JP4611039B2 - antenna - Google Patents

Description

  The present invention relates to an antenna having an air gap between a patch and a ground.

  In many wireless applications, including wireless local area networks (LANs), wireless wide area networks (WANs), and wireless personal area networks (PANs), broadband high-gain planar antennas have been required and have been widely used in the past. Strip antennas (planar antennas) have been developed. As a kind of the microstrip antenna, a relatively wide band and high gain air gap antenna as shown in Patent Document 1 has been developed. This air gap antenna is used in, for example, a DSRC (Dedicated Short Range Communication) machine in ITS (Intelligent Transport System).

  As shown in FIG. 8, the air gap antenna holds a conductor plate serving as a patch and a conductor plate serving as a ground in parallel, and is composed of air (space), that is, an air gap, between the two conductor plates of the patch and the ground. Antenna. The antenna gain and bandwidth are controlled by the air gap. In general, power supply to a square or circular patch is coaxial power supply from the back, and the coaxial central conductor (or power supply pin) and the patch are connected by soldering. Here, the air gap antenna can obtain the linearly polarized wave / circularly polarized wave characteristics by the feeding method and the patch shape, like the microstrip antenna generally formed of a dielectric substrate. In addition, the air gap antenna is composed of air whose relative dielectric constant is as close to 1 as possible, and has a large patch size (about λ / 2), so it is often used for applications where there is no limit on the size. Further, the air gap antenna can also adjust (tune) the resonance frequency by using a change in dielectric constant caused by inserting a dielectric material into the air gap. When a dielectric material is inserted into the air gap, the dielectric material is configured to be in contact with the ground and not in contact with the patch. In the air gap antenna shown in Patent Document 1, the polarization is a straight line (either vertical or horizontal).

JP-A-8-307134

  However, the air gap antenna having a conventional structure has an inductance (inductive) component when the coaxial central conductor of the power feeding unit is connected through a space, and impedance matching is lost. There was a problem. Here, even if the patch and the ground are shortened in order to suppress the inductance component, there is a problem that the frequency bandwidth as the antenna characteristic is narrowed.

  In addition, since the air gap antenna is air between the patch and the ground, there is a problem that it is weak in strength such as deformation due to external force. In addition, the air gap antenna must have two conductor plates, a patch and a ground, formed in parallel. When the air gap antenna is formed obliquely, there is a problem that the antenna characteristics change.

  Furthermore, the air gap antenna has a coaxial central conductor (or feed pin) and a patch that are connected by soldering, so the structure of the feed section is inexpensive, but soldering is performed at frequencies where the patch is relatively large. There is also a problem that the heat escapes during the connection, and the connection is difficult.

  Therefore, the present invention provides an air gap antenna that can improve impedance characteristics and improve assemblability and strength / holdability.

Means and effects for solving the problems

An antenna according to the present invention includes a patch formed of a conductor plate, a ground formed of a conductor plate that is installed in parallel with the patch and forms an air gap between the patch, and a non-contact electrically. A coaxial connector that is connected to a coaxial cable and feeds power, the central conductor being formed in a concave shape and inserted into the central conductor. The connected feed pin and the patch are caulked and connected to the patch via the feed pin , and the outer conductor is fixed to the ground by a metal fixing means, and the ground line and having electrically connected to Ru coaxial connector, the air gap substantially the same height, the feeding pin and said patch connecting the centers of the patches and the feeding point that is caulked connected The is one disposed near two or either one side in the vicinity of both sides of the patch, and a dielectric material is secured to the patch and the ground by the resin fixing means, said feed pin A head formed with a diameter that can be caulked with the patch; a diameter that can be inserted into the central conductor portion; and the head can be caulked with being inserted into the central conductor portion. a leg portion which is formed in such a length, is formed from, characterized in Rukoto.

According to this, at least one side (one side or both ends) of the patch on a straight line connecting the feeding point and the center of the patch, which is a point where the patch and the central conductor of the coaxial connector are connected, is substantially the same as the air gap. Since the dielectric material having the height of is inserted, the input impedance characteristic of the antenna is improved. Further, since the number of fixing points by the dielectric material having substantially the same height as the air gap is increased, the patch and the ground can be kept parallel, resistance to external force can be improved, and deformation can be prevented. In addition, since the feed pin fixed to the patch is formed to be slightly thick for caulking connection, the inductance component of the feed pin itself is reduced and the input impedance characteristic of the antenna is improved. Further, caulking is used as a connecting means between the patch conductor plate and the power supply pin, and the power supply pin is inserted and connected to the concave portion of the central conductor of the coaxial connector, so that a structure that does not require soldering is obtained, and assemblability is improved. .

Here, the antenna according to the present invention has substantially the same height as the air gap, is disposed near the center of the patch, and is fixed to the patch and the ground by a metal fixing means. , May be further provided .

According to this, since the number of fixing points by the dielectric material having substantially the same height as the air gap increases, it is possible to keep the patch and the ground parallel to each other, improve resistance to external force, and prevent deformation. it can. Further, by using metal fixing means as the dielectric material fixing means, the patch and the ground are electrically short-circuited, and effects such as electrostatic countermeasures and suppression of higher-order modes can be obtained.

  The best mode for carrying out the antenna according to the present invention will be described below with reference to a specific example with reference to the drawings.

  First, an air gap antenna according to an embodiment of the present invention will be described below with reference to FIGS. 1A and 1B are views showing an air gap antenna according to an embodiment of the present invention, wherein FIG. 1A is a top view, FIG. 1B is a front view, and FIG. 1C is a side view. FIG. 2 is a top view showing an air gap antenna patch according to an embodiment of the present invention. FIG. 3 is a top view showing the ground of the air gap antenna according to the embodiment of the present invention. 4A and 4B are views showing a coaxial connector of an air gap antenna according to an embodiment of the present invention, wherein FIG. 4A is a partially sectional side view, and FIG. 4B is a top view. FIG. 5 is a side view showing the power supply pin of the air gap antenna according to the embodiment of the present invention.

  As shown in FIG. 1, the air gap antenna 10 includes air (space) by a patch 1 formed of a conductive plate (for example, brass or nickel plating) and a ground 2 formed of a conductive plate (for example, aluminum). ), That is, the air gap 9 is formed.

  The patch 1 is an element part of the air gap antenna 10 and is formed so that the side length is about ½ wavelength. As shown in FIG. 2, the patch 1 is formed with a feeding point 1 a that is a hole for caulking and connecting a feeding pin 5 described later. Further, two screw holes 3a for fixing a dielectric spacer (dielectric material) 3 to be described later with resin screws 8 are formed in the vicinity of both ends of the patch 1 on a straight line connecting the feeding point 1a and the center of the patch 1. Has been. A screw hole 4a for fixing a dielectric spacer 4 (to be described later) with a metal screw 7 is formed at the center.

  The ground 2 is a ground portion of the air gap antenna 10, and the antenna directivity changes depending on the dimensions. As shown in FIG. 3, the screw holes 3b for fixing the dielectric spacer 3 with the resin screws 8 are formed in the ground 2 at positions corresponding to the screw holes 3a formed in the patch 1 by tapping. Has been. Further, a screw hole 4b for fixing a dielectric spacer 4 (to be described later) with a metal screw 7 is formed at the center corresponding to the screw hole 4a formed in the patch 1 by tapping. Further, a screw hole 2a for fixing a coaxial connector 6 described later is provided by tapping at a position corresponding to the feeding point 1a formed in the patch 1. In addition, five holes 2b for attaching the air gap antenna 10 are provided at four corners of the ground 2 (one at each of the three corners and two at one corner). The five holes 2b for attaching the air gap antenna 10 may not be provided. Further, as shown in FIG. 3, a notch for making the mounting direction of the air gap antenna 10 unique is formed in the center of the right side of the ground 2, but the notch may not be formed. Absent.

  As shown in FIGS. 1B and 1C, the air gap 9 has two dielectric spacers (dielectric materials) configured to have a height substantially the same as the height of the air gap 9. 3 is arranged in the vicinity of both ends of the patch 1 on a straight line connecting a feeding point 5a described later and the center of the patch 1. In the air gap antenna 10 according to the present embodiment, two dielectric spacers 3 are arranged on both sides of the patch 1 on a straight line connecting a feeding point 5a described later and the center of the patch 1, but at least The effect of the present invention can be obtained if one is arranged in the vicinity of either one of the sides. After the two dielectric spacers 3 are inserted into the air gap 9, the screw holes 3 a formed in the patch 1 are screwed together with resin screws 8 from the patch 1 side to the screw holes 3 b formed in the ground 2. It is fixed by being penetrated. Thereby, the dielectric spacer 3 is fixed in contact with both the patch 1 and the ground 2. Here, by using the resin screw 8 as the fixing means for the dielectric spacer 3, the antenna characteristics are not affected. The fixing means for the dielectric spacer 3 is not limited to the resin screw 8, but may be other fixing means as long as the material is resin. The shape of the dielectric spacer 3 is a cylindrical shape having substantially the same height as the height of the air gap 9.

  Further, in the air gap 9, in order to hold the patch 1, one dielectric spacer 4 configured to have substantially the same height as the height of the air gap 9 is disposed near the center of the patch 1. . After one dielectric spacer 4 is inserted into the air gap 9, the screw hole 4 a formed in the patch 1 is screwed with the metal screw 7 from the patch 1 side to the screw hole 4 b formed in the ground 2. It is fixed by being penetrated. Thereby, the dielectric spacer 4 is fixed in contact with both the patch 1 and the ground 2. Here, by using the metal screw 7 as the fixing means for the dielectric spacer 4, the patch 1 and the ground 2 are electrically short-circuited, and effects such as countermeasures against static electricity and suppression of higher-order modes can be obtained. The fixing means for the dielectric spacer 4 is not limited to the metal screw 7, but may be other fixing means as long as the material is metal. The shape of the dielectric spacer 4 is a cylindrical shape having substantially the same height as the height of the air gap 9. Furthermore, the dielectric spacer 4 may not be installed.

  As shown in FIG. 1 (b), at the feeding point 1a, the patch 1 and the feeding pin 5 inserted into the central conductor portion (center conductor) 6a of the coaxial connector 6 to be described later are connected by caulking. Here, as shown in FIG. 4A and FIG. 4B, the coaxial connector 6 includes a concave central conductor portion 6a into which the feed pin 5 is inserted and an outer conductor portion (outer conductor) 6b. Then, it is connected to a coaxial cable (not shown) and supplied with power. The central conductor portion 6a and the outer conductor portion 6b are formed so as not to be in electrical contact with each other. On the other hand, the feed pin 5 is formed of a head 5a and a leg 5b, as shown in FIG. The leg portion 5b is inserted into the concave central conductor portion 6a of the coaxial connector 6 from the distal end portion, and is electrically connected to the central conductor portion 6a of the coaxial connector 6. The head 5 a is caulked with the patch 1 at a feeding point 1 a formed on the patch 1. Here, the head 5a is formed with a slightly thicker diameter (for example, about 2.5 to 3.0 mm) so that it can be caulked with the patch 1, and the leg 5b is formed with a smaller diameter than the head 5a. The In FIG. 5, the leg portion 5b is formed with a smaller diameter than the head portion 5a, but the size of the diameter of the head portion 5a and the leg portion 5b is not related. That is, the head 5a is formed with a diameter that allows caulking connection to the patch 1, and the leg 5b can be inserted into the central conductor 6a. As described above, in the coaxial connector 6, power is supplied to the patch 1 from the central conductor portion 6 a via the power supply pin 5. As shown in FIG. 1B, the leg 5b is formed with a length that allows the head 5a to be caulked and connected between the patch 1 and the feeding point 1a while being inserted into the central conductor 6a. As shown in FIG. 4B, the coaxial connector 6 has two screw holes 6c, and a not-shown metal screw is screwed into the screw hole 6c and the screw hole 2a formed in the ground 2. Thus, the coaxial connector 6 is fixed to the ground 2. The fixing means for the coaxial connector 6 is not limited to a metal screw, but may be other fixing means as long as the material is metal.

  Next, the measurement results of measuring the voltage standing wave ratio (VSWR) characteristics when the conventional air gap antenna is used and when the air gap antenna according to the embodiment of the present invention is used are shown in FIG. And it demonstrates based on FIG. FIG. 6 shows measurement results obtained by measuring VSWR characteristics when a conventional air gap antenna is used. In FIG. 6, in order to facilitate the comparison of the VSWR characteristics, the measurement results obtained by measuring the VSWR characteristics when the conventional air gap antenna is used are shown by a solid line, and according to the embodiment of the present invention shown in FIG. 7. The measurement results obtained by measuring the VSWR characteristics when the air gap antenna 10 is used are shown by overlapping with dotted lines. FIG. 7 shows measurement results obtained by measuring the VSWR characteristics when the air gap antenna 10 according to the embodiment of the present invention is used. In FIG. 7, in order to facilitate the comparison of the VSWR characteristics, the measurement result of measuring the VSWR characteristics when the air gap antenna 10 according to the embodiment of the present invention is used is shown by a solid line, and the conventional technique shown in FIG. The measurement results obtained by measuring the VSWR characteristics when using the air gap antenna of FIG.

  The air gap antenna 10 according to the embodiment of the present invention used in the measurement has a 2.4 GHz band and the shape of the patch 1 is a right-handed circularly polarized square, and one side of the patch 1 formed of brass or nickel plating. The length was 54.4 mm, the thickness was 1 mm, the height of the air gap 9 was 4.3 mm, the length of one side of the ground 2 made of aluminum was 80 mm, and the thickness was 3 mm. Further, in the patch 1, a screw hole 4a having an outer diameter of φ3.2 mm at the center, a feeding point 1a having an outer diameter of φ2 mm at a position 15 mm from the center, and a center on a straight line connecting the feeding point 1a from the center. Two screw holes 3a having an outer diameter of φ3.5 mm were formed at a position of 2 mm, that is, a position of 4 mm from both ends. The feeding point 1 a was formed so that the straight line connecting the feeding point 1 a from the center of the patch 1 was parallel to the side of the patch 1. In the gland 2, five holes 2b having an outer diameter of φ3.5 mm were formed at the four corners. Then, a cylindrical resin spacer (dielectric spacer) 4 having an outer diameter of 15 mm is fixed to the patch 1 and the ground 2 so that the center is disposed in the screw hole 4a, and a cylindrical resin having an outer diameter of 6 mm is disposed so that the center is disposed in the screw hole 3a. A spacer (dielectric spacer) 3 was fixed to the patch 1 and the ground 2. Furthermore, the feed pin 5 was formed such that the thickest part of the head 5a had an outer diameter of φ3.0 mm and the leg portion 5b had an outer diameter of φ0.92 mm. An SMA connector was used as the coaxial connector 6. On the other hand, the conventional air gap antenna is formed in the same shape as the air gap antenna 10 according to the embodiment of the present invention used for the measurement, and the dielectric spacer 3 is not inserted into the air gap 9 and is SMA coaxial. The connector center conductor and the patch 1 were connected by soldering at the feeding point 1a.

  As shown in FIGS. 6 and 7, when compared with a center frequency of 2.42 GHz ± 0.02 GHz, the VSWR characteristic of the conventional air gap antenna is 2.0, whereas the air according to the embodiment of the present invention is used. It can be seen that the VSWR characteristic of the gap antenna is kept low at 1.34, and the VSWR characteristic is improved.

As described above, according to the air gap antenna 10 according to the embodiment of the present invention, on the straight line connecting the feed point 1a, which is the point where the patch 1 and the central conductor 6a of the coaxial connector 6 are connected, and the center of the patch 1. Since the two dielectric spacers 3 having substantially the same height as the air gap 9 are inserted in the vicinity of both ends of the patch 1, the input impedance characteristic of the air gap antenna 10 is improved. In addition, since the dielectric spacers 3 and 4 having substantially the same height as the air gap 9 increase the number of fixing points of the patch 1 with respect to the ground 2 of the air gap antenna 10, the patch 1 and the ground 2 are kept parallel. In addition, the resistance to external force can be improved and deformation can be prevented.

  Further, since the head 5a of the feed pin 5 fixed to the patch 1 is formed to be slightly thick for caulking connection, the inductance component of the feed pin 5 itself is reduced, and the input impedance characteristic of the air gap antenna 10 is reduced. Will improve. In addition, since caulking is used as a connecting means between the patch 1 and the power supply pin 5 and the power supply pin 5 is inserted and connected to the concave portion of the central conductor 6a of the coaxial connector 6, a structure that does not require soldering is obtained. Will improve.

  In addition, about the air gap antenna 10 which concerns on embodiment of this invention, the influence which it has on an antenna radiation characteristic is a range which can be disregarded.

  As mentioned above, although this invention is described in said preferable embodiment, this invention is not restrict | limited only to it. Various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention. In addition, the specific examples illustrate the configuration of the present invention and do not limit the present invention.

  For example, the shape of the air gap antenna 10 is not limited to the shape shown in FIG. In other words, any shape can be used as long as the air gap antenna is configured such that the conductor plate serving as the patch and the conductor plate serving as the ground are held in parallel and the space between the two conductor plates of the patch and the ground is constituted by air (space). Even if it exists, this invention is applicable.

It is a figure which shows the air gap antenna which concerns on embodiment of this invention, (a) is a top view, (b) is a front view, (c) is a side view. It is a top view which shows the patch of the air gap antenna which concerns on embodiment of this invention. It is a top view which shows the ground of the air gap antenna which concerns on embodiment of this invention. It is a figure which shows the coaxial connector of the air gap antenna which concerns on embodiment of this invention, (a) is a partial cross section side view, (b) is a top view. It is a side view which shows the electric power feeding pin of the air gap antenna which concerns on embodiment of this invention. It is the measurement result which measured the VSWR characteristic at the time of using the conventional air gap antenna. It is the measurement result which measured the VSWR characteristic at the time of using the air gap antenna which concerns on embodiment of this invention. It is the schematic which shows the conventional air gap antenna.

Explanation of symbols

1 Patch 1a Feed point 2 Ground 3 Dielectric spacer (dielectric material)
5 Power supply pin 6 Coaxial connector 6a Center conductor (center conductor)
6b Outer conductor (outer conductor)
9 Air gap 10 Air gap antenna

Claims (2)

A patch formed of a conductor plate;
A ground formed by a conductive plate installed in parallel with the patch and forming an air gap with the patch;
A coaxial connector comprising a central conductor and an outer conductor formed so as to be electrically non-contacted, and connected to a coaxial cable to feed power, wherein the central conductor is configured in a concave shape, The feed pin inserted into and connected to the center conductor and the patch are caulked and connected to the patch via the feed pin , and the outer conductor is connected to the ground by a metal fixing means. is fixed, and a coaxial connector that will be connected the ground electrically,
Two or any one of the two sides near the both sides of the patch on a straight line connecting the feeding point where the feeding pin and the patch are caulked and having the same height as the air gap is one disposed near, the dielectric material is secured to the patch and the ground by the resin fixing means,
Equipped with a,
The power supply pin has a head formed with a diameter that can be caulked to the patch, a diameter that can be inserted into the central conductor, and the head that is inserted into the central conductor. antenna characterized but a leg portion which is formed by caulking connectable lengths, the Rukoto formed from.   A dielectric material having substantially the same height as the air gap, disposed near the center of the patch, and fixed to the patch and the ground by a metal fixing means;
  The antenna according to claim 1, further comprising:

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