JP2013017038A - Folding reverse l antenna, and folding reverse l antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable impedance matching while keeping a low profile even when being arranged close to a conductor.SOLUTION: An L-shaped first element 10 composed of an extension part 10a on which a midway bent part 10c is formed and a bent part 10b, and an L-shaped folding element 11 composed of an extension part 11a on which a midway bent part 11c is formed and a bent part 11b are connected by a connection element 12 at the tips of the L-shaped elements. The bent parts 10b and 11b are connected to an upright element 13 erected on a bottom board 15. A power feeding part 14 is arranged between a bottom edge of the bent part 10b and the upright element 13. Impedance of the power feeding part 14 can be adjusted by adjusting widths of and an interval between the L-shaped first element 10 and the L-shaped folding element 11, and positions at which the midway bent part 10c and 11c are formed.

Description

  The present invention relates to a folded inverted L antenna and a folded inverted L antenna apparatus 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. 26 is a perspective view showing the configuration of a conventional folded inverted L antenna, and FIG. FIG. 27 is a top view showing the same, and FIG. 28 is a right side view showing the configuration of the conventional folded inverted L antenna.
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. Will be 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. 29 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. 29, 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 962 MHz and inverted triangle mark 3 indicated by inverted triangle mark 2 are obtained. At 1040 MHz shown, VSWR is about 2.0, and the center frequency of the frequency band of VSWR 2.0 is about 1001 MHz indicated by inverted triangle mark 1. The specific resonance band in this case is about 7.8%.

JP 2002-290138 A JP 2006-25412 A

By the way, when the conventional folded inverted L antenna 100 shown in FIGS. 26 to 28 is installed in a wireless communication device, it is installed in a wireless communication device in which the size of the internal space is limited. In the wireless communication device, there is a circuit board or the like 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 circuit board. As a result, impedance matching cannot be performed, and the VSWR of the folded inverted L antenna 100 deteriorates and the resonance band becomes narrow.
Accordingly, an object of the present invention is to provide a folded inverted L antenna and a folded inverted L antenna device that can perform impedance matching even when placed in close proximity to a conductor while being in a low posture.

  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 The plate-like first extending portion, which is connected so as to extend substantially parallel to the ground plane and has a bent portion formed in the middle thereof, is substantially perpendicular to the tip of the second bent portion. A plate-like second extending portion that is connected in such a manner as to extend substantially parallel to the ground plate and has a bent portion formed in the middle thereof, and tips of the first extending portion and the second extending portion A plate-like connecting element that connects each other, and the first element is configured by the first extending portion and the first bent portion, A folding element is configured by the second extending portion and the second bent portion, and is formed in the middle of the width of the first element and the folding element, the first extending portion, and the second extending portion. The most important feature is that the impedance is adjusted by adjusting the position of the bent portion.

  In the folded inverted L antenna of the present invention, the impedance of the antenna element itself depends on the width of the first element and the folded element and the position of the bent part formed in the middle of the first extending part and the second extending part. Adjustment is possible over a wide range, and a wide resonance band can be realized even if the conductor is arranged close to the conductor. 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 front 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 description of the dimension of the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the VSWR characteristic 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 it as the height parameter of an intermediate | middle bending part 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 it as the height parameter of an intermediate | middle bending part in the folding reverse L antenna concerning 1st Example of this invention. It is a figure which shows the resonance bandwidth characteristic at the time of setting it as the height parameter of an intermediate | middle bending part 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 position of an intermediate | middle bending 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 position of an intermediate | middle bending 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 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 perspective view which shows the structure which installed the folding reverse L antenna concerning 1st Example of this invention on the ground plane with which the circuit board was provided. It is a front view which shows the structure which installed the folding reverse L antenna concerning 1st Example of this invention on the ground plane with which the circuit board was provided. It is a top view which shows the structure which installed the folding reverse L antenna concerning 1st Example of this invention on the ground plane provided with the circuit board. It is a right view which shows the structure which installed the folding reverse L antenna concerning 1st Example of this invention on the ground plane provided with the circuit board. It is a figure which shows the VSWR characteristic at the time of installing the folding reverse L antenna concerning 1st Example of this invention on the ground plane provided with the circuit board. It is a perspective view which shows the structure of the folding reverse L antenna apparatus provided with the folding reverse L antenna concerning 2nd Example of this invention. It is a perspective view which shows the structure of the element base part in the folding reverse L antenna apparatus 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 perspective view which shows the structure of the electric power feeding board | substrate in the folding reverse L antenna apparatus of this invention. It is a perspective view which shows the structure of the holding | maintenance metal fitting in the folding reverse L antenna apparatus 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 VSWR characteristic of the conventional folding reverse L antenna.

FIG. 1 is a perspective view showing the configuration of a folded inverted L antenna 1 according to the first embodiment of the present invention, FIG. 2 is a front view showing the configuration of the folded inverted L antenna 1 of the first embodiment, and FIG. FIG. 3 is a top view showing the configuration of the folded inverted L antenna 1, and FIG. 4 is a right side view showing the configuration of the folded inverted L antenna 1 of the first embodiment.
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 has an elongated plate-like shape arranged substantially parallel to the ground plane 15, and has a stretched portion 10a in which a step of an intermediate bent portion 10c is formed in the middle, and is folded at a substantially right angle at the end of the stretched portion 10a. It is comprised from the bending part 10b of the predetermined length bent and connected. In addition, the folding element 11 is disposed substantially parallel to the first element 10 and is an elongated plate that is disposed substantially parallel to the base plate 15 and is formed with a step portion of the intermediate bent portion 11c in the middle. And a bent portion 11b that is bent and connected to the end portion of the extending portion 11a at a substantially right angle. 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 connected to each other. They are arranged almost in parallel with a gap.

A coaxial cable (not shown) 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 so that the folded inverted L antenna 1 is fed.
The notation of the dimensions of the respective parts of the folded inverted L antenna 1 of the first embodiment is shown in FIG. 5, and the folded inverted L antenna of the first embodiment when the dimensions of the respective parts of the folded inverted L antenna 1 are the following dimensions. The frequency characteristic of the voltage standing wave ratio (VSWR) of 1 is shown in FIG. The folded inverted L antenna 1 according to the first embodiment is assumed to be installed on a ground plate 15 having a size that can be regarded as electrically infinite, and the design frequency is 900 MHz (wavelength λ of free space: about 333.3 mm). And 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 0.141λ (about 47 mm), the distance Ed between the first element 10 and the folding element 11 is about 0.015λ (about 5 mm), and the width Ew01 of the first element 10 Is approximately 0.023λ (approximately 7.5 mm), the width Ew02 of the folding element 11 is approximately 0.003λ (approximately 1 mm), the length Ew03 of the connecting element 12 is approximately 0.030λ (approximately 10 mm), and the intermediate bent portion 10c. 11c, the length Es01 from the end of the connection element 12 is about 0.027λ (about 9 mm), and the length Es02 from the upper ends of the bent portions 10b, 11b of the intermediate bent portions 10c, 11c is about 0.084λ. (About 28 mm), the height Eh from the base plate 15 on the connecting element 12 side of the extending portion 10a and the extending portion 11a is about 0.101λ (about 33.5 mm), and the height Hs of the intermediate bent portions 10c and 11c is about 0.012λ About 4 mm), the height Gh of the rising element 13 in the power feeding section 14 is about 0.053λ (about 17.5 mm), and the gap Gp between the upper end of the rising element 13 and the tip of the bent portion 10b is about 0.012λ. (About 4 mm), the length EL02 of the bent portion 10b is about 0.036λ (about 12 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 0.3 mm.

  Referring to the frequency characteristics of the VSWR shown in FIG. 6, in the folded inverted L antenna 1 of the first embodiment, a good VSWR value of about 1.0 is obtained for the VSWR at the design frequency f (900 MHz). A VSWR of about 2.0 is obtained at 860 MHz indicated by 1 and 947 MHz indicated by the inverted triangle mark 3, and the center frequency of the frequency band of VSWR 2.0 is approximately 903.5 MHz indicated by the inverted triangle mark 2. A good VSWR of about 1.1 is obtained at a center frequency of about 903.5 MHz. In this case, the specific resonance band is about 9.6%. As described above, it is considered that the reason why the small and low-profile antenna has a wide band is that the intermediate bent portion 10c is formed in the first element 10 and the intermediate bent portion 11c is formed in the folding element 11. It is done.

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 impedance characteristics of the feeding portion 14 of the folded inverted L antenna 1 when the height Hs of the intermediate bent portions 10c and 11c is changed as a parameter between 0λ (0 mm) and 0.075λ (about 25 mm) are shown. 7 shows the VSWR characteristics at 900 MHz. Referring to FIG. 7, as the height Hs is increased from 0λ to 0.075λ, the resistance component increases from about 45Ω to about 60Ω, but the reactance component is constant at about 0Ω. When the height Hs is about 0.012λ (about 4 mm), the impedance of the power feeding section 14 is matched to about 50Ω. Note that the impedance of the folded inverted L antenna 1 can be finely adjusted by changing the height Hs, thereby making it possible to perform impedance matching.
Referring to FIG. 8, the VSWR changes from about 1.1 to about 1.0 and about 1.2 as the height Hs is increased from 0λ to 0.075λ, but a good VSWR characteristic is obtained. It has been. When the height Hs is about 0.012λ (about 4 mm) indicated by an inverted triangle mark, the best value of VSWR of about 1.0 is obtained.
Further, FIG. 9 shows the resonance bandwidth characteristics of the folded inverted L antenna 1 when the height Hs of the intermediate bent portions 10c and 11c is changed between 0λ (0 mm) and 0.075λ (about 25 mm) as a parameter. Show. Referring to FIG. 9, the resonance bandwidth increases from about 84 MHz (about 9.3%) to about 95 MHz (10.6%) as the height Hs is increased from 0λ to 0.075λ. When the height Hs is about 0.012λ (about 4 mm) indicated by the inverted triangle mark, a wide band of about 87 MHz (about 9.6%) is obtained, and when the height Hs is about 0.06λ (about 20 mm) A wide band of about 95 MHz can be obtained.

Next, when the length Es02 from the upper ends of the bent portions 10b and 11b of the intermediate bent portions 10c and 11c is changed from 0.003λ (about 1 mm) to 0.138λ (about 46 mm), the power feeding unit 14 FIG. 10 shows the impedance characteristics and FIG. 11 shows the VSWR characteristics at 900 MHz. Referring to FIG. 10, when the length Es02 is increased from 0.003λ to 0.138λ, the resistance component becomes constant at about 50Ω, but the reactance component decreases from about 20Ω to about 0Ω. When the length Es02 is about 0.084λ (about 28 mm) indicated by an inverted triangle mark, the impedance of the power feeding unit 14 is matched to about 50Ω. It should be noted that the impedance of the folded inverted L antenna 1 can be finely adjusted by changing the length of Es02, which makes it possible to perform impedance matching.
Referring to FIG. 11, as the length Es02 is increased from 0.003λ to 0.138λ, the VSWR changes from about 1.4 to about 1.0 and about 1.1. Is obtained. When the length Es02 is about 0.084λ (about 28 mm) indicated by an inverted triangular mark, the best value of VSWR of about 1.0 is obtained.

Next, when the width Ew01 of the first element 10 which is the width of the extending portion 10a and the bent portion 10b is changed from 0.005λ (about 1.65 mm) to 0.030λ (about 10 mm), the power feeding unit 14 FIG. 12 shows the impedance characteristics and FIG. 13 shows the VSWR characteristics at 900 MHz. Referring to FIG. 12, as the width Ew01 is increased from 0.005λ to 0.030λ, the resistance component decreases from about 75Ω to about 40Ω, but the reactance component becomes constant at about 0Ω. When the width Ew01 is about 0.023λ (about 7.5 mm) indicated by an inverted triangle mark, the impedance of the power feeding unit 14 is matched to about 50Ω. Note that the impedance of the folded inverted L antenna 1 can be finely adjusted by changing the length of the width Ew01, thereby enabling impedance matching.
Referring to FIG. 13, as the width Ew01 is increased from 0.005λ to 0.030λ, the VSWR changes from about 1.4 to about 1.0 and to about 1.1. Has been obtained. When the width Ew01 is about 0.023λ (about 7.5 mm) indicated by an inverted triangle mark, the best value of VSWR of about 1.0 is obtained.

Next, the impedance characteristic of the power feeding unit 14 when the width Ew02 of the folding element 11 which is the width of the extending portion 11a and the bent portion 11b is changed from 0.003λ (about 1 mm) to 0.015λ (about 5 mm). FIG. 14 shows the VSWR characteristics at 900 MHz. Referring to FIG. 14, as the width Ew02 is increased from 0.003λ to 0.015λ, the resistance component increases from about 50Ω to about 70Ω, and the reactance component also increases from about 0Ω to about 20Ω. When the width Ew02 is about 0.003λ (about 1 mm) indicated by an inverted triangle mark, the impedance of the power feeding section 14 is matched to about 50Ω. Note that the impedance of the folded inverted L antenna 1 can be finely adjusted by changing the length of the width Ew02, thereby enabling impedance matching.
Referring to FIG. 15, as the width Ew02 is increased from 0.003λ to 0.015λ, the VSWR changes from about 1.0 to about 1.5, but good VSWR characteristics are obtained. When the width Ew02 is about 0.003λ (about 1 mm) indicated by an inverted triangle mark, the best value of VSWR of about 1.0 is obtained.

  The folded inverted L antenna 1 according to the first 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 or the like is built in the wireless communication device, and the folded inverted L antenna 1 may be installed close to a conductor such as the circuit board. When the folded inverted L antenna 1 according to the first embodiment of the present invention installed in the wireless communication device is arranged close to the conductor and affected by the conductor, the influence of the conductor is adjusted by adjusting the dimensions. Can be avoided as much as possible. FIG. 16 is a perspective view showing a configuration in which the folded inverted L antenna 1 of the first embodiment is arranged close to the circuit board 20, and FIG. 16 shows the folded inverted L antenna 1 of the first embodiment close to the circuit board 20. FIG. 17 is a front view showing the arrangement, and FIG. 18 is a top view showing the arrangement in which the folded inverted L antenna 1 of the first embodiment is arranged close to the circuit board 20, and the inverted inverted L of the first embodiment. A right side view showing a configuration in which the antenna 1 is arranged close to the circuit board 20 is shown in FIG.

  As shown in these drawings, the folded inverted L antenna 1 of the first embodiment is arranged upright on a ground plane 15 built in the wireless communication device. In this case, the folded inverted L antenna 1 is disposed on the ground plate 15 in the vicinity of the circuit board 20 supported on both sides by the board support portions 21. At this time, the extending portion 10a of the first element 10 and the extending portion 11a of the folding element 11 are opposed to the upper surface of the circuit board 20 at a narrow interval and substantially parallel to each other, and the bent portion 10b and the folding element 11 of the first element 10 are opposed. The bent portion 11b faces the circuit board 20 almost in parallel with a narrow interval. The ground plane 15 has a size that can be regarded as electrically infinite.

  Here, it is assumed that the width of the circuit board 20 is about 20 mm and the height of the arranged circuit board 20 is about 15 mm. In this case, the distance between the extended portions 10a and 11a ahead of the intermediate bent portions 10c and 11c and the circuit board 20 is about 18.5 mm, and the extended portions 10a and 11a and the circuit board before the intermediate bent portions 10c and 11c. The distance from 20 is about 14.5 mm. When the design frequency of the folded inverted L antenna 1 of the first embodiment is set to 900 MHz, the width Ew01 of the extending portion 10a and the bent portion 10b of the first element 10 is about 0.012λ (about 4 mm), and the folded element 11, the width Ew02 of the extending portion 11a and the bent portion 11b is changed to about 0.012λ (about 4 mm), and the distance Ed between the first element 10 and the folding element 11 is changed to about 0.017λ (about 5.5 mm). Yes.

FIG. 20 shows the frequency characteristics of the VSWR when the folded inverted L antenna 1 of the first embodiment having such dimensions is arranged close to the circuit board 20 as shown in FIGS.
Referring to FIG. 20, in the folded inverted L antenna 1 of the first embodiment, the VSWR is slightly deteriorated to about 1.2 at the design frequency (900 MHz), but a good VSWR value is obtained. The VSWR is about 2.0 at 873 MHz indicated by the inverted triangle mark 1 and 938 MHz indicated by the inverted triangle mark 3, and the center frequency of the frequency band of VSWR 2.0 is about 905.5 MHz indicated by the inverted triangle mark 2. The VSWR at the center frequency of about 905.5 MHz is about 1.2, which is a good value. The specific resonance band in this case is about 7.2%, which is slightly narrower than the case without the circuit board 20, but it can be seen that a sufficiently wide resonance band is obtained even under the influence of the circuit board 20. As described above, when the folded inverted L antenna 1 of the first embodiment is disposed close to a conductor such as the circuit board 20, impedance matching is achieved by adjusting the dimensions of the width Ew01, the width Ew02, and the interval Ed. It can be seen that the influence of the circuit board 20 that deteriorates the VSWR characteristics and the resonance band can be suppressed as much as possible.

Next, FIG. 21 is a perspective view showing the configuration of the folded inverted L antenna device 2 of the present invention. The folded inverted L antenna device 2 is an antenna device disposed on a ground plane 15 including a circuit board 20 supported on both sides by a substrate support portion 21. The folded inverted L antenna according to the second embodiment of the present invention. An antenna 3 is provided.
The folded inverted L antenna device 2 of the present invention shown in FIG. 21 includes an insulating element base 25 made of synthetic resin, the folded inverted L antenna 3 of the second embodiment according to the present invention, a power supply substrate 38, and the like. , And holding metal fittings 39.

  A perspective view showing the configuration of the element base 25 is shown in FIG. As shown in FIG. 22, the element base portion 25 made of synthetic resin includes an element support portion 25a composed of a first step portion 25b and a second step portion 25c, and a leg portion 25d. The element support portion 25a has an elongated rectangular plate shape. A step is formed between the first step portion 25b and the second step portion 25c, and the second step portion 25c is formed one step lower than the first step portion. ing. Thin columnar bosses 25f are formed to protrude from the four corners of the upper surface of the second step portion 25c. Further, a low step which is one step higher is formed at the tip of the first step portion 25b, and a pair of bosses 25f are formed from the center of the step. Further, a columnar leg portion 25d is formed to extend substantially perpendicularly from the back surface of the tip portion of the first step portion 25b. A conical insertion portion 25e is formed at the tip of the leg portion 25d, and the diameter of the base of the insertion portion 25e is narrowed. When the fitting portion 25e is fitted into the mounting hole formed in the circuit board 20, the fitting portion 25e is inserted so as not to easily come out of the mounting hole due to the narrowed portion at the base of the fitting portion 25e.

  FIG. 23 is a perspective view showing the configuration of the folded inverted L antenna 3 of the second embodiment. The folded inverted L antenna 3 of the second embodiment is formed by processing a metal plate, and as shown in FIG. 23, it is an elongated plate and is formed with a step in the middle bent portion 30c in the middle. An L-shaped first element 30 composed of 30a and a bent portion 30b of a predetermined length bent at a right angle from the extending portion 30a, and a stepped portion of the intermediate bent portion 31c are formed in the middle of an elongated plate shape. And an L-shaped folding element 31 arranged substantially in parallel with the first element 30 including a bent part 31b bent at a right angle from the extending part 31a. Further, it has a fixed portion 36 formed by being bent and fixed to the ground plate 15, and a plate-like rising element 33 erected almost vertically on the ground plate 15. The other side portion is formed to have substantially the same width as the bent portion 31b. A mountain-shaped portion 33b is formed which extends in the lateral direction from the boundary between the rising element 33 and the bent portion 31b and bulges at the center. In addition, elongated rectangular fixing pieces 33a bent at substantially right angles are formed on both side surfaces of the lower portion of the rising element 33, respectively. Further, an elongated fixed piece 33a bent at a substantially right angle is formed at a lower portion of the outer side surface of the bent portion 30b, and an elongated fixed piece 33a bent at a substantially right angle is formed on the inner side surface of the bent portion 31b. Is formed. These four fixing pieces 33a are formed to be substantially parallel.

  Further, 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 are predetermined. They are arranged almost in parallel with an interval. Further, two fitting holes 32a are formed on both sides of the connection element 32, and two of the extended portions 30a in front of the intermediate bent portion 30c and two of the extended portions 31a in front of the intermediate bent portion 31c. A fitting hole 32a is formed at each location. The fitting hole 32a will be described. The folded inverted L antenna 3 is fixed to the element base 25. However, when the folded inverted L antenna 3 is placed on the upper surface of the element base 25, the six fitting holes 32a are formed. Each of the six bosses 25f formed on the upper surface of the element base portion 25 is fitted therein. At this time, the tip of the connection element 32 comes into contact with a step formed on the upper surface of the first step portion 25b. The folded inverted L antenna 3 can be fixed to the element base portion 25 by welding so as to crush the boss 25f inserted through the fitting hole 32a and projecting from the upper portion.

FIG. 24 shows the configuration of the power supply board 38 which is a printed board. As shown in FIG. 24, the power supply substrate 38 has a rectangular shape. A substantially rectangular connection pattern 38b is formed on the upper surface of the power supply substrate 38, and a ground pattern 38c is formed below the connection pattern 38b. Is formed. A vertically long insertion hole 38 d is formed on both sides slightly below the center of the power supply substrate 38. In addition, shallow grooves are formed on both sides of the upper side surface and the lower side surface of the power supply substrate 38. The core wire 35a of the introduced coaxial cable 35 is soldered to the connection pattern 38b. Further, the shield portion 35b of the coaxial cable 35 is soldered to the ground pattern 38c. Further, a holding bracket 39 that holds the coaxial cable 35 is fixed to the power supply substrate 38.
A perspective view showing the configuration of the holding metal fitting 39 is shown in FIG. As shown in this figure, the holding metal fitting 39 is formed by processing an elongated rectangular metal plate. At both ends of the holding metal fitting 39, a bent piece 39b which is bent at a substantially right angle is formed, and a chevron 39a which is bent so as to swell in a semicircular shape is formed at the center. The two bent pieces 39b of the holding metal fitting 39 are inserted into the insertion holes 38d of the power supply board 38 to which the coaxial cable 35 is connected, and the bent pieces 39b protruding from the insertion holes 38d of the power supply board 38 to the back side. The tip is bent inward as indicated by the broken line. As a result, the coaxial cable 35 is held in the chevron 39 a of the holding metal fitting 39.

  The power supply board 38 thus assembled is inserted between the fixed pieces 33a of the folded inverted L antenna 3, and the four fixed pieces 33a are inserted into shallow grooves formed on both sides of the power supply board 38. To do. Then, as shown by broken lines in FIG. 23, each of the four fixing pieces 33a is bent so as to sandwich the back surface of the power supply substrate 38, whereby the power supply substrate 38 is folded substantially vertically and the rising element 33 of the inverted L antenna 3 and It comes to adhere along the inner side of bending part 30b, 31. Next, the lower end of the bent portion 30b is soldered to the upper portion of the connection pattern 38b, and the upper end of the rising element 33 is soldered to the ground pattern 38c. As a result, the power feeding unit 34 is configured, and power is fed from the coaxial cable 35 to the folded inverted L antenna 3 via the power feeding board 38. Further, the shield portion 35b of the coaxial cable 35 is held in the mountain-shaped portion 33b formed by extending in the lateral direction from the boundary portion between the rising element 33 and the bent portion 31b. The tip is soldered to the ground pattern 38c.

Thereby, the folded inverted L antenna device 2 according to the present invention is assembled. When the folded inverted L antenna device 2 is mounted in a wireless communication device provided with the circuit board 20 supported on the ground plane 15 by the substrate support portion 21, the rising element 33 in the folded inverted L antenna 3 is provided. Screws 37 are respectively inserted into the pair of insertion holes 36a of the fixing portion 36 that is formed by being bent at the lower end of the screw. Further, the fitting portion 25 e at the tip of the leg portion 25 d of the element base portion 25 is fitted into a mounting hole formed in the circuit board 20. Next, the folded inverted L antenna device 2 can be attached to the ground plate 15 in the wireless communication device by screwing the screw 37 inserted into the insertion hole 36a to the ground plate 15.
The folded inverted L antenna apparatus 2 of the present invention is smaller in size because the extended portions 30a and 31a of the folded inverted L antenna 3 are provided with intermediate bent portions 30c and 31c to shorten the length in the major axis direction. Can be Further, since the folded inverted L antenna 3 can be secured to the element base portion 25 for protection, an antenna suitable for mass production can be provided with high accuracy.

The folded inverted L antenna 3 of the second embodiment according to the present invention described above exhibits the same electrical characteristics as the electrical characteristics exhibited by the folded inverted L antenna 1 of the first embodiment. The folded inverted L antenna according to each embodiment of the present invention can realize a wide band while being a small and low-profile antenna by optimizing the dimensions of each part in conjunction with each other.
In the above description, the impedance of the power feeding part is adjusted by adjusting the width and interval of the first element and the folding element, but the power feeding part is adjusted by adjusting the position of the intermediate bent part formed in the extending part. The impedance may be adjusted. In addition, since impedance adjustment can be performed even when a conductor such as a circuit board 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 shape of the circuit board or the like. Since the impedance can be adjusted, it can be optimized as a built-in antenna.

DESCRIPTION OF SYMBOLS 1 Folding reverse L antenna, 2 Folding reverse L antenna apparatus, 3 Folding reverse L antenna, 10 1st element, 10a extension part, 10b bending part, 10c intermediate bending part, 11 Folding element, 11a extension part, 11b Bending Part, 11c Intermediate bending part, 12 Connecting element, 13 Rising element, 14 Feeding part, 15 Ground plane, 20 Circuit board, 21 Substrate support part, 25 Element base part, 25a Element support part, 25b First step part, 25c 2nd step part, 25d Leg part, 25e Insertion part, 25f Boss, 30 1st element, 30a Extension part, 30b Bending part, 30c Intermediate bending part, 31 Folding element, 31a Extension part, 31b Bending part, 31c Intermediate bending part, 32 connecting element, 32a fitting hole, 33 upright element, 33a fixing piece, 33b chevron, 34 feeding part, 35 coaxial cable, 35 Core wire, 35b Shield part, 36 Adhering part, 36a Insertion hole, 37 Screw, 38 Power supply board, 38b Connection pattern, 38c Ground pattern, 38d Insertion hole, 39 Holding bracket, 39a Angle part, 39b Bent piece, 100 Folding reverse L Antenna, 110 1st element, 110a Extension part, 110b Bending part, 111 Folding element, 111a Extension part, 111b Bending part, 112 Connection element, 114 Feeding part, 115 Ground plane

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 that is connected to the tip of the first bent portion at a substantially right angle, extends substantially parallel to the ground plane, and has a bent portion formed in the middle thereof;
A plate-like second extending portion that is connected to the tip of the second bent portion so as to be substantially perpendicular, extends substantially parallel to the base plate, and has a bent portion formed in the middle thereof;
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 The impedance adjustment is performed by adjusting the width of the element and the folded element, and the position of the bent part formed in the middle of the first extending part and the second extending part. A folded inverted L antenna. The folded inverted L antenna according to claim 1;
An insulating element base portion comprising a rectangular plate-shaped element support portion formed with a step in the middle, and a leg portion extending substantially perpendicularly from the tip of the back surface of the element support portion;
A power supply board configured with the power supply unit;
The first extending portion, the second extending portion, and the connection element are supported in close contact with the upper surface of the element support portion of the element base portion, and the rising element and the first folding portion are supported. The folded inverted L antenna device, wherein the feeding substrate is fixed to the back side of the bent portion and the second bent portion.   A tip of the leg portion of the element base portion is fixed to a circuit board disposed on the ground plate, and a fixing portion formed at a lower end of the rising element is fixed to the ground plate. The folded inverted L antenna device according to claim 2.

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