JP2004128531A - N-line helical antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an N-line helical antenna which broadens its radiation and improves its characteristic impedance. <P>SOLUTION: The N-line helical antenna has a ground plate (GP), four helical radiation elements (11-14) helically wound around a virtual cylinder erecting on the ground plate, a conductor wall (15) surrounding the four helical radiation elements on the ground plate, and a coupler (16) for electrically crosswise coupling the four top ends of the four helical radiation elements. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital radio capable of receiving a radio wave from an artificial satellite (hereinafter, also referred to as “satellite wave”) or a radio wave on the ground (hereinafter, also referred to as “terrestrial wave”) to listen to digital radio broadcasting. The present invention relates to a receiver, and particularly to an antenna used for a digital radio receiver.
[0002]
[Prior art]
Recently, digital radio receivers that receive radio waves (satellite waves) or terrestrial waves from artificial satellites to enable digital radio broadcasting have been developed, and have been put to practical use in the United States. This digital radio receiver is mounted on a mobile station such as an automobile, and is capable of receiving radio waves having a frequency of about 2.3 GHz and listening to radio broadcasts. Since the frequency of the reception radio wave is about 2.3 GHz, the reception wavelength (resonance wavelength) λ _{2.3 at} that time is about 128 mm.
[0003]
The terrestrial wave is a signal obtained by receiving a satellite wave once at an earth station, shifting the frequency slightly, and retransmitting the signal with linear polarization.
[0004]
In order to receive such a radio wave having a frequency of about 2.3 GHz, it is necessary to install an antenna outside the vehicle. Various antennas having various structures have been proposed, but a cylindrical (cylindrical) antenna rather than a planar (flat) antenna is generally used. The reason is that wider directivity is achieved by forming the antenna in a cylindrical (cylindrical) shape.
[0005]
As is well known in this technical field, an electromagnetic wave radiated into free space is a transverse wave having an electric field and a magnetic field that oscillate in a plane perpendicular to the traveling direction of the wave. The electric and magnetic fields vary in intensity within the plane, and this is called polarization. Satellite waves are circularly polarized waves, whereas terrestrial waves are linearly polarized waves.
[0006]
Hereinafter, an antenna for receiving satellite waves (circularly polarized waves) will be mainly described. A helical antenna is known as one of cylindrical (cylindrical) antennas. A helical antenna has a structure in which at least one antenna conductor is wound in a helical shape (helical shape) around a cylindrical or cylindrical (hereinafter referred to as “cylindrical”) member on a ground plate (earth plate). Thus, the above-described circularly polarized wave can be efficiently received. Therefore, the helical antenna is used exclusively for receiving satellite waves. As the material of the cylindrical member, an insulating material such as plastic is used. Further, for example, four antenna conductors are used. On the other hand, it is actually extremely difficult to wind a plurality of antenna conductors in a helix around a cylindrical member. Therefore, instead, a helical antenna in which an antenna pattern film formed by printing a plurality of conductor patterns on an insulating sheet is wound around a cylindrical member has been proposed.
[0007]
Various helical antennas having such a structure have been proposed.
[0008]
For example, Patent Literature 1 discloses a “helical antenna structure” in which a cylindrical member of a helical antenna is modified to increase the strength of the structure. That is, according to Patent Document 1, in the conventional helical antenna, when the cylindrical member is a cylinder, since the inside is hollow, the center axis of the member of the hollow cylindrical member is used to solve the problem of low strength. At least three ribs are formed symmetrically and radially between the inner peripheral surface and the inner peripheral surface.
[0009]
Patent Literature 2 discloses a “helical antenna” that can easily adjust the resonance frequency of a helical antenna to a desired resonance frequency. That is, in Patent Document 2, a screw hole with a female thread is provided in the inner peripheral wall at the upper end of the hollow cylindrical member, and a ceramic bolt having a relative dielectric constant εr of 10 to 100 is screwed into the screw hole. I have to. When the ceramic bolt is inserted into the screw hole of the hollow cylindrical member, the length of the hollow cylindrical member can be equivalently shortened due to the wavelength shortening effect.
[0010]
Furthermore, one of the applicants of the present invention did not use a cylindrical member, but instead formed a cylindrical body by rolling the antenna pattern film itself into a cylindrical body, and fixedly disposed the cylindrical body at one end in the axial direction on a circuit board. Antenna ”(see Japanese Patent Application No. 2001-225515).
[0011]
In the case of a helical antenna having a structure in which a plurality of antenna conductors are wound in a helix (helical shape), a satellite wave (circularly polarized wave) received by the helical antenna is phase-shifted by a phase shifter (phase conversion circuit). Are shifted so that the phases are matched (adjusted), then amplified by a low noise amplifier (LNA) and sent to the receiver body. Here, the combination of the helical antenna (antenna), the phase shifter (phase conversion circuit), and the LNA is called an antenna device.
[0012]
In other words, in a helical antenna having a plurality of antenna conductors, in order to drive the helical antenna, power is supplied to each antenna conductor and the circularly polarized wave received by the plurality of antenna conductors is shifted by a phase shifter (phase conversion circuit). ). In the helical antenna, the length of each antenna lead is selected in the range of 0.8 to 1.2λ.
[0013]
In addition, the present applicant provided a conductor wall around the four-wire helical radiating element, and by appropriately selecting the diameter and height of the conductor wall, widened the main beam width as compared with the case without the conductor wall and achieved cross polarization. A “4-wire helical antenna with a conductor wall” that reduces waves has been proposed (see, for example, Non-Patent Document 1, Japanese Patent Application No. 32288/2002).
[0014]
[Patent Document 1]
JP 2001-326523 A
[Patent Document 2]
JP 2001-339227 A
[Non-patent document 1]
Masakazu Ikeda and 2 others, "4-wire helical antenna with conductor wall", The Institute of Electronics, Information and Communication Engineers, 2001 Communication Society Conference, Proceedings 1, September 21-21, 2001, B-1-70 , P. 76
[0017]
[Problems to be solved by the invention]
In the above-described four-wire helical antenna with a conductor wall, the radiation characteristics can be adjusted by attaching a conductor wall around the quadrilateral helical antenna. However, it is desired to further spread the radiation. It is also desirable that the characteristic impedance can be improved.
[0018]
Therefore, an object of the present invention is to provide an N-ray helical antenna that can spread radiation.
[0019]
Another object of the present invention is to provide an N-ray helical antenna capable of improving characteristic impedance.
[0020]
[Means for Solving the Problems]
The present inventors have continued to improve the 4-wire helical antenna to further increase the radiation. As a result, the present inventors have discovered (confirmed) that the radiation can be expanded by connecting the four crowns of the four helical radiating elements constituting the four-wire helical antenna in a cross. Further, in such a structure, the characteristic impedance of the antenna becomes extremely low. Therefore, the present inventors have found (confirmed) that the characteristic impedance can be improved (increased) by folding each of the four helical radiation elements from the top and short-circuiting the ground plate.
[0021]
The number of helical radiating elements is not limited to four, but may be plural.
[0022]
That is, according to the first aspect of the present invention, the ground plate (GP) and N (N is an integer of 2 or more) erected on the outer peripheral surface of the virtual cylinder and erected on the ground plate. ) Helical radiating elements (11 to 14), a conductor wall (15) provided on the ground plate around the N helical radiating elements, and a head of N points of the N helical radiating elements An N-ray helical antenna characterized by having a coupling portion (16) for electrically coupling the tops to each other is obtained.
[0023]
In the N-line helical antenna according to the first aspect, it is preferable that the N helical radiating elements (11 to 14) are arranged on the outer peripheral surface of the virtual cylinder at equal angular intervals. When N is 4, the connecting portion (16) connects the tops of the four points of the four helical radiating elements in a cross shape.
[0024]
According to the second aspect of the present invention, a ground plate (GP) and N (N is an integer of 2 or more) helically wound on the outer peripheral surface of the virtual cylinder standing on the ground plate. Helical radiating elements (11 to 14), a conductor wall (15) provided on the ground plate around the N helical radiating elements, and a top of N points of the N helical radiating elements. A coupling portion (16) electrically coupled to each other, and N helical radiating elements each having N folding lines (21 to 24) for folding back from the top and short-circuiting to a ground plate. A characteristic N-ray helical antenna is obtained.
[0025]
In the N-line helical antenna according to the second aspect, the N helical radiating elements (11 to 14) are arranged on the outer peripheral surface of the virtual cylinder at equal angular intervals, and the N folded lines ( 21 to 24) are preferably arranged at a predetermined distance from an adjacent helical radiating element. When N is 4, the connecting portion (16) connects the tops of the four points of the four helical radiating elements in a cross shape.
[0026]
According to the third aspect of the present invention, a ground plate (GP) and N (N is an integer of 2 or more) helically wound on the outer peripheral surface of the virtual cylinder standing on the ground plate. Helical radiating elements (11 to 14) and a coupling portion (16) for electrically coupling the N tops of N points of the N helical radiating elements to each other. Can be
[0027]
In the N-line helical antenna according to the third aspect, it is preferable that the N helical radiating elements (11 to 14) are arranged on the outer peripheral surface of the virtual cylinder at equal angular intervals. When N is 4, the connecting portion (16) connects the tops of the four helical radiating elements at four points in a cross shape.
[0028]
According to the fourth aspect of the present invention, a ground plate (GP) and N (N is an integer of 2 or more) helically wound on the outer peripheral surface of the virtual cylinder standing on the ground plate. Helical radiating elements (11 to 14), and N helical radiating elements are respectively folded from the top of the helical radiating element, and have N folded lines (21 to 24) for short-circuiting to a ground plate. Helical antenna is obtained.
[0029]
In the N-line helical antenna according to the fourth aspect, the N helical radiating elements (11 to 14) are arranged on the outer peripheral surface of the virtual cylinder at equal angular intervals, and the N folded lines ( 21 to 24) are preferably arranged at a predetermined distance from an adjacent helical radiating element.
[0030]
It is to be noted that the reference numerals in the parentheses are provided for facilitating the understanding of the present invention, are merely examples, and are not limited thereto.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0032]
First, a conventional four-wire helical antenna (including a four-wire helical antenna with a conductor wall) will be described with reference to the drawings for easy understanding of the present invention.
[0033]
1 to 3 show the structure and coordinate system of a conventional four-wire helical antenna. FIG. 1 is a schematic perspective view showing a conventional 4-wire helical antenna, FIG. 2 is a schematic plan view showing a conventional 4-wire helical antenna, and FIG. 3 is a schematic front view showing a conventional 4-wire helical antenna. The x-axis and the y-axis are respectively taken in the vertical direction and the horizontal direction which are orthogonal to each other in the horizontal plane. I have.
[0034]
The first to fourth helical radiating elements 11, 12, 13, and 14 having a height h are arranged on the outer peripheral surface of the virtual cylinder at 90-degree intervals on the ground plate GP to form a right-handed four-wire helical antenna. I do. To the first to fourth feeding points F1, F2, F3, F4 of the first to fourth helical radiating elements 11 to 14, (F1, F2, F3, F4) = (1, j, -1, -j). Power is supplied in the phase of A conductor wall 15 having a diameter D _WL and a height h _WL surrounding the first to fourth helical radiating elements 11 to 14 is provided on the ground plate GP. In the illustrated example, each of the helical radiating elements 11 to 14 is erected on the outer peripheral surface of the virtual cylinder in a helical manner after being erected vertically by a small distance Δh from the ground plate GP.
[0035]
Here, a design frequency 2.3GHz (wavelength lambda _2.3 ≒ 128mm), the antenna theoretical cylinder circumference C = 1.0λ _2.3, the diameter _D WL = _{0.38λ 2.3} conductor wall 15, the distance Assuming that Δh = 0.04λ _2.3 and the area of the ground plate GP = ∞, the characteristics of the four-wire helical antenna are analyzed by a finite difference time domain method (FDTD) simulation.
[0036]
FIG. 4 shows the half power width HPBW and the axial ratio when the height h _WL of the conductor wall 15 is changed when the inclination angle α of the helical of each of the helical radiating elements 11 to 14 from the horizontal plane is 24 °. AR <shows the following beamwidth _{BW AR <and 3 dB} 3 dB. When the height h _WL of the conductor wall 15 is equal to or greater than 0.14λ _2.3 , both HPBW and BW _{AR < 3 dB} tend to be wider than when the conductor wall 15 does not exist (h _WL = 0). You can see that there is.
[0037]
FIG. 5A is a radiation pattern when the height h _WL of the conductor wall 15 is 0, 0.10λ _2.3 , 0.12λ _2.3 , and 0.14λ _2.3 , respectively. the radiation pattern of the left hand circular polarization E _L, a solid line indicates the radiation pattern of right-handed circularly polarized wave E _R, FIG. 5 (b) is a axial ratio patterns. In the present embodiment, a diameter (thickness) sigma is 0.001Ramuda _2.3 of each helical radiating elements 11 to 14, the length _{S arm} helical portion of each helical radiating elements 11 to 14 (arm) is about 0 shows a case of .3λ _2.3.
[0038]
6 to 8 show a structure and a coordinate system of the four-wire helical antenna according to the first embodiment of the present invention. FIG. 6 is a schematic perspective view showing the four-wire helical antenna according to the first embodiment, FIG. 7 is a schematic plan view showing the four-wire helical antenna according to the first embodiment, and FIG. 8 is the first embodiment. FIG. 2 is a schematic front view showing a four-wire helical antenna according to an embodiment. The x-axis and the y-axis are respectively taken in the vertical direction and the horizontal direction which are orthogonal to each other in the horizontal plane. I have.
[0039]
The difference from the conventional four-wire helical antenna illustrated in FIGS. 1 to 4 is that the illustrated four-wire helical antenna couples the tops of four points of the first to fourth helical radiating elements 11 to 14 with a cross. That is, a coupling portion 16 is further provided. Therefore, those having the same functions as those of the conventional four-wire helical antenna are denoted by the same reference numerals, and description thereof will be omitted. The parameters that have been set are the same as those of the prior art, and therefore, their description is omitted.
[0040]
9 to 11 show the helical radiating elements 11 to 14 in which the helical inclination angles α from the horizontal plane are 22 °, 24 °, and 26 °, respectively, and the height _hWL of the conductor wall 15 is changed. when, showing the half-power width HPBW and the axial ratio AR <3 dB below the beam width _{BW AR <3 dB.} In any case, the height _{h WL} conductor wall 15 is 0.10Ramuda _2.3 or more, compared to when there is no conductor walls 15 no _(h WL = 0) and coupling unit 16 (FIG. 4) Thus, it can be seen that both HPBW and BW _{AR < 3 dB} tend to be wider.
[0041]
FIG. 12A is a radiation pattern when the height h _WL of the conductor wall 15 is 0, 0.10λ _2.3 , 0.12λ _2.3 , and 0.14λ _2.3 , respectively, and a dashed line. the radiation pattern of the left hand circular polarization E _L, a solid line indicates the radiation pattern of right-handed circularly polarized wave E _R, FIG. 12 (b) is a axial ratio patterns.
Figure 12 (b) and FIG. 5 (b) and as evidenced by comparing the, when the height _{h WL} conductor wall 15 is 0.10Ramuda _2.3 or more, four-wire helical antenna according to this embodiment It can be seen that the radiation spreads more than the conventional four-wire helical antenna.
[0042]
Also, as is clear from the comparison between the diagrams in the uppermost column in FIGS. 10 and 12B and the diagrams in the uppermost column in FIGS. 4 and 5B, the case where the conductor wall 15 is not provided (h _WL = 0) ), The four-wire helical antenna according to the present embodiment has a wider BW _{AR < 3 dB} than the conventional four-wire helical antenna, despite the narrower HPBW, and consequently has wider radiation. I understand. That is, even if the coupling portion 16 is provided without the conductor wall 15, there is an effect of spreading the radiation.
[0043]
FIGS. 13 to 15 show a structure and a coordinate system of a 4-wire helical antenna according to the second embodiment of the present invention. FIG. 13 is a schematic perspective view showing a four-wire helical antenna according to the second embodiment, FIG. 14 is a schematic plan view showing a four-wire helical antenna according to the second embodiment, and FIG. FIG. 2 is a schematic front view showing a four-wire helical antenna according to an embodiment. The x-axis and the y-axis are respectively taken in the vertical direction and the horizontal direction which are orthogonal to each other in the horizontal plane. I have.
[0044]
The difference from the four-wire helical antenna according to the first embodiment of the present invention illustrated in FIGS. 6 to 8 is that the illustrated four-wire helical antenna includes first to fourth helical radiation elements 11 to 14, respectively. The first to fourth fold lines 21, 22, 23, and 24, which are folded back from the top of the four points and short-circuited to the ground plate GP, are further provided. Therefore, those having the same functions as those of the four-wire helical antenna according to the first embodiment of the present invention are denoted by the same reference numerals, and description thereof will be omitted. The set parameters are also the same as those in the first embodiment of the present invention, and the description thereof will be omitted.
[0045]
The four-wire helical antenna illustrated, first through distance ΔS between the fourth folding line 21 to 24 corresponding to the first to fourth helical radiating elements 11 to 14 is set to 0.015λ _2.3. Hereinafter, the four-wire helical antenna according to the second embodiment is referred to as a “folded two-wire four-wire helical antenna”, and the four-wire helical antenna according to the first embodiment described above is referred to as a “one-wire four-wire antenna”. We will call it a helical antenna.
[0046]
16 (a) is in the folded 2 linear four-wire helical antenna, the height _{h WL} conductor wall 15 is the radiation pattern when the 0.14Ramuda _2.3, dashed line radiation pattern of left hand circular polarization _{E L} , the solid line indicates the radiation pattern of right-handed circularly polarized wave E _R, FIG. 16 (b) is a axial ratio patterns.
[0047]
FIG. 17 (a), in one linear four-wire helical antenna, a radiation pattern when the height _{h WL} conductor wall 15 0.14Ramuda _2.3, dashed line radiation pattern of left hand circular polarization _{E L,} the solid line indicates the radiation pattern of right-handed circularly polarized wave E _R, FIG. 17 (b) is a axial ratio patterns.
[0048]
As is clear from the comparison between FIG. 16 and FIG. 17, there is little difference in the radiation pattern between the folded two-wire type four-wire helical antenna and the one-wire type four-wire helical antenna. That is, in the folded 2 linear four-wire helical antenna, HPBW = 148 _°, whereas a _{BW AR} <3dB = 134 °, in one linear four-wire helical _{antenna, HPBW = 150 °, BW AR} < at 3 dB = 132 ° is there. However, the characteristic impedance Zin of the folded two-wire four-wire helical antenna is 19.3 + j7.4 [Ω], whereas the characteristic impedance Zin of the single-wire four-wire helical antenna is 7.41 + j2.7 [Ω]. ]. That is, it is understood that the folded two-wire type four-wire helical antenna can improve (increase) the characteristic impedance Zin as compared with the one-wire type four-wire helical antenna.
[0049]
From the above, it is presumed that there is an effect that the characteristic impedance Zin can be improved (increased) simply by providing the folded lines 21 to 24 without the conductor wall 15 or the coupling portion 16.
[0050]
As described above, the present invention has been described by the preferred embodiments, but it is needless to say that the present invention is not limited to the above embodiments. For example, in the above embodiment, an example in which the number of helical radiating elements is four has been described. However, the number of helical radiating elements is not limited to four, and may be plural.
[0051]
【The invention's effect】
As is clear from the above description, in the present invention, by providing a coupling portion that electrically couples the tops of the N points of the N helical radiation elements to each other, it is possible to obtain an effect that radiation can be spread. Further, according to the present invention, the characteristic impedance can be improved by providing N helical radiating elements from the top of the helical radiating elements and providing N fold lines for short-circuiting to the ground plate.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a conventional four-wire helical antenna.
FIG. 2 is a schematic plan view showing the conventional four-wire helical antenna shown in FIG.
FIG. 3 is a schematic front view showing the conventional four-wire helical antenna shown in FIG.
FIG. 4 shows a half-power width when a height h _WL of a conductor wall is changed when a tilt angle α of a helical of each helical radiation element from a horizontal plane in a conventional four-wire helical antenna is 24 °. HPBW and the axial ratio AR <3 dB below the beam width _{BW AR <is} a graph showing the _{3 dB.}
FIG. 5 (a) shows a conventional four-wire helical antenna in which the height h _WL of the conductor wall is 0, 0.10λ _2.3 , 0.12λ _2.3 , and 0.14λ _2.3 , respectively. FIG. 7B is a graph showing a radiation pattern at the time of FIG.
FIG. 6 is a schematic perspective view showing a four-wire helical antenna according to the first embodiment of the present invention.
FIG. 7 is a schematic plan view showing the four-wire helical antenna shown in FIG.
FIG. 8 is a schematic front view showing the four-wire helical antenna shown in FIG.
FIG. 9 shows the height h _WL of the conductor wall when the inclination angle α of the helical of each helical radiation element from the horizontal plane is 22 ° in the four-wire helical antenna according to the first embodiment of the present invention. when changing a graph showing the half-power width HPBW and the axial ratio AR <3 dB below the beam width _{BW AR <3 dB.}
FIG. 10 is a diagram illustrating the height h _WL of the conductor wall when the inclination angle α of the helical of each helical radiation element from the horizontal plane is 24 ° in the four-wire helical antenna according to the first embodiment of the present invention. when changing a graph showing the half-power width HPBW and the axial ratio AR <3 dB below the beam width _{BW AR <3 dB.}
FIG. 11 shows the height h _WL of the conductor wall when the inclination angle α of the helical of each helical radiation element from the horizontal plane is 26 ° in the four-wire helical antenna according to the first embodiment of the present invention. when changing a graph showing the half-power width HPBW and the axial ratio AR <3 dB below the beam width _{BW AR <3 dB.}
FIG. 12A is a diagram illustrating the height h _WL of the conductor wall in the four-wire helical antenna according to the first embodiment of the present invention, which is 0, 0.10λ _2.3 , and 0.12λ ₂ , respectively. ₃ is a graph showing a radiation pattern at 0.14λ _2.3 , and (b) is a graph showing an axial ratio pattern.
FIG. 13 is a schematic perspective view showing a four-wire helical antenna according to a second embodiment of the present invention.
FIG. 14 is a schematic plan view showing the four-wire helical antenna shown in FIG.
15 is a schematic front view showing the four-wire helical antenna shown in FIG.
16A is a graph showing a radiation pattern when the height h _WL of the conductor wall is 0.14λ _{2.3 in} the folded two-wire type four-wire helical antenna, and FIG. 16B shows an axial ratio pattern. It is a graph.
17A is a graph showing a radiation pattern when the height h _WL of the conductor wall is 0.14λ _{2.3 in} the one-wire type four-wire helical antenna, and FIG. 17B is a graph showing an axial ratio pattern. It is.
[Explanation of symbols]
GP Ground plate 11 to 14 Helical radiating element 15 Conductor wall 16 Joint 21 to 24 Folded line

Claims (11)

Ground plate,
N (N is an integer of 2 or more) helical radiating elements erected on the ground plate and wound helically on the outer peripheral surface of the virtual cylinder;
A conductor wall provided on the ground plate around the N helical radiation elements;
An N-line helical antenna, comprising: a coupling portion that electrically couples N tops of the N points of the N helical radiation elements to each other. The N-ray helical antenna according to claim 1, wherein the N helical radiating elements are arranged on the outer peripheral surface of the virtual cylinder at equal angular intervals. 3. The N-ray helical antenna according to claim 2, wherein the N is 4, and the coupling unit cross-connects four crowns of the four helical radiation elements in a cross shape. 4. Ground plate,
N (N is an integer of 2 or more) helical radiating elements erected on the ground plate and wound helically on the outer peripheral surface of the virtual cylinder;
A conductor wall provided on the ground plate around the N helical radiation elements;
A coupling part that electrically couples the N crowns of the N helical radiating elements to each other;
An N-ray helical antenna, wherein each of the N helical radiating elements is folded from the top of the head and has a ground plate and N folded lines for short-circuiting. The N helical radiating elements are arranged at equal angular intervals on the outer peripheral surface of the virtual cylinder, and the N folded lines are arranged at a predetermined interval from an adjacent helical radiating element. An N-ray helical antenna according to claim 4. 6. The N-ray helical antenna according to claim 5, wherein the N is 4, and the coupling unit couples four crowns of the four helical radiating elements in a cross shape. Ground plate,
N (N is an integer of 2 or more) helical radiating elements erected on the ground plate and wound helically on the outer peripheral surface of the virtual cylinder;
An N-line helical antenna, comprising: a coupling portion that electrically couples N tops of the N points of the N helical radiation elements to each other. The N-ray helical antenna according to claim 7, wherein the N helical radiating elements are arranged on an outer peripheral surface of the virtual cylinder at equal angular intervals. 9. The N-ray helical antenna according to claim 8, wherein the N is 4, and the coupling unit connects four crowns of the four helical radiating elements in a cross shape. Ground plate,
N (N is an integer of 2 or more) helical radiating elements erected on the ground plate and wound helically on the outer peripheral surface of the virtual cylinder;
An N-ray helical antenna, wherein each of the N helical radiating elements is folded from the top of the head and has a ground plate and N folded lines for short-circuiting. The N helical radiating elements are arranged at equal angular intervals on the outer peripheral surface of the virtual cylinder, and the N folded lines are arranged at a predetermined interval from an adjacent helical radiating element. An N-ray helical antenna according to claim 10.

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