Patent Publication Number: US-7589677-B2

Title: Wireless electronic product with step-shaped wideband antenna

Description:
FIELD OF THE INVENTION 
   The present invention relates to a wireless electronic product, and more particularly to a wireless electronic product with a step-shaped wideband antenna. 
   BACKGROUND OF THE INVENTION 
   As wireless electronic products are manufactured with a short, small, light and thin design, the space within a casing of the wireless electronic product is decreased greatly, and the area reserved on a printed circuit board of the wireless electronic product for installing an antenna becomes very small, and thus research and development engineers and manufacturers attempt to print antennas in different shapes (such as a circular or polygonal shape) on the printed circuit board, and try to find an antenna with the most appropriate shape and size and having a lower cost and an easy-to-adjust feature. However, no antenna with the aforementioned conditions has been designed on a printed circuit board yet, mainly because the production conditions such as the mass production and the high production yield rate have to be taken into consideration for the actual production of the antennas. 
   Based on the foregoing reasons, designers and manufacturers designed and developed a microstrip bell-shaped antenna as shown in  FIG. 1 , wherein electronic components and circuits of a wireless electronic product are installed on a printed circuit board  1  of the wireless electronic product, and the printed circuit board  1  has a bell-shaped antenna  10  printed at a position adjacent to an end of the printed circuit board  1 , and both sides of the bell-shaped antenna  10  are expanded towards both sides of the printed circuit board  1 , and a microstrip feedline  12  is extended to a position adjacent to an another end of the printed circuit board  1 , and an end of the microstrip feedline  12  is connected to a signal line (not shown in the figure) of the printed circuit board  1 , such that the outwardly extended shape of the bell-shaped antenna  10  allows the current produced by the microstrip feedline  12  due to an electro-inductive effect to flow along a tapered path on both sides of the bell-shaped antenna  10 , and the current can be distributed uniformly on the bell-shaped antenna  10  to effectively reduce the electro-inductive effect of the microstrip feedline  12  and provide the required bandwidth. Since the bell-shaped antenna  10  can be printed directly onto the printed circuit board  1 , the bell-shaped antenna  10  can meet the requirements for mass productions and a high yield of the production. 
   For example, the maximum width of the bell-shaped antenna as shown in  FIG. 1  is equal to 17.87 mm; the maximum length is equal to 15.558 mm; and the bandwidth falls within a range of 1.912059 GHz˜4.967982 GHz (as shown in  FIG. 2 ) to cover the frequency required by a ultra wideband (UWB) wireless electronic product. However, some wireless electronic products designed according to customer requirements have narrow space in their casing, such that after the positions of electronic components and circuits on the printed circuit board are adjusted, the area reserved on the printed circuit board for printing the bell-shaped antenna is insufficient. Therefore, finding a way of manufacturing an antenna with a bandwidth and electric properties similar to those of the bell-shaped antenna demands immediate attentions and feasible solutions. 
   SUMMARY OF THE INVENTION 
   In view of the problems and shortcomings of the prior art, the inventor of the present invention based on years of experience in the related industry to conduct extensive researches and experiments, and finally developed a wireless electronic product with a step-shaped wideband antenna in accordance with the invention to effectively overcome the aforementioned shortcomings of the prior art, such that the antenna with a smaller size and a bandwidth and electric properties similar to those of a traditional bell-shaped antenna can be printed onto a printed circuit board to solve the problem of unable to print the traditional bell-shaped antenna onto an even smaller area reserved on the printed circuit board. 
   It is a primary objective of the present invention to provide a wireless electronic product with a step-shaped wideband antenna, wherein a printed circuit board is installed on a wireless electronic product, and the printed circuit board has a connector installed at an end of the top surface of the printed circuit. The step-shaped wideband antenna comprises a wideband antenna and a microstrip feedline, wherein the wideband antenna is disposed on the top surface of the printed circuit board, and the shape of the wideband antenna is extended from an another end of the printed circuit board towards the central position of the printed circuit board to form a tapered step-shaped antenna symmetrically on both sides, and the microstrip feedline is extended from an end of the wideband antenna away from the another end of the printed circuit board and coupled with the signal line, such that the current produced by microstrip feedline due to an electro-inductive effect flows along a zigzag step-shaped path on both sides of the wideband antenna, and the current can be distributed uniformly on the wideband antenna to effectively reduce the electro-inductive effect of the microstrip feedline, so as to provide a bandwidth condition similar to the traditional bell-shaped antenna and make the distance between both ends of the wideband antenna smaller than the distance between both ends of the traditional bell-shaped antenna to effectively miniaturize the antenna. 
   To make it easier for our examiner to understand the shape, structure, design principle and performance of the present invention, we use a preferred embodiment together with the attached drawings for the detailed description of the invention as follows: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a bell-shaped antenna of a wireless electronic product in accordance with a prior art; 
       FIG. 2  is a schematic view of an actual measured frequency range of a bell-shaped antenna as depicted in  FIG. 1 ; 
       FIG. 3  is a schematic view of a wireless electronic product with a step-shaped wideband antenna in accordance with the present invention; 
       FIG. 4  is a schematic view of an actual measured frequency range of a step-shaped wideband antenna as depicted in  FIG. 3 ; 
       FIG. 5  is a schematic view of an actual measured frequency range of the step portions substantially in a bending angle in accordance with the present invention; and 
       FIG. 6  is a schematic view of an actual measured frequency range of the step portions substantially in an inclined angle in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 3  for a wireless electronic product with a step-shaped wideband antenna, a printed circuit board  20  is installed in a wireless electronic product  2 , and the printed circuit board  20  includes a connector  22  disposed at an end of the top surface of the printed circuit board  20 , a signal transceiving loop  24  disposed at the top surface of the printed circuit board  20  and adjacent to the central position of the printed circuit board  20 , a conducting wire extended from the signal transceiving loop  24  in a direction to the another end of the printed circuit board  20  to serve as a signal line  28 , and a ground plane  26  (as shown in a frame of dotted line in  FIG. 3 ) disposed at the bottom surface of the printed circuit board  20  and at a position corresponding to the signal transceiving loop  24  and the signal line  28 , wherein the top surface of the printed circuit board  20  has a wideband antenna  3 , and the shape of the wideband antenna  3  is formed by extending from the another end of the printed circuit board  20  towards the central position of the printed circuit board  20  to form a tapered step-shaped antenna symmetrically on both sides, and a microstrip feedline  30  is extended from an end of the wideband antenna  3  away from the another end of the printed circuit board  20  and coupled with the signal line  28 . If the microstrip feedline  30  produces a current due to the electro-inductive effect, the current will flow along the zigzag step-shaped path of both sides of the wideband antenna  3 , so that the current can be distributed uniformly on the wideband antenna  3  to effectively reduce the electro-inductive effect of the microstrip feedline  30  and provide a bandwidth condition similar to the traditional bell-shaped antenna, and the distance between both ends of the wideband antenna  3  is smaller than the distance between both ends of the traditional bell-shaped antenna in order to effectively miniaturize the antenna. 
   In this invention, no metal exists around the periphery of the wideband antenna, so that the valid bandwidth of the wideband antenna  3  can be adjusted to a frequency band range required by various different products without installing an additional matching circuit, and thus the invention can effectively improve the tolerance of mass productions and provide a casing design that fits different products. 
   Referring to  FIG. 3  for a preferred embodiment of the present invention, the width of the printed circuit board  20  is equal to 22.6 mm, and the length from an end of the signal line  28  to the another end of the printed circuit board  20  is equal to 13.2 mm, and the length of the microstrip feedline  30  extended from an end of the ground plane  26  adjacent to the another end of the printed circuit board  20  to the end of the wideband antenna  3  away from the another end of the printed circuit board  20  is equal to 2.0 mm. Further, both sides of the wideband antenna  3  form symmetric first to fifth step portions  31 ,  32 ,  33 ,  34 ,  35  from the corresponding position adjacent to the ground plane  26  to both sides of the another end of the printed circuit board  20 . 
   It is noteworthy to point out that both ends of the first to fifth step portions  31 ,  32 ,  33 ,  34 ,  35  of the preferred embodiment are substantially right-angled. However, the implementation of the present invention is not limited to such arrangement only. Regardless of the shape (such as a bending angle or an inclined angle) of the step portions  31 ,  32 ,  33 ,  34 ,  35 , the step portions referred by this invention are in step shapes each with an extendable length at both sides of the wideband antenna  3 . 
   Further, the width of first step portion  31  extended from the microstrip feedline  30  to both sides of the printed circuit board  20  is equal to 4.65 mm, and the length extended towards the another end of the printed circuit board  20  is equal to 3.0 mm, and the width of the second step portion  32  extended from a position adjacent to the first step portion  31  to both sides of the printed circuit board  20  is equal to 3.0 mm, and the length extended towards the another end of the printed circuit board  20  is equal to 3.0 mm, and the width of the third step portion  33  and the fourth step portion  34  extended from a position adjacent to a previous step portion to both sides of the printed circuit board  20  is equal to 1.0 mm, and the length extended towards the another end of the printed circuit board  20  is equal to 2.0 mm, and the width of the fifth step portion  35  extended from a position adjacent to the fourth step portion  34  to both sides of the printed circuit board is equal to 1.0 mm, and the length extended to the another end of the printed circuit board  20  is equal to 1.4 mm. 
   From the description above, the total width of the step portions  31 ,  32 ,  33 ,  34 ,  35  and the microstrip feedline  30  is equal to 21.5 mm, and the total length of the step portions  31 ,  32 ,  33 ,  34 ,  35  and the microstrip feedline  30  is equal to 12.4 mm. In  FIG. 4 , the signal gain value of the step-shaped wideband antenna approaching a bandwidth range covered by −10 dB falls within a range of 3.1 GHz˜4.8 GHz, which complies with the frequency range of a ultra wide band (UWB) wireless electronic product defined by the Federal Communication Commission (FCC). If the external shape of the step portions  31 ,  32 ,  33 ,  34 , is in a bending angle as shown in  FIG. 5 , or the external shape of the step portions  31 ,  32 ,  33 ,  34 ,  35  is in an inclined angle as shown in  FIG. 6 , the signal gain value of the step-shaped wideband antenna approaching a bandwidth range covered by −10 dB falls within a range of 3.1 GHz˜4.8 GHz, which also complies with the frequency range of a ultra wide band (UWB) wireless electronic product defined by the Federal Communication Commission (FCC). 
   In the comparison between the dimensions and the bandwidth range of the aforementioned step-shaped wideband antenna and the dimensions and the bandwidth range of the traditional bell-shaped antenna, the bandwidth ranges of both antennas comply with the frequency range of a ultra wide band (UWB) wireless electronic product defined by the Federal Communication Commission (FCC), but the length and width of the step-shaped wideband antenna of the invention are obviously smaller than the length and width of the traditional bell-shaped antenna, and thus the invention can transmit and receive with a bandwidth range similar to that of a bell-shaped antenna, and also can miniaturize the antenna effectively. 
   While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.