Abstract:
An inverted-F antenna includes a radiation element, a ground element, a loop conductive pin, a signal feed-in portion, and a signal line. The antenna is designed as the signal feed-in portion and the ground portion sharing a single pin, thus solving the problem of the conventional inverted-F antenna having complicated components and increased cost due to using two independent components in parallel including a conductive pin and a signal feed-in portion for grounding and receiving feed-in signals.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to an inverted-F antenna, in particular, to an inverted-F antenna with a signal feed-in point and a ground point sharing a single conductive pin. 
         [0003]    2. Related Art 
         [0004]    Wireless communication technology of using electromagnetic wave to transmit signals can achieve the effect of communicating remote devices without connecting materials, thus having a mobile advantage, so that the products utilizing the wireless communication technology are gradually increased, such as mobile phones, and notebook computers. Since the products utilize electromagnetic wave to transmit signals, antennae used for transmitting and receiving electromagnetic wave signals become necessary. The current antennae mainly include antennae exposed out of the device and build-in antennae. The antennae exposed out of the device may affect the volume and appearance of the products, and also be liable to be bent or broken due to the impact of the external force. Therefore, the build-in antennae become a trend. 
         [0005]    Referring to  FIG. 1 , a schematic view of a conventional build-in antenna is shown. The antenna is an inverted-F antenna having a strip-shaped radiation element  1 , a plate ground element  2  opposite to and spaced with the radiating antenna, and a conductive pin  3  and a signal feed-in portion  4  located between the strip-shaped radiation element  1  and the plate ground element  2 . The conductive pin  3  connects one end of the radiation element  1  to the ground element  2 , so as to serve as a ground pin. The signal feed-in portion  4  is disposed at a central position between the two ends of the radiation element  1 , so as to receive the signals fed in from the signal line  5 . When the signal feed-in portion  4  receives a signal current fed in from the signal line  5 , the signal current is distributed to the left and right directions. Referring to  FIG. 1 , when the signal current flows directly from the signal feed-in portion  4  to the conductive pin  3 , due to the opposite flowing directions of the signal current at the signal feed-in portion  4  and that at the conductive pin  3 , the signal current at the left path may be counteracted to avoid resonating to generate the electromagnetic wave. The length L of the right path equals to the length of the right part of the signal feed-in portion  4  in the radiation element  1 , that is approximately a quarter of the wavelength. Therefore, the electromagnetic wave having a specific frequency (f=c/λ) is emitted, the electromagnetic wave signal at this frequency is sensed, and the sensed signal current is transmitted to the signal line  5  through the signal feed-in portion  4  and then lead to the outside. 
         [0006]    Since inverted-F antenna may only transmit and receive the electromagnetic wave at a single frequency, two independent conductive pin  3  and signal feed-in portion  4  are used for grounding and receiving the feed-in signal, which causes complicated components. Moreover, the strip-shaped pin disposed between the radiation element  1  and the ground element  2  fix the disposing position, and thus the input and output impedance is difficult to be adjusted as demanded. 
         [0007]    Accordingly, the Patent Publication No. 00563274 has provided an antenna with a signal feed-in portion and a ground point sharing a single pin, so as to realize the simplification and solve the problems in the conventional art. Referring to  FIG. 2 , a conventional N-shaped conductive pin antenna  200  includes a radiation element  11 , a ground element  12 , a conductive pin  13 , a signal feed-in portion  14 , and a signal line  15 . The conductive pin  13  is N-shaped, and has two ends connected to the radiation element  11  and the ground element  12  respectively. The signal feed-in portion  14  is located on the conductive pin  13  for connecting the signal line  15  and transmitting the signal current. 
         [0008]    The conventional N-shaped conductive pin structure may indeed realize the simplification and solve the problems in the conventional art. However, in order to achieve multiple functions, the current 3C device is not only provided with a 3G wireless communication antenna, but also a Wi-Fi antenna, thereby achieving the wireless network connection. Nevertheless, when the 3C products tend to be small and delicate, the 3G antenna may be closer to the devices affecting each other such as the wireless network antenna. As a direct result, the 3G radiation efficiency is reduced, and the quality of the signal is affected. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the above problem, the present invention provides an inverted-F antenna. A design of loop conductive pin is used to replace the conventional design of two conductive pins. 
         [0010]    The inverted-F antenna provided in the present invention includes a radiation element, a ground element, a loop conductive pin, a signal feed-in portion, and a signal line. The radiation element is used for resonating to transmit and receive two different frequencies f 1  and f 2 . The ground element is a plate ground element opposite to and spaced with the radiating antenna. The loop conductive pin is located between the radiation element and the ground element, and assumes a loop structure in the center with two ends connected to the radiation element and the ground element respectively. The signal feed-in portion is connected to the loop structure, for connecting the signal line and transmitting a signal current. 
         [0011]    In an inverted-F antenna disclosed in the present invention, the loop structure is used to improve the antenna radiation efficiency and increase the bandwidth of radiation. Being capable of replacing the conventional design of two conductive pins, the inverted-F antenna of the present invention may also have improved radiation efficiency at a low frequency compared with the design of N-shaped conductive pin when being close to the devices such as wireless network antenna. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the present invention, and wherein: 
           [0013]      FIG. 1  is a schematic view of a conventional build-in antenna; 
           [0014]      FIG. 2  is a schematic view of a conventional N-shaped conductive pin antenna; 
           [0015]      FIG. 3  is a schematic view of a first embodiment of the present invention; 
           [0016]      FIG. 4  is a schematic view of a second embodiment of the present invention; 
           [0017]      FIG. 5A  shows a low-frequency test result of the conventional N-shaped conductive pin antenna singly disposed below a panel; 
           [0018]      FIG. 5B  shows a high-frequency test result of the conventional N-shaped conductive pin antenna singly disposed below a panel; 
           [0019]      FIG. 6A  shows a low-frequency test result of the loop conductive pin antenna in the first embodiment of the present invention singly disposed below a panel; 
           [0020]      FIG. 6B  shows a high-frequency test result of the loop conductive pin antenna in the first embodiment of the present invention singly disposed below a panel; 
           [0021]      FIG. 7  shows actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIGS. 5A ,  5 B,  6 A, and  6 B; 
           [0022]      FIG. 8  is a curve diagram drawn according to the data in  FIG. 7 ; 
           [0023]      FIG. 9A  shows a low-frequency test result of the conventional N-shaped conductive pin antenna close to a WiFi antenna (at a distance of 16 mm); 
           [0024]      FIG. 9B  shows a high-frequency test result of the conventional N-shaped conductive pin antenna close to the WiFi antenna (at a distance of 16 mm); 
           [0025]      FIG. 10A  shows a low-frequency test result of the loop conductive pin antenna in the first embodiment of the present invention close to the WiFi antenna (at a distance of 16 mm); 
           [0026]      FIG. 10B  shows a high-frequency test result of the loop conductive pin antenna in the first embodiment of the present invention close to the WiFi antenna (at a distance of 16 mm); 
           [0027]      FIG. 11  shows actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIGS. 9A ,  9 B,  10 A, and  10 B; 
           [0028]      FIG. 12  is a curve diagram drawn according to the data in  FIG. 11 ; 
           [0029]      FIG. 13A  is a curve diagram drawn according to the actual radiation efficiencies of the conventional N-shaped conductive pin antenna in  FIGS. 7 and 11 ; and 
           [0030]      FIG. 13B  is a curve diagram drawn according to the actual radiation efficiencies of the loop conductive pin antenna in the present invention in  FIGS. 7 and 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Features and implementations of the present invention are described herein below with accompanying drawings. 
         [0032]    Referring to  FIG. 3 , a schematic view according to a first embodiment of the present invention is shown. The antenna  300  includes a radiation element  21 , a ground element  22 , a loop conductive pin  23 , a signal feed-in portion  24 , and a signal line  25 . 
         [0033]    The radiation element  21  is used for resonating to transmit and receive a first frequency f 1  and a second frequency f 2 , and a length of the radiation element  21  depends on the wavelengths of the two different frequencies. The radiation element  21  is divided into a first section  26  resonating at the first frequency f 1  and a second section  27  resonating at the second frequency f 2 . A length L 1  of the first section  26  approximately equals to a quarter of the wavelength λ 1  of the first frequency f 1 , and a length L 2  of the second section  27  approximately equals to a quarter of wavelength λ 2  of the second frequency f 2 . Therefore, the length L (L=L 1 +L 2 ) of the radiation element  21  is a sum of a quarter of the wavelengths λ 1  and λ 2  of the two resonating frequencies f 1  and f 2 . 
         [0034]    The ground element  22  is a plate ground element opposite to and spaced with the radiating antenna. The size of the ground element  22  is relevant to the bandwidth of the antenna  300 . In other words, the impedance and the bandwidth of the antenna  300  may change with the effective area of the ground element  22 . 
         [0035]    The loop conductive pin  23  is located between the radiation element  21  and the ground element  22 , and has a first support arm  28 , a second support arm  29 , and a loop structure  30 . The first support arm  28  has a first end  28   a  connected to a joint  31  of two sections  26  and  27  at a first side  21   a  of the radiation element  21 , a second end  28   b  extending to the ground element  22  along the radiation element  21  without contacting the ground element  22 . The second support arm  29  has a first end  29   a  connected to the ground element  22 , and a second end  29   b  extending to a second side  21   b  of the radiation element  21  along the ground element  22  without contacting the radiation element  21 . The loop structure  30  vertically bridges the first support arm  28  and the second support arm  29 , and has a first end  30   a  connected to the second end  28   b  of the first support arm  28  not connected to the radiation element  21 , and a second end  30   b  connected to the second end  29   b  of the second support arm  29  not connected to the ground element  22 . The loop structure may be U-shaped, horseshoe-shaped, or of other loop shapes. In this embodiment, the first support arm  28  and the second support arm  29  are respectively perpendicular to the radiation element  21  and the ground element  22 , and are parallel to each other. The two ends  30   a  and  30   b  of the loop structure  30  are vertically connected to the first support arm  28  and the second support arm  29  respectively. 
         [0036]    The signal feed-in portion  24  is connected to the first end  30   a  of the loop structure  30  of the loop conductive pin  23 , so as to connect the signal line  25 . A signal current is transmitted or received to the loop conductive pin  23  and the signal line  25  through the signal feed-in portion  24 . 
         [0037]    When a signal is emitted, the signal current is transmitted from the signal line  25  to the loop conductive pin  23  through the signal feed-in portion  24 , and distributed to the first support arm  28  and the loop structure  30 . The signal current flowing to the first support arm  28  is directly fed into the radiation element  21  through the joint  31 . Then, the signal current is resonated to radiate an electromagnetic wave signal through the radiation element  21 . Likewise, when the radiation element  21  senses the electromagnetic wave to generate a signal current, the signal current is transmitted to the first support arm  28  through the joint  31 . At this point, most of the signal current is directly fed into the signal feed-in portion  24  through the first support arm  28 , and transmitted to the outside through the signal line  25 . 
         [0038]    The loop conductive pin  23  is used to prevent resonating to transmit the electromagnetic wave due to the different flowing directions of the current signal at two ends of the loop structure  30  when the signal current flows at the loop structure  30 , so as to reduce the interference on the radiation element  21 . Moreover, grooves at the center of the loop structure have a current coupling effect to increase the radiation bandwidth. Referring to  FIG. 4 , a schematic view according to a second embodiment of the present invention is shown. The difference between the structure of the device in the second embodiment and that in the first embodiment lies in that a structure  44  for fixing low-frequency radiation end is fabricated at a low-frequency radiation end  43  on a ground element  42  close to a radiation element  41 . By means of a separating column made of non-conductive material, the low-frequency radiation end  43  and the structure  44  for fixing low-frequency radiation end are fixed. Therefore, when a antenna  400  is operated at a low frequency, the distance between the low-frequency radiation end  43  and a ground element  42  is fixed, so as to prevent the radiation element  41  close to the low-frequency radiation end  43  from contacting the ground element  42 . 
         [0039]      FIGS. 5A and 5B  show test results of the conventional N-shaped conductive pin antenna singly disposed below a panel, which are standing wave rates (SWR) respectively measured at a low frequency (824 MHz-960 MHz) and at a high frequency (1710 MHz-2170 MHz). 
         [0040]      FIGS. 6A and 6B  show test results of the loop ground antenna in the first embodiment of the present invention disposed below a panel, which are SWRs respectively measured at a low frequency (824 MHz-960 MHz) and at a high frequency (1710 MHz-2170 MHz). 
         [0041]      FIG. 7  shows actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIGS. 5A ,  5 B,  6 A, and  6 B ( 
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         [0000]    antenna radiation efficiency)(e test : measurement efficiency) (e VSWR =1−[Γ] 2 :impedance mismatching efficiency, where 
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         [0000]    cable transmission efficiency). 
         [0042]      FIG. 8  is a curve diagram drawn according to the data of actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIG. 7 . It can be known from  FIG. 8  that, the loop conductive pin antenna in the present invention is more advantageous than the conventional N-shaped conductive pin antenna in better antenna radiation efficiency at the low frequency. 
         [0043]      FIGS. 9A and 9B  show test results of the conventional dual-frequency antenna close to a wireless network antenna (at a distance of 16 mm), which are SWRs respectively measured at a low frequency (824 MHz-960 MHz) and at a high frequency (1710 MHz-2170 MHz). 
         [0044]      FIGS. 10A and 10B  show test results of the loop conductive pin antenna in the first embodiment of the present invention close to the wireless network antenna (at a distance of 16 mm), which are SWRs respectively measured at a low frequency (824 MHz-960 MHz) and at a high frequency (1710 MHz-2170 MHz). 
         [0045]      FIG. 11  shows actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIGS. 9 and 10 . 
         [0046]      FIG. 12  is a curve diagram drawn according to the data of actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIG. 11 . It can be known from  FIG. 12  that, the loop conductive pin antenna in the present invention is more advantageous than the conventional N-shaped conductive pin antenna in obviously improved antenna radiation efficiency at the low-frequency portion close to the wireless network antenna. 
         [0047]      FIGS. 13A and 13B  are curve diagrams drawn according to the actual radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention in  FIGS. 7 and 11 .  FIG. 13  shows, respectively at the upper and lower parts, the antenna radiation efficiencies of the conventional N-shaped conductive pin antenna and the loop conductive pin antenna in the first embodiment of the present invention singly disposed below the panel and close to the wireless network antenna. It can be known from  FIGS. 13A and 13B  that, the antenna radiation efficiency of the conventional N-shaped conductive pin antenna close to the wireless network antenna is obviously lower than the antenna radiation efficiency of the singly disposed antenna. Moreover, the loop conductive pin design of the present invention makes no obvious difference when being close to the wireless network antenna.