Abstract:
A multi-loop antenna includes two or more than two antennas units with different lengths, receiving signals with different frequencies respectively; and several slices of conductors, with different lengths, making the connections between above-mentioned antennas units. As different connections between the antennas are made, different connection modules are formed. Thus the antenna gets to receive signals of multiband frequency and/or broadband frequency.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a multi-loop antenna, especially to the antenna with two or more slices of conductors that connect with two or more antenna units that receiving signals of different frequencies, and thus achieving good capacity in receiving multiband frequency and/or broadband frequency. 
     2. Description of the Prior Art 
     The structure of an internal antenna in a mobile phone in prior art shown in FIGS. 1A and 1B. On top of the FIG. 1A is the antenna substrate  200 , and the grounding substrate  100  is beneath the antenna substrate  200 . The aforementioned substrates are connected by a component  300 . In general, as shown in FIG. 1B, the distance between the antenna substrate  200  and the grounding substrate  100  is extended in order to increase the bandwidth of the frequency. The longer the distance “d” is, the lower the equivalent value Q is, meanwhile, the frequency bandwidth of the signals is increased. 
     However, the thickness of a conventional mobile phone is limited, so the distance between the antenna substrate and the grounding substrate is restricted. Therefore, an idea of multi-loop structure of antenna circuit is invented to produce diverse combinations in neighboring antenna units in order to receive multi frequency. By the means of the multi-loop design, the antenna may receive frequency with multiband resonance. 
     A present structure of a conventional antenna is shown in FIGS. 2A and 2B. It is clearly shown that the present structure, which is on the antenna substrate  200 , comprising two antenna units  4   a  and  4   b . Wherein, a longband antenna  4   a  is located in the outside of the antenna substrate  200  and connects to the grounding end, and a shortband antenna  4   b  is located in the inside of the antenna substrate  200 , connecting the feeding end. There is a conductor  4   c  mounted between the longband  4   a  and the shortband  4   a . A current  900  may enter the feeding end, passing through shortband  4   a , connecting conductor  4   c  and longband  4   b , and then to the grounding end. Thus a complete circuit is formed. 
     In this type of sliced antenna in mobile phones, the position and the amount of the conductors  4   c  is fixed. Therefore, it can just form only one circuit and receive dual-band frequency. 
     Moreover, as the circuit of this type of antenna is fixed, the received dual frequency is also fixed. As a result, the frequency ratio cannot be tuned. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a multi-loop antenna, which increases the frequency bandwidth by means of the antenna units receiving different frequencies and being connected together. It is another object of the present invention to enable the adjustment of the proportion of the wideband/multiband frequencies by means of the antenna units connected by two or more conductors, wherein the antenna units, which receive different ranges of signals. According to the multi-loop antenna of the present invention, by means of two or more connecting conductors, different modules of connections may be accomplished, and the ability and flexibility of receiving wideband signals may also be achieved, and thus the frequency ratio and the flexibility of signal receiving are increased. It is a further object of the present invention. 
     The present invention will be better understood and its numerous objects and advantages will become apparent to those skilled in the art by referencing to the following drawings in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are perspective views of the embodiment showing a conventional hidden antenna in a mobile phone. 
     FIG. 2A is a perspective view of the embodiment showing the circuit structure of a conventional sliced antenna in a mobile phone. 
     FIG. 2B is a perspective view of the embodiment showing the current circuit of a conventional sliced antenna in a mobile phone. 
     FIGS. 3A and 3B are perspective views showing the current circuit of a multi-loop antenna of the present invention. 
     FIG. 4 is a perspective view of the preferred embodiment showing the multi-loop antenna of the present invention. 
     FIG. 5A is a plane view showing the construction of a single-loop antenna. 
     FIG. 5B is a diagram showing the VSWR values of the antenna in FIG. 5A corresponding to different frequencies. 
     FIG. 6A is a plane view showing the construction of a two-loops antenna. 
     FIG. 6B is a diagram showing the VSWR values of the antenna in FIG. 6A corresponding to different frequencies. 
     FIG. 7A is a plane view showing the construction of a three-loops antenna. 
     FIG. 7B is a diagram showing the VSWR values of the antenna in FIG. 7A corresponding to different frequencies. 
     FIG. 8A is a plane view showing the construction of a four-loops antenna. 
     FIG. 8B is a diagram showing the VSWR values of the antenna in FIG. 8A corresponding to different frequencies. 
     FIGS. 9A,  9 B and  9 C are the top view, the plane view, and the side view of an antenna of the FIG. 8A having practical dimensions. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1A to  2 B are the schematic drawings showing the embodiments of circuit of a conventional sliced antenna. The functions and defects of the conventional embodiments have been described above. 
     FIGS. 3A and 3B are schematic drawings showing the circuit according to the multi-loop antenna of the present invention. The multi-loop antenna of the present invention consists of two or more of antenna units a 1  and a 2 , wherein the antenna unit a 1  is connected to the grounding end; the other antenna unit a 2  is connected to the feeding end. The antenna unit a 1  may receive a specific frequency of signal, and the antenna unit a 2  receives another specific frequency. There are also two or more conductors c 1  and c 2  which mount between the antenna units a 1  and a 2 . According to the structure mentioned above, the circuit a 1 -c 1 -a 2  receives a specific range of frequency, and the circuit a 1 -c 2 -a 2 , of which the equivalent length is different to the a 1 -c 1 -c 2  circuit, receives another specific range of frequency, as shown in FIGS. 3B and 3C. Because the frequencies received by the antenna units a 1  and a 2  are different, as they are connected together by the conductors c 1  and c 2 , it may form two or more modules and may receive multiband and/or wideband frequency signals, and the bandwidth of the antenna is increased. 
     Referring now to FIG. 4 it will be observed from the drawing that the preferred embodiment of the multi-loop antenna of the present invention. The antenna unit (longband) a 1  is located at the center of the antenna substrate  20 , which is surrounded by the antenna unit (shortband) a 2 ; these two antenna units a 1 , a 2  are apart from each other for a specific distance and are linked with two or more conductors c 1  and c 2 . 
     From FIG. 4, there is a grounding end d 1  protruding from the antenna unit (longband) a 1 , and a feeding end d 2  protruding from the antenna unit (shortband) a 2 . Wherein, the materials of the grounding end d 1  and the feeding end d 2  are made of the same material as the antenna unit (longband) a 1  and the antenna unit (shortband) a 2 . The feeding end and the grounding end are also formed in one piece with the antenna and are connected with the grounding substrate  10 . According to the structure mentioned above, a multi-loop antenna of the present invention is formed. 
     EXAMPLE 1 
     Please refer to FIG. 5A, it shows an example of construction of single-loop antenna. 
     From the diagram of FIG. 5B, it is clearly shown that when the VSWR is not greater than 2, the central frequency of low frequency is about 1.15 GHz with the band width of 50 MHz; the central frequency of high frequency is about 1.9 GHz with 80 MHz bandwidth, respectively. 
     EXAMPLE 2 
     Please refer to FIG. 6A, is shows an example of construction of two-loops antenna. 
     From the diagram of FIG. 6B, it is clearly shown that when the VSWR is not greater than 2, the central frequency of low frequency is about 1.15 GHz with the band width of 80 MHz, the central frequency of high frequency is about 1.67 GHz with 50 MHz bandwidth, respectively. 
     EXAMPLE 3 
     Please refer to FIG. 7A, is shows an example of construction of three-loops antenna. 
     From the diagram of FIG. 7B, it is clearly shown that when the VSWR is not greater than 2, the central frequency of low frequency is about 1.13 GHz with the band width of 80 MHz, the central frequency of high frequency is about 1.4 GHz with 50 MHz bandwidth, respectively. 
     EXAMPLE 4 
     As shown in FIG. 8A, it shows an example of four-loops antenna. 
     From the diagram of FIG. 8B, it is clearly shown that its low frequency is about 1.2 GHz with a bandwidth of 210 MHz, while its dimensions of practical uses can be seen from FIGS. 9A,  9 B and  9 C. 
     It is known from the above description that the structure of the multi-loop antenna of the present invention enables the antenna to receive signals with two groups or above modules. Thus the variability and the flexibility while receiving signals are improved, and the bandwidth of receiving frequency is broadened. 
     While the present invention has been described herein with reference to particular embodiments thereof, latitude of modification, various changes and substitutions are intended in the foregoing disclosure. And in some instances, some features of the invention will be employed without a corresponding use of other features without departing from the spirit of the invention as set forth herein.