EP1703588B1

EP1703588B1 - Low radiating power antenna

Info

Publication number: EP1703588B1
Application number: EP05250444A
Authority: EP
Inventors: Li-Haur Chiu; Wen-Lin Liang
Original assignee: Xie Neng Biotech Corp
Current assignee: Xie Neng Biotech Corp
Priority date: 2005-01-28
Filing date: 2005-01-28
Publication date: 2008-01-16
Anticipated expiration: 2025-01-28
Also published as: ATE384345T1; DE602005004376T2; EP1703588A1; DE602005004376D1

Abstract

An antenna (100) includes a radiating unit, a feeding element (6), and a conductive coupler (5). The radiating unit includes a pair of parallel first and second radiating elements (3, 4). The feeding element (6), which supplies an antenna current from an external source to the first and second radiating elements (3, 4) of the radiating unit, is coupled to the first and second radiating elements (3, 4) of the radiating unit. The conductive coupler (5) is coupled to the first and second radiating elements (3, 4) of the radiating unit for enabling the antenna current to flow along the first and second radiating elements (3, 4) of the radiating unit in opposite directions.

Description

The invention relates to an antenna, more particularly to an antenna that has a relatively low radiating power.
A conventional antenna, which generates electromagnetic signals within the non-ionizing radiation spectrum (0 to 2.4x10²⁵Hz) for reception by a receiver (not shown), includes a pair of parallel radiating elements and a feeding element. The feeding element is coupled to the radiating elements, and serves to supply an antenna current from an external signal-generating source to the radiating elements. The antenna current flows along the radiating elements in the same direction.
The aforementioned conventional antenna is disadvantageous in that it has a relatively high radiating power. As such, the receiver requires a filter, which is relatively large and bulky. This is highly undesirable when portability of the receiver is essential.
US 2001/0000659 discloses a reader and/or writer apparatus having an antenna lying substantially in a plane. The antenna has two radiating elements, which are coupled by connecting an end of one element that is proximate an end of the other element.
DE 19904943 discloses an antenna for an automobile in which first and second radiating elements are coupled together in a corresponding way to US 2001/0000659 .
Therefore, the object of the present invention is to provide an antenna that is capable of overcoming the aforesaid drawback of the prior art.
According to the present invention there is provided an antenna comprising: a first radiating unit that includes a pair of parallel first and second radiating elements; a first feeding element for supplying an antenna current from an external source to said first and second radiating elements of said first radiating unit, said first feeding element being coupled to said first and second radiating elements of said first radiating unit; and a first conductive coupler coupled to said first and second radiating elements of said first radiating unit, said first conductive coupler enabling the antenna current to flow along said first and second radiating elements of the fist radiating unit in opposite directions; wherein: each of said first and second radiating elements of said first radiating unit has first and second ends; said first and second ends of said first radiating element of said first radiating unit are respectively disposed proximate to said second and first ends of said second radiating element of said first radiating unit; said first feeding element is coupled to said first ends of said first and second radiating elements of said first radiating unit; said first conductive coupler is coupled to said second ends of said first and second radiating elements of said first radiating unit; said antenna further comprising a second conductive coupler that is coupled to said first ends of said first and second radiating elements of said first radiating unit.
Preferred features of the invention are set out in Claims 2 to 4.
Other features and advantages of the present invention will become apparent in the following detailed description of examples and preferred embodiments with reference to the accompanying drawings, of which:

Figure 1 is a schematic view of a first example of an antenna;
Figure 2 is a schematic view of a second example of an antenna;
Figure 3 is a schematic view of a third example of an antenna;
Figure 4 is a schematic view of a fourth example of an antenna ;
Figure 5 is a schematic view of a fifth example of an antenna;
Figure 6 is a schematic view of a sixth example of an antenna;
Figure 7 is a schematic view of the first preferred embodiment of an antenna according to the present invention; and
Figure 8 is a schematic view of the second preferred embodiment of an antenna according to the present invention.

Referring to Figure 1, the first example of an antenna 100 is shown to include a first radiating unit, a first feeding element 6, and a first conductive coupler 5.
The first radiating unit includes a pair of parallel first and second radiating elements 3, 4, each of which has first and second ends 31, 41, 32, 42. In this example, each of the first and second radiating elements 3, 4 of the first radiating unit is generally straight. Moreover, the first and second ends 31, 32 of the first radiating element 3 of the first radiating unit are respectively disposed proximate to the first and second ends 41, 42 of the second radiating element 4 of the first radiating unit.
The first feeding element 6 is coupled to the first ends 31, 41 of the first and second radiating elements 3, 4 of the first radiating unit, and serves to supply an antenna current from an external source 2 to the first and second radiating elements 3, 4 of the first radiating unit.
The first conductive coupler 5 is coupled to the second ends 32, 42 of the first and second radiating elements 3, 4 of the first radiating unit. The construction as such enables the antenna current to flow from the first end 31 to the second end 32 of the first radiating element 3 of the first radiating unit in a first direction, as indicated by arrow (A), and from the second end 42 to the first end 41 of the second radiating element 4 of the first radiating unit in a second direction, as indicated by arrow (B), opposite to the first direction. In this example, the first conductive coupler 5 is a conductive wire.
From the above description, since the first and second radiating elements 3, 4 of the first radiating unit are coupled to each other by the first conductive coupler 5, the antenna 100 of this invention has a relatively high antenna impedance and a relatively low antenna inductance. Moreover, since the flows of the antenna current along the first and second radiating elements 3, 4 of the first radiating unit are in opposite directions, electromagnetic signals generated by the first and second radiating elements 3, 4 of the first radiating unit cancels each other in part. Accordingly, the antenna 100 of this invention has a relatively low radiation power, thereby enabling precise control of an operating frequency of the antenna 100.
Figure 2 illustrates the second example of an antenna 100. When compared with the previous example, each of the first and second radiating elements 3, 4 of the first radiating unit is generally spiral, and winds around the second end 32, 42 of a respective one of the first and second radiating elements 3, 4 of the first radiating unit. Moreover, each of the first and second radiating elements 3, 4 of the first radiating unit is formed from a coated conductive wire. Further, the first conductive coupler 5 is a resistor.
It is noted that, in this example, the first and second radiating elements 3, 4 of the first radiating unit lie in the same plane.
In an alternative example, each of the first and second radiating elements 3, 4 of the first radiating unit may be provided on a printed circuit board or a semiconductor substrate.
Based on experimental results, when the first conductive coupler 5 has a resistance value of 20Ω, the antenna 100 of this invention has an antenna impedance of 10Ω and an antenna inductance of 90 µH.
Figure 3 illustrates the third example of an antenna. When compared with the second example, the antenna 100 further includes a second radiating unit, a second feeding element 6', and a second conductive coupler 5'.
The second radiating unit includes a pair of parallel first and second radiating elements 3', 4', each of which has first and second ends 31' , 41', 32', 42'. Like the first and second radiating elements 3, 4 of the first radiating unit, each of the first and second radiating elements 3' , 4' of the second radiating unit is generally spiral, and winds around the second end 32', 42' of a respective one of the first and second radiating elements 3', 4' of the second radiating unit.
It is noted, in this example, that the first and second radiating elements 3, 4, 3', 4' of the first and second radiating units lie on the same plane.
The second feeding element 6' is coupled to the first and second radiating elements 3', 4' of the second radiating unit, and serves to supply an antenna current from the external source 2 to the first and second radiating elements 3' , 4' of the second radiating unit.
The second conductive coupler 5' is coupled to the second ends 32', 42' of the first and second radiating elements 3', 4' of the second radiating unit.
Figure 4 illustrates the fourth example of an antenna 100. When compared with the second example, each of the first and second radiating elements 3, 4 of the first radiating unit includes a plurality of bends, each of which defines a right angle.
Figure 5 illustrates the fifth example of an antenna 100. When compared with the second example, the first and radiating elements 3, 4 of the first radiating unit lie in different planes.
Figure 6 illustrates the sixth example of an antenna 100. When compared with the previous examples, each of the first and second radiating elements 3, 4 of the first radiating element unit is meandering in shape, and includes a plurality of bends, each of which defines a right angle.
It is noted that, in this example, the first and second radiating elements 3, 4, of the first radiating unit lie in the same plane.
Figure 7 illustrates the first preferred embodiment of an antenna 100 according to the present invention. When compared with the first example, the first and second ends 31, 32 of the first radiating element 3 of the first radiating unit are respectively disposed proximate to the second and first ends 42, 41 of the second radiating element 4 of the first radiating unit. Moreover, the antenna 100 further includes a second conductive coupler 5' that is coupled to the first ends 31, 41 of the first and second radiating elements 3, 4 of the first radiating unit. The construction as such enables the antenna current to flow from the first end 31 to the second end 32 of the first radiating element 3 of the first radiating unit in the first direction, as indicated by arrow (A), and from the first end 41 to the second end 42 of the second radiating element 4 of the first radiating unit through the second coupler 5' in the second direction, as indicated by arrow (B).
Figure 8 illustrates the second preferred embodiment of an antenna 100 according to the present invention. When compared with the first embodiment, each of the first and second radiating elements 3, 4 of the first radiating unit is generally spiral. The first radiating element 3 of the first radiating unit winds around the second end 32 of the first radiating element 3 of the first radiating unit, whereas the second radiating element 4 of the first radiating unit winds around the first end 42 of the second radiating element 4 of the first radiating unit.
Although each of the first and second radiating units of the antenna 100 this invention is exemplified using only at most a pair of first and second radiating elements 3, 4, 3', 4', it should be apparent to those skilled in the art that the number of radiating elements may be increased as required.

Claims

An antenna (100) comprising:
a first radiating unit that includes a pair of parallel first and second radiating elements (3, 4);

a first feeding element (6) for supplying an antenna current from an external source to said first and second radiating elements (3, 4) of said first radiating unit, said first feeding element (6) being coupled to said first and second radiating elements (3, 4) of said first radiating unit; and

a first conductive coupler (5) coupled to said first and second radiating elements (3, 4) of said first radiating unit, said first conductive coupler (5) enabling the antenna current to flow along said first and second radiating elements (3, 4) of the first radiating unit in opposite directions; wherein:
each of said first and second radiating elements (3, 4) of said first radiating unit has first and second ends (31, 41, 32, 42);

said first and second ends (31, 32) of said first radiating element (3) of said first radiating unit are respectively disposed proximate to said second and first ends (42, 41) of said second radiating element (4) of said first radiating unit;

said first feeding element (6) is coupled to said first ends (31, 41) of said first and second radiating elements (3, 4) of said first radiating unit;

said first conductive coupler (5) is coupled to said second ends (32, 42) of said first and second radiating elements (3, 4) of said first radiating unit;

said antenna (100) further comprising a second conductive coupler (5') that is coupled to said first ends (31, 41) of said first and second radiating elements (3, 4) of said first radiating unit.
An antenna (100) according to claim 1, characterized in that each of said first and second radiating elements (3, 4) of said first radiating unit is generally straight.
An antenna (100) according to claim 1, characterized in that each of said first and second radiating elements (3, 4) of said first radiating unit is generally spiral.
An antenna (100) according to any one of claims 1 to 3, characterized in that said first and second radiating elements (3, 4) of said first radiating unit are arranged to lie on the same plane.