Patent Publication Number: US-7719474-B2

Title: Antenna Structure with fixing unit

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an antenna structure, and more particularly, to an antenna structure comprising a fixing unit. The fixing unit is in contact with a signal transmission unit and a hole of a substrate to fix the signal transmission unit on the substrate. 
   2. Description of the Prior Art 
   Please refer to  FIG. 1 .  FIG. 1  is a diagram illustrating a typical patch antenna  100 . As shown in  FIG. 1 , the patch antenna  100  includes a substrate  110  and a metal stick  120 . The substrate  110  is made of a dielectric material, such as ceramic. The top surface and the bottom surface of the substrate  110  are both coated with metal to act as a radiation electrode  112  and a ground electrode  114  respectively. In addition, the substrate  110  also has a through hole  116 . The metal stick  120  is disposed in the through hole  116  to connect the radiation electrode  112  with a signal processing device (not shown in  FIG. 1 ). 
   However, a slight difference in the relative position of the metal stick on the substrate may result in variations in antenna characteristics, such as resistance, frequency, and the degree of circular polarization. Therefore, in the mass production of patch antenna, the manufacturing variations of the inner diameters of the through holes and the outer diameters of the metal sticks, as well as the relative shifting of the metal position during assembly would result in a wide distribution in their characteristics. 
   SUMMARY OF THE INVENTION 
   It is therefore one of the objectives of the present invention to provide an antenna structure with a fixing unit to reduce the characteristic variations of the patch antenna caused by the distribution in position of the metal sticks on the substrate, resulting from variation of the diameters of metal sticks and through holes, as well as the relative position of each metal stick placed inside the through holes. 
   According to an exemplary embodiment of the claimed invention, an antenna structure is disclosed. The antenna structure comprises: a substrate, which is made of a dielectric material and has at least a through hole; a signal transmission unit, which has a transmission path and goes through the through hole; and at least a fixing unit, which is made of a flexible or deformable material. The fixing unit is in contact with the surface of the signal transmission unit and the inner surface of the through hole to fix the signal transmission unit on the substrate. 
   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 
       FIG. 1  is a diagram illustrating a typical patch antenna. 
       FIG. 2  is a schematic diagram illustrating an antenna structure according to a first embodiment of the present invention. 
       FIG. 3  is a schematic diagram illustrating an antenna structure according to a second embodiment of the present invention. 
       FIG. 4  is a schematic diagram illustrating an antenna structure according to a third embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. Also, the term “electrically connect” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
   Different features of the present invention are detailed as below with reference to the figures, and for convenience of explanation, the same elements in separate figures are indicated by the same reference numerals. 
   Please refer to  FIG. 2 .  FIG. 2  is a schematic diagram illustrating an antenna structure  200  according to a first embodiment of the present invention. To make the concept of the present invention easily appreciable, the antenna structure  200  is assumed to be a patch antenna in this embodiment; this is, however, for illustrative purposes and not a limitation of the prevent invention. As shown in  FIG. 2 , the antenna structure  200  comprises a substrate  210 , a signal transmission unit  220  and a fixing unit  230 . The substrate  210  is made of a dielectric material and has a through hole  216 . The signal transmission unit  220  has a transmission path  222  and goes through the through hole  216 . The fixing unit  230  is in contact with the signal transmission unit  220  and the through hole  216  to fix the signal transmission unit  220  on the substrate  210 , and fixes the position of the signal transmission unit  220  in the through hole  216 . In this embodiment, the substrate  210  of the antenna structure  200  is made of a ceramic material (i.e., the antenna structure  200  is a ceramic patch antenna); this is, however, for illustrative purposes and not a limitation of the prevent invention. For instance, the substrate can be made of a glass material, a polymer material, a magnetic material or a compound material comprising at least one of the above-mentioned dielectric materials. 
   As shown in  FIG. 2 , the through hole  216  is a circular through hole, the signal transmission unit  220  is a metal stick, and the fixing unit  230  is a screw thread on a surface of the signal transmission unit  220 . The outer diameter of the screw thread ( 230 ) is approximately equal to the inner diameter of the circular through hole ( 216 ). The metal stick ( 220 ) and the screw thread ( 230 ) are both made of copper and are formed in whole (as one piece). Since copper has good malleability, the screw thread ( 230 ) can help to fix the position of the metal stick ( 220 ) in the circular through hole ( 216 ) for ensuring every produced patch antenna has identical characteristics, such as resistance, frequency, circular polarization degree and so on. 
   In the above embodiment, the fixing unit  230  is a spiral fixing unit on the surface of the signal transmission unit  220  (i.e., the screw thread); however, this is not a limitation of the present invention. In practice, the fixing unit can be a unit of any shape, protruding from the signal transmission unit (e.g., a circular protruded unit or a bar protruded unit). In addition, the antenna structure is not limited to only one fixing unit; in other words, the antenna structure can comprise a plurality of fixing units. Take  FIG. 3  for example.  FIG. 3  is a schematic diagram illustrating an antenna structure  300  according to a second embodiment of the present invention. As shown in  FIG. 3 , the antenna structure  300  comprises a plurality of fixing units  330 , which are a plurality of bar protruding units on a surface of a signal transmission unit  320 . Please note that the plurality of fixing units  330  are symmetrically disposed on the surface of the signal transmission unit  320  in this embodiment; however, this is not a limitation of the present invention. In another embodiment of the present invention, the plurality of protruding units on the signal transmission unit can be not symmetrical with respect to each other. As long as the positions of the plurality of protruding units on the surface of the signal transmission unit can match the shape of the through hole, to allow excellent position accuracy on the substrate, then good consistency in the antenna characteristics of the signal transmission unit can be achieved. 
   In the first embodiment of the present invention, the signal transmission unit  220  and the fixing unit  230  in the antenna structure  200  are formed in whole; this is, however, for illustrative purposes and not a limitation of the prevent invention. In other embodiments of the present invention, the signal transmission unit and the fixing unit can be two independent units respectively, and their materials can also be different from each other. In addition, the fixing unit  230  is made of copper; this is, however, for illustrative purposes and not a limitation of the prevent invention. In practice, the fixing unit can be made of a flexible or deformable material, such as metal, rubber, plastic or paper. Take  FIG. 4  for example.  FIG. 4  is a schematic diagram illustrating an antenna structure  400  according to a third embodiment of the present invention. The fixing unit  430  is a plastic washer that surrounds and contacts with the signal transmission unit  420 , as shown in  FIG. 4 . The plastic washer ( 430 ) is able to transform properly to help fix the position of signal transmission unit  420  in the through hole  416 . 
   In the first embodiment of the present invention, the fixing unit  230  is disposed on the surface of the signal transmission unit  220 ; this is, however, for illustrative purposes and not a limitation of the prevent invention. In other embodiments, the fixing unit(s) can be disposed only on the inner surface of the through hole or also on surfaces of the signal transmission unit. In addition, the through hole can comprise a groove corresponding to the fixing unit (e.g., the protruding unit) on its inner surface. The fixing unit (e.g., the protruding unit) on the signal transmission unit is mortised in the groove to help fix the signal transmission unit in the through hole. However, this is also not a limitation of the present invention. For example, the groove can be disposed only on the surface of the signal transmission unit or on both surfaces of the signal transmission unit and the through hole. 
   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.