JP3283920B2 - Multi-frequency antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna suitable for an apparatus for transmitting and receiving a plurality of circularly polarized radio waves in all directions (omnidirectional), such as a radio beacon, a radio lighthouse, and a base station radio equipment. is there.

[0002]

2. Description of the Related Art As one of antennas for transmitting and receiving circularly polarized radio waves omnidirectionally in a horizontal plane, for example, Japanese Unexamined Patent Publication No. Hei.
A shape as shown in JP-A-604 is known.

In this type of antenna, as shown in FIG. 17, a cylinder 4 is provided at a position having a radius d from a center conductor 103 serving as a feed element, and a center conductor 103 is provided on a cylindrical surface 401 thereof.
A plurality of parasitic elements 4 arranged in parallel at an angle of π / 4 with respect to
02, 402, 402,... Cylindrical surface 40
1 is made parallel to the center conductor 103.

The X, Y, and Z orthogonal axes in FIG. 17 are set such that the XY plane is a horizontal plane and the Z axis is a vertical direction for convenience of consideration.

The center conductor 103 is taken in the direction of the Z-axis, and a pair of parasitic wire elements 402, 402 located at both ends of the diameter when viewed from the center conductor 103 are connected to the center conductor 10
3 and the center conductor 103 at the opposite locations at a distance d along the XY plane with respect to the center conductor 103, respectively.
/ 4 and are spatially crossed with each other at an angle of π / 2.

[0006] The set of such parasitic wire elements has a cylindrical surface 4.
A plurality of sets are provided on the 01. In the configuration shown in FIG. 17, the distance d is set so as to satisfy a condition of kd ≒ π / 2 (including a case where an equal sign is satisfied) (k is a wave number),
The length L of each of the parasitic wire elements 402, 402, 402,... Is selected so that the effect as a reflector with respect to the center conductor 103 and the effect as a director with respect to the used wavelength λ are the same. Make settings so that the functions are also exhibited.

When the center conductor 103 is excited in such a manner, non-directional circularly polarized radio waves in a horizontal plane are radiated to the space outside the cylinder 4.

[0008]

SUMMARY OF THE INVENTION The present invention has the following structure.
It is an object of the present invention to develop a circularly polarized antenna having omnidirectionality in one plane into one that can be shared by multiple frequencies.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a central conductor serving as a feed element and a parasitic element (hereinafter referred to as "proximity parasitic element") are provided in close proximity to the central conductor in parallel with the feed element.

[0010] The center conductor is excited by multiple frequencies. The proximity parasitic element radiates a radio wave by the induction.

A plurality of cylinders are multiplexed around the center conductor and the proximity parasitic element, respectively, and the cylinder surface of each cylinder has an angle of π / 4 with respect to the center conductor and the proximity parasitic element. A plurality of linear passive elements (hereinafter, referred to as "linear passive elements") are arranged in parallel.

In this case, the center conductor is made to operate as an antenna for one used wavelength, and the proximity parasitic element is made to operate as an antenna for several other used wavelengths.

In each of the cylindrical bodies, a linear parasitic element provided on each of the cylindrical surfaces serves as a director and a reflector for each of the use wavelengths corresponding to each of the cylindrical bodies. It is made to have both functions.

[0014]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG.
Is a side view showing an embodiment of the present invention, and FIG. 3 is a partially cutaway perspective view showing an embodiment of the present invention. In these figures, the same symbols indicate the same structural points.

FIGS. 1, 2 and 3 show an embodiment in which two wavelengths are used.

In this example, one dipole is used as the proximity parasitic element, the main dipole as the feeding element is excited at two frequencies, and the cylindrical body is double, and each of the cylindrical bodies is a straight cylinder. is there.

In FIG. 1, DA is a dipole (hereinafter, referred to as “main dipole”) that is both a central conductor and a feed element, DP is a dipole as a proximity parasitic element (hereinafter, referred to as “parasitic dipole”), and BN1. Is a balun for the main dipole DA (hereinafter sometimes referred to as “balun 1”), BN2 is a balun for the passive dipole DP (hereinafter sometimes referred to as “balun 2”), C
Y1 is a straight cylinder of radius R1 centered on the main dipole DA (hereinafter referred to as “outer cylinder”), and CY2 is a straight cylinder of radius R2 centered on the parasitic dipole DP (hereinafter referred to as “inner cylinder”). , PA1 are linear passive elements provided on the cylindrical surface of the outer cylinder CY1 (hereinafter referred to as “outer parasitic elements”).
That. ), PA2 is a linear parasitic element provided on the cylindrical surface of the inner cylinder CY2 (hereinafter referred to as "inner parasitic element").

The three orthogonal axes X, Y, and Z shown in FIG. 3 are provided for convenience of explanation, and the XY plane is taken as a horizontal plane, and the Z axis is taken as a vertical direction. These three axes also apply to FIGS. 1 and 2.

FIG. 2 is a perspective view of the material of the cylindrical surface of the outer cylinder CY1 and the material of the cylindrical surface of the inner cylinder CY2.

Main dipole DA and passive dipole D
Take P in the Z-axis direction.

The balun BN1 acts as a well-known predetermined balanced-unbalanced converter with respect to the radio wave (wavelength λ1) radiated by the main dipole DA, and similarly, the balun BN2 generates the radio wave (wavelength λ2) radiated by the parasitic dipole DP. ) Has the function of a known balanced / unbalanced converter.

Each of the outer parasitic elements PA1 is erected at an angle of π / 4 with respect to the generatrix of the outer cylinder CY1, and has a length of 2 · 通 る passing through the main dipole DA across the main dipole DA.
It is arranged so as to be located at both ends of the string of R1.

Each of a pair of outer parasitic elements on both sides of the main dipole DA has an attitude of π / 4 with respect to the main dipole DA and mutually has an angle of π /
They cross at an angle of 2. That is, the outer cylinder CY1 is provided with a plurality of such pairs of outer parasitic elements.

Similarly, each of the inner parasitic elements PA2 provided on the cylindrical surface of the inner cylinder CY2 is erected at an angle of π / 4 with respect to the generatrix of the cylinder, and the parasitic dipole DP
Are arranged at both ends of a chord having a length of 2 · R2 with respect to the center, and a plurality of such pairs are provided.

Each of these inner parasitic elements PA2 has:
It is located at an angle of π / 4 with respect to the parasitic dipole DP, and those located at both ends of the string passing through the parasitic dipole DP cross each other at an angle of π / 2.

FIG. 1 shows a state in which six (three pairs) of both the outer parasitic element PA1 and the inner parasitic element PA2 are installed so that only their heads are visible.

The cylindrical surface of each of the outer cylinder CY1 and the inner cylinder CY2 is a support base on which each outer parasitic element PA1 and each inner parasitic element PA2 is erected. It is made of a material that is transparent to the wavelength λ2 used by the dipole DP.

Main dipole DA and passive dipole DP
Means that they are juxtaposed in the Z-axis direction at extremely close locations.

A set of antennas is formed by the main dipole DA and the outer parasitic elements PA1 (plurality) provided on the cylindrical surface of the outer cylinder CY1. This set of antennas is hereinafter referred to as “outer antenna”.

Similarly, another set of antennas is formed by the parasitic dipole DP and the inner parasitic element PA2 (plurality) provided on the cylindrical surface of the inner cylinder CY2. This set of antennas is hereinafter referred to as “inner antenna”.

The main dipole DA is designed to exhibit the maximum radiation efficiency for the radiation wavelength λ1, and the passive dipole DP is designed to exhibit the maximum radiation efficiency for the radiation wavelength λ2.

When the wave number of the main dipole DA with respect to the radiation wavelength λ1 is k1, and the wave number of the parasitic dipole DP with respect to the radiation wavelength λ2 is k2, k1 · R1 ≒ π /
2 (including the case where the equals sign holds) and k2 ·
The magnitudes of R1 and R2 are set so that R2 ≒ π / 2 (including the case where the equality is satisfied).

Each length L1 of the outer parasitic element PA1
Is set so that the action of each outer parasitic element PA1 as a waveguide and the action as a reflector are the same for the wavelength λ1 of the radio wave radiated by the main dipole DA.

Similarly, the length L2 of each of the inner parasitic elements PA2 is determined by the function of each inner parasitic element PA2 as a director with respect to the wavelength λ2 of the radio wave radiated by the parasitic dipole DP, and as a reflector. It is set so that the action to be exhibited is the same.

[0035]

The main dipole DA is excited at two frequencies by signals of wavelengths λ1 and λ2 through a feeder FD (coaxial cable).

The main dipole DA radiates radio waves of wavelength λ1, and the passive dipole DP radiates radio waves of wavelength λ2 by induction.

The wavelength λ1 radiated from the main dipole DA
The outer parasitic element PA1 acts as a director and acts as a reflector for the radio wave of, and an omnidirectional circularly polarized radio wave propagates in the space outside the outer cylinder CY1.

For the radio wave of wavelength λ2 radiated from the parasitic dipole DP, the inner parasitic element PA2 functions as a director and a reflector, and the inner cylinder CY.
An omnidirectional circularly-polarized radio wave propagates in a space outside (in practice, outside the outer cylinder CY1).

Examples of characteristics obtained by the embodiment having the shapes shown in FIGS. 1, 2, 3 will be described below with reference to FIGS. 4, 5, 6, 7, 8, 9, and 1.
0 is shown in each figure.

In each of these figures, in each measurement, the outer cylinder CY1 and the inner cylinder CY2 are assembled in a predetermined shape, and the measurement is performed while changing (changing) the setting conditions for one of the cylinders. is there.

Further, the following (1) to (1) to
The specifications of (8) are common.

(1) Height of main dipole DA (length in Z-axis direction) D1 = 55 mm (2) Height of passive dipole DP (length in Z-axis direction)
D2 = 37 mm (3) Length of balun BN1 (balun 1) of main dipole DA (length in Z-axis direction) B1 = 53 mm (4) Length of balun BN2 (balun 2) of passive dipole DP (Z-axis) (Length in the direction) B2 = 38 mm (5) Diameter of balun BN1 A1 = 12 mm (6) Diameter of balun BN2 A2 = 20 mm (7) Outer parasitic element PA1 and inner parasitic element PA2
(8) Outer parasitic element PA1 and inner parasitic element PA2
Each thickness T = 0.25 mm The meaning of each of FIGS. 4, 5, 6, 7, 8, 9 and 10 is as follows.

FIG. 4 shows the characteristics measured for the outer antenna, and the length L1 of the outer parasitic element PA1 is 96 m.
m, and taking the radius R1 of the outer cylinder CY1 as a parameter, the frequency f1 of the radio wave radiated by the main dipole DA
Consider the change in the axial ratio and the change in the return loss when changing.

FIG. 5 shows the characteristics measured for the outer antenna, where the frequency f1 of the radio wave radiated by the main dipole DA is fixed at 1215 MHz, and the length of the outer parasitic element PA1 is determined using the radius R1 of the outer cylinder CY1 as a parameter. The change in the axial ratio when L1 is changed.

FIG. 6 shows the characteristics measured for the inner antenna, and the length L2 of the inner parasitic element PA2 is 68 m.
m, with the radius R2 of the inner cylinder CY2 as a parameter, the change in the axial ratio and the change in the return loss when the frequency f2 of the radio wave radiated by the parasitic dipole DP is changed.

FIG. 7 shows characteristics measured for the inner antenna. The inner parasitic element PA2 is fixed with the frequency f2 of the radio wave radiated from the parasitic dipole DP fixed at 1775 MHz and the radius R2 of the inner cylinder CY2 as a parameter.
Is a graph that considers the change in the axial ratio when the length L2 is changed.

FIG. 8 shows the length L1 of the outer parasitic element PA1.
= 96 mm and the radius R1 of the outer cylinder R1 = 50 mm, and the length L2 = 68 mm of the inner parasitic element PA2, respectively, when the radius R2 of the inner cylinder CY2 was changed,
Radio waves radiated from the main dipole DA (frequency f1 = 121
5 MHz) and a change in the axial ratio of a radio wave (frequency f2 = 1775 MHz) radiated from the passive dipole DP.

FIG. 9 shows the directional characteristics measured for the outer antenna, where the radius R1 of the outer cylinder CY1 is 50 m.
m, length L1 of outer parasitic element PA1 = 96 mm, height D1 of main dipole = 55 mm, and balun 1 (BN1)
The main dipole DA when the height B1 = 53 mm
Indicates directivity in a horizontal plane and directivity in a vertical plane when a radio wave having a frequency f1 = 1215 MHz is radiated.

FIG. 10 shows the directional characteristics measured for the inner antenna, where the radius R2 of the inner cylinder CY2 is 30 m.
m, length L2 of inner parasitic element PA2 = 68 mm, height D2 of parasitic dipole DP = 37 mm, and balun 2
When the height B2 of (BN2) is 38 mm, the directivity in the horizontal plane and the directivity in the vertical plane when the passive dipole DP radiates radio waves of frequency f2 = 1775 MHz are shown.

[0050]

[Consideration] By combining the figures of FIGS. 4 to 10, the outer antenna and the inner antenna as a whole have good characteristics in these two frequency bands.

4 and 6, when the outer cylinder CY1 and the inner cylinder CY2 are each used alone, the center frequency (1215 MHz for the outer cylinder, 1775 MHz for the inner cylinder: outer parasitic element PA1 and inner parasitic element) (The frequency at which the parasitic element PA2 exhibits the same function as a director and the function as a reflector provided by its respective lengths L1 and L2). On the other hand, it is understood that both the axial ratio and the return loss are quite sensitive.

From FIGS. 5 and 7, both the outer cylinder CY1 and the inner cylinder CY2 are changed by changing the radii R1 and R2.
Each use frequency (f1 = 1215M for outer antenna)
Hz, f2 = 1775 MHz for the inner antenna), the length L1 of the outer parasitic element PA1 and the length L2 of the inner parasitic element PA2 are respectively predetermined lengths (in the case of the outer parasitic element PA1, L1 = 96 mm, In the case of the inner parasitic element PA2, L2 = 68 mm: a length at which the function presented as a director and the function presented as a reflector are the same for the used frequency f1 = 1215 MHz of the outer antenna and the used frequency f2 = 1775 MHz of the inner antenna. It can be seen that the axial ratio is quite sensitive when changing on both sides around the parentheses.

FIG. 8 shows that when the radius R2 of the inner cylinder CY2 is changed, the axial ratio of the radiated radio wave from the outer antenna changes in this frequency band even though the axial ratio of the radiated radio wave from the inner antenna changes. Is not affected. That is, it is understood that the coupling between both antennas is extremely small.

From FIGS. 9 and 10, it can be seen that both the outer antenna and the inner antenna obtain extremely good omnidirectionality in the horizontal plane.

From FIGS. 9 and 10, it can be seen that both the outer antenna and the inner antenna have good figure-eight characteristics in the vertical plane.

[0056]

Other Embodiments (1) A plurality of passive dipoles may be provided for one frequency. In this case, for example, as shown in FIGS. 11, 12, and 13, a plurality of parasitic dipoles DP1, DP2, DP3,... Having the same specifications are arranged symmetrically around the main dipole DA.

In FIGS. 11, 12, and 13, the outer cylinder and the inner cylinder are omitted, and only the portion showing the positional relationship between the main dipole DA and the passive dipoles DP1, DP2, DP3,.

In this case, each of the inner parasitic elements PA1 formed on the cylindrical surface of the inner cylinder CY2 is centered on the center of symmetry (position coincident with the main dipole DA) of each of the parasitic dipoles DP1, DP2, DP3,. Place a pair (at the end) at the ends of the string passing through the center of symmetry
A plurality of such pairs are attached to the cylindrical surface.

In this way, each parasitic dipole D
P1, DP2, DP3,... Radiate radio waves of the same frequency (the same phase and amplitude) by induction from the main dipole DA, and the radiations are combined, so that each parasitic dipole DP1 is located at the same position as the main dipole DA. , DP2, DP
The radiation is the same as that of one parasitic dipole DP obtained by combining 3,. Therefore, the center of the inner cylinder CY2 can be matched with the center of the outer cylinder CY1, and both cylinders can be provided without eccentricity.

(2) The parasitic element PA1 (plural) installed on the cylindrical surface of the outer cylinder CY1 and the parasitic element PA2 (plural) installed on the cylindrical surface of the inner cylinder CY2 are shown in FIG. (For the inner antenna, when there are a plurality of parasitic dipoles DP1, DP2, DP3,..., The composite center thereof) When viewed from the same side, the direction in which they are laid on the respective cylindrical surfaces on the same side is the same direction (parallel). As shown in FIG. 14, this means that each of the parasitic elements PA1, PA2
Are the main dipole DA and the parasitic dipole DP (or, in the case of a plurality, the respective parasitic dipoles DP1, DP2, DP
3,... Are formed at an angle of π / 4, respectively, and a parasitic element PA1 provided on the cylindrical surface of the outer cylinder CY1 and a parasitic element PA2 provided on the cylindrical surface of the inner cylinder CY2 are provided. May be arranged so as to be orthogonal to each other. 14 also shows the outer cylinder CY1 and the inner cylinder CY2 in a transparent manner, similarly to FIG.
A1 and A2 and their lengths are B1 and B2.
Notation of the name and the symbol is omitted.

(3) In the case of FIG. 2, the radio wave radiated by the outer antenna and the radio wave radiated by the inner antenna have the same direction of rotation of the circularly polarized plane. In the case of FIG. 14, the turning directions of the polarization planes of the radio waves radiated from both antennas are opposite to each other.

(4) Outer cylinder CY1 and inner cylinder CY2
If the number of linear parasitic elements formed on each cylindrical surface (the number of pairs) is too small, omnidirectional characteristics cannot be obtained. If too large, the radiated power will be out of the cylinder. Since the propagation does not occur, there is an appropriate number (approximate number) from the practical viewpoint.

In each of the above-described embodiments, "6 (3 pairs)" is the optimum number in the two frequency bands.

(5) Directivity in a vertical plane is obtained by stacking a double-cylinder shared antenna as shown in FIG. 2 or FIG. 14 by stacking two or more stages in the vertical direction (Z-axis direction). Can be narrowed down.

(6) Each of the linear parasitic elements (the outer parasitic element PA1 and the inner parasitic element PA2) is shown in FIGS. 1, 2, 3 and 14 in a state of being bent along a cylindrical surface. Although shown, they may be constructed linearly.

Also in this case, each linear parasitic element is located in a plane parallel to the Z-axis and π with respect to the Z-axis (generic line of the cylinder surface).
"Pair" with a / 4 attitude and symmetrically positioned with respect to the main or passive dipole
Is installed so as to spatially cross at an angle of π / 2 with respect to the linear passive element.

In this case, these linear parasitic elements PA
1, a base supporting PA2 is formed as a cylindrical surface of a straight cylindrical body CY.

For example, as shown in FIGS. 15 and 16, the cross section may have any shape such as a convex polygon or a concave polygon.
In FIGS. 15 and 16, the position indicated by the symbol P indicates the position of the main dipole DA or the parasitic dipole DP (in the case of a plurality of parasitic dipoles DP1, DP2, DP3,..., They are combined). .

A straight cylindrical body CY having a shape as shown in FIGS.
When the linear passive elements PA1 and PA2 are erected on the cylindrical surface so as to form π / 4 with respect to the generatrix, the required condition of the erection posture with respect to the main dipole DA or the passive dipole DP is satisfied.

If the straight cylindrical body CY is made so that the cross section is symmetrical with respect to the position of P as shown in FIGS.
The requirement that the linear passive elements PA1, PA2, etc. be symmetrically arranged with respect to the position of P is satisfied.

(7) The frequencies used are not limited to two. In general, implementations at more than two frequencies are contemplated as being within the present invention.

That is, when three or more operating frequencies are used, two or more passive dipoles are arranged in accordance with each operating frequency. However, in the case where a plurality of parasitic dipoles DP1, DP2, DP3,... Are used for any one frequency as shown in FIG. Think of it as a parasitic dipole.

A cylindrical body CY is formed for each used wavelength of the main dipole DA and each parasitic dipole DP, and a linear parasitic element is erected on the cylindrical surface.

When arranging these cylindrical bodies in a multiplex manner, it is not necessary to use cylindrical bodies having the same shape. For example, the first cylindrical body has a shape as shown in FIG. 16, the second cylindrical body has a shape as shown in FIG. 15, and the third cylindrical body has a shape such as a cylinder. It may be combined. Even when two or more right polygonal cylinders are used, it is not necessary that the number of surfaces (the number of sides of the polygonal cross section) of each straight cylindrical body is equal.

When the number of cylindrical bodies increases, there is a practical problem that the radiated power does not propagate to the outside. Therefore, there is a limit in terms of the number of frequencies to be used in this embodiment in terms of implementation.

(8) When the operation is performed at two frequencies, FIG.
It is not necessary to limit the use of the main dipole DA at the lower frequency and the use of the passive dipole DP at the higher frequency as in the embodiments shown in FIGS. The main dipole DA may be used at a higher frequency. In this case, if the power radiated by induction from the parasitic dipole DP can provide the required energy to be applied to the outer cylinder CY1, the outer cylinder CY1 may be adapted to the working wavelength of the parasitic dipole DP. .

Similarly, when the operation is performed at three or more frequencies, it is not necessary to limit the use frequency of the main dipole DA so as to be suitable for the innermost tubular body or the outermost tubular body. Absent. Of the three or more cylindrical bodies multiplexed, any one at an intermediate position may be adapted to the wavelength used by the main dipole DA.

In the present invention, “first, second, third, third
The designation such as “the fourth frequency,...” Is not limited to the meaning of the order of higher or lower frequency, and the designation of the “first, second, third, fourth,. Such designations are not meant to limit the order in which the cylinders are arranged from the inside or from the outside, and these are used only to distinguish three or more of the same kind from each other. .

(9) The cylindrical surface of each cylindrical body is a support base on which the linear passive elements PA1 and PA2 are laid. However, the support base is not necessarily provided at all locations of each of the linear passive elements. It need not be present without gaps.

When each of the linear parasitic elements PA1 and PA2 is made of a hard material, the self-sustainability is high. Therefore, one or at most several ends of each of the linear parasitic elements PA1 and PA2 are provided. Each of the linear parasitic elements PA1 and PA2 is only discretely supported as appropriate within a range of the main dipole DA or the parasitic dipole DP (or a composite of a plurality of parasitic dipoles DP1, DP2, DP3,...). Π / 4 and these dipoles D
In some cases, a predetermined condition that the arrangement is symmetrical with respect to A and DP may be satisfied.

Such a supporting method is easy when each of the linear parasitic elements PA1 and PA2 is linear, but has a curvature corresponding to the cylindrical surface of each of the linear parasitic elements PA1 and PA2. It is possible even when you have a bend that follows.

The phrase “installed on the cylindrical surface of the cylindrical body” means that
The above-described predetermined condition is satisfied not only when the entire linear passive elements PA1 and PA2 are evenly attached to the material forming the cylinder surface, but also when there is no actual carrier at a location corresponding to the cylinder surface. At each point corresponding to the cylindrical surface, each linear parasitic element P
It is understood that A1 and PA2 exist.

[0083]

[Effect] Since the coupling between the outer antenna and the inner antenna is small, when the radius of the cylinder of one of these antennas, the length of the linear parasitic element, the operating frequency, etc., change.
Since the influence of the characteristics of the other antenna is small or extremely small, it is possible to design each antenna from the same viewpoint as when designing each antenna independently.

Further, since the operating frequency of each antenna can be independently selected and adjusted, there is a great practical advantage.

Further, no special power supply circuit for generating circularly polarized waves is required.

Further, it is possible to easily obtain a circularly polarized wave that revolves in the opposite directions with both antennas.

This antenna can be realized with a simple structure, and each of the antennas obtains extremely good omnidirectionality in the horizontal plane and figure-eight characteristics in the vertical plane.

[0088]

[Use] (1) It can be used for communication between a base station and a mobile station in mobile communication. For example, cars, ships,
It can be used for helicopters, artificial satellites, cordless telephones, personal radios, etc.

(2) It can be used for frequency diversity communication in an urban area or the like.

(3) It can be used for a mobile telemeter or the like and is used when a channel for tracking or position locating and a channel for transmitting measurement data are shared.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a side view showing the embodiment of the present invention.

FIG. 3 is a partially cutaway perspective view showing an embodiment of the present invention.

FIG. 4, showing an embodiment of the present invention, is a diagram illustrating frequency-to-axis ratio characteristics and frequency-to-return loss characteristics of an antenna formed by an outer cylinder.

FIG. 5 is a view showing an embodiment of the present invention and is a view showing a length-to-axis ratio characteristic of an uncharged electron on a cylindrical surface of an antenna formed by an outer cylinder.

FIG. 6, showing an embodiment of the present invention, is a diagram illustrating frequency-to-axis ratio characteristics and frequency-to-return loss characteristics of an antenna formed by an inner cylinder.

FIG. 7, showing an embodiment of the present invention, is a diagram illustrating length-to-axis ratio characteristics of a parasitic element on a cylindrical surface of an antenna formed by an inner cylinder.

FIG. 8 is a view showing an embodiment of the present invention, in which the influence of the outer antenna when the radius of the inner cylinder is changed is shown by an axial ratio characteristic.

FIG. 9 is a view showing an embodiment of the present invention and showing the directivity in the horizontal plane of the outer antenna and the figure 8 characteristic in the vertical plane.

FIG. 10 is a view showing the embodiment of the present invention and showing the directivity in the horizontal plane of the inner antenna and the figure 8 characteristic in the vertical plane.

FIG. 11, showing an embodiment of the present invention, is a partially omitted plan view showing an example of arrangement of proximity parasitic dipole elements.

FIG. 12 shows an embodiment of the present invention, and is a partially omitted plan view showing an example of the arrangement of proximity parasitic dipole elements.

FIG. 13 shows the embodiment of the present invention, and is a partially omitted plan view showing an example of the arrangement of proximity parasitic dipole elements.

FIG. 14 is a side view showing an embodiment of the present invention.

FIG. 15 is a partially omitted transverse sectional view showing an embodiment of the present invention.

FIG. 16 is a partially omitted transverse sectional view showing the embodiment of the present invention.

FIG. 17 is a perspective view showing a conventional example.

[Explanation of symbols]

DA: Main dipole DP, DP1, DP2, DP3: Parasitic dipole BN1: Balun (balun 1) of main dipole DA BN2: Balun (balun 2) of parasitic dipole DP CY1: Outer cylinder CY2: Inner cylinder PA1 ... Outer Parasitic element PA2 ... Inner parasitic element L1 ... Length of outer parasitic element PA1 L2 ... Length of inner parasitic element PA2 103 ... Dipole 4 ... Cylinder 402 ... Linear parasitic element 3 ... Balun

Continuation of the front page (56) References JP-A-1-3111604 (JP, A) JP-A-53-53 (JP, A) JP-A-3-241902 (JP, A) JP-A-60-218907 (JP, A) , A) JP-A-4-287505 (JP, A) JP-A-63-18804 (JP, A) Nozomi Hasebe Toru Hamaki Koichi Sakaguchi, Circularly polarized omnidirectional antenna, The Institute of Electronics, Information and Communication Engineers Autumn 1988 Conference Lecture Papers, Japan, The Institute of Electronics, Information and Communication Engineers, B-1-23 (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01Q 19/28 H01Q 9/28

Claims (9)

(57) [Claims] In an antenna having a multiple cylindrical body, one or a plurality of proximity parasitic elements are disposed very close to a feed element and parallel to the feed element.
, And the proximity parasitic elements are formed so as to conform to the second, third, fourth,... Frequencies, respectively. A linear parasitic element having the same function as a director and a function as a reflector with respect to the first frequency is erected on the cylindrical surface, and any other one or another constituting the multiplex cylindrical body A linear parasitic element having the same action as a director and the same action as a reflector for each of the second, third, fourth,... Frequencies is provided on each of the cylindrical surfaces of the plurality of cylindrical bodies. A multi-frequency antenna that is erected and has the above-mentioned feed element excited at multiple frequencies. 2. The multi-frequency antenna according to claim 1, wherein there is one proximity parasitic element for each of one or a plurality of arbitrary second, third, fourth,... Frequencies. antenna. 3. The multi-frequency antenna according to claim 1, wherein a plurality of proximity parasitic elements are provided for each of one or more of the second, third, fourth,... Multi-frequency antenna symmetrically arranged with respect to. 4. The multi-frequency antenna according to claim 1, wherein the linear parasitic element and the other arbitrary cylindrical body are provided on the cylindrical surface of the arbitrary one cylindrical body. A multi-frequency shared antenna in which the linear parasitic elements installed on the cylindrical surface of the multi-frequency antenna are parallel to each other. 5. The multi-frequency antenna according to claim 1, 2, or 3, further comprising: a linear parasitic element provided on a cylindrical surface of an arbitrary cylindrical body and another arbitrary cylindrical body. A multi-frequency shared antenna in which the linear parasitic elements installed on the cylindrical surface are orthogonal to each other. 6. The multi-frequency antenna according to claim 1, wherein at least one of the multiple tubular bodies is a cylinder. 7. The multi-frequency antenna according to claim 1, wherein the frequency is 2
And a cylindrical body corresponding to each frequency is a cylinder. 8. The multi-frequency antenna according to claim 1, wherein at least one of the multiple cylindrical bodies is a polygonal cylinder. 9. A multi-frequency antenna comprising the multi-frequency antenna according to claim 1, 2, 3, 4, 5, 6, 7 or 8 provided in a plurality of stages in a direction along the feed element.