JP2013017034A - Folded inverted l antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a folded inverted L antenna that can perform impedance matching even when the folded inverted L antenna is disposed close to a conductor while holding a low posture.SOLUTION: A front end of an L-shaped first element 10 comprised of an extension part 10a and a bent part 10b, and a front end of an L-shaped folding element 11 comprised of an extension part 11a and a bent part 11b are connected to each other by a connection element 12. The bent parts 10a and 10b are connected to an upright element 13 disposed vertically on a ground plane 15, thereby constructing a folded inverted L antenna 1. A feeding part 14 is disposed between a lower end of the bent part 10a and the upright element 13. An impedance of an antenna element itself can be adjusted in a wide range according to the width and interval of the first element 10 and the folding element 11, and the position of the feeding part 14.

Description

  The present invention relates to a low inverted folded inverted L antenna that can be installed in a wireless communication device.

2. Description of the Related Art Conventionally, as a transmission / reception antenna mounted on a wireless communication device, a small antenna is desired for convenience of carrying. Further, since the internal space of the wireless communication device is limited, an antenna that can be installed close to a conductor in the wireless communication device is desired. A folded inverted L antenna has been proposed as a small antenna installed in a conventional wireless communication device. FIG. 30 is a perspective view showing the configuration of a conventional folded inverted L antenna, and FIG. A top view shown in FIG. 31 is shown, and a right side view showing a configuration of a conventional folded inverted L antenna is shown in FIG.
The folded inverted L antenna 100 shown in these drawings has a first element 110 and a folded element 111 that are bent in an L shape, and is disposed upright on a planar ground plate 115. . The first element 110 is an elongated linear extending portion 110a disposed substantially parallel to the ground plate 115, and is bent substantially at a right angle from the end of the extending portion 110a and is erected on the ground plate 115 substantially vertically. It is comprised from the bending part 110b. Further, the folding element 111 is disposed substantially parallel to the first element 110, and is bent at a substantially right angle from the elongated wire extending portion 111a disposed substantially parallel to the base plate 115 and the end of the extending portion 111a. And a bent portion 111b that is erected almost vertically on the main plate 115. The tip of the extending portion 110a in the first element 110 and the tip of the extending portion 111a in the folding element 111 are connected by the connecting element 112, and the first element 110 and the folding element 111 are substantially parallel with a predetermined interval. Has been placed.

A power feeding unit 114 is provided between the front end of the bent portion 110 b of the first element 110 and the ground plate 115, and power is fed from the power feeding unit 114 to the folded inverted L antenna 100. Here, FIG. 33 shows the frequency characteristic of the voltage standing wave ratio (VSWR) of the conventional folded inverted L antenna 100 under the following conditions. As a condition, the folded inverted L antenna 100 is installed on a ground plate 115 having a size that can be regarded as electrically infinite, and designed with a design frequency of 1000 MHz (wavelength λ: about 300 mm). In this case, the dimensions of each part of the folded inverted L antenna 100 are as follows. The length EL001 of the extending portions 110a and 111a is about 0.141λ (about 42.3 mm), and the distance Ed0 between the first element 110 and the folding element 111 is about 0.024λ (about 7.2 mm). The width Ew001, the width Ew002 of the folding element 111, the width Ew003 of the connecting element 112 is about 0.003λ (about 0.9 mm), and the height Eh0 of the extending portions 110a and 111a from the ground plate 115 is about 0.097λ (about 29.29). 1 mm), the height Gp0 from the bottom plate 115 of the bent portion 110b fed from the power feeding portion 114 is about 0.013λ (about 3.9 mm), and the length EL002 of the bent portion 110b is about 0.084λ ( About 25.2 mm). Note that the thickness of each element of the folded inverted L antenna 100 is about 0.9 mm.
Referring to FIG. 33, in the conventional folded inverted L antenna 100, a good characteristic of VSWR of about 1.2 is obtained at the design frequency (1000 MHz), and 940 MHz and inverted triangle mark 3 indicated by inverted triangle mark 2 are obtained. At 1066 MHz shown, VSWR is about 3.0, and the center frequency of the frequency band of VSWR 3.0 is about 1003 MHz indicated by the inverted triangle mark 1. In this case, the specific resonance band is about 12.6%.

JP 2002-290138 A JP 2006-25412 A

By the way, when the conventional folded inverted L antenna 100 shown in FIGS. 30 to 32 is installed in the wireless communication device, it is installed in the wireless communication device in which the size of the internal space is limited. In the wireless communication device, there is a shield case used for the wireless communication device, and the impedance of the folded inverted L antenna 100 changes under the influence of a conductor such as the shield case. As a result, impedance matching cannot be performed, and the VSWR of the folded inverted L antenna 100 is deteriorated and the resonance band is narrowed.
Accordingly, an object of the present invention is to provide a folded inverted L antenna that can perform impedance matching even when placed close to a conductor while having a low attitude.

  In order to achieve the above object, a folded inverted L antenna according to the present invention includes a plate-like upright element standing almost vertically on a conductive ground plane, and a power feeding portion from the upper end of one side of the upright element. A plate-like first bent part extending through the plate, a plate-like second bent part extending from the upper end of the other side of the rising element, and a substantially right angle to the tip of the first bent part Is connected to the front end of the plate-like first extending portion extending substantially parallel to the ground plane and the second bent portion, and extends substantially parallel to the ground plane. A plate-like second extending portion, and a plate-like connecting element that connects the ends of the first extending portion and the second extending portion, and the first extending portion and the first extending portion. A first element is formed by one bent portion, and a folded element is formed by the second extending portion and the second bent portion, The main feature is that impedance adjustment is performed by adjusting the width of one element and the folding element, the distance between the first element and the folding element, and the position of feeding from the ground plane of the feeding section. Yes.

  In the folded inverted L antenna of the present invention, the impedance of the antenna element itself can be adjusted in a wide range according to the width and interval of the first element and the folded element and the feeding position, and even if it is arranged close to the conductor A simple resonance band can be realized. For this reason, it is possible to provide a folded inverted L antenna that is downsized and miniaturized.

It is a perspective view which shows the structure of the folding reverse L antenna concerning 1st Example of this invention. It is a top view which shows the structure of the folding reverse L antenna concerning 1st Example of this invention. It is a right view which shows the structure of the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the frequency characteristic of the voltage standing wave ratio (VSWR) of the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the length of the extending | stretching part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic at the time of setting the length of the extending | stretching part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the width | variety of the extending | stretching part of a 1st element as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic at the time of setting the width | variety of the extending | stretching part of a 1st element as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the space | interval of a 1st element and a folding element as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic when the space | interval of a 1st element and a folding element is made into the parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the width | variety of the extending | stretching part of a 2nd element as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic at the time of setting the width | variety of the extending | stretching part of a 2nd element as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the width | variety of a connection part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic when the width | variety of a connection part is made into the parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the height from the ground plane of an extending | stretching part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic at the time of setting the height from the ground plane of an extending | stretching part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the impedance characteristic at the time of setting the height from the ground plane of a feed part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic at the time of setting the height from the ground plane of a feed part as a parameter in the folding reverse L antenna concerning 1st Example of this invention. It is a perspective view which shows the structure of the folding reverse L antenna concerning 2nd Example of this invention. It is a top view which shows the structure of the folding reverse L antenna concerning 2nd Example of this invention. It is a right view which shows the structure of the folding reverse L antenna concerning 2nd Example of this invention. It is a perspective view which shows the structure of the folding reverse L antenna concerning 3rd Example of this invention. It is a top view which shows the structure of the folding reverse L antenna concerning 3rd Example of this invention. It is a right view which shows the structure of the folding reverse L antenna concerning 3rd Example of this invention. It is a perspective view which shows the structure of the folding reverse L antenna concerning 4th Example of this invention. It is a front view which shows the structure of the folding reverse L antenna concerning 4th Example of this invention. It is a top view which shows the structure of the folding reverse L antenna concerning 4th Example of this invention. It is a right view which shows the structure of the folding reverse L antenna concerning 4th Example of this invention. It is a figure which shows the frequency characteristic of VSWR of the folding reverse L antenna concerning 4th Example of this invention. It is a perspective view which shows the structure of the conventional folding reverse L antenna. It is a top view which shows the structure of the conventional folding reverse L antenna. It is a right view which shows the structure of the conventional folding reverse L antenna. It is a figure which shows the frequency characteristic of VSWR of the conventional folding reverse L antenna.

FIG. 1 is a perspective view showing the configuration of the folded inverted L antenna 1 according to the first embodiment of the present invention, FIG. 2 is a top view showing the configuration of the folded inverted L antenna 1 of the first embodiment, and FIG. FIG. 3 is a right side view showing the configuration of the folded inverted L antenna 1.
The folded inverted L antenna 1 of the first embodiment shown in these drawings is formed by processing a metal plate, and has a first element 10 and a folded element 11 bent in an L shape, It is arranged upright on a planar ground plate 15. The first element 10 includes an elongated plate-like extending portion 10a disposed substantially parallel to the ground plate 15, and a bent portion 10b having a predetermined length that is bent and connected to an end portion of the extending portion 10a at a substantially right angle. It is composed of Further, the folding element 11 is disposed substantially parallel to the first element 10 and is bent at a substantially right angle to the elongated plate-like extending portion 11a disposed substantially parallel to the base plate 15 and the end of the extending portion 11a. And the bent portion 11b connected to each other. In addition, the bottom plate 15 has a lower end connected to the bottom plate 15 and has a plate-like rising element 13 that is erected almost vertically on the bottom plate 15. A power feeding portion 14 is provided between the tip of the bent portion 10 b and the lower end of the bent portion 11 b is connected to the upper end of the other side portion of the rising element 13. The leading end of the extending portion 10a in the first element 10 and the leading end of the extending portion 11a in the folding element 11 are connected via a plate-shaped connecting element 12 having a predetermined width, and the first element 10 and the folding element 11 are predetermined. They are arranged almost in parallel with an interval.

A coaxial cable is introduced into the feeding portion 14 between the tip of the bent portion 10b of the first element 10 and the upper end of the rising element 13, and the core wire of the coaxial cable is connected to the end of the bent portion 10b. At the same time, the shield portion of the coaxial cable is connected to the upper end of the rising element 13, and the folded inverted L antenna 1 is fed.
Here, the frequency characteristics of the voltage standing wave ratio (VSWR) of the folded inverted L antenna 1 of the first embodiment under the following conditions are shown in FIG. As a condition, the folded inverted L antenna 1 of the first embodiment is installed on the ground plane 15 having a size that can be regarded as electrically infinite, and the design frequency is 1000 MHz (wavelength λ: about 300 mm). In this case, the dimensions of each part of the folded inverted L antenna 1 of the first embodiment are as follows. The length EL01 of the extending portion 10a and the extending portion 11a is about 0.138λ (about 41.4 mm), the distance Ed between the first element 10 and the folding element 11 is about 0.024λ (about 7.2 mm), and the first element 10 has a width Ew01 of about 0.018λ (about 5.4 mm), the folding element 11 has a width Ew02 of about 0.003λ (about 0.9 mm), and the connecting element 12 has a length Ew03 of about 0.033λ (about 9.35 mm). 9 mm), the height Eh from the base plate 15 of the extending portion 10a and the extending portion 11a is about 0.097λ (about 29.1 mm), and the height Gh of the rising element 13 in the power feeding portion 14 is about 0.058λ (about 17). .4 mm), the gap Gp between the upper end of the rising element 13 and the tip of the bent portion 10b is about 0.013λ (about 3.9 mm), and the length EL02 of the bent portion 10b is about 0.026λ (about 7.3 mm). 8 mm). Thus, the folded inverted L antenna 1 of the first embodiment is a low-profile small antenna, and each part of the folded inverted L antenna 1 is made of a metal plate having a thickness of about 1.0 mm.

  Referring to the frequency characteristics of the VSWR in FIG. 4, in the folded inverted L antenna 1 of the first embodiment, a good characteristic of VSWR of about 1.0 is obtained at the design frequency (1000 MHz). The VSWR is about 3.0 at 926 MHz shown and 1092 MHz shown by the inverted triangle mark 3, and the center frequency of the frequency band of VSWR 3.0 is about 1009 MHz shown by the inverted triangle mark 1. The VSWR at the center frequency of about 1009 MHz is good at about 1.1. In this case, the specific resonance band is about 16.6%.

  Next, impedance characteristics and VSWR characteristics when the dimensions of each part in the folded inverted L antenna 1 of the first embodiment are used as parameters are shown below. First, the length EL01 of the extending portion 10a and the extending portion 11a is changed as a parameter between 0.10λ (about 30 mm) and 0.2λ (about 60 mm). The impedance characteristic in this case is as shown in FIG. 5. Referring to FIG. 5, when the length EL01 is about 0.138λ (about 41.40 mm) indicated by the inverted triangle mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. When the length EL01 is about 0.1255λ (about 37.65 mm) indicated by the inverted triangle mark 2, the impedance is 60.64-j63.45Ω, and the length EL01 is about 0. It can be seen that the impedance is 44.45 + 32.36Ω when 151λ (about 45.305 mm). FIG. 6 shows the VSWR characteristics when the length EL01 of the extending portion 10a and the extending portion 11a is changed between 0.10λ (about 30 mm) and 0.2λ (about 60 mm) as a parameter. Referring to FIG. 6, when the length EL01 is about 0.138λ (about 41.40 mm) indicated by the inverted triangular mark 1, VSWR is about 1.0, which is the best value. Further, when the length EL01 is about 0.1255λ (about 37.65 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0, and the length EL01 is about 0.151λ (about approx. 45.305 mm), it can be seen that VSWR is about 2.0. As shown in FIG. 5, by changing the length EL01, the real component of the impedance decreases, but when the length EL01 exceeds about 0.12λ, the change becomes small and the imaginary component of the impedance gradually increases. . From this, by changing the length EL01, the impedance of the folded inverted L antenna 1 can be adjusted in a wide range, thereby making it possible to perform impedance matching. As shown in FIG. 6, it is found that the length EL01 is preferably about 0.1255λ to about 0.151λ.

  Second, the width Ew01 of the first element 10 is changed between about 0.001λ (about 0.3 mm) to 0.5λ (about 150 mm) as a parameter. The impedance characteristic in this case is as shown in FIG. 7. Referring to FIG. 7, when the width Ew01 is about 0.018λ (about 5.4 mm) indicated by the inverted triangle mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. It can also be seen that when the width Ew01 is about 0.100λ (about 30.0 mm) indicated by the inverted triangular mark 2, the impedance is 28.00 + j15.90Ω. Further, the VSWR characteristic when the width Ew01 of the first element 10 is changed between about 0.001 (about 0.3 mm) to 0.5λ (about 150 mm) as a parameter is as shown in FIG. Referring to FIG. 8, when the width Ew01 is about 0.018λ (about 5.4 mm) indicated by the inverted triangular mark 1, VSWR is about 1.0, which is the best value. Further, it is understood that when the width Ew01 is about 0.100λ (about 30.0 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0. As shown in FIG. 7, by changing the width Ew01, the real component of the impedance gradually decreases, but when the width Ew01 exceeds about 0.05λ, the change becomes small, and the imaginary component of the impedance gradually increases. Go. From this, it is possible to finely adjust the impedance of the folded inverted L antenna 1 by changing the width Ew01, thereby enabling impedance matching. As shown in FIG. 8, the width Ew01 is preferably about 0.1λ or less.

  Third, the distance Ed between the first element 10 and the folding element 11 is changed between about 0.001λ (about 0.3 mm) to 0.2λ (about 60 mm) as a parameter. The impedance characteristic in this case is as shown in FIG. 9. Referring to FIG. 9, when the interval Ed is about 0.024λ (about 7.20 mm) indicated by the inverted triangle mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. It can also be seen that when the distance Ed is about 0.100λ (about 30.0 mm) indicated by the inverted triangular mark 2, the impedance is 52.87 + j35.17Ω. FIG. 10 shows the VSWR characteristics when the distance Ed between the first elements 10 is changed as a parameter between about 0.001λ (about 0.3 mm) and 0.2λ (about 60 mm). Referring to FIG. 10, when the interval Ed is about 0.024λ (about 7.20 mm) indicated by the inverted triangular mark 1, about 1.0 is obtained as the VSWR, which is the best value. It can also be seen that when the distance Ed is about 0.100λ (about 30.0 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0. As shown in FIG. 9, by changing the interval Ed, the real number component of the impedance becomes substantially constant, and the imaginary number component of the impedance gradually rises. From this, it is possible to finely adjust the impedance of the folded inverted L antenna 1 by changing the interval Ed, and thereby impedance matching can be performed. Then, as shown in FIG. 10, it is understood that the distance Ed is preferably about 0.1λ or less.

  Fourth, the width Ew02 of the folding element 11 is changed as a parameter between about 0.001λ (about 0.3 mm) and 0.1λ (about 30 mm). The impedance characteristic in this case is as shown in FIG. 11. With reference to FIG. 11, when the width Ew02 is about 0.003λ (about 0.90 mm) indicated by the inverted triangle mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. It can also be seen that when the width Ew02 is about 0.033λ (about 9.90 mm) indicated by the inverted triangle mark 2, the impedance is 95.43 + j15.69Ω. FIG. 12 shows the VSWR characteristics when the width Ew02 of the folding element 11 is changed between about 0.001λ (about 0.3 mm) to 0.1λ (about 30 mm) using the width Ew02 as a parameter. Referring to FIG. 12, when the width Ew02 is about 0.003λ (about 0.90 mm) indicated by the inverted triangular mark 1, VSWR is about 1.0, which is the best value. It can also be seen that when the width Ew02 is about 0.033λ (about 9.90 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0. As shown in FIG. 11, by changing the width Ew02, the real component of the impedance gradually increases, and the imaginary component of the impedance also gradually increases. From this, by changing the width Ew02, the impedance of the folded inverted L antenna 1 can be adjusted in a wide range, and thereby impedance matching can be performed. As shown in FIG. 12, the width Ew02 is preferably about 0.033λ or less.

  Fifth, the length Ew03 of the connection element 12 is changed as a parameter between about 0.001λ (about 0.3 mm) and 0.16λ (about 48 mm). The impedance characteristic in this case is as shown in FIG. 13. Referring to FIG. 13, when the length Ew03 is about 0.033λ (about 9.90 mm) indicated by the inverted triangle mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. It can also be seen that when the length Ew03 is about 0.155λ (about 46.50 mm) indicated by the inverted triangular mark 2, the impedance is 40.75 + j29.66Ω. FIG. 14 shows the VSWR characteristics when the length Ew03 of the connection element 12 is changed as a parameter between about 0.001λ (about 0.3 mm) and 0.16λ (about 48 mm). Referring to FIG. 14, when the length Ew03 is about 0.033λ (about 9.90 mm) indicated by the inverted triangular mark 1, VSWR is about 1.0, which is the best value. It can also be seen that when the length Ew03 is about 0.155λ (about 46.50 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0. As shown in FIG. 13, by changing the length Ew03, the real component of the impedance becomes substantially constant, and the imaginary component of the impedance rises slightly but becomes substantially constant. From this, the impedance of the folded inverted L antenna 1 can be finely adjusted by changing the length Ew03, thereby making it possible to perform impedance matching. Then, as shown in FIG. 14, it is understood that the length Ew03 is preferably about 0.155λ or less.

  Sixth, the height Eh of the extending portion 10a and the extending portion 11a from the base plate 15 is changed as a parameter between about 0.05λ (about 15 mm) and 0.2λ (about 60 mm). The impedance characteristic in this case is as shown in FIG. 15. Referring to FIG. 15, when the height Eh is about 0.097λ (about 29.10 mm) indicated by the inverted triangular mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. It can also be seen that when the height Eh is about 0.086λ (about 25.80 mm) indicated by the inverted triangular mark 2, the impedance is 44.81−j32.28Ω. Furthermore, when the height Eh is about 0.110λ (about 33.00 mm) indicated by the inverted triangle mark 3, it can be seen that the impedance is 54.88 + j37.63Ω. FIG. 16 shows the VSWR characteristics when the height Eh from the base plate 15 of the extending portion 10a and the extending portion 11a is changed between about 0.05λ (about 15 mm) and 0.2λ (about 60 mm) as a parameter. As shown. Referring to FIG. 16, when the height Eh is about 0.097λ (about 29.10 mm) indicated by the inverted triangular mark 1, VSWR is about 1.0, which is the best value. It can also be seen that when the height Eh is about 0.086λ (about 25.80 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0. Further, when the height Eh is about 0.110λ (about 33.00 mm) indicated by the inverted triangular mark 3, it can be seen that the VSWR is about 2.0. As shown in FIG. 15, by changing the height Eh, the real component of the impedance increases very slowly, and the imaginary component of the impedance gradually increases. From this, by changing the height Eh, the impedance of the folded inverted L antenna 1 can be adjusted in a wide range, thereby making it possible to perform impedance matching. Then, as shown in FIG. 16, it is understood that the height Eh is preferably about 0.086λ to about 0.110λ.

  Seventh, the height Gh of the rising element 13 is changed as a parameter between about 0.001λ (about 0.3 mm) and 0.20λ (about 60 mm). The impedance characteristic in this case is as shown in FIG. 17. Referring to FIG. 17, when the height Gh is about 0.058λ (about 17.40 mm) indicated by the inverted triangular mark 1, the impedance is 50.17 + j0.10Ω. Thus, it is matched to approximately 50Ω. It can also be seen that when the height Gh is about 0.126λ (about 37.80 mm) indicated by the inverted triangular mark 2, the impedance is 95.17 + j13.64Ω. FIG. 18 shows the VSWR characteristics when the height Gh of the rising element 13 is changed as a parameter between about 0.001λ (about 0.3 mm) and 0.20λ (about 60 mm). Referring to FIG. 18, when the height Gh is about 0.058λ (about 17.40 mm) indicated by the inverted triangle mark 1, VSWR is about 1.0, which is the best value. It can also be seen that when the height Gh is about 0.126λ (about 37.80 mm) indicated by the inverted triangular mark 2, the VSWR is about 2.0. As shown in FIG. 17, by changing the height Gh, the real component of the impedance becomes almost constant until the height Gh exceeds about 0.10λ, but rises and falls when it exceeds about 0.10λ. The imaginary number component of the impedance becomes substantially constant until the height Gh exceeds about 0.12λ, but rises and falls when it exceeds about 0.12λ. From this, the impedance of the folded inverted L antenna 1 can be adjusted by changing the height Gh, thereby making it possible to perform impedance matching. Then, as shown in FIG. 18, it is understood that the height Gh is preferably about 0.126λ or less.

Next, FIG. 19 is a perspective view showing the configuration of the folded inverted L antenna 2 according to the second embodiment of the present invention, FIG. 20 is a top view showing the configuration of the folded inverted L antenna 2 of the second embodiment, and FIG. A right side view showing the configuration of the folded inverted L antenna 2 of the second embodiment is shown in FIG.
The folded inverted L antenna 2 of the second embodiment shown in these figures is formed by processing a metal plate, and the length Ew03 of the connecting element 12 in the folded inverted L antenna 1 of the first embodiment is very long. This corresponds to a folded inverted L antenna. That is, in the folded inverted L antenna 2 of the second embodiment, the extending portion 20a of the first element 20 and the extending portion 21a of the folded element 21 are integrated by the connecting element 22 to have a flat plate shape. The connecting element 22 has a long and thin flat plate shape and is disposed substantially parallel to the ground plate 25. One end portion of the connection element 22 is bent in an L shape substantially at a right angle, and the upper end of the bent portion 20b of the first element 20 is connected to the lower end of one side portion of the bent connection element 22 to be folded. The upper end of the bent portion 21 b of the folding element 21 is connected to the lower end of the other side portion of the bent connection element 22. In addition, the bottom plate 25 has a lower end connected to the base plate 25 and has a plate-like upright element 23 standing substantially vertically on the main plate 25. A power supply unit 24 is provided between the lower end of the bent portion 20 b and the lower end of the bent portion 21 b is connected to the upper end of the other side portion of the rising element 23.

A coaxial cable is introduced into the power feeding portion 24 between the lower end of the bent portion 20b and the upper end of the rising element 23 in the first element 20, and the core wire of the coaxial cable is connected to the lower end of the bent portion 20b. The shield portion of the coaxial cable is connected to the upper end of the rising element 23, and the folded inverted L antenna 2 is fed. The ground plane 25 on which the folded inverted L antenna 2 according to the second embodiment is installed has a size that can be considered to be electrically infinite.
Here, the dimensions of each part when the design frequency of the folded inverted L antenna 2 of the second embodiment is 1000 MHz (wavelength λ: about 300 mm) are as follows. The length EL01 of the extending part 20a and the extending part 21a is about 0.138λ (about 41.4 mm), and the distance Ed between the bent part 20b and the bent part 21b corresponding to the distance between the first element 20 and the folded element 21. Is approximately 0.024λ (approximately 7.2 mm), the width Ew01 of the bent portion 20b of the first element 20 is approximately 0.018λ (approximately 5.4 mm), and the width Ew02 of the bent portion 21b of the folded element 21 is approximately 0. 0.003λ (about 0.9 mm), the length Ew03 of the connecting element 22 is about 0.155λ (about 46.5 mm), and the height Eh of the extending portion 20a and the extending portion 21a from the ground plate 25 is about 0.097λ (about 29.1 mm), the height Gh of the rising element 23 in the power feeding unit 24 is about 0.058λ (about 17.4 mm), and the gap Gp between the upper end of the rising element 23 and the lower end of the bent portion 20b is about 0.2 mm. 013λ (approximately 3.9 mm), bent portion 20b The length EL02 is about 0.026λ (about 7.8 mm). In this way, the folded inverted L antenna 2 of the second embodiment is a low-profile small antenna, and each part of the folded inverted L antenna 2 is made of a metal plate having a thickness of about 1.0 mm. The frequency characteristics of the VSWR of the folded inverted L antenna 2 of the second embodiment having such dimensions are substantially the same as those of the folded inverted L antenna 1 of the first embodiment.

Next, FIG. 22 is a perspective view showing the configuration of the folded inverted L antenna 3 according to the third embodiment of the present invention, FIG. 23 is a top view showing the configuration of the folded inverted L antenna 3 of the third embodiment, and FIG. A right side view showing the configuration of the folded inverted L antenna 3 of the third embodiment is shown in FIG.
The folded inverted L antenna 3 of the third embodiment shown in these drawings is formed by processing a metal plate, and the length Gh of the rising element 13 in the folded inverted L antenna 1 of the first embodiment is increased. By bending, it corresponds to a folded inverted L antenna in which the bent portions 10b and 11b are omitted. In other words, the folded inverted L antenna 3 of the third embodiment has the first element 30 and the folded element 31 and is arranged upright on the planar ground plane 35. The first element 30 is composed of an elongated plate-like extending portion 30a disposed substantially parallel to the ground plane 35, and the folding element 31 is disposed substantially parallel to the extending portion 30a and substantially parallel to the ground plane 35. It is comprised from the elongate plate-shaped extending | stretching part 31a made. In addition, the bottom plate 35 has a lower end connected thereto, and has a plate-like rising element 33 which is erected substantially vertically on the ground plate 35 and whose upper portion is bent in an L shape at a right angle. ing. A portion between one side of the bent tip of the rising element 33 and one end of the extending portion 30a is a power feeding portion 34, and one end of the extending portion 31a is connected to the other side of the leading end of the rising element 33. Yes. The leading end of the extending portion 30a in the first element 30 and the leading end of the extending portion 31a in the folding element 31 are connected by a connecting element 32 having a plate-like predetermined width, and the first element 30 and the folding element 31 have a predetermined interval. It will be arranged almost parallel.

A coaxial cable is introduced into the power feeding portion 34 between one end of the extending portion 30 a and the tip of the rising element 33 in the first element 30, and the core wire of the coaxial cable is connected to the lower end of the extending portion 30 a and the coaxial cable. Is connected to the upper end of the rising element 33, and the folded inverted L antenna 3 is fed. Note that the ground plane 35 on which the folded inverted L antenna 3 of the third embodiment is installed has a size that can be regarded as being electrically infinite.
Here, the dimensions of each part when the design frequency of the folded inverted L antenna 3 of the third embodiment is 1000 MHz (wavelength λ: about 300 mm) are as follows. The length EL01 of the extending portion 31a of the folded element 31 is about 0.138λ (about 41.4 mm), the length EL01 ′ of the extending portion 30a of the first element 30 is about 0.00.096λ (about 28.8 mm), The width Ew01 of the extending portion 30a of the first element 30 is about 0.018λ (about 5.4 mm), the width Ew02 of the extending portion 31a of the folded element 31 is about 0.003λ (about 0.9 mm), and the length of the connecting element 32 The height Eh03 is about 0.00.033λ (about 9.9 mm), the height Eh of the extending portion 30a and the extending portion 31a from the ground plane 35 is about 0.097λ (about 29.1 mm), and the length of the rising element 33 Gh is about 0.126λ (about 37.8 mm), and the gap Gp between the tip of the rising element 33 and one end of the extending portion 30a is about 0.013λ (about 3.9 mm). As described above, the folded inverted L antenna 3 of the third embodiment is a low-profile small antenna, and each part of the folded inverted L antenna 3 is made of a metal plate having a thickness of about 1.0 mm. The frequency characteristics of the VSWR of the folded inverted L antenna 3 of the third embodiment having such dimensions are substantially the same as those of the folded inverted L antenna 1 of the first embodiment.

  The folded inverted L antenna according to each embodiment of the present invention can be installed in a wireless communication device in which the size of the internal space is limited. In this case, a circuit board, a shield case for shielding the circuit board, and the like are built in the wireless communication device, and the folded inverted L antenna may be installed close to a conductor such as the circuit board or the shield case. . When the folded inverted L antenna according to the present invention installed in the wireless communication device is arranged close to the conductor and is affected by the conductor, it can be avoided as much as possible by adjusting the dimensions. . FIG. 25 is a perspective view showing the configuration of the folded inverted L antenna 4 of the fourth embodiment in which the dimensions are adjusted when the folded inverted L antenna 1 of the first embodiment is arranged close to the shield case. A side view showing the configuration of the folded inverted L antenna 4 of the fourth embodiment is shown in FIG. 26, a top view showing the configuration of the folded inverted L antenna 4 of the fourth embodiment is shown in FIG. 27, and the folded inverted L antenna of the fourth embodiment. FIG. 28 is a right side view showing the configuration 4.

  The folded inverted L antenna 4 of the fourth embodiment shown in these drawings is configured by adjusting the dimensions of the folded inverted L antenna 1 of the first embodiment shown in FIGS. 1 to 3. Since the configuration of the folded inverted L antenna 4 is the same as that of the folded inverted L antenna 1 of the first embodiment, the description thereof is omitted. The folded inverted L antenna 4 of the fourth embodiment is arranged upright on a ground plane 45 built in the wireless communication device. In this case, the folded inverted L antenna 4 is disposed adjacent to a rectangular parallelepiped metallic shield case 46 that shields the circuit board disposed on the ground plane 45. At this time, the extending portion 40a of the first element 40 and the extending portion 41a of the folding element 41 are opposed substantially parallel to the upper surface of the shield case 46 at a gap Ga, and the bent portion 40b and the folding element 41 of the first element 40 are opposed. The bent portion 41b faces the side surface of the shield case 46 substantially in parallel with the gap Gs. The ground plane 45 has a size that can be regarded as electrically infinite.

  Here, the horizontal width SL of the shield case 46 is about 0.147λ (about 44 mm), the vertical width Sd is about 0.377λ (about 113 mm), and the height Sh is about 0.057λ (about 17 mm). ing. The dimensions of each part when the design frequency of the folded inverted L antenna 4 of the fourth embodiment is 1000 MHz (wavelength λ: about 300 mm) are as follows. The length EL01 of the extending portion 40a and the extending portion 41a is about 0.173λ (about 51.9 mm), the width Ew01 of the bent portion 40b of the first element 40 is about 0.007λ (about 2.1 mm), and the folding element 41 The width Ew02 of the bent portion 41b is about 0.023λ (about 6.9 mm), the length Ew03 of the connecting element 42 is about 0.033λ (about 9.9 mm), and from the base plate 45 of the extended portion 40a and the extended portion 41a. The height Eh is about 0.097λ (about 29.1 mm), the height Gh of the rising element 43 in the power feeding section 44 is about 0.058λ (about 17.4 mm), the upper end of the rising element 43 and the bent portion The distance Gp from the lower end of 40b is about 0.013λ (about 3.9 mm), and the length EL02 of the bent portion 40b is about 0.026λ (about 7.8 mm). As described above, the folded inverted L antenna 4 of the fourth embodiment is a low-profile small antenna, and each part of the folded inverted L antenna 4 is made of a metal plate having a thickness of about 1.0 mm.

FIG. 29 shows the frequency characteristics of the VSWR of the folded inverted L antenna 4 of the fourth embodiment having such dimensions.
Referring to FIG. 29, in the folded inverted L antenna 2 of the fourth embodiment, the VSWR is hardly deteriorated to about 1.1 at the design frequency (1000 MHz). Further, at 951 MHz indicated by the inverted triangle mark 2 and 1058 MHz indicated by the inverted triangle mark 3, the VSWR is about 3.0, and the center frequency of the frequency band of the VSWR 3.0 is about 1004.5 MHz indicated by the inverted triangle mark 1. The VSWR at the center frequency of about 1004.5 MHz is about 1.2, which is a good value. The specific resonance band in this case is about 10.7%, which is slightly narrower than the folded inverted L antenna 1 of the first embodiment, but a sufficiently wide resonance band is obtained even under the influence of the shield case 46. I understand. Thus, in the folded inverted L antenna 4 of the fourth embodiment, it is understood that impedance matching is performed by adjusting the dimensions, and the influence of the shield case 46 that degrades the VSWR characteristic and the resonance band can be suppressed as much as possible. .

The folded inverted L antennas of the second and third embodiments according to the present invention described above exhibit the same electrical characteristics as the electrical characteristics exhibited by the folded inverted L antenna of the first embodiment.
In the folded inverted L antenna according to each embodiment of the present invention described above, the impedance of the antenna element itself can be adjusted in a wide range according to the width and interval of the first element and the folded element and the feeding position, and the proximity to the conductor. Even if they are arranged as described above, a wide resonance band can be realized. In addition, since impedance adjustment can be performed by changing the position of the power feeding unit, it is possible to flexibly cope with the antenna installation environment. Furthermore, since impedance adjustment can be performed even when a conductor such as a shield case is close to the folded inverted L antenna, a small antenna can be realized and the antenna element shape can be changed according to the case shape of the shield case or the like. Since the impedance can be adjusted with this, it can be optimized as a built-in antenna.
Further, since the folded inverted L antenna according to the present invention has a planar structure, mass production can be performed with high accuracy at low cost. Furthermore, even if the element length substantially parallel to the ground plane is about λ / 7, the specific resonance band can be about 16.6%, so that the antenna can be downsized.

1, 2, 3, 4, 5, 6, 7, 8 Folded inverted L antenna, 5a element portion, 5b element base portion, 6a element portion, 6b element base portion, 10 first element, 10a extension portion, 10a bending Part, 10b bending part, 11 folding element, 11a extending part, 11b bending part, 12 connecting element, 13 rising element, 14 feeding part, 15 ground plane, 20 first element, 20a extending part, 20b bending part, 21 Folding element, 21a Extending part, 21b Bending part, 22 Connecting element, 23 Rising element, 24 Feeding part, 25 Ground plane, 30 First element, 30a Extending part, 31 Folding element, 31a Extending part, 32 Connecting element, 33 Standing element, 34 Power feeding part, 35 Ground plane, 40 First element, 40a Extending part, 40b Bending part, 41 Folding element, 41a Extending part, 41b Bending part, 42 Connecting element , 43 Standing element, 44 Power feeding part, 45 Ground plane, 46 Shield case, 100 Antenna, 110 First element, 110a Extending part, 110b Bending part, 111 Folding element, 111a Extending part, 111b Bending part, 112 Connecting element , 114 Power supply unit, 115 Ground plane, 116 Shield case

In order to achieve the above object, a folded inverted L antenna according to the present invention includes a plate-like rising element that is erected substantially perpendicularly to a conductive ground plane and has a lower end connected to the ground plane, and the rising element. A plate-like first bent portion extending from the upper end of one side portion through the power feeding portion, a plate-like second bent portion extending from the upper end of the other side portion of the rising element, and the first The plate-like first extending portion that is connected to the front end of the bent portion at a substantially right angle, and extended substantially parallel to the ground plate, and connected to the front end of the second bent portion at a substantially right angle. A plate-like second extending portion extending substantially parallel to the ground plate, and a plate-like connecting element for connecting tips of the first extending portion and the second extending portion, The first extending portion and the first bent portion constitute a first element, and the second extending portion and the second bent portion A return element is configured, and impedance adjustment is performed by adjusting the width of the first element and the folded element, the distance between the first element and the folded element, and the power feeding position of the power feeding unit from the ground plane. The most important feature is that

Claims (3)

A plate-like rising element erected almost vertically on a conductive ground plane;
A plate-like first bent part extending from the upper end of one side of the rising element through the power feeding part;
A plate-like second bent portion extending from the upper end of the other side of the rising element;
A plate-like first extending portion connected to the front end of the first bent portion at a substantially right angle and extending substantially parallel to the ground plane;
A plate-like second extending portion connected to the tip of the second bent portion so as to be substantially perpendicular, and extending substantially parallel to the ground plate;
A plate-like connecting element that connects the ends of the first extending portion and the second extending portion;
The first extending portion and the first bent portion constitute a first element, and the second extending portion and the second bent portion constitute a folding element, and the first element Folding reverse L, wherein the impedance is adjusted by adjusting the width of the element and the folding element, the distance between the first element and the folding element, and the feeding position of the feeding portion from the ground plane. antenna.   2. The length of the first extending portion and the second extending portion is about 0.1255λ to about 0.151λ when the wavelength of the design frequency is λ. Folded inverted L antenna.   When the wavelength of the design frequency is λ, the width of the first extending portion is about 0.001λ to about 0.1λ, and the distance between the first extending portion and the second extending portion is about The width of the second extending portion is about 0.001λ to about 0.033λ, and the power feeding position of the power feeding portion from the ground plane is about 0.001λ to about 0. 3. The folded inverted L antenna according to claim 1, wherein the inverted inverted L antenna is set to 126λ.

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