JP2005094745A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and light antenna device with a simple structure, which can transmit and receive radio waves in a wide band and be used in lower frequency bands. <P>SOLUTION: The antenna comprises a conductor side which is a base plate and a radiant element. The radiant element has a conical part with a half vertical angle of θ1 whose top is placed facing the conductor side. The radiant element also has a conical trapezoid part having a side with an angle of θ2 to the central axis of the conical part from the predetermined height of the conical part. Relation between the angles θ1 and θ2 is θ1>θ2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a horizontal omnidirectional antenna that can be used for mobile communication devices, small information terminals, and other wireless devices, and more particularly to a horizontal omnidirectional antenna that achieves a wider bandwidth and is smaller and lighter. .

Monopole antennas and discone antennas are known as omnidirectional antennas in a horizontal plane composed of a ground plane and a radiating element. For example, FIG. 20 shows a configuration of a conventional monopole antenna. In FIG. 20, reference numeral 101 denotes a disk-shaped conductor, and a coaxial connector 102 is attached to the disk-shaped conductor 101 from below, and a central conductor that extends upward from the coaxial connector 102 and penetrates the disk-shaped conductor 101. 103 is insulated from the disk-shaped conductor 101. The length h of the radiation element 103 of the monopole antenna needs to be about ¼ of the wavelength of the electromagnetic wave having the lowest resonance frequency. At this time, the detailed dimensions of the radiating element are determined depending on the impedance characteristics.
FIG. 21 shows a configuration of a conventional discone antenna. The discone antenna has a structure 104 in which the shape of the central conductor 103 of the monopole antenna is an inverted conical shape, and this shape can also be considered as one of the biconical antennas having a disk shape. An ideal discone antenna has an infinite size and is not frequency dependent, but with a discone antenna with a finite size, the upper limit of the operating wavelength is limited to about four times the length h of the radiating element. Is done. An example in which a broad band is achieved in the omnidirectional antenna in the horizontal plane constituted by the ground plane and the radiating element as described above will be shown below.

FIG. 22 shows an antenna disclosed in Patent Document 1, for example. The antenna includes a skirt portion 110 in which spiral conductive elements 112 a and 112 b are formed along the circumferential surface of the conical base 111, and a meander on the plane of a circular flat base body 121 disposed near the top of the skirt portion 110. And a top load portion 120 on which a conductive element 122 is formed. In the antenna, the band is widened based on the reason that the meandering conductive element 122 formed on the planar substrate 121 has a relatively wide band shape, and can have multiple resonances due to the presence of a plurality of meander lines. Is planned.
In addition, the spiral conductive elements 112a and 112b formed in the skirt portion can realize an electrical length longer than the apparent length, and thus can be formed smaller than a conventional discone antenna. However, in the antenna, it is necessary to form a meander-like or spiral conductor pattern on the substrate, and the conductor pattern needs to be densified as the bandwidth becomes wider, so the structure becomes complicated.
FIG. 23 shows an antenna disclosed in Patent Document 2, for example. The antenna is composed of a conductor 142 whose outer peripheral surface of the radiating element is a semi-elliptical rotor and a flat ground plane 143. In the antenna, the radiating element 142 is formed in a semi-elliptical rotator shape or a hemispherical shape, thereby reducing the size and increasing the bandwidth. However, in such an antenna using a planar ground plane, the dimensional element of the radiating element is dominant in the usable frequency band, so that the antenna is not enlarged in order to be usable at a lower frequency. must not.
JP 09-083238 A JP 09-153727 A

In the conventional monopole antenna and discone antenna, the antenna structure becomes complicated when attempting to increase the bandwidth, and the antenna must be enlarged in order to be usable in a lower frequency band.
The present invention has been made in view of the above points, and it is intended to provide a small and lightweight antenna device having a simple structure, capable of transmitting and receiving in a wide band, usable in a lower frequency band, and the like. It is aimed.
Specifically, an object of the present invention is to reduce the size of the antenna by widening the usable frequency band of the antenna to the low frequency side.
Further, the present invention has an object to make the antenna radiating element low in profile and to make the antenna small by widening the usable frequency band of the antenna to the low frequency side. .
Furthermore, an object of the present invention is to further reduce the posture of the radiating element in the antenna according to claim 4 or 5, and to reduce the size of an information communication device equipped with the antenna.
Further, in the inventions of claims 7 to 8, an object of the antenna of claims 1 to 7 is to reduce the weight of the antenna.

In order to solve the above-described problems, the invention according to claim 1 is an antenna including a conductor surface serving as a ground plane and a radiating element, wherein the radiating element is a half whose top is opposed to the conductor surface. A shape having a cone-shaped portion having an apex angle θ1, and further having a truncated cone-shaped portion having a side surface having an angle θ2 with respect to a central axis of the cone-shaped portion from a predetermined height of the cone-shaped portion; An antenna in which the relationship between the angles θ1 and θ2 satisfies θ1> θ2 is the main feature.
According to a second aspect of the present invention, there is provided an antenna composed of a conductor surface serving as a ground plane and a radiating element. The radiating element has a hemispherical portion on a bottom surface of a conical shape portion having a top portion facing the conductor surface. The main feature is an antenna having a structure in which bottom surfaces are joined.
The invention according to claim 3 is mainly characterized in that the antenna according to claim 1 is configured such that the bottom surface of the hemispherical portion is joined to the bottom surface of the frustoconical portion of the radiating element.
The invention according to claim 4 is a discone antenna comprising a conductor surface serving as a ground plane and a conical conductor with the top facing the conductor surface, wherein the conductor surface is centered on the top of the conical conductor. The main feature is an antenna having a conical depression.
According to a fifth aspect of the present invention, in the antenna according to the first, second, or third aspect, the conductor surface has a conical depression centered on the top of the conical portion of the radiating element. Features.
According to a sixth aspect of the present invention, in the antenna according to the fourth or fifth aspect, the depth of the conical recess is substantially the same as the height of the radiating element.
The invention according to claim 7 is the antenna according to any one of claims 1 to 6, wherein the conductor surface or the radiating element has a structure in which a conductive metal film is formed on an outer peripheral surface of a dielectric. To do.
The invention according to claim 8 is the antenna according to claims 1 to 7, wherein the conductor surface or the radiating element has a structure in which a conductive metal film is formed on an outer peripheral surface of the dielectric, and the dielectric The structure is hollow.

According to the first aspect of the present invention, in the antenna constituted by the conductor surface serving as the ground plane and the radiating element, the radiating element has a conical portion having a half apex angle θ1 with the apex facing the conductor surface. And a shape having a truncated cone-shaped portion having a side surface with an angle of θ2 with respect to the central axis of the cone-shaped portion from a predetermined height of the cone-shaped portion, and the relationship between the angles θ1 and θ2 is θ1 By using> θ2, the usable frequency band is widened to the low frequency side, and the antenna can be downsized.
According to the second aspect of the present invention, in the antenna constituted by the conductor surface serving as the ground plane and the radiating element, the configuration of the radiating element is hemispherical on the bottom surface of the conical portion with the top facing the conductor surface By adopting a configuration in which the bottom surfaces of the shape portions are joined, the usable frequency band is widened to the low frequency side, and the antenna can be downsized.
According to the invention of claim 3, in the antenna of claim 1, the usable frequency band is obtained by joining the bottom surface of the hemispherical portion to the bottom surface of the frustoconical portion of the radiating element. A wide band is formed on the low frequency side, and the antenna can be miniaturized.
According to the fourth and fifth aspects of the present invention, the conical depression centered on the top of the conical portion of the radiating element is formed on the conductor surface serving as the ground plane, so that the portion where the radiating element protrudes from the ground plane is reduced. In addition to the attitude, the usable frequency band is widened to the low frequency side, and the antenna can be downsized.
According to the invention described in claim 6, in the antenna according to claim 4 or 5, the protrusion of the radiating element on the ground plane is formed by setting the depth of the conical depression to the same level as the height of the radiating element. The usable frequency band can be widened to the lower frequency side.
According to the invention described in claim 7, in the antenna according to claims 1 to 6, the structure of the ground plane or the radiating element is a structure in which a conductive metal film is formed on the outer peripheral surface of the dielectric. Weight can be reduced.
According to the invention described in claim 8, in the antenna according to claims 1 to 7, the structure of the ground plane or the radiating element is a structure in which a conductive metal film is formed on the outer peripheral surface of the dielectric, and the structure of the dielectric Making the antenna hollow makes it possible to reduce the weight of the antenna.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of an antenna according to an embodiment of the present invention. This antenna is an antenna composed of a conductor surface serving as a ground plane 1 and a radiating element 3 that is electrically connected to a coaxial line 2. The radiating element 3 has a conical shape with a half apex angle θ 1 with the top facing the conductor surface 1. A portion 3a, and a shape having a truncated cone shape portion 3b having a side face with an angle θ2 with respect to the central axis of the cone shape portion 3a from a predetermined height position (upper bottom surface) of the cone shape portion, The relationship between the angles θ1 and θ2 is θ1> θ2.
FIG. 2 is a graph showing the correlation between θ1-θ2 and F-Fdc of the antenna of FIG. The vertical axis represents frequency deviation (F-Fdc), and the horizontal axis represents antenna angle (θ1-θ2). Note that F is a lower limit frequency of the operating band of the antenna (a band where the return loss is −10 dB or less), and Fdc is a lower limit frequency of the discone antenna in which the maximum diameter of the radiating element is equal to that of the antenna.
As is apparent from this figure, it can be seen that the frequency deviation increases in the region of θ1 <θ2, decreases from 0 to θ2 at the boundary, and has the minimum frequency deviation in the region of θ1> θ2.
FIG. 3 is a graph showing a correlation between D / H of the antenna of FIG. 1 and (θ1−θ2) max. The vertical axis represents the Max value of θ1-θ2, and the horizontal axis represents the ratio D / H between the width D and the height H of the antenna. As is clear from this figure, it is understood that D / H and (θ1−θ2) max have a positive correlation.

FIG. 4 is a cross-sectional view showing the configuration of the antenna according to Embodiment 1 of the present invention. The antenna according to this embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has a conical shape portion 3a having a half apex angle θ1 = 22 ° with the top portion facing the top surface of the ground plane, and further has a conical shape from the upper end portion (position of height 9 mm) of the conical shape portion 3a. This is a shape in which a truncated cone-shaped portion 3b having a side surface with an angle θ2 formed with the central axis of the portion 3a is continuously formed. The angles θ1 and θ2 have a relationship of θ1> θ2, and satisfy the requirement described in claim 1. The ground plane 1 and the radiating element 3 are mainly composed of a good conductor such as copper. Since the angle θ2 = 0 °, the truncated cone shape portion 3b is a cylindrical shape portion.
The operation of the antenna having such a configuration will be described. FIG. 5 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss vs. frequency characteristics of a conventional discone antenna whose maximum diameter and height of the radiating element are equal to the present antenna are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 10.8 GHz in the case of the conventional discone antenna, but is reduced to 9.4 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the usable frequency band can be widened to the low frequency side, so that the antenna can be downsized.

FIG. 6 is a cross-sectional view showing a configuration of an antenna according to Embodiment 2 of the present invention. The antenna of the present embodiment is fed by a coaxial line, and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has a configuration in which the bottom surface of the hemispherical portion 3d having a diameter of 9.6 mm is joined to the bottom surface (upper surface in the drawing) of the conical portion 3c having a half apex angle of 22 °. The ground plane and the radiating element are made of copper as a main material.
The operation of the antenna having such a configuration will be described. FIG. 7 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss vs. frequency characteristics of a conventional discone antenna whose maximum diameter and height of the radiating element are equal to the present antenna are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 10.4 GHz in the case of the conventional discone antenna, but is reduced to 9.9 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the usable frequency band can be widened to the low frequency side, so that the antenna can be downsized.

FIG. 8 is a cross-sectional view showing a configuration of an antenna according to Embodiment 3 of the present invention. The antenna according to this embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has a cone-shaped portion 3e having a half apex angle θ1 = 22 ° with the top facing the surface of the ground plane 1, and further has a conical shape from the upper end (position of height 7 mm) of the cone-shaped portion 3e. It has a configuration in which a frustoconical portion (that is, a columnar portion) 3f having a side surface with an angle of θ2 = 0 ° with the central axis of the portion 3e is provided, and the bottom surface of the hemispherical portion 3g is joined to the upper bottom surface thereof. The ground plane 1 and the radiating element 3 are made of a copper film formed on the outer peripheral surface of the dielectric, and are lighter than when the entire antenna is made of copper.
The operation of the antenna having such a configuration will be described. FIG. 9 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss vs. frequency characteristics of a conventional discone antenna whose maximum diameter and height of the radiating element are equal to the present antenna are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 11.2 GHz in the case of the conventional discone antenna, but is reduced to 9.8 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the usable frequency band can be widened to the low frequency side, so that the antenna can be downsized.

FIG. 10 is a cross-sectional view showing a configuration of an antenna according to Embodiment 4 of the present invention. The antenna according to this embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has a conical shape with a half apex angle of 22 ° with the top facing the surface of the ground plane 1. The ground plane 1 has a conical depression 1a centered on the top of the radiating element. Therefore, the portion where the radiating element 3 protrudes from the ground plane 1 is lowered. The depth of the recess 1a is 4.5 mm, and the angle formed by the inclined surface of the recess 1a with the horizontal direction is 28 °. The ground plane 1 and the radiating element 3 are made of a copper film formed on the outer peripheral surface of a hollow dielectric, and are lighter than when the entire antenna is made of copper.
The operation of the antenna having such a configuration will be described. FIG. 11 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss vs. frequency characteristics of a conventional discone antenna in which the shape of the radiating element is the same as that of the present antenna and the ground plane is a flat plate are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 9.7 GHz in the case of the conventional discone antenna, but is reduced to 8.7 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the portion where the radiating element protrudes from the ground plane can be lowered, and the usable frequency band can be widened to the low frequency side. Can be miniaturized.

FIG. 12 is a cross-sectional view showing a configuration of an antenna according to Embodiment 5 of the present invention. The antenna according to this embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has the same shape as the radiating element of the antenna shown in the first embodiment. The ground plane 1 has a conical depression 1a centered on the top of the radiating element. Therefore, the portion where the radiating element protrudes from the ground plane is lowered. The depth of the recess 1a is 4.5 mm, and the angle formed by the slope of the recess with the horizontal direction is 28 °. The ground plane and the radiating element are made of copper as a main material.
The operation of the antenna having such a configuration will be described. FIG. 13 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss versus frequency characteristics of a conventional discone antenna in which the maximum diameter and height of the radiating element are equal to those of the present antenna and the ground plane is flat are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 10.8 GHz in the case of the conventional discone antenna, but is reduced to 8.4 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the portion where the radiating element protrudes from the ground plane can be lowered, and the usable frequency band can be widened to the low frequency side. Can be miniaturized.

FIG. 14 is a cross-sectional view showing a configuration of an antenna according to Embodiment 6 of the present invention. The antenna according to this embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has the same shape as the radiating element of the antenna shown in the second embodiment. The ground plane 1 has a conical depression 1 a centered on the top of the radiating element 3. Therefore, the part where the radiating element protrudes from the ground plane is lowered. The depth of the recess is 4.5 mm, and the angle between the slope of the recess and the horizontal direction is 28 °. The ground plane and the radiating element are made of copper as a main material.
The operation of the antenna having such a configuration will be described. FIG. 15 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss versus frequency characteristics of a conventional discone antenna in which the maximum diameter and height of the radiating element are equal to those of the present antenna and the ground plane is flat are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 10.4 GHz in the case of the conventional discone antenna, but is reduced to 9.0 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the portion where the radiating element protrudes from the ground plane can be lowered, and the usable frequency band can be widened to the low frequency side. Can be miniaturized.

FIG. 16 is a cross-sectional view showing a configuration of an antenna according to Embodiment 7 of the present invention. The antenna according to this embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 24 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has the same shape as the radiating element of the antenna shown in the third embodiment. The ground plane 1 has a conical depression 1 a centered on the top of the radiating element 3. Therefore, the portion where the radiating element protrudes from the ground plane is lowered. The depth of the recess is 4.5 mm, and the angle between the slope of the recess and the horizontal direction is 28 °. The ground plane and the radiating element are made of copper as a main material.
The operation of the antenna having such a configuration will be described. FIG. 17 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss versus frequency characteristics of a conventional discone antenna in which the maximum diameter and height of the radiating element are equal to those of the present antenna and the ground plane is flat are also shown by broken lines. The lower limit frequency at which the return loss is -10 dB or less is 11.2 GHz in the case of the conventional discone antenna, but is reduced to 8.8 GHz in the case of this antenna.
As is apparent from this embodiment, by applying the present invention, the portion where the radiating element protrudes from the ground plane can be lowered, and the usable frequency band can be widened to the low frequency side. Can be miniaturized.

FIG. 18 is a cross-sectional view showing a configuration of an antenna according to Embodiment 8 of the present invention. The antenna of the present embodiment is fed by a coaxial line 2 and includes a ground plane 1 having a diameter of 42 mm and a radiating element 3 having a height of 15 mm. The radiating element 3 has the same shape as the radiating element 3 of the antenna shown in the first embodiment. The ground plane 1 has a conical recess 1a centered on the top of the radiating element 3, the depth of the recess is 15 mm, and the angle between the inclined surface of the recess and the horizontal direction is 40 °. In the antenna of this embodiment, since the height of the radiating element is equal to the depth of the conical depression, the radiating element does not protrude above the ground plane. The ground plane and the radiating element are made of copper as a main material.
The operation of the antenna having such a configuration will be described. FIG. 19 shows the return loss vs. frequency characteristics of the antenna of this embodiment with a solid line. For comparison, the return loss versus frequency characteristics of a conventional discone antenna in which the maximum diameter and height of the radiating element are equal to those of the present antenna and the ground plane is flat are also shown by broken lines. The lower limit frequency at which the return loss is −10 dB or less is 10.8 GHz in the case of the conventional discone antenna, but is reduced to 8.2 GHz in the case of this antenna.
As is clear from this embodiment, by applying the present invention, the projecting portion of the radiating element on the ground plane can be eliminated, and the usable frequency band can be widened to the low frequency side. Miniaturization is possible.
When the antenna according to the present embodiment is mounted on an information communication device, the device can be reduced in size by forming the antenna using a metal casing as a ground plane, and can be mounted without impairing the aesthetic appearance. In this case, since the antenna does not protrude from the housing, it is possible to avoid an increase in the size of the entire device even if the antenna is increased in size and widened.
Although the present invention has been described based on the embodiments, the present invention is by no means limited to the requirements shown here, such as the shapes raised in the above embodiments and combinations with other elements. With respect to these points, the present invention can be changed within a range that does not detract from the gist of the present invention, and can be appropriately determined according to the application form.

The block diagram of the antenna which concerns on Claim 1 of this invention. The graph which shows the correlation of (theta) 1- (theta) 2 and F-Fdc of the antenna of FIG. The graph which shows the correlation of D / H of the antenna of FIG. 1, and ((theta) 1- (theta) 2) max. The block diagram of the antenna which concerns on Example 1 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 1. FIG. The block diagram of the antenna which concerns on Example 2 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 2. FIG. The block diagram of the antenna which concerns on Example 3 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 3. FIG. The block diagram of the antenna which concerns on Example 4 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 4. FIG. The block diagram of the antenna which concerns on Example 5 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 5. FIG. The block diagram of the antenna which concerns on Example 6 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 6. FIG. The block diagram of the antenna which concerns on Example 7 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 7. FIG. The block diagram of the antenna which concerns on Example 8 of this invention. The graph which shows the return loss vs. frequency characteristic of the antenna of Example 8. FIG. The block diagram of the conventional monopole antenna. The block diagram of the conventional discone antenna. The block diagram of the antenna disclosed by Unexamined-Japanese-Patent No. 09-083238. The block diagram of the antenna disclosed by Unexamined-Japanese-Patent No. 09-153727.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground plane 2 Coaxial line 3 Radiating element 4 Conical shape part 5 Frustum shape part

Claims (8)

  In an antenna including a conductor surface serving as a ground plane and a radiating element, the radiating element has a conical shape portion having a half apex angle θ1 with the top portion facing the conductor surface, and further, a predetermined shape of the conical shape portion is determined. From the height, a shape having a truncated cone shape portion having a side surface with an angle θ2 with respect to the central axis of the cone shape portion, and the relationship between the angles θ1 and θ2 is θ1> θ2. antenna.   In the antenna composed of a conductor surface serving as a ground plane and a radiating element, the radiating element has a configuration in which the bottom surface of the hemispherical portion is joined to the bottom surface of the conical portion with the top portion facing the conductor surface. Characteristic antenna.   2. The antenna according to claim 1, wherein a bottom surface of the hemispherical portion is joined to a bottom surface of the frustoconical portion of the radiating element.   In a discone antenna composed of a conductor surface serving as a ground plane and a conical conductor with the top facing the conductor surface, the conductor surface has a conical depression centered on the top of the conical conductor. An antenna characterized by the fact that   4. The antenna according to claim 1, wherein the conductor surface has a conical depression centered on a top of the conical portion of the radiating element. 5.   6. The antenna according to claim 4, wherein a depth of the conical depression is substantially the same as a height of the radiating element.   The antenna according to claim 1, wherein the conductor surface or the radiating element has a structure in which a conductive metal film is formed on an outer peripheral surface of a dielectric. 8. The antenna according to claim 1, wherein the conductor surface or the radiating element has a structure in which a conductive metal film is formed on an outer peripheral surface of a dielectric, and the structure of the dielectric is hollow. And antenna.

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