JP3232944B2 - Antenna device - 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 device used for a mobile communication base station, for example.

[0002]

2. Description of the Related Art Conventionally, a coaxial dipole collinear array antenna device used as a standard in a mobile communication base station or the like has a complicated connection structure between a radiation dipole and a coaxial line for feeding, and is difficult to process. Tended to be high. Further, the conventional collinear array antenna has a problem that when the antenna is tilted, the radiation characteristic and the gain are greatly deteriorated.

A conventional example of a coaxial dipole array antenna device has a typical shape shown in FIG. In addition, FIG.
P. Volta, “Design and Level
option of an Omnidirectio
nal Antenna With a Collin
ear Array of Slots, "Micro
wave Journal, Vol. 25, no. 1
2, p. 111, FIG. 1, p. 115, FIG.
3, 1982. FIG. In FIG. 11, the antenna type is collectively referred to as collinear antenna 1,
2 is a choke, 3 is a radiation dipole, 4 is a dipole excitation slit, 5 is a coaxial outer conductor of a circular coaxial line, and 6 is a coaxial inner conductor.

Next, the operation will be described. The signal input to the coaxial line causes a potential difference between the slits in the antenna axis direction in the coaxial-dipole conversion slit 4, and the dipole 3 is excited. In addition, some of the input signals
The light passes through the coaxial-dipole converter in the direction of the next element antenna, and the next element antenna is excited by the same operation principle. In this way, each element antenna is excited,
The coaxial dipole operates as an array antenna. The choke 2 is loaded to reduce the unbalanced current flowing on the outer coaxial conductor 5. This type of antenna
The dipole excitation slit 4 is difficult to process, and there is a problem that the cost is increased. As an antenna design method, when it is desired to form the main beam of the antenna in a direction orthogonal to the antenna axis direction, the arrangement intervals of the element antennas should be set to equalize the excitation phases of each element antenna and suppress the generation of grating lobes Generally, the wavelength is selected to be equal to or less than the used wavelength when viewed from the outside free space, and the feeding point interval between adjacent element antennas is generally selected so that the electric length of the feeding coaxial line becomes a multiple of the wavelength. When performing beam tilt, the element spacing may be determined based on the concept of a traveling-wave-fed linear array antenna such that the phases of the signals emitted from the elements in the desired observation direction match. However, when the beam is tilted, the radiation characteristics and gain of the antenna generally tend to be greatly deteriorated. For example, FIG. 12 is an actual measurement example of an antenna radiation pattern corresponding to the presence or absence of a beam tilt. It can be seen that the radiation characteristics when the beam is not tilted are good, but when the beam is tilted, the radiation characteristics of the antenna are greatly disturbed. This is a phenomenon that occurs because the excitation distribution of each element antenna is disturbed because the element antennas are coupled via the feed line, which is a problem not only for coaxial dipole array antennas but also for traveling wave fed collinear array antennas in general. Become.

[0005]

As described above, the conventional collinear antenna has a problem that the structure is complicated and the cost is high, and furthermore, when the beam is tilted, the radiation characteristics of the antenna are greatly deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an antenna device having a simple structure, low cost, and having little deterioration in antenna radiation characteristics even when a beam is tilted.

[0007]

According to the present invention, there is provided an antenna device comprising: a coaxial line; and a slit provided in the outer conductor of the coaxial line substantially perpendicularly to a direction in which the coaxial line extends and dividing the outer conductor. , The above coaxial line penetrates the hollow interior,
A conductor pipe arranged to cover the slit and having an electrical length of about １ ／ wavelength in an operating frequency band.

According to a second aspect of the present invention, there is provided an antenna device comprising: a circular coaxial line; a slit provided in the outer conductor of the circular coaxial line substantially perpendicular to a direction in which the circular coaxial line extends; The above circular coaxial line penetrates the inside,
A circular conductor pipe having a central axis of the circular coaxial line as the central axis and arranged so as to cover the slit, and having an electric length in a used frequency band of about 波長 wavelength.

[0009] The antenna device according to claim 3 is based on claim 1.
Or the antenna device according to item 2, wherein the conductor pipe or the circular conductor pipe is arranged such that the slit is located substantially at the center in the longitudinal direction of the conductor pipe or the circular conductor pipe.

According to a fourth aspect of the present invention, there is provided the antenna device according to the first, second or third aspect, wherein a part or all of the space between the outer conductor of the coaxial line or the circular coaxial line and the conductor pipe or the circular conductor pipe is provided. It is characterized by having a body.

According to a fifth aspect of the present invention, there is provided an antenna device comprising the antenna device according to the first, second, third or fourth aspect as an element antenna, and a plurality of the element antennas provided in a direction in which a coaxial line or a circular coaxial line extends. Is formed.

The antenna device according to claim 6 is the antenna device according to claim 5.
In the above described antenna device, the plurality of element antennas are the same.

According to a seventh aspect of the present invention, there is provided an antenna device comprising: a coaxial line; and a plurality of slits provided in the outer conductor of the coaxial line substantially perpendicular to a direction in which the coaxial line extends, and dividing the outer conductor. A dielectric pipe provided so that the coaxial line penetrates the inside thereof, and formed around the outer surface of the dielectric pipe so as to cover each of the plurality of slits. An array antenna comprising a plurality of strip-shaped conductor layers having a width of 1/2 wavelength, wherein element antennas each including the slit and the strip-shaped conductor layer are arranged.

According to an eighth aspect of the present invention, in the antenna device of the fifth, sixth or seventh aspect, the arrangement interval of the slits is set to be substantially an integral multiple of the electrical length in a used frequency band. .

According to a ninth aspect of the present invention, in the antenna device according to the fifth, sixth or seventh aspect, the arrangement interval of the slits is set to an arrangement interval that makes the combined directivity of the element antenna desired. It is assumed that.

According to a tenth aspect of the present invention, in the antenna device of the fifth aspect, the dimensions of the slit in each element antenna, the dimensions of the conductor pipe or the circular conductor pipe, the slits and the conductor pipe or the circular conductor pipe are provided. The excitation amplitudes of the respective element antennas are made substantially equal by changing and selecting the arrangement relationship.

An antenna device according to an eleventh aspect of the present invention is the antenna device according to any one of the fifth to tenth aspects, wherein a load impedance serving as a short circuit, an open circuit, or a matching terminal is loaded at the end of the coaxial line. It is a feature.

According to a twelfth aspect of the present invention, in the antenna device according to any one of the first to eleventh aspects, a dielectric radome for covering an outer surface of the conductor pipe, the circular conductor pipe, or the strip-shaped conductor layer is provided. It is characterized by the following.

[0019]

According to the antenna device of the first aspect, an antenna having a simple structure can be realized by electromagnetically coupling the radiation conductor of the coaxial dipole antenna with the slit in the outer conductor of the feed coaxial line.

In the antenna device according to the second aspect, since the circular coaxial line and the circular conductor pipe are arranged so that their central axes coincide with each other, an antenna having an omnidirectional radiation characteristic in a plane perpendicular to the extending direction of the circular coaxial line. A device is obtained.

In the antenna device according to the third aspect, the conductor pipe or the circular conductor pipe is arranged such that the slit is located substantially at the center in the longitudinal direction of the conductor pipe or the circular conductor pipe. Appears almost short-circuited, and the reflection caused by the discontinuity of the coaxial line due to the slit can be reduced.

According to the antenna device of the fourth aspect, the conductor pipe or the circular conductor pipe can be supported on the coaxial line by the dielectric, and various characteristics of the antenna can be adjusted by selecting the dielectric constant and dimensions of the dielectric. And increase the variations in antenna design.

In the antenna device according to the fifth aspect, since the element antenna is a coaxially-fed electromagnetic coupling dipole antenna, and a plurality of the antennas are provided in multiple stages, the operating characteristics as an array antenna can be obtained.

In the antenna device of the sixth aspect, since the element antennas have the same shape, the number of parts can be reduced.
A low-cost antenna device can be realized.

In the antenna device according to the seventh aspect, since the element antenna is formed by providing the strip-shaped conductor layer on the outer peripheral surface of the dielectric pipe, the element antenna can be manufactured by etching or the like, and the assembly cost can be reduced.

In the antenna device according to the eighth aspect, since the feed phases of the respective element antennas are selected to be substantially equal, the main beam can be formed in a direction orthogonal to the arrangement direction of the element antennas.

In the antenna device according to the ninth aspect, since the arrangement interval of the slits is set to an arrangement interval that makes the combined directivity of the element antennas desired, the antenna device has multiple functions, for example, a beam tilt characteristic can be realized. .

According to the tenth aspect of the present invention, the dimensions of the slit in each element antenna, the dimensions of the conductor pipe or the circular conductor pipe, and the positional relationship between the slit and the conductor pipe or the circular conductor pipe are changed and selected. As a result, the excitation amplitudes of the plurality of element antennas are made substantially equal, so that a high gain antenna device can be obtained.

In the antenna device according to the eleventh aspect, since the load impedance serving as a short circuit, an open circuit, or a matching terminal is loaded at the end of the coaxial line, the power incident on the end of the coaxial line can be reused. Can be improved.

In the antenna device according to the twelfth aspect, the dielectric radome improves the strength of the antenna device against the load of wind pressure and protects the antenna device from an external environment.

[0031]

【Example】

Embodiment 1 FIG. FIG. 1 is a diagram illustrating the antenna device according to the first embodiment. In FIG. 1, reference numeral 7 denotes a circular hollow conductor pipe having an electrical length of about に お け る wavelength at a working frequency which operates as a radiation dipole, and 8 denotes a small annular slit as compared with the wavelength formed in the outer coaxial conductor 5. It is. The hollow conductor pipe 7 is provided at a position covering the annular slit from the outside.
The central axes of the hollow conductor pipe 7 and the coaxial outer conductor 5 and the coaxial inner conductor 6 of the coaxial line do not always coincide.

Next, the operation will be described. When a signal injected into the outer coaxial conductor 5 and the inner coaxial conductor 6 of the coaxial line reaches the annular slit 8, a potential difference is generated in the annular slit 8 in the coaxial line extending direction. Since the hollow conductor pipe 7 and the outer coaxial conductor 5 form another coaxial line, the potential difference serves as a secondary wave source, and an electromagnetic field is generated in the hollow pipe.
The cavity formed by the hollow conductor pipe 7 and the outer coaxial conductor 5 has an electric length of about 波長 wavelength with respect to the fundamental electrostatic mode, and thus is close to the resonance frequency. In this case, a current similar to a half-wave dipole is generated in the hollow conductor pipe 7, and an electromagnetic wave is radiated outside the antenna. It is considered that the radiation of the electromagnetic wave is generated from both ends of the hollow conductor pipe 7 and the outer skin of the hollow conductor pipe 7, but the difference between the radius of the hollow conductor pipe 7 and the radius of the coaxial outer conductor is smaller than the wavelength. It is considered that radiation from the outer wall of the hollow conductor pipe 7 becomes dominant.

The use of the hollow conductor pipe 7 has the following advantages. It is considered that the provision of the annular slit 8 in the feed coaxial outer conductor 5 causes discontinuity in the line and deteriorates the reflection characteristics. However, if the annular slit 8 is disposed near the center of the hollow conductor pipe 7, the discontinuity is reduced. Reflection is reduced. Because the hollow hype 7 has a total length of about 約 wavelength and is open at the end, the center of the hollow conductor pipe 7 looks almost short-circuited in the cavity,
This is because the impedance expected by the annular slit 8 approaches 0.

The input impedance of the antenna that can be seen by the annular slit 8 can also be adjusted so that the center axes of the hollow conductor pipe 7 and the coaxial outer conductor 5 and the coaxial inner conductor 6 of the coaxial line do not coincide with each other. Furthermore, the input impedance can be adjusted by offsetting the annular slit 8 from the center of the hollow conductor pipe 7.

Next, advantages of the antenna of FIG. 1 will be described. The antenna of FIG. 1 has a simpler structure than the element used in the conventional coaxial dipole antenna of FIG. In particular, since there is no need to join the outer coaxial conductor 5 and the radiating hollow conductor pipe 7, the processing steps are greatly simplified. Also, the number of parts is small. Furthermore, there is an advantage that the design is good because the structure is simple.

In this embodiment, it is assumed that the outer coaxial conductor 5, the inner coaxial conductor 6, and the hollow conductor pipe 7 of the coaxial line are circular. However, any cross section through which an electrostatic mode such as a square coaxial propagates can be used. An antenna of the same type as that of the present invention can be formed using a line having a shape. The operation principle in that case is the same as the content described in the present embodiment.

Embodiment 2 FIG. FIG. 2 is a diagram illustrating the antenna device according to the second embodiment. In FIG. 2, reference numeral 9 denotes a dielectric spacer inserted between the outer coaxial conductor 5 and the hollow conductor pipe 7. Other symbols are the same as above.

Next, the operation will be described. First, the dielectric spacer has an advantage that it operates as a support mechanism for fixing the hollow conductor pipe 7 to the outer coaxial conductor 5. Electrically, the dielectric spacer 9 functions to fill the dielectric formed in the cavity formed by the coaxial outer conductor 5 and the hollow conductor pipe 7, and the dielectric spacer 9 has a larger diameter than the case where no dielectric exists. When a dielectric having a relative permittivity of more than 1 is used, the electric length in the antenna extension direction with respect to the basic TEM mode has a function of making it look long. Therefore, the antenna resonance frequency shifts to the longer wavelength side. If this effect is used, the length of the hollow conductor pipe 7 can be made shorter than when no dielectric is loaded, and the antenna can be downsized. In particular, the dielectric spacer 9 also has the effect of changing the amount of excitation of a higher-order mode in the cavity localized near the annular slit 8 that excites the cavity. There is also an advantage that a new degree of freedom for adjusting the coupling amount of the cavity is generated, and variations in antenna design are increased.

FIG. 2 shows an example in which the dielectric spacer 9 is uniformly provided between the hollow conductor pipe 7 and the outer coaxial conductor 5.
For example, two dielectric spacers are provided at both ends of the hollow conductor pipe 7.
It is also conceivable to use it in such a way that it is partially provided.

Embodiment 3 FIG. FIG. 3 is a diagram illustrating the antenna device according to the third embodiment. In FIG. 3, a is the radius of the hollow conductor pipe 7 measured from the center of the circular coaxial line composed of the outer coaxial conductor 5 and the inner coaxial conductor 6, and the circular hollow conductor pipe 7 measures the radius from any direction. Are also arranged rotationally symmetrically with respect to the antenna extension axis so as to coincide with a. It is assumed that the annular slit 8 has the same rotational symmetry.

Next, the operation will be described. If the hollow conductor pipe 7 is provided rotationally symmetrically as shown in FIG. 3, the annular slit 8 is also rotationally symmetric, and the propagation mode of the coaxial line is the fundamental TEM mode, which is rotationally symmetric, the physical characteristics of the antenna are: All become rotationally symmetric. Therefore, the radiation directivity is also rotationally symmetric. That is, if the direction of the antenna extension axis is defined as the vertical direction, the radiation pattern of the antenna becomes omnidirectional in the horizontal plane. In this way, a practically important omnidirectional antenna in a vertically polarized horizontal plane can be realized.

It should be noted that even if a dielectric or the like is filled between the outer coaxial conductor 5 and the hollow conductor pipe 7, the above-mentioned non-directionality in the horizontal plane is not lost if the material to be filled has the above rotational symmetry.

Embodiment 4 FIG. FIG. 4 is a diagram illustrating the antenna device according to the fourth embodiment. FIG. 4 shows a configuration in which an antenna composed of a feed coaxial line, a hollow conductor pipe 7 and an annular slit 8 is provided in multiple stages in the extension direction of the coaxial line.

Next, the operation will be described. The operating principle of the electromagnetically coupled coaxial dipole units 7 and 8 which are element antennas is as follows.
As described in the first embodiment, the description is omitted. When the element antennas are arranged in multiple stages as shown in FIG. 4, the antenna operates as a so-called collinear array antenna, and an array antenna directional characteristic that cannot be obtained by the element antenna alone can be realized. When a signal is input to the feed coaxial line, first,
The signal reaches the element antenna at the stage, and a part of the power of the signal is radiated to the outside. A part of the remaining electric power is reflected to the power supply side, and the other becomes incident electric power to the next element antenna. Thereafter, the array antenna is excited by the same principle. The above is the principle of operation of a traveling wave array antenna, in which the number of element antennas and the coupling efficiency with the feed line are large and sufficient power is radiated to the outside of the antenna until the signal reaches the antenna end, or This is realized when the line is matched and terminated at the antenna termination section.

Further, the antenna can be operated by a standing wave. In this case, the amount of coupling between each element antenna and the feed line is reduced, and the input power sufficiently reaches the array antenna terminal portion, where the signal is reflected again to the element antenna side and overlapped. The antenna shown in FIG.
Can be used for both standing wave operation. In this case, as described above, the adjustment of the coupling amount between the element antenna and the feed line is essential, but the adjustment of the coupling amount depends on the arrangement position of the hollow conductor pipe 7, the diameter of the hollow conductor pipe 7, and the annular shape. It can be performed by the width of the slit 8. Especially in actual design and manufacturing,
Although it may be necessary to fine-tune the antenna, this antenna can be adjusted relatively easily by fine-tuning the position of the hollow conductor pipe 7 or replacing the hollow conductor pipe 7 with one having a different diameter or length. Can be performed. FIG.
To make such an adjustment with the conventional collinear antenna of
Processing is troublesome and not easy.

Embodiment 5 FIG. FIG. 5 is a diagram illustrating the antenna device according to the fifth embodiment. In FIG. 5, the total number of elements of the electromagnetically coupled coaxial dipole is assumed to be n + 1, and the intervals between the annular slits 8 for feeding the element antenna are x1, x2,. . . , X
Let it be n. Further, x1 to xn are all equal, and are set to be approximately an integral multiple of the electrical length of the fed coaxial line at the used wavelength.

Next, the operation principle will be described. When the configuration of FIG. 5 is used, since the element antennas are fed in phase, the main beam of the array antenna is formed in a manner orthogonal to the antenna extension direction. This radiation pattern having a peak in the vertical direction of the antenna is important in conforming to standard specifications such as an antenna for a mobile communication base station. In addition,
Polarization is vertical polarization when the antenna extension axis direction is defined as vertical. In FIG. 5, the shapes of the element antennas are drawn differently, but this is for the following reason. The excitation phase of the antenna is considered to be substantially equal in each element, and the main beam direction of the array antenna is determined from the element antenna excitation phase. However, the array antenna excitation freedom includes the element antenna excitation amplitude. Changing the shape of each element antenna as shown in FIG. 5 changes the excitation amplitude of the element antenna. That is, from the viewpoint of array directivity synthesis of the array antenna, the antenna device of FIG. 5 realizes a degree of freedom for providing an array excitation amplitude distribution. According to such a configuration, for example, a low side lobe pattern or the like can be formed, and there is an advantage that the functionality of the antenna is increased.

Embodiment 6 FIG. FIG. 6 is a diagram illustrating the antenna device according to the sixth embodiment. In FIG. 6, the total number of the electromagnetically coupled coaxial dipoles is n + 1, and the intervals between the element antenna feeding ring slits 8 are x1, x2,. . . , X
n, and x1 to xn are determined so that an array combined directional pattern is desired.

Next, the operation principle will be described. In the case of the configuration of FIG. 6, by appropriately selecting the positions from x1 to xn,
The excitation phase of the element antenna can be freely set, and the directivity can be synthesized by the phase of the array antenna. For example,
If the intervals of the annular slits 8 are all equal and the excitation phase of the element antenna is linearly tapered, the main beam can be tilted. This beam tilt antenna
This is an important one that is typically used for mobile communication base station antennas. Not only this beam tilt, but various desired radiation patterns can be obtained by directivity synthesis by phase,
This antenna is considered to be multifunctional.

Embodiment 7 FIG. FIG. 7 is a diagram illustrating the antenna device according to the seventh embodiment. In FIG. 7, a dielectric spacer 9 is inserted between the coaxial line and the hollow metal pipe 7, and each element antenna is excited by the annular slit 8. Further, the diameter a of the hollow conductor pipe 7 constituting each element antenna
The length l, the distance b between the annular slit 8 and the hollow conductor pipe 7, and the dimensions of the annular slit 8 are all equally selected for each element antenna.

Next, the operation will be described. The physical operation principle of the antenna has been described in the first, second, and fourth embodiments, and thus will be omitted. The inherent operation and advantage when the shape of each element antenna is equally selected will be described below. First, since the shape of each element antenna is the same, the number of parts can be kept low, and the cost is reduced. Also, for example,
In the configuration of FIG. 7, the following processing method is also possible. First, the element antenna radiating portion can be manufactured integrally with the dielectric spacer by etching or the like. If the radiating section manufactured in this way is inserted into a coaxial line, the antenna can be manufactured in a short time, and the assembly cost can be reduced. Further, regarding the number of antenna stages, a manufacturing method in which a plurality of hollow conductor pipes 7 and the dielectric spacers 9 which are integrally processed are prepared, and these are overlapped and spliced may be considered. Alternatively, a radiating section having a large number of stages may be manufactured in advance, and the radiating section may be cut short as necessary. In addition, in the antenna device as shown in FIG. 7, since the dielectric spacer 9 covers the entire antenna, there is an advantage that the mechanical strength of the antenna is increased and an antenna that is strong against wind pressure can be realized.

Embodiment 8 FIG. FIG. 8 is an equivalent circuit describing electric characteristics of the antenna device according to the eighth embodiment, and a configuration diagram of the antenna device is similar to FIG. When the TEM mode is transmitted to the coaxial feed line,
The impedances when the corresponding element antennas are viewed from the respective annular slits 8 as excitation points of the element antennas # 1 to #n are Z1 to Zn, respectively. Also, Z
LD is the load impedance at the end of the coaxial line. For example, when the array antenna is fed from the left side of the coaxial feed line toward the plane of FIG. 4, ZLD is the load impedance at the right end of the coaxial line. In this case, since the coaxial line is open, ZLD is infinite. The value of ZLD can be changed by loading or short-circuiting a matching termination at the end of the coaxial line. In the above configuration,
In this embodiment, the excitation amplitude of each element antenna is selected to be substantially equal using the equivalent circuit of FIG.

Next, the operation will be described. When the excitation amplitudes of the respective elements in the operating state are all equal, that is, when the powers consumed in Z1 to Zn in the equivalent circuit of FIG. 8 are all equal, the array antenna has uniform amplitude distribution excitation.
Further, when the excitation phases of the respective elements are all equal, that is, when the electric lengths of the coaxial lines connecting the respective element antennas are all equal, the antennas are excited with a uniform distribution, and the directional gain is maximized. Also, when a linear scanning is applied to the electric length of the coaxial line to give a beam scanning phase to the element antenna,
If the excitation amplitudes of the elements are equal, a high gain can be realized. That is, the antenna according to this embodiment can achieve high gain.

Next, a method for determining the dimensions of the element antenna will be described. The equivalent circuit of FIG. 8 can be easily analyzed by a method used in ordinary circuit theory, for example, an F matrix method or the like. First, the element antenna excitation phase is given by selecting the electrical length of the coaxial line connecting the element antennas to a length that realizes a desired excitation phase, such as an equal phase and a beam scanning phase. Under the above conditions, the solution of the equivalent circuit in FIG. 8, that is, the voltage and current distribution at each point of the line are obtained as a function of Z1 to Zn. Where Z1
If the condition that the power consumed by .about.Zn is equal is imposed, a conditional expression to be satisfied by Z1 to Zn is obtained, and the values of Z1 to Zn can be determined. When the values of Z1 to Zn are # 1
The target impedance design target values of the individual element antennas # to #n are obtained. Thereafter, the element antenna parameters may be determined so that the above-mentioned Z1 to Zn are realized independently for each element antenna. A hollow metal pipe 7 is used for the element antenna.
There are sufficient design degrees of freedom, such as the length, radius, width of the annular slit 8, and the target value can be achieved. The following analysis model can be considered as a design guide of the element antenna input impedance. Consider a coaxial line in which the hollow conductor pipe 7 is an outer conductor and the coaxial outer conductor 5 is an inner conductor. This coaxial line can be considered to be two coaxial lines whose ends are open and whose entire length is the length of the hollow conductor pipe from the annular slit in the line extending direction. The element antenna can be approximately provided by a model in which the above two coaxial lines are connected in series by an annular slit serving as a feeding point. The element antenna can be easily realized by roughly determining the dimensions using this model and then finely adjusting it experimentally. Since the above-described design method uses the equivalent circuit of FIG. 8, the effect that the element antenna is coupled via the feed line can be considered.
Be accurate. Deterioration of antenna characteristics at the time of beam tilt described earlier with reference to FIG. 12 is due to coupling between elements via the above-described feed line.
Since the element antenna design target value is given in consideration of this effect, deterioration of antenna characteristics can be prevented, and a high-performance antenna can be realized.

In this embodiment, a design method has been described in which the excitation amplitudes of the respective elements are all equal. However, a design method in which each element is given an arbitrary amplitude and phase can be realized in substantially the same manner as described above. In this case, the excitation amplitude of each element antenna,
Under the condition that the phase is set to a desired amount, a method is conceivable in which a feasible range of Z1 to Zn is given, and the equivalent circuit parameters in FIG.

Embodiment 9 FIG. FIG. 9 is a perspective view and a side view illustrating a ninth embodiment of the antenna device according to the present invention.
In the figure, reference numeral 10 denotes a dielectric radome loaded outside the antenna.

Next, the operation will be described. First, by loading the dielectric radome 10, the influence from the surrounding environment such as rain is reduced. In general, a collinear antenna is often required to have a small diameter, and wind pressure always poses a problem. In the present invention, the dielectric radome 10 is also useful for improving the antenna strength against wind pressure. When the antenna has rotational symmetry with respect to the antenna extension axis, and the antenna extension direction is the vertical direction, and the antenna has omnidirectional characteristics in a horizontal plane, the dielectric radome 1
If 0 is cylindrical and formed in a circular rotational symmetry, antenna strength can be maintained and omnidirectionality in a horizontal plane can be maintained.

Embodiment 10 FIG. FIG. 10 is a diagram for explaining Embodiment 10 of the antenna device of the present invention. FIG.
0 is an explanatory diagram relating to a feed line termination of the coaxial electromagnetic coupling dipole array antenna. FIG. 10 (b) (c)
FIG. 10D is an enlarged view of the end of FIG. 10A, FIG. 10B is a case where the end is open-ended, FIG.
(D) is a configuration example in the case of matching termination. 11 is
A fixing screw for electrically connecting and fixing the conductor cap 12 to the outer coaxial conductor 5 and the inner coaxial conductor 6 is a chip resistor 13 fixed to the outer coaxial conductor 5 and the inner coaxial conductor 6 by soldering or the like. The inner coaxial conductor 6 and the outer coaxial conductor 5 are electrically connected via a resistor. In particular, if the resistance value of the chip resistor 13 is set equal to the characteristic impedance of the coaxial line,
A simple matching termination is realized. In addition, L in FIG.
This is the distance from the antenna end point to the annular slit 8, which is the feed point of the element antenna closest to the end point.

Next, the operation will be described. When a standing wave is excited in an antenna, an open end or a short-circuited terminal is suitable. In this case, L is determined such that the reflected wave from the end of the feed line is superimposed again on the element antenna with a desired phase using the open or short-circuited terminal shown in FIG. For example, when each element antenna is excited with the same phase, if it is an open end, L is the electric length of the feed coaxial line and is approximately 波長 wavelength,
If short-circuited, L is approximately 1/4 of the electrical length of the feed coaxial line.
In general, the wavelength is selected, and in this case, the reflected wave is superimposed in phase with the incident wave at the element antenna feeding point. If such a configuration is used, the power incident on the end of the feed line without being completely radiated can be reused, so that there is an advantage that the antenna efficiency is increased.

When the antenna is excited by a traveling wave, a matching termination can be used. For example, when arranging element antennas at equal intervals and obtaining a beam tilt characteristic by giving a linear taper to the excitation phase, when a reflected wave from the antenna end is re-emitted, an unnecessary beam in the opposite direction to the desired beam occurs, Antenna characteristics deteriorate. By using the matching termination as shown in FIG. 10, such unnecessary radiation can be reduced. However, since the power consumed by the antenna matching termination unit is lost, the antenna efficiency is lower than in the case of using an open termination or a short termination. In order to improve the antenna efficiency reduction at the time of beam tilt, sufficient power is radiated before the signal reaches the final element antenna, and an open or short terminal is used at the end, and the reflected power from the terminal is reduced. The antenna may be designed to be re-radiated only at the last element antenna. With this ingenuity, a highly efficient beam tilt antenna without unnecessary beams can be realized.

[0061]

As described above, according to the first aspect of the present invention, since there is no need to join the outer coaxial conductor and the radiating hollow conductor pipe, the structure is simple and the processing steps can be simplified.

According to the second aspect of the present invention, an antenna device having omnidirectional radiation characteristics in a plane perpendicular to the direction in which the circular coaxial line extends can be obtained.

According to the invention of claim 3, reflection caused by discontinuity of the coaxial line due to the slit can be reduced.

According to the fourth aspect of the present invention, the conductor pipe or the circular conductor pipe can be supported on the coaxial line, and various characteristics of the antenna can be adjusted, thereby increasing the antenna design variation.

According to the fifth aspect of the present invention, since the element antenna is a coaxially-fed electromagnetically coupled dipole antenna and a plurality of such antennas are provided in multiple stages, the operating characteristics as an array antenna can be obtained.

According to the sixth aspect of the present invention, since the element antennas have the same shape, the number of components can be reduced, and a low-cost antenna device can be realized.

According to the seventh aspect of the present invention, the element antenna can be manufactured by etching or the like, and the assembly cost can be reduced.

According to the eighth aspect of the present invention, since the feed phases of the element antennas are selected to be substantially equal, a main beam can be formed in a direction orthogonal to the arrangement direction of the element antennas. Antenna device that meets the technical specifications.

According to the ninth aspect of the present invention, since the excitation phase of each element antenna is set so as to realize a desired combined directivity, it is multifunctional, for example, a beam tilt characteristic can be realized. Thus, an antenna device conforming to standard specifications such as an antenna for a mobile communication base station can be obtained.

According to the tenth aspect, a high gain antenna device can be obtained.

According to the eleventh aspect, the efficiency of the antenna device can be improved.

According to the twelfth aspect of the present invention, the strength of the antenna device against wind pressure can be improved, and the antenna device can be protected from the external environment.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first embodiment according to an antenna device of the present invention.

FIG. 2 is a diagram illustrating a second embodiment according to the antenna device of the present invention.

FIG. 3 is a diagram illustrating a third embodiment of the antenna device according to the present invention;

FIG. 4 is a diagram illustrating a fourth embodiment according to the antenna device of the present invention;

FIG. 5 is a diagram for explaining a fifth embodiment according to the antenna device of the present invention;

FIG. 6 is a diagram illustrating a sixth embodiment according to the antenna device of the present invention;

FIG. 7 is a diagram illustrating a seventh embodiment according to the antenna device of the present invention;

FIG. 8 is a view for explaining an eighth embodiment according to the antenna device of the present invention;

FIG. 9 is a diagram illustrating a ninth embodiment according to the antenna device of the present invention;

FIG. 10 is a tenth embodiment according to the antenna device of the present invention;
FIG.

FIG. 11 is a diagram illustrating a conventional antenna device.

FIG. 12 is a diagram illustrating radiation characteristics of a conventional antenna device.

[Explanation of symbols]

1 collinear antenna, 2 choke, 3 radiation dipole, 4 dipole excitation slit, 5 coaxial outer conductor, 6 coaxial inner conductor, 7 hollow conductor pipe, 8 annular slit, 9 dielectric spacer, 10 dielectric radome,
11 fixing screw, 12 conductor cap, 13 chip resistor.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiyuki Chatani 325 Kamimachiya, Kamakura-shi Kamakura Works, Mitsubishi Electric Corporation (56) References JP-A-49-89460 (JP, A) JP-A-1- 206705 (JP, A) JP-A-6-69719 (JP, A) JP-A-1-280902 (JP, A) JP-A-2-147916 (JP, U) JP-A-59-157314 (JP, U) Japanese Utility Model Showa 64-44707 (JP, U) Japanese Patent Publication 50-23583 (JP, B1) Japanese Utility Model Showa 40-15240 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 13/10 H01Q 13/20 H01Q 21/08 JICST file (JOIS)

Claims (12)

(57) [Claims] 1. A coaxial line and an outer conductor of the coaxial line,
A slit is provided substantially perpendicular to the direction in which the coaxial line extends, and the slit separates the outer conductor, and the coaxial line penetrates the hollow inside thereof, and is arranged so as to cover the slit. And a conductor pipe having a length of 1/2 wavelength. 2. A circular coaxial line and an outer conductor of the circular coaxial line are provided substantially perpendicular to the direction in which the circular coaxial line extends,
The slit that divides the outer conductor, the circular coaxial line penetrates the hollow inside, the central axis of the circular coaxial line is set as the central axis, and is disposed so as to cover the slit. An antenna device comprising: a circular conductor pipe having a length of about 波長 wavelength. 3. The antenna device according to claim 1, wherein the conductor pipe or the circular conductor pipe is arranged such that the slit is located substantially at the center in the longitudinal direction of the conductor pipe or the circular conductor pipe. apparatus. 4. The antenna device according to claim 1, wherein a dielectric is provided in a part or the whole between the outer conductor of the coaxial line or the circular coaxial line and the conductor pipe or the circular conductor pipe. . 5. An array antenna comprising: the antenna device according to claim 1, 2, 3, or 4 as an element antenna, and a plurality of the element antennas provided in a direction in which a coaxial line or a circular coaxial line extends. Antenna device. 6. The antenna device according to claim 5, wherein
An antenna device wherein a plurality of element antennas are the same. 7. A coaxial line and an outer conductor of the coaxial line,
A plurality of slits that are provided substantially perpendicular to the direction of extension of the coaxial line and divide the outer conductor, a dielectric pipe provided so that the coaxial line penetrates the hollow inside thereof, and an outer surface of the dielectric pipe A plurality of strip-shaped conductor layers formed on the circumference so as to cover each of the plurality of slits and having an electric length in a used frequency band of about 1/2 wavelength; An antenna device comprising an array antenna in which element antennas composed of layers are arranged. 8. The antenna device according to claim 5, wherein an arrangement interval of the slits is set to substantially an integral multiple of an electric length in a used frequency band. 9. The antenna device according to claim 5, wherein an arrangement interval of the slits is set to an arrangement interval that makes the combined directivity of the element antenna desired. 10. The antenna device according to claim 5, wherein the dimensions of the slit in each element antenna, the dimensions of the conductor pipe or the circular conductor pipe, and the positional relationship between the slit and the conductor pipe or the circular conductor pipe are changed. An antenna device characterized in that the excitation amplitudes of the element antennas are made substantially equal by selecting the antennas. 11. The antenna device according to claim 5, wherein a load impedance serving as a short circuit, an open circuit, or a matching terminal is loaded at an end of the coaxial line. 12. The antenna device according to claim 1, further comprising a dielectric radome that covers an outer surface of the conductor pipe, the circular conductor pipe, or the strip-shaped conductor layer.