Antenna device

Abstract

An antenna device operating at a center frequency, includes a substrate and a conductive layer. The substrate has a first plane. The conductive layer is disposed on the first plane of the substrate. The conductive layer has a printed pattern including a radiating element and a matching element. The radiating element has several tortuous portions arranged along a first direction. Adjacent two of the tortuous portions are substantially parallel with and electrically coupled to each other. The matching element has several protruding portions arranged along the first direction. Adjacent two of the protruding portions are substantially parallel with and electrically isolated from each other. Each of the protruding portions of the matching element is sandwiched between adjacent two of the tortuous portions of the radiating element along a second direction, and the second direction is not parallel with the first direction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an antenna device, and particularly relates to an antenna device having a form of a printed antenna and adapted to anti-theft applications for vehicles.BACKGROUND

[0002] With a development of emerging energy and electric engines, various vehicles have been widely used in daily life. In order to meet safety requirements, vehicles are usually equipped with anti-theft device(s). In addition, the anti-theft device has a transceiver for wireless communication to receive remote control signals from the vehicle driver, or detect movements of suspicious persons in the surrounding region.

[0003] The conventional anti-theft device for vehicle usually employs transceivers operating at a frequency of 315 MHz. Furthermore, the transceivers usually employ a helical antenna with a center frequency of 315 MHz.

[0004] However, the helical antenna of the anti-theft device for vehicle has several drawbacks, which may deteriorate the performance and life of the anti-theft device for vehicle. For example, long-term vibrations during movement of the vehicle may cause a break of the helical antenna, especially for a truck equipped with a diesel engine. Furthermore, during a manufacturing process of the anti-theft device for vehicle, the helical antenna must be assembled and soldered onto a circuit board, which increases the difficulty for manufacturing. Moreover, the helical antenna is usually made of an elastic material, which may cause the helical antenna to be stretched or deformed, and hence causing a varying of the size of the helical antenna.

[0005] In view of the above issues, it is desirable to have an improved antenna device for the industry of the field of vehicle anti-theft, which is able to replace the conventional helical antenna with a printed antenna and achieve a center frequency meeting a specification for user requirements.SUMMARY

[0006] According to one embodiment of the present disclosure, an antenna device is provided. The antenna device operates at a center frequency and includes a substrate and a conductive layer. The substrate has a first plane. The conductive layer is disposed on the first plane of the substrate. The conductive layer has a printed pattern including a radiating element and a matching element. The radiating element has several tortuous portions arranged along a first direction. Adjacent two of the tortuous portions are substantially parallel with and electrically coupled to each other. The matching element has several protruding portions arranged along the first direction. Adjacent two of the protruding portions are substantially parallel with and electrically isolated from each other. Each of the protruding portions of the matching element is sandwiched between adjacent two of the tortuous portions of the radiating element along a second direction, and the second direction is not parallel with the first direction.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1A is a schematic diagram of an antenna device 1000 according to an embodiment of the present disclosure. FIG. 1B is a top view of the antenna device 1000 in FIG. 1A. FIG. 2A, which is a top view of the printed pattern 81 of the antenna device 1000. FIG. 2B, which is a top view of one of the tortuous portions of the radiating element 100. FIG. 2C, which is a top view of one of the protruding portions of the matching element 200. FIG. 2D, which is a top view showing the relative arrangement of the protruding portion 210, two adjacent tortuous portions 130 and 140 and the ground region 300. FIG. 3 is a schematic diagram showing several equivalent capacitors formed by the matching element 200 of the antenna device 1000. FIGS. 4A and 4B are diagrams illustrating the frequency response of the antenna device 1000.

[0008] In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.DETAILED DESCRIPTION

[0009] FIG. 1A is a schematic diagram of an antenna device 1000 according to an embodiment of the present disclosure. As shown in FIG. 1A, the antenna device 1000 is integrated into an electronic device 2000. The electronic device 2000 is, for example, a transceiver for wireless communication, and can be employed to anti-theft applications for vehicles. The electronic device 2000 includes a printed circuit board, and the printed circuit board includes a substrate 50 and a conductive layer 80. The conductive layer 80 is disposed on a first plane 51 of the substrate 50. The antenna device 1000 of the present disclosure is formed by a portion of the substrate 50 and a portion of the conductive layer 80. The antenna device 1000 has a form of a printed antenna, and the conductive layer 80 has a printed pattern 81 which is predefined.

[0010] FIG. 1B is a top view of the antenna device 1000 in FIG. 1A. As shown in FIG. 1B, the antenna device 1000 has a radiating region 100R. The radiating region 100R has a width W1 in a first direction X and a length L1 in a second direction Y. The first direction X is substantially perpendicular to the second direction Y. In this embodiment, the width W1 is smaller than the length L1. The width W1 is, for example, equal to 10.5 mm. Furthermore, the length L1 is, for example, equal to 33 mm.

[0011] The printed pattern 81 is disposed corresponding to the radiating region 100R. The printed pattern 81 at least includes a radiating element 100, a matching element 200 and a ground region 300. The radiating element 100 and the matching element 200 are located within the radiating region 100R, and the ground region 300 is disposed along and close to a boundary of the radiating region 100R. The antenna device 1000 may transmit / receive radio frequency signals by radiating electromagnetic waves through the radiating element 100. The radiating element 100 has, for example, several tortuous -shaped patterns. In this embodiment, the radiating element 100 extends from a reference position P1 at a upper left corner to a reference position P2, along a direction opposite to the second direction Y. Furthermore, the radiating element 100 makes a turn of approximately 90 degrees at the reference position P2, and then extends along the first direction X. Moreover, the radiating element 100 makes another turn of approximately 90 degrees and then extends along the second direction Y. Likewise, the radiating element 100 makes still another turn of approximately 90 degrees and extends along the first direction X, and makes yet another turn of approximately 90 degrees and extends along an opposite direction of the second direction Y. Repeated as the above arrangement, and the radiating element 100 extends to a reference position P3, and then extends along the second direction Y to arrive the reference position P4.

[0012] The matching element 200 extends along the second direction Y. The matching element 200 is electrically isolated from the radiating element 100. Furthermore, the matching element 200 is sandwiched between adjacent two of several tortuous-shaped patterns of the radiating element 100. The ground region 300 surrounds the radiating element 100 along the first direction X and the second direction Y. Furthermore, the ground region 300 is electrically coupled to the matching element 200 in the first direction X. In operation, the matching element 200 may form several equivalent capacitors between the radiating element 100 and the ground region 300. The antenna device 1000 operates at a predefined center frequency according to these equivalent capacitances. The arrangement of the radiating element 100, the matching element 200 and the ground region 300 of the printed pattern 81 will be described in more detail below by reference to FIGS. 2A to 2C.

[0013] Firstly, please refer to FIG. 2A, which is a top view of the printed pattern 81 of the antenna device 1000. The radiating element 100 of the printed pattern 81 has several tortuous portions arranged along the first direction X, for example, six tortuous portions 110-160. Adjacent two of the tortuous portions 110-160 are substantially parallel with and electrically coupled to each other. For example, the tortuous portion 110 is adjacent to the tortuous portion 120, and the tortuous portion 110 is substantially parallel with and electrically coupled to the tortuous portion 120. Likewise, the adjacent tortuous portions 120 and 130 are substantially parallel with and electrically coupled to each other. Similarly, adjacent tortuous portions 150 and 160 are substantially parallel with and electrically coupled to each other.

[0014] The matching element 200 has several protruding portions arranged along the first direction X, for example, three protruding portions 210-230. Adjacent two of the protruding portions 210-230 are substantially parallel with each other and electrically isolated from each other. For example, the adjacent protruding portions 210 and 220 are substantially parallel with each other and electrically isolated from each other, the adjacent protruding portions 220 and 230 are substantially parallel with each other and electrically isolated from each other. Furthermore, one of the protruding portions 210-230 of the matching element 200 is sandwiched between adjacent two of the tortuous portions 110-160 of the radiating element 100 along the second direction Y. For example, the protruding portion 210 is sandwiched between the adjacent tortuous portions 130 and 140 along the second direction Y. The protruding portion 220 is sandwiched between the adjacent tortuous portions 140 and 150 along the second direction Y. The protruding portion 230 is sandwiched between the adjacent tortuous portions 150 and 160 along the second direction Y.

[0015] In contrast, one or more of the tortuous portions 110-160 of the radiating element 100 are sandwiched between adjacent two of the protruding portions 210-230 of the matching element 200 along the second direction Y. For example, the tortuous portion 140 is sandwiched between the adjacent protruding portions 210 and 220 along the second direction Y. The tortuous portion 150 is sandwiched between the adjacent protruding portions 220 and 230 along the second direction Y.

[0016] Next, please refer to FIG. 2B, which is a top view of one of the tortuous portions of the radiating element 100. The tortuous portion 110 is taken as an example for FIG. 2B, which includes a first section 111, a second section (112) 112 and a third section 113. Each of the first section 111, the second section 112 and the third section 113 has a strip shape. The length of the first section 111 is substantially equal to the length of the second section 112 (or, in another example, the length of the first section 111 is slightly greater than the length of the second section 112).

[0017] The first section 111 extends in the second direction Y. The second section 112 also extends in the second direction Y and is substantially parallel with the first section 111. The third section 113 extends in the first direction X and is electrically coupled to the first section 111 and the second section 112. According to the above arrangement, the first section 111, the second section 112 and the third section 113 form a "U-turn" pattern. Furthermore, the second section 112 of the tortuous portion 110 is electrically coupled to the adjacent tortuous portion 120 (the tortuous portion 120 is not shown in FIG. 2B).

[0018] Next, please refer to FIG. 2C, which is a top view of one of the protruding portions of the matching element 200. The protruding portion 210 is taken as an example for FIG. 2C. The protruding portion 210 has a strip shape, and has a first end 210e1 and a second end 210e2. The second end 210e2 is disposed opposite to the first end 210e1 according to the second direction Y.

[0019] Next, please refer to FIG. 2D, which is a top view showing the relative arrangement of the protruding portion 210, two adjacent tortuous portions 130 and 140 and the ground region 300. The protruding portion 210 extends between two adjacent tortuous portions 130 and 140 along the second direction Y, with the second end 210e2. The length of the protruding portion 210 is shorter than the length of the first section 131 and the length of the second section 132 of the tortuous portion 130. Likewise, the length of the protruding portion 210 is shorter than the length of the first section 141 and the length of the second section 142 of the tortuous portion 140.

[0020] Furthermore, the protruding portion 210 is substantially parallel with and electrically isolated from the second section 132 of the tortuous portion 130. Likewise, the protruding portion 210 is substantially parallel with and electrically isolated from the first section 141 of the tortuous portion 140. Furthermore, the ground region 300 is electrically coupled to the first end 210e1 of the protruding portion 210 in the first direction X.

[0021] As described above, in operation, the matching element 200 may form several equivalent capacitors between the radiating element 100 and the ground region 300. For example, the protruding portion 210 of the matching element 200 forms an equivalent capacitor. The equivalent capacitor is equivalently coupled between the two adjacent tortuous portions 130 and 140 of the radiating element 100 and the ground region 300. Hereinafter, details for the matching element 200 to form several equivalent capacitors will be described by reference to FIG. 3.

[0022] FIG. 3 is a schematic diagram showing several equivalent capacitors formed by the matching element 200 of the antenna device 1000. As shown in FIG. 3, a signal input end e_in of the antenna device 1000 is electrically coupled to the radiating element 100. A matching element 200 is disposed between the radiating element 100 and the ground region 300. The protruding portion 210 of the matching element 200 forms an equivalent capacitor C1. The equivalent capacitor C1 is equivalently coupled between the radiating element 100 and the ground region 300. Likewise, the other two protruding portions 220 and 230 of the matching element 200 form an equivalent capacitor C2 and an equivalent capacitor C3 respectively. The equivalent capacitor C2 and the equivalent capacitor C3 are both equivalently coupled between the radiating element 100 and the ground region 300.

[0023] The antenna device 1000 operates at a predefined center frequency based on the capacitive effect of the equivalent capacitors C1, C2, and C3. In this embodiment, the center frequency is, for example, 315 MHz, which is adapted to an operating frequency of a regular anti-theft device for vehicle. Alternatively, in other examples, relative arrangement of the matching element 200 and the radiating element 100 may be adjusted to change the equivalent capacitances C1, C2 and C3, such that the center frequency of the antenna device 1000 may change.

[0024] FIGS. 4A and 4B are diagrams illustrating the frequency response of the antenna device 1000. Firstly, please refer to FIG. 4A, the frequency response of the antenna device 1000 is represented by a forward reflection coefficient S11 of the antenna device 1000 at different frequencies. In a design of the printed pattern 81 of the antenna device 1000, according to relative arrangement of the protruding portions 210, 220 and 230 of the matching element 200 and the radiating element 100, predefined equivalent capacitances C1, C2 and C3 may be formed between the radiating element 100 and the ground region 300, such that the frequency response of the antenna device 1000 may meet the specification for user requirements. The embodiment of FIG. 4A shows that, at a frequency of 315 MHz, the forward reflection coefficient S11 of the antenna device 1000 has a valley (i.e., a minimum value of the forward reflection coefficient S11 is reached). This indicates that, the center frequency of the antenna device 1000 is substantially equal to 315 MHz, which meets the specification of the anti-theft device for vehicle, as required by the user.

[0025] Next, referring to FIG. 4B, relative arrangement of the protruding portions 210, 220 and 230 of the matching element 200 and the radiating element 100 may be changed, thereby adjusting the equivalent capacitances C1, C2, and C3 between the radiating element 100 and the ground region 300, and the center frequency of the antenna device 1000 may hence be changed. The embodiment of FIG. 4B shows that, at a frequency of 433 MHz, the forward reflection coefficient S11 of the antenna device 1000 has a local minimum value. This indicates that, the center frequency of the antenna device 1000 is changed to 433 MHz.

[0026] Based on the above embodiments, the antenna device 1000 of the present disclosure may form at least one equivalent capacitor between the radiating element 100 and the ground region 300, by disposing the matching element 200 between the radiating element 100 and the ground region 300 of the printed pattern 81. With the capacitive effect of the equivalent capacitors, the center frequency of the antenna device 1000 may be adjusted to meet the specification for user requirements. Compared to the helical antenna of the conventional anti-theft device for vehicle, the size of the antenna device 1000 of the present disclosure is greatly reduced. Furthermore, the antenna device 1000 of the present disclosure may be manufactured in a simple way with a form of the printed antenna, which also greatly reduces the manufacturing cost.

[0027] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplars only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

Claims

1. An antenna device (1000), operating at a center frequency, the antenna device (1000) comprising: a substrate (50), having a first plane (51); and a conductive layer (80), disposed on the first plane (51) of the substrate (50), the conductive layer (80) has a printed pattern (81), and the printed pattern (81) comprising: a radiating element (100), having a plurality of tortuous portions (110-160) arranged along a first direction (X), wherein adjacent two of the tortuous portions (110-160) are substantially parallel with and electrically coupled to each other; and a matching element (200), having a plurality of protruding portions (210-230) arranged along the first direction (X), wherein any adjacent two of the protruding portions (210-230) are substantially parallel with and electrically isolated from each other, wherein each of the protruding portions (210-230) of the matching element (200) is sandwiched between adjacent two of the tortuous portions (110-160) of the radiating element (100) along a second direction (Y), and the second direction (Y) is not parallel with the first direction (X).

2. The antenna device of claim 1, wherein the second direction (Y) is substantially perpendicular to the first direction (X).

3. The antenna device of claim 1 or 2, wherein at least one of the tortuous portions (110-160) of the radiating element (100) are sandwiched between adjacent two of the protruding portions (210-230) of the matching element (200) along the second direction (Y).

4. The antenna device of anyone of the claims 1 to 3, wherein each of the tortuous portions (110-160) of the radiating element (100) comprises: a first section (111), extending in the second direction (Y); a second section (112), substantially parallel with the first section (111); and a third section (113), extending in the first direction (X), and electrically coupled to the first section (111) and the second section (112), wherein each of the first section (111), the second section (112) and the third section (113) has a strip shape, and the first section (111), the second section (112) and the third section (113) form a "U-turn" shape.

5. The antenna device of claim 4, wherein each of the protruding portions (210-230) of the matching element (200) is substantially parallel with and electrically isolated from the first section (111) and the second section (112) of each of the tortuous sections of the radiating element (100).

6. The antenna device of claim 4 or 5, wherein a length of the first section (111) of each of the tortuous portions (110-160) of the radiating element (100) is substantially equal to a length of the second section (112), and the length of the first section (111) of each of the tortuous portions (110-160) is greater than a length of each of the protruding portions (210-230) of the matching element (200).

7. The antenna device of anyone of the claims 1 to 6, wherein each of the protruding portions (210-230) of the matching element (200) has a strip shape, and each of the protruding portion has: a first end, which is not sandwiched between adjacent two of the tortuous portions (110-160) of the radiating element (100); and a second end, arranged opposite to the first end according to the second direction (Y).

8. The antenna device of claim 7, wherein each of the protruding portions (210-230) of the matching element (200) extends between adjacent two of the tortuous portions (110-160) of the radiating element (100) along the second direction (Y), with the second end.

9. The antenna device of claim 7 or 8, wherein the printed pattern (81) further comprising: a ground region (300), surrounding the radiating element (100) along the first direction (X) and the second direction (Y), and is electrically coupled to the first end of each of the protruding portions (210-230) of the matching element (200) in the first direction (X).

10. The antenna device of claim 9, wherein each of the protruding portions (210-230) of the matching element (200) forms an equivalent capacitance between the radiating element (100) and the ground region (300).

11. The antenna device of claim 10, wherein the antenna device operates at the center frequency based on the equivalent capacitances (C1-C3) formed by the protruding portions (210-230) of the matching element (200).

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