor of the beamwidth adjustment device  10  can be a symmetric geometrical shape, such as orthogonal cross, concentric circle, spot eccentric circle, or radiative distribution, etc., and the conductor is placed above, below or in the same plane of the opening  102  of the feedhorn  100  by a fixed component (shown in  FIG. 1 ). The fixed component is mainly used for fixing the conductor at the feedhorn  100 , as other components and methods obtaining the same objective belong to the claimed invention. For example, the fixed component is a weld, so that the conductor can be welded at the outer rim of the opening  102  or the inner surface of the ring  104  of the feedhorn, or is a pillar extending from the ring  104  to the opening  102 , so that the conductor can be installed on the top of the pillar, so as to reach the goal of fixing the conductor at the feedhorn  100 . In brief, the beamwidth is modified according to a size, a shape, or a position of the conductor placed at the feedhorn  100 . Therefore, the present invention can adjust a width of abeam emitted from the feedhorn  100  to the satellite antenna through the beamwidth adjustment device  10 , thereby increasing signal reception efficiency of the satellite antenna, so as to enhance the reception quality. Furthermore, the present invention can perfectly match the feedhorn  100  to different satellite antennas (e.g. different F/D design). 
         [0019]    In  FIG. 1 , the beamwidth adjustment device  10  is a design of orthogonal polarization, and is capable of reflecting to extend an electric field feedback path and gather current so that the directionality of the beam can be enhanced, to reach the goal of gathering beams, thereby avoiding that a part of beams with wider beamwidth cannot be received, so as to increase reception efficiency of the satellite antenna. The design of the orthogonal polarization can be symmetrical or asymmetrical orthogonal (e.g. length, width or height). In addition, a size of the opening of the feedhorn  100  can be decreased without affecting a match with the dish when the beamwidth is decreased by the beamwidth adjustment device  10 , so as to reduce the manufacture cost. 
         [0020]    As can be seen, when the size of the opening of the feedhorn  100  is fixed, the feedhorn  100  can match the dish perfectly with the beamwidth adjustment device  10 , so as to increase the reception quality. On the other hand, when the opening size of the feedhorn  100  is decreased, the beamwidth can be maintained or optimized via the beamwidth adjustment device  10  of the present invention. Therefore, the area of the opening of the feedhorn  100  can be reduced efficiently, to increase a feasibility of installation with multiple satellite antennas. 
         [0021]    Note that, the beamwidth adjustment device  10  of the present invention can be applied into any kind of feedhorns, such as conical, pyramidal, corrugated, dielectric-load, lens-corrected, dielectric or array, etc., or into different shapes of the opening, such as a square, circle, rectangle, rhombus or ellipse, etc. 
         [0022]    Therefore, the feedhorn  100  can obtain an optimization antenna gain through different shapes of the beamwidth adjustment devices. For example, please refer to  FIG. 2-5 , which illustrate schematic diagrams of beamwidth adjustment devices  20 - 50  according to embodiments of the present invention. In  FIG. 2 , the conductor of the beamwidth adjustment device  20  and the opening  102  are not located in the same plane and formed as a radiative circularity. In  FIG. 3 , the conductor of the beamwidth adjustment device  30  and the opening  102  are located in the same plane and formed as a concentric circularity. In  FIG. 4 , the conductor of the beamwidth adjustment device  40  and the opening  102  are located in the same plane and formed as a non-continuous circularity. In  FIG. 5 , the conductor of the beamwidth adjustment device  50  and the opening  102  are not located in the same plane and formed as an eccentric circularity. Therefore, the beamwidth adjustment devices  30 ,  40  of  FIG. 3  and  FIG. 4 , can make high frequencies match the electric field reflection, so as to maintain the beam pattern. On the other hand, the beamwidth adjustment devices  20 ,  50  of  FIG. 2  and  FIG. 5 , can adjust the beamwidth according to different frequencies, such as low, intermediate, or high frequency, to obtain a beamwidth appropriated for the design of the dish, so as to reduce antenna loss and obtain the optimization antenna gain. In addition, the beamwidth adjustment devices  10 ,  20 ,  30 ,  40 ,  50  of the present invention can be utilized for impedance match improvement, to reduce the return loss of the antenna. 
         [0023]    From the above, except installation in the same plane of the opening  102  of the feedhorn  100 , the beamwidth adjustment device of the present invention can be installed above or below the opening  102  as well. For example, in  FIG. 6 , the beamwidth adjustment device  10  is installed in a waterproof component  200  for covering the feedhorn  100 , such as a feed cap. Furthermore, the beamwidth adjustment device  10  can be electroplated on the waterproof component  200  with a form of conductive film, be included in the water proof component  200  upon injection molding, or be installed on the waterproof component  200  with a metal foil form made of cupronickel oxide. Note that, except the beamwidth adjustment device  10 , the beamwidth adjustment devices  20 ,  30 ,  40 ,  50  can be applied into the waterproof component  200  as well. 
         [0024]    Please refer to  FIG. 7-9 , which are schematic diagrams of beams emitted from the feedhorn  100  operated in a frequency of 10.7 GHz without any beamwidth adjustment device, with the beamwidth adjustment device  10 , and with the beamwidth adjustment device  30  respectively. As can be seen in  FIG. 7-9 , the beamwidth formed by the feedhorn  100  without the beamwidth adjustment device is wider than the beamwidth formed by the feedhorn  100  with the beamwidth adjustment device  10 . Compared to  FIG. 8-9 , the beamwidth formed by the beamwidth adjustment device  10  with the shape of orthogonal cross is narrower than the beamwidth formed by the feedhorn  100  with no beamwidth adjustment device at 10 dB, and the beamwidth formed by the beamwidth adjustment device  30  with the shape of concentric circle is wider than the beamwidth formed by the feedhorn  100  with no beamwidth adjustment device at 10 dB. Please refer to  FIG. 10 , which is a comparison table of the beamwidths of  FIG. 7-9 . As can be seen in  FIG. 10 , the beamwidth of the feedhorn  100  without the beamwidth adjustment device is 80.22 degree (an average of the beamwidth measured in horizontal, vertical and 45 degree direction), whereas the beamwidth of the feedhorn  100  with beamwidth adjustment device  10  is 69.35 degree, so as to match the dish with F/D=0.6. On the other hand, the beamwidth of the feedhorn  100  with the beamwidth adjustment device  30  is 92.66 degree, thereby matching the dish with F/D=0.4. As can be seen, the beamwidth at 10 dB formed by the feedhorn  100  can be adjusted plus and minus 15 degree by the beamwidth adjustment device. Note that, the present invention can adjust the beamwidth to conform the characteristic of the satellite antenna without modification of the opening size of the feedhorn or a mold size. 
         [0025]    In conclusion, in the prior art, the beamwidth can not be adjusted to match the dish perfectly, causing poor reception quality. In comparison, in the present invention a required beamwidth can be obtained for different dish designs (e.g. different F/D values) without modification the size of the feedhorn, so as to increase reception quality. Furthermore, with decrease opening size of the feedhorn, the beamwidth adjustment device of the present invention can maintain the same beamwidth to match the dish, so as to reduce cost efficiently. 
         [0026]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.