JPH11266119A - Multistage antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multistage antenna that can have, for instance, many antenna elements more than three stages, without disturbing the directivity of the antenna. SOLUTION: Antenna elements 4 and 6 are constituted by fixing central parts of circular cone shaped grounded elements 4g and 6g on a conductive arm 2 and fixing central parts of feeding elements 4h and 6h to the conductive arm 2 by way of insulators 10 and 12, plural feeding lines connected to each of the feeding lines 4h and 6h are arranged in the conductive arm 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-stage antenna which can be used, for example, as a vertical diversity antenna.

[0002]

2. Description of the Related Art A diversity antenna is used as an antenna of a base station of a mobile communication system such as a personal handy horn system or a portable telephone in order to prevent a change in reception level due to fading. The diversity antenna has a plurality of antennas arranged at a certain interval. A vertical diversity antenna that adopts the vertical direction as the arrangement direction of the plurality of antennas is advantageous from the viewpoint of landscape because if each antenna is housed in one case, it looks like one antenna in appearance.

[0003] As the vertical diversity antenna, for example, there is the following. Two upper and lower antennas are arranged along the vertical direction. The upper and lower antennas are each composed of a collinear antenna. These upper and lower antennas are fed by an upper antenna coaxial cable and a lower antenna coaxial cable, respectively. The coaxial cable for the upper antenna passes through the lower antenna.

[0004]

In the above vertical diversity antenna, it may be desirable to arrange three or more collinear antennas in order to improve the gain. However, the collinear antenna has a complicated structure, and it is particularly difficult to adopt a configuration in which a collinear antenna having three or more stages of diversity is arranged.

As a method of feeding power to the upper and lower collinear antennas, serial feeding may be considered. However, when the upper and lower collinear antennas are accommodated in the above-described case, the reflection at the case is large, the current distribution is disturbed, and the directivity on the vertical plane may be significantly deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-stage antenna capable of having a large number of antenna elements such as three or more, without disturbing the directivity of the antenna. Another object of the present invention is to provide a multi-stage antenna that is not affected by reflection from a case or the like.

[0007]

According to the first aspect of the present invention,
A conductive arm, a central portion fixed to the conductive arm, a conical grounding element whose diameter increases from the central portion toward the tip, and a central portion fixed to the conductive arm via an insulator. From the central portion to the tip portion, from a conical feed element whose diameter increases toward the tip,
A plurality of antenna elements having a conical grounding element and a central part or a tip end of a feeding element adjacent to each other, and a plurality of feeding lines inserted into the conductive arm and connected to the respective feeding elements. , Have.

According to the first aspect of the present invention, in each antenna element, a dipole antenna is formed by the ground element and the feed element, so that a signal received by each of these antenna elements is transmitted via each feed line. Transmitted. Since each feed line is laid in the conductive arm, the current distribution of the antenna element outside the conductive arm is not disturbed. Further, since both the feed element and the ground element are conical elements, the antenna becomes a broadband antenna.

According to a second aspect of the present invention, in the first aspect of the present invention, the grounding element and the feeding element are arranged so that a length of about の of a wavelength of a received radio wave is in a length direction of the conductive arm. Have along.

According to the second aspect of the present invention, since the grounding element and the feeding element have a length of about の of the wavelength of the received radio wave, the current of a half wavelength of the reception wavelength can be favorably obtained. Ride between these.

According to a third aspect of the present invention, in the first aspect of the present invention, the feeding element has a length of about １ ／ of the wavelength of the received radio wave from the feeding point thereof along the conductive arm. And a tip thereof is connected to the conductive arm.

According to the first aspect of the present invention, there is a possibility that an unnecessary current flows on the outer surface of the conductive arm. But,
With the configuration according to the third aspect of the present invention, the power supply element includes:
It functions in the same way as a super top, and can cut unnecessary current flowing through the outer surface of the conductive arm.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the feed element is located at a position having a length of about １ ／ of the wavelength of the received radio wave from the feed point thereof along the conductive arm. And a short-circuit plate connected to the conductive arm.

[0014] According to the invention described in claim 4, unnecessary current flowing to the outer surface of the conductive arm can be cut.

According to a fifth aspect of the present invention, there is provided an electro-optical device comprising: a conductive arm;
It has two sets of antenna elements coupled to the conductive arm. The two sets of antennas have a central part on the conductive arm so that a current wave of about の of the wavelength of the received radio wave is placed between a ground element having a central part coupled thereto and a tip of the ground element. And an insulated power supply element. The two sets of antenna elements are arranged mirror-symmetrically with respect to a plane perpendicular to the length direction of the conductive arm as a reference plane. A conductive sleeve having an odd multiple of about 数 wavelength of the received radio wave is arranged along the conductive arm, and connects the feeding points of the two feeding elements of the two sets of antenna elements. . A power supply line is connected to one end of the sleeve.

According to the fifth aspect of the present invention, when power is supplied from the feeding point of one antenna element to the other antenna element via the conductive sleeve, the other antenna element is supplied with an opposite phase. However, since both antenna elements are arranged in a mirror surface, radio waves are radiated from both antennas in the same phase.
Therefore, the combined radiation lobe is horizontal.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the power supply element is formed in a conical shape, a cylindrical shape, or a disk shape having a length of about １ ／ of the wavelength of the received radio wave. And the grounding element is about 1/1 of the wavelength of the received radio wave.
It is formed in a conical, cylindrical or disk shape having a length of four.

According to the invention described in claim 6, various antenna elements can be used. In addition, the impedance when viewing the antenna element connected from one end to the other end of the sleeve and the impedance when viewing the antenna element connected to this from one end of the sleeve are an integral multiple of about の of the received radio wave. Since the length of the power supply line is the same, the values are the same. The current or voltage ratio is one to one,
It becomes an ideal stack antenna.

[0019] According to a seventh aspect of the present invention, there is provided the conductive arm,
It has two sets of antenna elements provided on the conductive arm. The two sets of antenna elements are arranged such that a current wave of about の of the wavelength of the received radio wave is placed between a ground element whose center is coupled to the conductive arm and a tip of the ground element.
And a feed element coupled to the conductive arm with a central part insulated. A first feeding line is connected to one feeding point of the two feeding elements. A second feed line connects the feed points of the two feed elements,
Is somewhat shorter than the wavelength of the received radio wave.

According to the seventh aspect of the present invention, the antenna element fed through the second feed line is fed earlier than the antenna element fed by the first feed line. Therefore, by selecting the appropriate length of the second feed line, the combined radiation characteristics of the two sets of antennas have the desired beam tilt angle.

According to an eighth aspect of the present invention, in the invention of the seventh aspect, the feed element is formed in a conical shape, a cylindrical shape, or a disk shape having a length of about の of the wavelength of the received radio wave. And the grounding element is about 1/1 of the wavelength of the received radio wave.
It is formed in a conical, cylindrical or disk shape having a length of four.

According to the invention described in claim 8, various antenna elements can be used.

According to a ninth aspect of the present invention, there is provided an arm, a plurality of antenna elements provided on the arm, and a radome arranged so as to surround the periphery of the antenna element.
A ring-shaped resonator disposed between the inner surface of the radome and the antenna element. The ring-shaped resonator radiates from the antenna element, is reflected by the radome via the ring-shaped radiator, and reaches the ring-shaped resonator when the radio wave is in phase with the radio wave radiated from the antenna element. Is selected.

When no ring-shaped radiator is provided, the radio wave radiated from the antenna element is reflected by the radome,
Return to the antenna element. Therefore, the impedance of the antenna element increases. To prevent this, a ring-shaped resonator is provided, and the radio wave reflected by the radome through the ring-shaped resonator and returned to the antenna element again through the ring-shaped resonator is combined with the radio wave radiated from the antenna element. It is in phase.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The multi-stage antenna according to the first embodiment of the present invention is used, for example, as a vertical diversity antenna. This vertical diversity antenna is shown in FIG.
As shown in FIG.
The arm 2 is made of a material having conductivity, for example, metal. The arm 2 is, for example, a circular pipe having a diameter of λ / 16 (λ is the center wavelength of a radio wave received by the vertical diversity antenna).

The arm 2 is provided with a pair of antenna elements including an upper antenna element 4 and a lower antenna element 6. Although not shown, a plurality of pairs of the antenna elements are provided along the length direction of the arm 2.

The upper antenna element 4 has a ground element 4g and a feed element 4h. The lower element 6 is also a ground element 6
g and a feed element 6h. 4g of these grounding elements
And 6g and the feed elements 4h and 6h are formed in a hollow conical shape whose diameter increases from the center toward the tip.

The grounding elements 4g and 6g are arranged at predetermined intervals in the length direction of the arm 2. Grounding element 4g
And 6g are directly fixed to the arm 2.
In this fixed state, the maximum diameter portion (tip portion) of the grounding element 4 g faces upward of the arm 2, and the maximum diameter portion (tip portion) of the grounding element 6 g faces downward of the arm 2.

A sleeve 8 made of a conductive material, for example, a metal, is attached to the outer peripheral surface of the arm 2 between the grounding elements 4g and 6g via, for example, ring-shaped insulating materials 10 and 12. The upper end of the sleeve 8 is arranged close to the grounding element 4g, and the lower end of the sleeve 8 is arranged close to the grounding element 6g.

At the upper end of the sleeve 8, the center of the feed element 4h, that is, the feed point is fixed. At the lower end of the sleeve 8, a central portion of the feed element 6h, that is, a feed point is fixed. In this fixed state, the largest diameter portion (tip portion) of the feed element 4h faces downward, and the largest diameter portion (tip portion) of the feed element 6h faces upward.

As described above, the upper antenna element 4 and the lower antenna element 6 are arranged mirror-symmetrically with the plane S perpendicular to the arm 2 as the plane of symmetry between the largest diameter portions of the feed elements 4h and 6h. I have.

A power supply line, for example, a coaxial cable 14 is inserted into the arm 2. The center conductor 14i is connected to the center of the feed element 4h, that is, the feed point.
Therefore, the feeding points of the feeding elements 4 h and 6 h are connected via the sleeve 8. In addition, this 1 not shown
The other pair of antenna elements above the pair of antenna elements are similarly supplied with power via the coaxial cable 16. Similarly, another pair of antenna elements below the pair of antenna elements is fed by a coaxial cable (not shown). The outer conductor of each coaxial cable is connected to the arm 2.

Grounding elements 4g and 6g and feeding elements 4h and 6
h both have a length of about λ / 4 along the length direction of the arm 2. These maximum radii h are between λ / 24 and λ
/ 4. Therefore, the angle θ between the grounding elements 4g and 6g and the feeding elements 4h and 6h with the arm 2 is 10 to 3
5 degrees. The sleeve 8 has an odd multiple of λg / 2,
For example, λg / 2 (λg is the center wavelength in the coaxial tube of the radio wave received by the vertical diversity antenna in the coaxial structure formed between the sleeve 8 and the arm 2).

In such a vertical diversity antenna, when the feed elements 4h and 6h are fed by the coaxial cable 14, as shown in FIG. 2, between the ground element 4g of the upper antenna element 4 and the feed element 4h, Antenna element 6
A current wave of λ / 2 rides between the grounding element 6g and the feeding element 6h. Therefore, the upper antenna element 4 and the lower antenna element 6 each function as a dipole antenna.

In particular, since the sleeve 8 has a length of λg / 2, the feeding elements 4h of the upper antenna element 4 and the feeding element 6h of the lower antenna element 6 are fed in opposite phases.
However, since the upper antenna element 4 and the lower antenna element 6 are arranged mirror-symmetrically, the radio waves radiated from the upper antenna element 4 and the lower antenna element 6 have the same phase. As a result, the combined radiation lobe is horizontal.

Further, since the sleeve 8 has a length of λg / 2, the impedance when the sleeve 8 and the lower antenna element 6 are viewed from the feeding point of the upper antenna element 4 is:
It becomes equal to the impedance of the upper antenna element 4. Therefore, the current ratio or the voltage ratio between the upper antenna element 4 and the lower antenna element 6 is 1: 1, and an ideal stack antenna is obtained. Therefore, if the impedance of the upper antenna element 4 and the lower antenna element 6 is set to twice the design impedance (for example, 50Ω), the matching of the upper antenna element 4 and the lower antenna element 6 can be achieved.

Further, the coaxial cable 14 passes through the inside of the conductive arm 2. Therefore, since the radio wave radiated from the coaxial cable 14 is shielded by the conductive arm 2, even if the coaxial cable 14 passes through the inside of the lower antenna element 6, the electric current distribution of the lower antenna element 6 is disturbed. There is no.

The grounding elements 4g and 6g and the feeding element 4
Since h and 6h are conical, a broadband antenna can be obtained, and it can be easily manufactured by a diaphragm type or the like. Further, since the lengths of the grounding elements 4g and 6g and the feeding elements 4h and 6h along the arm 2 are selected to be λ / 4, they function in the same manner as the supertop, and as shown by the dotted line in FIG. Unnecessary current flowing to the arm 2 can be cut, and unnecessary current flowing to the surface of the sleeve 8 can also be cut. These unwanted currents
The phase of the current radiated from the feed elements 4h and 6h is often different from that of the feed elements 4h and 6h, which disturbs the directivity of the antenna and lowers the gain.

The vertical diversity antenna of this embodiment has conical grounding elements 4g and 6g and a feeding element 4h
And 6h, the feed elements 4h and 6h can be replaced with disk-shaped elements 4h1 and 6h1 having a radius of, for example, λ / 4, as shown in FIG. In this case, in order to cut unnecessary current that tends to flow on the surface of the sleeve 8,
0 may be provided. Also in this case, the unnecessary currents flowing on the surface of the arm 2 are cut by the grounding elements 4g and 6g functioning as super tops.

Alternatively, as shown in FIG. 3B, both the grounding elements 4g2 and 6g2 and the feeding elements 4h2 and 6h2
A cylindrical element having a length of λ / 4 in the arm 2 along the length direction may be used. In FIG. 3B, the grounding element may be the conical element shown in FIG. 1, the grounding element may be a conical element, and the feeding element may be a disk-shaped or conical element.

FIG. 4 shows a frequency characteristic of a combined maximum radiation direction gain of a pair of antenna elements 4 and 6 of the vertical diversity antenna. With these antenna elements 4 and 6,
Nearly 4.5 from 1895 MHz to 1920 MHz
A gain of dB is obtained. FIG. 5 shows a frequency characteristic of a combined standing wave ratio of a set of antenna elements 4 and 6 of the vertical diversity antenna. These antenna elements 4 and 6
Then, the combined standing wave ratio is 1.4 to 1.19, which is a value that is sufficiently practical. FIG. 6 shows the combined vertical plane directivity of the antenna elements 4 and 6 at 1907.5 MHz.
FIG. 6 shows that the antenna elements 4 and 6 receive radio waves arriving from a substantially horizontal direction. FIG. 7 shows the combined horizontal plane directivity of the antenna elements 4 and 6 at 1907.5 MHz. FIG. 7 shows that the antenna elements 4 and 6 are non-directional in the horizontal plane.

FIG. 8 shows a vertical diversity antenna according to the second embodiment. The vertical diversity antenna shown in FIG. 1 has a directivity pointing in the horizontal direction. However, the vertical diversity antenna shown in FIG. 8 has a beam tilt whose directivity is lower than the horizontal plane, that is, has a downward beam tilt. A vertical diversity antenna having such a beam tilt is used when it is not desired to radiate a radio wave too far or to receive a radio wave from a distant place.

The vertical diversity antenna of FIG. 8 also includes the conductive arm 2, the upper antenna element 40, and the lower element antenna element 60, similarly to the vertical diversity antenna of FIG. The upper antenna element 40 and the lower antenna element 60 also include conical grounding elements 40g and 60g and conical feeding elements 40h and 60h. In the vertical diversity antenna of FIG.
And the lower antenna element 6 are arranged mirror-symmetrically. However, in this vertical diversity antenna, they are not arranged mirror-symmetrically. That is, the grounding element 40g of the upper antenna element 40, the feeding element 40h of the upper antenna element 4, the grounding element 60g of the lower antenna element 60, and the feeding of the lower antenna element 60 from the upper side of the arm 2 toward the lower side of the arm 2. The elements 60h are arranged in the order of the names. As shown in FIG. 9, a plurality of sets of antenna elements, each of which includes the upper antenna element 40 and the lower antenna element 60, are provided along the arm 2.

Of course, the grounding elements 40g and 60g are directly connected to the arm 2 at their central portions. Feeding elements 40h and 60h are attached to arm 2 at their central portions via insulating ring-shaped spacers 100 and 120. Each of the grounding elements 40g and 60g is arranged such that the maximum diameter portion thereof faces upward. Each feed element 40
h and 60h are arranged such that the largest diameter portions face downward.

Each of the grounding elements 40g and 60g and the feeding element 4
0h and 60h are formed to have substantially the same size as the ground elements 4g and 6g and the feed elements 4h and 6h in FIG.
The center of the grounding element 40g of the upper antenna element 40 and the center of the feeding element 40h are arranged as close as possible. Similarly, the center part of the grounding element 60g of the lower antenna element 60 and the center part of the feeding element 60h are arranged as close as possible. These upper antenna element 40 and lower antenna element 60 each function as a dipole antenna.

A central portion of the feed element 60h, that is, a feed point, is connected to a first feed line passing through the inside of the arm 2, for example, a center conductor 140i of the coaxial cable 140. The outer conductor of the coaxial cable 140 is connected to the arm 2. The impedance of the coaxial cable 140 is, for example, Z0. Note that Z0 is about 1/2 of the design impedance of the upper antenna element 40 and the lower antenna element 60.

The central part of the feeding element 40h, that is, the feeding point is
A second power supply line passing through the inside of the arm 2, for example, a central conductor 141i of the coaxial cable 141 is connected to a power supply point of the power supply element 60h. That is, the upper antenna element 40
And the feeding point of the lower antenna element 60 are serially connected. The length of the coaxial cable 141 is λ
It is chosen somewhat shorter than. This coaxial cable 14
The impedance of 1 is selected to be 2Z0 which is twice the impedance of the coaxial cable 140.

Assuming that the length of the coaxial cable 141 is λ,
Since the power feeding element 40h and the power feeding element 60h are fed in phase, no beam tilt occurs. When the length of the coaxial cable 141 is shorter than λ, the upper feed element 40h
Power is supplied in a phase advance from the lower power supply element 60h. As a result, the maximum radiation direction of the beam in the combined directional characteristics of the upper antenna element 40 and the lower antenna element 60 is directed downward below the horizontal plane, and the beam tilts.

Here, as shown in FIG.
The distance between 0 and the lower feed element 60 is d, the beam tilt angle is θ, the reduction rate of the coaxial cable 141 is η, and the coaxial cable 1 is
Assuming that the length of 41 is L, the phase difference Δφ between the upper antenna element 40 and the lower antenna element 60 is expressed by Expression 1.

[0050]

## EQU1 ## Δφ = (2π dsin θ / λ) = 2π− (2π
L / λη)

Therefore, sin θ is represented by the following equation (2).

[0052]

## EQU2 ## sin θ = (λ / d) [1- (L / λη)]

Therefore, by setting L / λη to be smaller than 1, that is, by selecting L shorter than ηλ, a downward beam tilt can be obtained.

The actual impedance of the upper antenna element 40 is selected to be 2Z0, and the actual impedance of the lower antenna element 60 is also selected to be Z0. As described above, the impedance of the coaxial cable 141 is 2Z0
Therefore, the combined impedance of the coaxial cable 141 and the upper antenna element 40 as viewed from the feeding point of the lower feeding element 60h is Z0. Therefore, the upper antenna element 40
And the lower antenna element 60 can be matched.

In FIG. 8, reference numeral 144 denotes the upper antenna element 40 and the lower antenna element 6.
This is a coaxial cable for feeding a lower antenna element, which is provided further above the antenna element consisting of zero. This also has an impedance of Z0.

As shown in FIG. 8, a sleeve 80 is provided along the arm 2 inside the feeding element 40h and the feeding element 60h.
And 82 are attached. Sleeves 80 and 82
It has a length of about λ / 4, and one end thereof is coupled to each of the feeding points of the upper feeding element 40h and the lower feeding element 60h, and the other end is directly connected to the arm 2, respectively. That is, the sleeves 80 and 82 are short-circuited on one side.

If the sleeves 80 and 82 are not provided, the feed elements 40h and 60h are close to the arm 2, so that
The radiation impedance decreases and the feed elements 40h and 60h
Also, radio waves are radiated between the arms 2 and do not operate well as an antenna. Further, a large amount of unnecessary current flows through the arm 2, the radiation pattern of the radio wave is deteriorated, and the gain is reduced.

However, when the sleeves 80 and 82 are provided, they operate as a supertop, and the feed element 4
0h and arm 2 and between feed element 60h and arm 2
, Respectively, can be increased. As a result, radio waves are satisfactorily radiated between the power feeding element 40h and the grounding element 40g and between the power feeding element 60h and the grounding element 60g, and the device operates normally. Since the lengths of the feed elements 40h and 60h are λ / 4, the feed points of the feed elements 40h and 60h (the sleeves 80 and 8)
2) is about λ / 4,
No unnecessary current flows on the surfaces of the sleeves 80 and 82.

As shown in FIG. 9, the upper antenna element 40
A plurality of sets of the antenna elements including the lower antenna element 60 are provided along the arm 2. These are surrounded by a radome, for example, a cylindrical outer case 200. The outer case 200 is used as an antenna for a wireless base station of a personal handy phone system, for example.
When this vertical diversity antenna is used, a strong FRP pipe is used for the outer case 200 to increase the strength.
Used as Therefore, the thickness of the outer case 200 may be about 10 mm.

In this case, radio waves radiated from the upper antenna element 40 and the lower antenna element 60
0, return to the upper antenna element 40 and the lower antenna element 60, and
The impedance of 0 becomes high. Particularly, when the distance between the largest diameter portion of the upper antenna element 40 and the lower antenna element 60 and the inner surface of the outer case 200 is about λ / 4, reflected waves are radiated from the upper antenna element 40 and the lower antenna element 60. And the impedance becomes very high.

Therefore, around each of the upper antenna element 40 and the lower antenna element 60, for example, about λ / 4 to λ / 2
Are disposed respectively.
These resonance rings 202 are arranged at a distance of about λ / 40 to λ / 8 from each of the upper antenna element 40 and the lower antenna element 60. These resonance rings 202
Is provided, the impedance of each of the upper antenna element 40 and the lower antenna element 60 can be reduced.

This is generally considered as follows. The phases of the radio waves radiated from the upper antenna element 40 and the radio wave radiated from the lower antenna element 60 are delayed by about 90 degrees by the resonance ring 202. Then, when reflected by the outer case 200, the phase is further delayed by 180 degrees. That is, a total of 270
Phase lags. The radio wave delayed by 270 degrees is further delayed by 90 degrees by the resonance ring 202, and returns to the upper antenna element 40 and the lower antenna element 60 with a total delay of 360 degrees. Therefore, the reflected radio wave and the radiated radio wave have the same phase, and the impedance is reduced. That is, the resonance ring 202 functions as a delay element of about 90 degrees.

By adjusting the width W of the resonance ring 202 and the distance from the resonance ring 202 to the upper antenna element 40 and the lower antenna element 60, the real part of the impedance of the upper antenna element 40 and the lower antenna element 60 can be adjusted. Can be adjusted. The imaginary part can be formed by adjusting the length of the sleeves 80 and 82.

The resonance ring 202 can be formed, for example, as follows. A linear metal foil having a width W, for example, an aluminum foil or a copper foil is formed on the rectangular film 204 by etching or the like. Further, at a position at a predetermined distance (a distance of about λ / 40 to λ / 8) from each of the upper antenna element 40 and the lower antenna element 60, for example, FR
An inner case 206 made of P is arranged. The film 204 on which the metal foil is formed is wound into a cylindrical shape, and the inner case 206
Adhere to the inner surface of

A resonance ring 202 is formed by wrapping an adhesive tape of aluminum or copper having a width W around the outer peripheral surface of the inner case 206 so as to correspond to each of the upper antenna element 40 and the lower antenna element 60. You may.

In the case of FIG. 9, the outer case 200 has an outer diameter of about 9
0 mm, the inner case 206 has a diameter of about 35 mm, and λ is about 160 mm.

FIG. 10 shows a frequency characteristic of a combined maximum radiation direction gain of a set of antenna elements 40 and 60 of the vertical diversity antenna. The antenna elements 40 and 6
At 0, a gain of approximately 3.5 to 4 dB is obtained from 1895 MHz to 1920 MHz. FIG. 11 shows a frequency characteristic of a combined standing wave ratio of a set of antenna elements 40 and 60 of the vertical diversity antenna. In the antenna elements 40 and 60, the combined standing wave ratio is 1.4 to 1.2, which is a value that is sufficiently practical.
FIG. 12 shows that the antenna elements 40 and 60 have 1907.5 MH.
3 shows the combined vertical plane directivity at z. From FIG. 12, it can be seen that the antenna elements 40 and 60 satisfactorily receive radio waves arriving from a direction inclined downward by θ with respect to a substantially horizontal plane. FIG. 13 shows the antenna elements 40 and 60 at 1907.
5 shows the combined horizontal plane directivity at 5 MHz. FIG. 13 shows that the antenna elements 40 and 60 are non-directional in the horizontal plane.

FIG. 14 shows a vertical diversity antenna according to the third embodiment. This vertical diversity antenna also has a beam tilt characteristic similarly to the vertical diversity antenna shown in FIGS. The configuration for this is the same as the vertical diversity antenna shown in FIGS. Therefore, the same reference numerals are given to the same parts, and the description thereof will be omitted.

In the vertical diversity antennas of FIGS. 8 and 9, the sleeves 80 and 82 are provided on the feed element 40h and the feed element 60h, so that the impedance between the feed element 40h, the feed element 60h, and the arm 2 is increased. . However, it is relatively troublesome to couple one ends of the sleeves 80 and 82 to the feed element 40h and the feed element 60h, respectively, and connect the other ends of the sleeves 80 and 82 directly to the arm 2.

Therefore, in the diversity antenna shown in FIG. 14, the short-circuit plate is connected near the maximum diameter portion of the feed elements 40h and 60h, that is, at a position of about λ / 4 so that the feed elements 40h and 60h and the arm 2 are connected. , For example, a conductive disk 2
10 and 212 are provided.

Therefore, the feed element 40h and the feed element 60
The impedance as viewed from the feeding point of h to the maximum diameter side increases.

However, there is a possibility that current from the feed elements 40 h and 60 h flows to the arm 2 through the disks 210 and 212. To prevent this, the lower grounding element 6
0g is brought closer to the upper feed element 40h, the lower feed element 60h is brought closer to the upper ground element 70g of another antenna element further below, and unnecessary current flows through the upper and lower ground elements 60g and 70g. Is desirable.

However, due to the distance between the antenna elements constituted by the upper antenna element 40 and the lower antenna element 60, the lower feed element 60h and the upper ground element 70g of another antenna element further below. When it is not possible to make the distance between them close, a conical element 214 functioning as a super-top may be attached to the arm 2 between them. Instead of the conical element 214, a cylindrical element may be provided. Also, the upper feed element 40 in the same set
If the distance between h and the lower grounding element 60g increases, a conical or cylindrical element may be attached to the arm between them.

In the vertical diversity antenna shown in FIGS. 8 and 9, and the vertical diversity antenna shown in FIG. 14, conical elements are used for the feed elements 40h and 60h and the ground elements 40g and 60g. However, FIG.
As in the case shown in (b), the feed elements 40h and 60h
Alternatively, a disk-shaped element or a cylindrical element can be used. Also, instead of the grounding elements 40g and 60g,
A cylindrical element as shown in FIG. 3B can also be used.

In each of the vertical diversity antennas shown in FIGS. 1, 8 and 9 and FIG. 14, the ground element, for example, 4g or 40g and the feed element 4h or 40h in one set of antenna elements are connected to the central portion thereof. Are arranged closest to each other along the arm 2, but may be arranged so that the largest diameter portions are adjacent to each other. Similar changes can be made to the grounding element, for example, 6g or 60g and the feeding elements 6h and 60h.

In each of the above embodiments, the present invention is applied to a vertical diversity antenna. However, the present invention is not limited to this, and a signal received by each antenna element is combined to obtain a high gain. It can also be an antenna.

[0077]

As described above, according to the first aspect of the present invention, in each antenna element, a signal received by a dipole antenna constituted by a ground element and a feed element is transmitted via each feed line. However, since each feed line is laid in the conductive arm, the current distribution of the antenna element outside these conductive arms is not disturbed, and both the feed element and the ground element are conical. Since the element is shaped like an antenna, it becomes a broadband antenna.

According to the second aspect of the present invention, since the grounding element and the feed element have a length of about の of the wavelength of the received radio wave, the current of the half wavelength of the received wavelength can be improved. Ride between these.

According to the third and fourth aspects of the present invention, the power supply element functions in the same manner as a supertop and can cut unnecessary current flowing through the outer surface of the conductive arm.

According to the fifth aspect of the present invention, when power is supplied from the feeding point of one antenna element to the other antenna element via the conductive sleeve, the other antenna element is supplied with an opposite phase. However, since both antenna elements are arranged in a mirror surface, radio waves are radiated from the two antennas in the same phase, and a multi-stage antenna having a combined radiation lobe in the horizontal direction can be obtained.

According to the sixth aspect of the invention, various antenna elements can be used. In addition, since each antenna element has a length that is an odd multiple of about 1/4 of the wavelength of the received radio wave, the impedance when viewing the antenna element connected from one end to the other end of the sleeve and one end of the sleeve And the impedance when the antenna element connected to the antenna element is viewed is based on the length of about の of the wavelength of the received radio wave, and has the same value. The current or voltage ratio becomes 1 to 1, which makes an ideal stack antenna.

According to the seventh aspect of the present invention, since the antenna element fed through the second feed line is fed in a more advanced phase than the antenna element fed by the first feed line, By selecting the two feeders to have an appropriate length, the combined radiation characteristics of the two antennas can be made to have a desired beam tilt angle.

According to the invention described in claim 8, various antenna elements can be used.

According to the ninth aspect of the present invention, the radio wave radiated from the antenna element is reflected by the radome through the ring resonator and returns to the antenna element again through the ring resonator. Since the ring-shaped resonator has the same phase as the radio wave radiated from the antenna element, it is possible to prevent the impedance of the antenna element from increasing.

[Brief description of the drawings]

FIG. 1 is an enlarged vertical sectional view of a vertical diversity antenna according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a current distribution in the antenna of FIG.

FIG. 3 is a schematic diagram showing a modification of the antenna of FIG. 1;

FIG. 4 is a gain-frequency characteristic diagram of the antenna of FIG. 1;

FIG. 5 is a diagram showing a standing wave ratio versus frequency characteristic of the antenna of FIG. 1;

FIG. 6 is a directional characteristic diagram of a vertical plane of the antenna of FIG. 1;

FIG. 7 is a directional characteristic diagram of a horizontal plane of the antenna of FIG. 1;

FIG. 8 is an enlarged vertical sectional view of a vertical diversity antenna according to a second embodiment of the present invention.

9 is a vertical sectional view of the vertical diversity antenna of FIG.

FIG. 10 is a gain-frequency characteristic diagram of the antenna of FIG. 8;

11 is a diagram showing a standing wave ratio versus frequency characteristic of the antenna of FIG. 8;

FIG. 12 is a directional characteristic diagram of a vertical plane of the antenna of FIG. 8;

FIG. 13 is a directional characteristic diagram of a horizontal plane of the antenna of FIG. 9;

FIG. 14 is an enlarged vertical sectional view of a vertical diversity antenna according to a third embodiment of the present invention.

[Explanation of symbols]

 2 Arm 4 6 40 60 Antenna element 4 g 6 g 40 g 60 g Grounding element 4 h 6 h 40 h 60 h Feed element 8 Sleeve 14 16 Coaxial cable (feed line) 80 82 Sleeve 140 Coaxial cable (first feed line) 141 Coaxial cable (second) Power supply line) 200 Outer case (radome) 202 Resonant ring 210 212 Conductive disk (short circuit plate)

Claims (9)

[Claims] 1. A conductive arm, a conical grounding element having a central portion fixed to the conductive arm and having a diameter increasing from the central portion toward a distal end portion; And a conical power feeding element whose diameter is increased from the central portion toward the front end portion, and the center portion or the front end portion of the conical grounding element and the power feeding element are adjacent to each other. A multi-stage antenna comprising: a plurality of antenna elements; and a plurality of feeder lines inserted into the conductive arm and connected to the respective feed elements. 2. The multi-stage antenna according to claim 1, wherein
The grounding element and the feeding element have a wavelength of about 1
A multi-stage antenna having a length of / 4 along the length of the conductive arm. 3. The multi-stage antenna according to claim 1, wherein
The multi-stage antenna, wherein the feed element has a sleeve having a length of about 1/4 of a received radio wave wavelength from the feed point thereof along the conductive arm, and a tip of the sleeve is connected to the conductive arm. 4. The multi-stage antenna according to claim 1, wherein
A multi-stage antenna, wherein the feed element has a short-circuit plate connected to the conductive arm from a position at a length of about 1/4 of a received radio wave wavelength along the conductive arm from a feed point of the feed element. 5. A current wave of about の of the wavelength of a received radio wave is placed between a conductive arm, a ground element having a center portion coupled to the conductive arm, and a tip of the ground element. A feed element coupled to the conductive arm with a central portion insulated at a central portion thereof, each of the two sets of antenna elements being mirror-symmetric with respect to a vertical plane as a reference plane in a longitudinal direction of the conductive arm. Two sets of arranged antenna elements and about one half of the wavelength of the received radio wave, which are arranged along the conductive arm and connect the feeding points of two feeding elements of the two sets of antenna elements. A multi-stage antenna comprising: a conductive sleeve having an odd multiple of the wavelength; and a feeder line connected to one end of the sleeve. 6. The multi-stage antenna according to claim 5, wherein
The feeding element is formed in a conical shape, a cylindrical shape, or a disk shape having a length of about １ ／ of the wavelength of the reception radio wave, and the grounding element is formed of a length of about １ ／ of the wavelength of the reception radio wave. A multi-stage antenna formed in a conical shape, a cylindrical shape or a disk shape having a thickness. 7. A conductive arm, a grounding element having a central portion coupled to the conductive arm, and a tip of the grounding element, so that a current wave of about 波長 of the wavelength of a received radio wave is placed on the conductive arm. A pair of antenna elements having a feed element coupled to the conductive arm with a central portion insulated at a central portion; a first feed line connected to one feed point of the two feed elements; A multi-stage antenna comprising: two feeding elements; and a second feeding line that is slightly shorter than the wavelength of the received radio wave. 8. The multi-stage antenna according to claim 7, wherein
The feeding element is formed in a conical shape, a cylindrical shape, or a disk shape having a length of about ４ wavelength of the reception radio wave, and the grounding element is formed to have a length of about の wavelength of the reception radio wave. A multi-stage antenna formed in a conical, cylindrical or disk shape having 9. An arm, a plurality of antenna elements provided on the arm, a radome disposed so as to surround the periphery of the antenna element, and a radome disposed between an inner surface of the radome and the antenna element. A ring-shaped resonator, the ring-shaped resonator comprising:
The radio wave radiated from the antenna element, reflected by the radome via the ring-shaped radiator, and arrives at the ring-shaped resonator is selected to have the same phase as the radio wave radiated from the antenna element. Multi-stage antenna.