JP4777276B2 - Antenna device - Google Patents

Description

  The present invention relates to a dual-frequency wireless LAN (Local Area Network) base station antenna device having a horizontally polarized wave as a main polarized wave and a non-directional radiation pattern in a horizontal plane.

  With the spread of notebook PCs (Personal Computers), IEEE802.11b / g (2.4GHz band, 2.4-2.5GHz), IEEE802.11a (5.2GHz band, 5.15-5.25GHz) Wireless Internet access services using wireless LAN cards compliant with the standard are spreading. Since the antenna for a wireless LAN card operates as a horizontally polarized antenna when a notebook PC is mounted, the base station antenna device for a wireless LAN has horizontal polarization as the main polarization in two frequency bands and is omnidirectional in the horizontal plane. There is a need for a base station antenna having a radiating pattern.

On the other hand, FIG. 10 is a conceptual diagram showing an example of a cylindrical slot antenna which is one of horizontally polarized omnidirectional antennas. In the cylindrical slot antenna, 12 is a cylindrical metal conductor, 13 is a slot, 15 is an outer conductor of the coaxial line, and 14 is an inner conductor of the coaxial line.
In the cylindrical slot antenna, the slot length required for resonance is mainly determined by the cylindrical diameter and the slot width, and the slot antenna has a single resonance band (see, for example, Non-Patent Document 1).

In the cylindrical slot antenna, in order to expand the reception band for the purpose of including two frequency bands, it is necessary to widen the slot width. However, since the slot length necessary for resonance becomes large, the antenna dimensions are It gets bigger.
In addition, it is difficult to produce a slot with two resonances with a cylindrical slot antenna, and in order to realize a non-directional radiation pattern in a horizontal plane, the diameter of the cylinder is set to 0.1 wavelength (0.1λ ₀ , Λ ₀ is a free space wavelength) (see, for example, Non-Patent Document 2).
HCJordan and WEMiller, "Slotted-cylinder antenna", Electronics, pp.90-93, Feb.1947 G. Sinclair, "The pattern of slotted-cylinder anntenas," Proceeding of IRE, pp1487, Dec.1948

As described above, in the cylindrical slot antenna, it is difficult to share two frequency bands and to realize an omnidirectional radiation pattern in the horizontal plane in these two frequency bands due to restrictions on the antenna configuration and antenna characteristics. It is.
The present invention has been made in view of such circumstances, and provides an antenna device that has horizontal polarization as a main polarization, operates in two frequency bands, and has a favorable omnidirectional radiation pattern in a horizontal plane. For the purpose.

The antenna device according to the present invention includes a first coaxial line that feeds power to an antenna including an outer conductor and an inner conductor, and one end between each of first and second arc-shaped plate conductors formed in an arc shape. And the other end of the first arc-shaped plate conductor is connected to the inner conductor of the coaxial line, and the second arc-shaped plate conductor The first antenna having the other end connected to the outer conductor of the coaxial line and having a first resonance frequency, and different heights in the direction perpendicular to the first plane formed by the arc of the first antenna Are arranged in an annular shape so that the inner circumferential surfaces of the arcs are opposed to each other, having a second gap between one end of each of the third and fourth arc-shaped plate conductors formed in an arc shape. The other end of the third arc-shaped plate conductor is connected to the inner conductor of the coaxial line, and the fourth arc-shaped plate conductor A second antenna having a second resonance frequency, the other end of which is connected to the outer conductor of the coaxial line, and the first arc-shaped plate conductor and the third arc-shaped plate conductor are It arrange | positions in the position which mutually opposes via the said inner conductor of the said coaxial line, The said 2nd circular arc shaped plate conductor and the said 4th circular arc shaped plate conductor oppose each other via the said outer conductor of the said coaxial line. The first antenna and the second antenna are arranged at positions such that the first gap and the second gap are the first and third arc-shaped plate conductors and the inner conductor of the coaxial line. the connection point and the second and fourth arcuate plate conductor and the I facing backward as viewed from the connection point between the outer conductor of the coaxial line urchin and the first and second arc-shaped plate conductor, And the ring formed by the third and fourth arcuate plate conductors are the first ring Are arranged so as not to overlap when viewed from a direction perpendicular to the plane, the sum of the lengths in the circumferential direction of the first and second arc-shaped plate conductor is approximately 1/2 wavelength at the first resonant frequency, The sum of the lengths in the circumferential direction of the third and fourth arc-shaped plate conductors is approximately ½ wavelength at the second resonance frequency .

  The antenna device according to the present invention is provided in front of a gap formed by one end of each of the first and second arcuate plate conductors, or in front of a gap formed by one end of each of the third and fourth arcuate plate conductors. A parasitic element is arranged.

  In the antenna device of the present invention, the first arc-shaped plate conductor and the third arc-shaped plate conductor are integrally formed into a shape connected at the other end, and the second arc-shaped plate conductor and the fourth arc-shaped plate are formed. A plate conductor is integrally formed in a shape connected at the other end, a connection portion at the other end of the first arc-shaped plate conductor and a third arc-shaped plate conductor is connected to the inner conductor, The connecting portion at the other end of the two arc-shaped plate conductors and the fourth arc-shaped plate conductor is connected to the outer conductor.

  The antenna device of the present invention is characterized in that the first to fourth arc-shaped plate conductors are formed into polygonal shapes by being formed into polygons.

  As described above, according to the antenna device of the present invention, two dipole antennas having different resonance frequencies, that is, a first antenna configured by annularly arranging the first and second arc-shaped plate conductors, A second antenna configured by annularly arranging the third and fourth arc-shaped plate conductors, the arc of the first and second arc-shaped plate conductors, and the third and fourth arc-shaped plate conductors; The planes formed by the respective rings constituting the arc are parallel to each other and are arranged at different positions perpendicular to the plane, that is, at different heights, or the plane of the second antenna with respect to the plane of the first antenna Have an angle, and the second antenna is arranged at different heights with respect to the direction perpendicular to the plane of the first antenna. The gap formed by the first and second arcuate plate conductors arranged in an annular shape and the gap formed by the third and fourth arcuate plate conductors arranged in an annular shape are feed points (that is, the first The first and third arcuate plate conductors are connected in different directions as seen from the connection point between the inner conductors of the first and third arcuate plate conductors or the connection points of the second and fourth arcuate plate conductors with the outer conductors. Since the first antenna and the second antenna do not interfere with each other in receiving radio waves, the first antenna and the second antenna have an omnidirectional radiation pattern in a horizontal plane having a horizontal polarization as a main polarization. A wireless LAN base station antenna that operates in a frequency band can be realized with a simple configuration.

The antenna device according to the present invention includes two dipole antennas (hereinafter referred to as antennas) having different resonance frequencies, that is, a first antenna and a second antenna, which are respectively configured on different parallel planes, that is, each antenna ring is formed. And the plane formed by the ring of the second antenna has an angle with respect to the plane formed by the ring of the first antenna. The second antenna is disposed at different heights with respect to the direction perpendicular to the plane of the first antenna. The first antenna is an antenna having a first resonance frequency in which a set of first and second arc-shaped plate conductors (arc-shaped plate conductors 1 and 2) is annularly arranged, and the second antenna is a first antenna. 3 and the fourth arc-shaped plate conductors (arc-shaped plate conductors 3 and 4) are antennas having a second resonance frequency arranged in an annular shape, and the antenna device of the present invention includes the first and second antenna devices. When the arc-shaped plate conductors are annularly arranged, a gap (second gap) formed between the opposing ends of the respective arc-shaped plate conductors and the third and fourth arc-shaped plate conductors are annularly arranged. In this case, a gap (second gap) formed between the opposing ends of each arc-shaped plate conductor is a feeding point (that is, a connection point between the arc-shaped plate conductors 1 and 3 and the inner conductor 5 or a circle). The first direction is such that the arcuate plate conductors 2 and 4 are not in the same direction when viewed from the outer conductor 6. It has a structure of arranging an antenna and a second antenna.
The other end of the first arc-shaped plate conductor is connected to the inner conductor, and the other end of the second arc-shaped plate conductor is connected to the outer conductor. Is provided with a gap (first gap). Similarly, the other end of the third arcuate plate conductor is connected to the inner conductor, and the other end of the fourth arcuate plate conductor is connected to the outer conductor. A gap (second gap) is provided between the one ends.

  Here, each of the first arc-shaped plate conductor, the second arc-shaped plate conductor, the third arc-shaped plate conductor, and the fourth arc-shaped plate conductor is formed into a conductive shape, for example, a metal conductor. It is a plate-shaped member. The first arc-shaped plate conductor and the second arc-shaped plate conductor are annularly arranged at positions where the inner circumferences of the arcs face each other, and similarly, the third arc-shaped plate conductor and the fourth arc-shaped plate conductor The conductors are annularly arranged at positions where the inner circumferences of the arcs face each other. The value obtained by adding the circumferential lengths of the first arc-shaped plate conductor and the second arc-shaped plate conductor is ½ wavelength (or approximately ½ wavelength by adjustment) at the first resonance frequency. The value obtained by adding the circumferential lengths of the third arc-shaped plate conductor and the fourth arc-shaped plate conductor is ½ wavelength (or approximately ½ wavelength by adjustment) at the second resonance frequency. Hereinafter, embodiments will be described.

<First Embodiment>
Hereinafter, an antenna device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a configuration example of the antenna device of the embodiment.
1 is a first arcuate plate conductor, 2 is a second arcuate plate conductor, 3 is a third arcuate plate conductor, 4 is a fourth arcuate plate conductor, 5 is an inner conductor of a coaxial line, 6 is An outer conductor 7 of the coaxial line is a feeding terminal.
In the present embodiment, an example in which the arcuate plate conductors 1, 2, 3, and 4 are arcuate is shown.

The apex portion 1a (the other end) of the arc-shaped plate conductor 1 is electrically connected to the inner conductor 5 of the coaxial line, and the apex portion 2a (the other end) of the arc-shaped plate conductor 2 is the outer conductor 6 of the coaxial line. It is connected to the. The arc-shaped plate conductor 1 and the arc-shaped plate conductor 2 are arranged in an annular shape (to form a cylindrical side surface) so that their inner peripheral surfaces (or concave portions) face each other, thereby constituting a first antenna. . Here, an end 1b (one end) opposite to the apex 1a of the arc-shaped plate conductor 1 and an end 2b (one end) opposite to the apex 2a of the arc-shaped plate conductor 2 in the circumferential direction are provided. ) Is provided with a gap.
The sum of the lengths of the arc-shaped plate conductor 1 and the arc-shaped plate conductor 2 in the circumferential direction is ½ wavelength ( ₀ ) with respect to the wavelength (λ ₀ ) at the first resonance frequency of the first antenna. .5λ ₀ ) or approximately the same length as ½ wavelength. Further, a height perpendicular to the circumferential direction (the height of a cylinder formed by arranging the circular arc-shaped plate conductors 1 and 2 in an annular shape) h1 is, for example, 0.04 wavelength (0 at the resonance frequency of the first antenna). .04λ ₀ ).

Similarly, the vertex 3a (the other end) of the arc-shaped plate conductor 3 is electrically connected to the inner conductor 5 of the coaxial line, and the vertex 4a (the other end) of the arc-shaped plate conductor 4 is connected to the outer side of the coaxial line. It is connected to the conductor 6. The arc-shaped plate conductor 3 and the arc-shaped plate conductor 4 are arranged in an annular shape so that their inner peripheral surfaces face each other, thereby constituting a second antenna. Here, an end 3b (one end) opposite in the circumferential direction to the apex 3a of the arc-shaped plate conductor 3 and an end 4b (one end in the circumferential direction opposite to the apex 4a of the arc-shaped plate conductor 4) ) Is provided with a gap.
The sum of the lengths of the arc-shaped plate conductor 3 and the arc-shaped plate conductor 4 in the circumferential direction is ½ wavelength ( ₀ ) with respect to the wavelength (λ ₀ ) at the first resonance frequency of the second antenna. .5λ ₀ ) or approximately the same length as ½ wavelength. The height perpendicular to the circumferential direction (the height of the cylinder formed by arranging the circular arc-shaped plate conductors 3 and 4 in an annular shape) h2 is, for example, 0.147 wavelengths (0 at the resonance frequency of the second antenna). .147λ ₀ ).

For example, in the present embodiment, the arc-shaped plate conductor 1 and the arc-shaped plate conductor 3 are disposed at positions facing each other via the inner conductor 5 of the coaxial line, and the arc-shaped plate conductor 2 and the arc-shaped plate conductor are arranged. 4 are arranged at positions facing each other via the inner conductor 5 of the coaxial line.
Here, FIG. 2 shows the antenna device as viewed from the front in the direction perpendicular to the gap surface of the second antenna in FIG. 1 (the X-axis direction in FIG. 1, ie, the direction perpendicular to the plane formed by the ends 3b and 4b). Shown in (a).
As shown in FIG. 2 (a), the first antenna formed by the arc-shaped plate conductors 1 and 2 and the second antenna formed by the arc-shaped plate conductors 3 and 4 are different positions in the Z-axis direction. That is, they are arranged at different heights. Here, the arcuate conductor 1 and the arcuate conductor 4 are arranged in the Z-axis direction so that the arcuate conductor 1 is on the upper side of the arcuate conductor 4 and is not in electrical contact with each other. Similarly, the arcuate conductor 2 and the arcuate conductor 3 are disposed in the Z-axis direction so that the arcuate conductor 2 is on the upper side of the arcuate conductor 3 and is not in electrical contact with each other.

2B, the side surfaces of the arcuate plate conductor 1 and the arcuate plate conductor 2 and the side surfaces of the arcuate plate conductor 3 and the arcuate plate conductor 4 are in the Z direction. On the other hand, they are arranged at different positions (at heights). Here, the Z direction is a plane that is formed by circularly arranging the arcs of the arc-shaped plate conductors 1 and 2, that is, a direction perpendicular to the bottom surface of the cylinder of the first antenna. Hereinafter, viewing the XY plane from the Z-axis direction is a plan view, and viewing the XZ plane from the Y-axis direction is a side view.
That is, the first plane formed by the ring formed by the arc-shaped plate conductor 1 and the arc-shaped plate conductor 2 and the second plane formed by the ring formed by the arc-shaped plate conductor 3 and the arc-shaped plate conductor 4 are defined. The first antenna and the second antenna are parallel to each other and formed at different positions (heights) in the Z-axis direction. Here, the arc-shaped plate conductor 1 is in a position where it is not in electrical contact with the arc-shaped plate conductor 4, and the arc-shaped plate conductor 2 is in a position where it is not in electrical contact with the arc-shaped plate conductor 3. An arcuate plate conductor is disposed.
In this embodiment, the plane formed by the ring of the first antenna and the plane formed by the ring of the second antenna are formed in parallel. However, the present invention is not limited to this arrangement. You may arrange | position so that it may have an angle.
Similarly, in a plan view (within the XY plane as viewed from the Z-axis direction), the ring gap formed by the arc-shaped plate conductor 1 and the arc-shaped plate conductor 2, the arc-shaped plate conductor 3 and the arc-shaped plate conductor. 4 is arranged in the opposite direction in the X axis. In the present embodiment, the gap between the first antenna and the gap between the second antenna is a feeding point (that is, a connection point between the arc-shaped plate conductors 1 and 3 and the inner conductor 5 or the arc-shaped plate conductors 2 and 4. Are arranged on a straight line passing through the connection point of the outer conductor 6), but it is not necessary to arrange them in completely opposite directions so that they do not face the same direction when viewed from the feeding point. What is necessary is just to arrange | position (that it faces in a different direction). Here, the X-axis direction is a direction perpendicular to the plane formed by the end 3b and the end 4b in the second antenna, and the Y-axis direction is a direction perpendicular to the XZ plane.

In the present embodiment, for example, the radius of the cylinder (first antenna) formed by the circular arc-shaped plate conductors 1 and 2 formed in an annular shape is about 10 mm and the height h1 is about 5 mm. A circular cylinder (second antenna) formed by the arc-shaped plate conductor 3 and the arc-shaped plate conductor 4 has a radius of about 6 mm and a height h2 of about 8 mm.
In order to adjust the impedance, the arc-shaped plate conductors 1 and 2 are annularly arranged so that a gap of about 5 mm is formed between the end 1b and the end 2b opposite to the feeding point. .
Similarly, in order to adjust the impedance, the arc-shaped plate conductors 3 and 4 are annularly arranged so that a gap of about 5 mm is formed between the end 3b and the end 4b opposite to the feeding point. Yes.
In the present embodiment, the first antenna is formed to have a resonance frequency of 2.4 GHz, and the second antenna is formed to have a resonance frequency of 5.2 GHz.
Further, in the present embodiment, the arc-shaped plate conductor has been described as a structure having a width in the Z-axis direction, but not limited to this structure, a structure having a width on the XY plane, Even in the XY plane, a structure having a width may be used.

FIG. 3 shows the resonance characteristics of the antenna device of FIG. 1 in the present embodiment, in which the horizontal axis shows the frequency and the vertical axis shows the return loss (dB display).
In this figure, when the frequency band in which the return loss is reduced by −10 dB is evaluated, it can be seen that good resonance characteristics are obtained in two frequency bands of about 2.4 GHz band and 5 GHz band.

FIG. 4 shows a radiation pattern in the horizontal plane (in the XY plane in FIG. 1) of the antenna in this embodiment. 4A shows a radiation pattern corresponding to the 2.4 GHz band, while FIG. 4B shows a radiation pattern corresponding to the 5.2 GHz band. As can be seen from FIGS. 4A and 4B, good omnidirectional radiation characteristics having horizontal polarization as the main polarization are realized in two frequency bands.
As described above, according to the antenna device of the first embodiment of the present invention, the first antenna and the second antenna are placed at different heights in the Z-axis direction, and each gap is a feeding point. Since they are arranged so that they do not face the same direction when viewed from the side, they do not become obstacles in the transmission / reception of the other antenna, so the horizontal polarization is the main polarization in two different frequency bands, and the non-directional radiation pattern in the horizontal plane A mobile communication base station antenna having the following can be realized.

<Second Embodiment>
Hereinafter, an antenna device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a conceptual diagram showing a configuration example of the antenna device of the embodiment.
The antenna device according to the second embodiment is located in front of the gap formed by the arc-shaped plate conductors 3 and 4 in FIG. 1 (in the X-axis direction) and at a position facing the outer peripheral surface of the arc-shaped plate conductors 3 and 4. The parasitic element 20 is arranged.
The parasitic element 20 is formed in the same shape as the arcuate plate conductors 1 to 4. When a cylinder which is the original shape of the parasitic element 20 is formed, the radius r of the cylinder is about 10 mm and the height h3 is 5 mm.

  FIG. 6 is a diagram showing a plan view of the present embodiment (projected view on the XY plane viewed from the Z-axis direction). As can be seen from FIG. 6, the second embodiment is similar to the first embodiment in the plan view (in the direction perpendicular to the plane formed by the arcs of the arc-shaped plate conductors 1 and 2, that is, the XY plane). The ring formed by the arcuate plate conductor 1 and the arcuate plate conductor 2 and the ring formed by the arcuate plate conductor 3 and the arcuate plate conductor 4 are disposed at positions where they do not overlap. The parasitic element 20 is disposed at a position where it does not contact the arcuate plate conductor 3 and the arcuate plate conductor 4.

FIG. 7 shows a radiation pattern in the horizontal plane (in the XY plane in FIG. 5) of the antenna device of this embodiment.
FIG. 7A shows a radiation pattern corresponding to the 2.4 GHz band, while FIG. 7B shows a radiation pattern corresponding to the 5.2 GHz band. As can be seen from FIGS. 7A and 7B, good omnidirectional radiation characteristics having horizontal polarization as the main polarization are realized in two frequency bands. Further, it can be seen that the deviation of the signal level of the radiation pattern in the horizontal plane is improved and reduced as compared with the first embodiment in which the parasitic element 20 shown in FIG. 4 is not added.
Further, in the first embodiment of FIG. 1, the long axis direction of the coaxial line is arranged perpendicular to the plane formed by the ring of the first antenna and the second antenna. As shown in the second embodiment, even if the long axis direction of the coaxial line is parallel to the plane formed by the ring of the first antenna and the second antenna (for example, the bottom surface of the cylinder), good.
The parasitic element 20 has the same shape as each arc plate conductor in the present embodiment, but a member having any one of a flat plate shape, a polygonal shape, and a corner shape may be used.

<Third Embodiment>
Hereinafter, an antenna device according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a conceptual diagram showing a configuration example of the antenna device of the embodiment.
The arc-shaped plate conductor 1 and the arc-shaped plate conductor 3 that are electrically connected to the inner conductor 5 in the first embodiment are integrally molded, and are also electrically connected to the outer conductor 6 in the same manner. The arc-shaped plate conductor 2 and the arc-shaped plate conductor 4 are integrally formed.

Here, the arc-shaped plate conductor 1 and the arc-shaped plate conductor 3 are connected to the apex portion 1a and apex portion 3a, which are respectively connected to the inner conductor 5, to form a connecting portion 120. The connecting portion 120 is used as the inner conductor. 5 is electrically connected. Similarly, the arcuate plate conductor 2 and the arcuate plate conductor 4 are connected to the apex 2a and apex 4a, which are respectively connected to the outer conductor 6, to form a connecting part 121, which is connected to the outer conductor. 6 is electrically connected.
As described above, the antenna device is manufactured by forming a pair of arc-shaped plate conductors connected to the same conductor (inner conductor 5 or outer conductor 6) that supplies power to the antenna and integrally molding them. There is an advantage that becomes easier.

<Fourth Embodiment>
Hereinafter, an antenna device according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a plan view showing a configuration example of the antenna device of the embodiment.
In the fourth embodiment shown in FIG. 9, the arc-shaped plate conductor 1, the arc-shaped plate conductor 2, the arc-shaped plate conductor 3, and the arc-shaped plate conductor 4 in the first embodiment are replaced with polygonal arc-shaped plate conductors. The configuration when replaced is shown. The present invention may also be applied to the second and third embodiments.
As described above, each of the arc-shaped plate conductor 1, the arc-shaped plate conductor 2, the arc-shaped plate conductor 3, and the arc-shaped plate conductor 4 is a polygonal (in this embodiment, octagonal) arc-shaped plate conductor 8. , 9, 10 and 11 are advantageous in that the manufacture of the arc-shaped plate conductor is simplified and the manufacture of the antenna device is facilitated.

  As described above, two dipole antennas having different resonance frequencies, that is, the first antenna and the second antenna are set to different heights in the Z-axis direction, and the respective gaps do not face the same direction when viewed from the feeding point. The arc-shaped plate conductor 1 and the arc-shaped conductor 3 connected to the inner conductor 5 and the arc-shaped plate conductor 2 and the arc-shaped conductor 4 connected to the outer conductor 6 are arranged so as not to be in electrical contact with each other. Therefore, the first antenna and the second antenna do not interfere with each other in receiving radio waves, and have a non-directional radiation pattern in a horizontal plane whose main polarization is horizontal polarization. A mobile communication base station antenna operating in a frequency band can be realized with a simple configuration.

It is a conceptual diagram which shows the structure of the antenna apparatus by the 1st Embodiment of this invention. It is a conceptual diagram which shows the structure of the antenna apparatus by the 1st Embodiment of this invention. It is a graph which shows a response | compatibility with the frequency and return loss of the antenna device by 1st Embodiment. It is a graph which shows the radiation pattern (radiation directivity characteristic) in the horizontal surface of the antenna apparatus by 1st Embodiment. It is a conceptual diagram which shows the structure of the antenna device by the 2nd Embodiment of this invention. It is a top view which shows the structure of the antenna apparatus by 2nd Embodiment by planar view. It is a graph which shows the radiation pattern in the horizontal surface of the antenna apparatus by 2nd Embodiment. It is a conceptual diagram which shows the structure of the antenna device by the 3rd Embodiment of this invention. It is a conceptual diagram which shows the structure of the antenna device by the 4th Embodiment of this invention. It is a conceptual diagram which shows the structure of the horizontal polarization directional antenna by a prior art example.

Explanation of symbols

1, 2, 3, 4 ... arc-shaped plate conductors 1a, 2a, 3a, 4a ... apex 1b, 2b, 3b, 4b ... end 5 ... inner conductor 6 ... outer conductor 7 ... feed terminal 8, 9, 10, DESCRIPTION OF SYMBOLS 11 ... Arc-shaped plate conductor 20 ... Parasitic element 120, 121 ... Connection part

Claims (4)

One coaxial line for feeding power to an antenna composed of an outer conductor and an inner conductor;
A first arcuate plate having a first gap between one end of each of the first and second arcuate plate conductors formed in an arcuate shape and arranged annularly so that the inner peripheral surfaces of the arcs face each other A first antenna having a first resonance frequency, wherein the other end of the conductor is connected to the inner conductor of the coaxial line, and the other end of the second arc-shaped plate conductor is connected to the outer conductor of the coaxial line; ,
Arranged at different heights in the vertical direction with respect to the first plane formed by the arc of the first antenna, between one end of each of the third and fourth arc-shaped plate conductors formed in an arc shape And the other end of the third arc-shaped plate conductor is connected to the inner conductor of the coaxial line, and a fourth arc shape is formed. A second antenna having a second resonance frequency with the other end of the plate conductor connected to the outer conductor of the coaxial line;
Have
The first arc-shaped plate conductor and the third arc-shaped plate conductor are arranged at positions facing each other via the inner conductor of the coaxial line, and the second arc-shaped plate conductor and the fourth arc-shaped plate conductor The arc-shaped plate conductor is disposed at a position facing each other through the outer conductor of the coaxial line,
In the first antenna and the second antenna, the first gap and the second gap are a connection point between the first and third arc-shaped plate conductors and the inner conductor of the coaxial line , or the second and fourth arcuate plate conductor and the I facing backward as viewed from the connection point between the outer conductor of the coaxial line urchin, and a ring formed of the first and second arc-shaped plate conductor The ring formed by the third and fourth arcuate plate conductors is arranged so as not to overlap when viewed from a direction perpendicular to the first plane ,
The sum of the lengths in the circumferential direction of the first and second arc-shaped plate conductors is approximately ½ wavelength at the first resonance frequency, and the length in the circumferential direction of the third and fourth arc-shaped plate conductors. The sum of the lengths is approximately ½ wavelength at the second resonance frequency. A parasitic element is disposed in front of the gap formed by one end of each of the first and second arcuate plate conductors or in front of the gap formed by one end of each of the third and fourth arcuate plate conductors. The antenna device according to claim 1 . The first arc-shaped plate conductor and the third arc-shaped plate conductor are integrally formed in a shape connected at the other end, and the second arc-shaped plate conductor and the fourth arc-shaped plate conductor are formed into the other end. Molded into the shape connected with
The connecting portion of the other end of the first arc-shaped plate conductor and the third arc-shaped plate conductor is connected to the inner conductor, and the other end of the second arc-shaped plate conductor and the fourth arc-shaped plate conductor. the antenna device according to claim 1 or claim 2, characterized in that connected to the outer conductor connecting portion of. The antenna device according to any one of claims 1 to 3, wherein the first to fourth arc-shaped plate conductors are formed in a polygonal shape by being formed into a polygonal shape.

Images