JPH07288417A - Directional variable antenna - Google Patents

Abstract

PURPOSE:To vary directionality in the direction of an azimuth angle, in the direction of an elevation angle or in both the directions by providing the extremely small number of variable phase shifters and variable power distributors corresponding to the number of antenna element in a directional variable array antenna. CONSTITUTION:To S-shaped double circularly arranged arrays 5 and 6, the phase of power to be fed to an antenna element 1 inside each circular arrangement is fixed but only the relative feeding phase between the circular arrangements is changed so that the directivity is changed in the full azimuth angle direction. On the other hand, the feeding phase to the antenna element in each circular arrangement is fixed but only the relative feeding amplitude ratio between the circular arrangements is changed so that the directivity can be changed in the full elevation angle direction. In order to change the relative feeding phase or feeding amplitude ratio of the reference circular arrangement 5 and each circular arrangement 6, feeding is performed by adding variable phase shifters or variable power distributors 7 corresponding to the respective circular arrangements or the plural circular arrangements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array antenna whose directivity can be changed.

[0002]

2. Description of the Related Art Conventionally, as a variable directivity antenna, FIG.
The array antenna shown in FIG. 5 is widely used. Figure 25
In the above, 1 is an antenna element, and 2 is a variable phase shifter, and the feeding phase for feeding each of the antenna elements 1 can be changed. Reference numeral 10 denotes a transceiver, which supplies electric power for feeding a plurality of antenna elements, sends a transmission signal to the antenna, and receives a reception signal from the antenna. Reference numeral 3 denotes a fixed power distributor, which distributes power from the transceiver 10 that feeds the antenna element 1. Reference numeral 4 denotes a power supply line for power supplied from the transceiver 10.

FIG. 26 shows an arrangement example of antenna elements at this time. In the conventional configuration, the variable phase shifter 2 is attached to each antenna element and all the feeding phases of each antenna element are controlled to change the directivity. When the antenna elements are arranged as shown in FIG. 26, 16 antenna elements and 15 phase shifters in total, one for each antenna element excluding the reference antenna element, are required.

Further, as a conventional example of a phase shifter used for an array antenna, "Technical Report on Technical Information" (SAT90-21) is available.
MW 90-71), pages 19 to 20. In this conventional example, a configuration diagram and a principle of operation of a 3-bit phase shifter are explained by combining a switched line type and a reflection type.

[0005]

When a land mobile body, a sea mobile body, or an aircraft communicates or transmits / receives data with a communication satellite, a broadcast satellite, or the like in outer space, an antenna that each mobile body must have is used. Require special performance. That is, while the position of the geostationary satellite does not change, the moving direction of each mobile unit and the angle with respect to the horizontal plane change variously, so the antenna mounted on each mobile unit always moves in the direction of the geostationary satellite. Must be adjusted to emit radio waves. In the conventional method, since beam-shaped radio waves must be radiated in all elevation and azimuth directions, in order to shake the beam, variable phase shifters are required for the number of antenna elements. It is necessary to adjust all of the vessels, and it takes time to adjust them. Further, since a large number of variable phase shifters are required, the cost becomes high, and the large number of them causes a problem of hindering miniaturization of the antenna.

An object of the present invention is to provide an array antenna which can be downsized and whose directivity can be changed.

It is another object of the present invention to provide a variable directivity antenna capable of changing the directivity in the azimuth direction and / or the elevation angle direction.

[0008]

[Means for Solving the Problems] For example, when a land-based mobile body existing only in a certain area communicates with a geostationary satellite, the elevation angle of the land-based mobile body looking at the geostationary satellite is almost constant. In this case, it is sufficient to radiate radio waves only at a fixed angle, and in the azimuth directions, radio waves must be radiated in all azimuth directions. In such cases,
It suffices to radiate a radio wave in a certain azimuth direction and shake the beam in the azimuth direction, or radiate a radio wave in all azimuth directions and shake the radio wave in the elevation angle direction. Also, these two methods may be combined.

In order to realize the above method, when it is not necessary to change the directivity in the elevation direction, the directional characteristics are formed in advance so as to have a required gain in the required elevation direction, and each circular shape is formed. The directivity is changed only in the azimuth direction by changing the relative feeding phase between the arrays using the variable phase shift means. In this case, in the directional variable antenna in which circular array antennas having at least two antenna elements are concentrically arranged in S-weight (S is an integer of 2 or more), the circular array antennas in S-weight are arranged. The circular array feeding section for feeding each of them and the circular array array antenna arranged in the S-weight are provided for each, and the electric power fed by the circular array feeding section is supplied to each of the antenna elements of the circular array antenna. And an antenna power feeding unit for feeding power, wherein the circular array power feeding unit is
A feeding circuit that outputs electric power, a circular array distributing unit that distributes electric power to each of the circular array antennas, and a feeding phase of the electric power distributed to each of the circular array antennas are shifted to change the feeding phase. Variable phase shifting means capable of

When it is not necessary to change the directivity in the azimuth direction, a mortar-shaped conical beam is formed in advance so as to have a necessary gain in all azimuth directions.
The cone beam is swung in the elevation direction by changing the power supply amplitude ratio between the circular arrays by a circular array power variable distribution means such as a variable power distributor. In this case, in a directional variable antenna in which circular array antennas including at least two antenna elements are concentrically arranged in S-weight (S is an integer of 2 or more), circular arrays for feeding power to each of the circular array antennas. The circular array power feeding unit includes an array power feeding unit and an antenna power feeding unit that feeds the power fed by the circular array power feeding unit to each of the antenna elements of the circular array antenna with equal power. Is provided, and a circular array power variable distribution means capable of distributing power to each of the circular array antennas and changing the power supply power ratio between the circular array antennas.

If it is necessary to change the directional characteristics in all azimuth angles and elevation angles, the above two methods are combined. As a method therefor, a circular array array is combined in S-fold, the feeding phase and the feeding amplitude for the antenna elements in each circular array are fixed, and only the relative feeding phase between the circular arrays is changed, or only the feeding amplitude ratio is changed. By changing either or both of them, the directional characteristics are changed in all the azimuth angle directions, the directional characteristics are changed in the elevation angle direction, or both are changed. With the array antenna having such a configuration, the number of variable phase shifters or the number of variable power distributors can be dramatically reduced.

[0012]

The present invention is constructed as described above, and its operation will be described below.

Formula F representing the directional characteristics of the array antenna
(Θ, φ) is an expression g representing the directional characteristic of the antenna element.
It is expressed by the following equation (1) using (θ, φ) and an array factor f (θ, φ) representing a term including the effects of the spatial arrangement of antenna elements, the feed amplitude, and the feed phase. .

[0014]

## EQU1 ## F (θ, φ) = g (θ, φ) · | f (θ, φ) | ... (1) where the center of the circular array is perpendicular to the plane in which the array antenna is constructed. The inclination from the vertical axis passing through, that is, the zenith angle is represented by θ, and the angle from the straight line connecting the reference antenna element of the array antenna and the array center, that is, the azimuth angle is represented by φ. As shown in the equation (1), the directional characteristics of the array antenna are mainly determined by the arrangement of antenna elements,
It is mostly determined by the array factor f (θ, φ) determined by the magnitude of the power supply and the phase of the power supply.

For example, in an S-fold (where S is an integer of 2 or more) circular array antenna, the amplitude of the power supplied to the antenna elements in each circular array is equal.
If the circularly arranged antenna elements are arranged at equal intervals, the s-th weight (s is the number of circular-array antennas from the center and is assumed to be from 1 to S).
The array factor f _s (θ, φ) of the circular array array is determined by the following equation (2).

[0016]

[Equation 2]

Here, u _s = k ₀ r _s sin θ, where k ₀ is the free space wave number, r _s is the array radius of the s-weight circular array array, and φ _sn is in the s-weight circular array array. The angle formed by the n-th antenna element and the reference antenna element with respect to the center of the circular array, ψ _s indicates the feeding phase difference from the reference circular array array of the s-th-order circular array array.

As an example, the feeding phase for each antenna element in the s-th circular array is changed by a constant phase to 2 mπ (m is a natural number) in one round, and from the equation (2), the antenna elements are finite. When the number of antenna elements N _s is made infinite in order to eliminate the non-uniformity of the array factor in the azimuth direction due to the number, the equation (2) becomes the following equation (3).

[0019]

[Equation 3]

Here, C is a constant of proportionality, and the order m of the Bessel function corresponds to making the feeding phase difference 2 mπ in one round of the circular array array.

Here, as an example, when S = 2, the feeding phase for the antenna elements in each circular array is 2 m per revolution.
Consider the case of π (Rad). F using the equation (3)
When (θ, φ) is obtained, it becomes as shown in equation (4).

[0022]

[Equation 4]

Here, ψ = ψ ₂ −ψ ₁ , u ₁ = k ₀ r ₁ si
Let nθ and u ₂ = k ₀ r ₂ sin θ. According to the equation (4), it is understood that the directivity changes in the azimuth angle φ direction by changing the feeding phase difference ψ with respect to the reference circular array (s = 1) and the second circular array. That is, in the double circular array, it is possible to change the directivity with respect to the azimuth angle φ direction with one variable phase shifter. Also,
It can be seen that by changing A ₁ and A ₂ , the array factor of the equation (4) represented by the linear sum changes the directional characteristics in the elevation direction.

In this case, the radius of the circular array is u _s
= Λ _s sin θ = k ₀ r _s sin θ, that is, r _s = λ _s /
Since it suffices to associate k ₀ with the radius r _s of each s-th circular array of the multiple circular array array, the Bessel function J of the m-th order
It is possible to determine r _s = λ _s / k ₀ so as to be proportional to the s-th λ _s from the smaller one that satisfies _m (λ) = 0. Actually, the method of obtaining the radius uses the numerical table of the zero points of the Bessel function from the approximation formula and the collection of formulas. Table 1 shows a table of zero points of the m-th order Bessel function.

[0025]

[Table 1]

First, the radius r ₁ of the innermost single circular array antenna is calculated from Table 1 above. When the free space wavelength λ is used, the free space wave number k ₀ of the radio wave is k ₀ = 2π
/ Λ, so r ₁ = λ ₁ / k ₀ ⇒ r ₁ / λ = λ ₁ / 2π
Becomes For example, when m = 1, 2π (Ra
d. ), The first array radius (radius r ₁ / radius normalized by the free space wavelength λ of the radio wave)
λ) refers to the value at the time of (m1-s1) shown in Table 1, and r ₁ /λ=3.83/(3.14×2)=0.61
Becomes Similarly, when the radii of the second, third and fourth folds are obtained, they can be calculated as 1.12, 1.62 and 2.12.

As described above, the circular array arrays are combined in S-fold, the feeding phase and the feeding amplitude for the antenna elements in each circular array are fixed, and the relative feeding phase and feeding amplitude ratio between the circular arrays are changed. By doing so, it is possible to change the directional characteristics in all azimuth angles and elevation angles.

[0028]

Embodiments Embodiments will be described below with reference to the drawings. In the present embodiment, first, a method of squeezing a beam at a specific elevation angle and radiating a radio wave in all azimuth angle directions and shaking a mortar-shaped conical beam in the elevation angle direction will be described. A mortar-shaped cone beam is shown in FIG. In FIG. 17, 17 is a cross section of the directional characteristics of the antenna, 18 is the direction of the communication satellite above the equator, 19 is the antenna plane, 20 is an axis perpendicular to the antenna plane, and 21 is the direction in which the directional characteristics change. In the present embodiment, in the multiple circular array antenna, the cone beam is changed with respect to the elevation angle direction by changing the amplitude ratio of the power supplied to each circular array antenna. That is, a variable directivity array antenna whose directivity changes in the elevation direction is realized.

In FIG. 3, as an embodiment of the present invention, an antenna in the case of a double circular array using eight antenna elements in the first circular array and 16 antenna elements in the second circular array. An example of element arrangement is shown. Further, FIG. 1 shows a configuration diagram of a feeding circuit of the array antenna in FIG. 3, and FIG.
FIG. 4 is a plan configuration diagram of a feeding circuit of the array antenna in FIG. 3. In FIGS. 3 and 5, 5 is a reference circular array array, 6 is a double circular array array, and 7 is a variable power distributor. A patch antenna or a helical antenna can be used as the antenna element. The electric power fed from the transceiver 10 is distributed to each circular array antenna by the variable power distributor 7, and at the branch portion of each circular array antenna with respect to the antenna element, the loss in the power supply line is considered by the distributor 11. The power is then distributed. As the variable power distributor 7 and the distributor 11, a Wilkinson type Y-type power distributor, a hybrid circuit (3 dB directional coupler), or the like may be used. As a hybrid circuit, a branch line type, 1
/ 4 wavelength distribution coupling type, rat race type, phase inversion type and the like. Since the voltage ratios to be distributed can be set respectively, these are set in consideration of the loss in the power supply line. In the case of the variable power distributor 7, a plurality of fixed power distributors that distribute at different voltage ratios and a switch that selects one of these fixed power distributors are provided in advance.
A selection instruction may be set from the instruction unit 20, and one of these fixed power distributors may be selected by a switch.

27 and 28 show an example of the configuration of another variable power distributor. 27 and 28,
Each of 24, 25, and 26 is a signal line, and is configured by a planar circuit such as a strip line.
Is a signal input line, and the signal lines 25 and 26 are signal output lines. Reference numeral 27 is a variable capacitance element such as a varactor diode whose capacitance can be changed. 28 is a circulator, 29 is a hybrid circuit, and 30 is a terminator. In FIG. 27 and FIG. 28, the instruction unit 20 gives an instruction of the amount of capacitance to the variable capacitance element 27, changes the amount of electric power reflected from the signal input line 24, and changes the amount of electric power output to the signal output line 25. ing.

As described above, the power distribution ratio can be changed by using the variable capacitance element.

In the present embodiment, in order to form a cone-shaped conical beam in the azimuth direction which is axisymmetric with respect to the zenith axis, the amplitudes of the electric powers fed to the respective circular array antennas are made different. The antenna elements in each circular array are distributed, and a feeding phase difference of 2π, that is, 360 degrees, is provided in one round. FIG. 4 shows the feeding phase for the n-th element. In the present embodiment, since the antenna elements are 8 elements in the first circular arrangement, the feeding phase difference of π / 4 (Rad.), That is, 45 degrees, is provided to the adjacent antenna elements. In addition, in the double circular array, the number of antenna elements is 16, so that for adjacent antenna elements,
Add a feed phase difference of 2.5 degrees. As a method of making the feeding phase difference between the antenna elements, there are a method of changing the feeding point of the antenna element and a method of changing the line length. As shown in FIG. 5, for each antenna element in the first circular array, the feeding point is changed by changing the feeding point of the antenna element using a line of equal length. For example, when a patch antenna that radiates circularly polarized waves is used as an antenna element, the feeding point of the adjacent patch antenna is 45 degrees (first circular array) or 22.5 degrees (with respect to the center of the patch antenna). The feeding phase can be shifted by 45 degrees or 22.5 degrees by displacing the feeding point by shifting the second circular arrangement. When a helical antenna is used as the antenna element, if the winding start angle of the adjacent helical antenna elements is shifted by 45 degrees or 22.5 degrees, the feeding phase becomes
They can be offset by 45 degrees or 22.5 degrees, respectively.
Therefore, use equal length feed lines to each antenna element,
The feeding phase of each antenna element is changed by changing the feeding point of the antenna element. Further, for the antenna elements in the double circular array, the feeding phase is changed by changing the length of the feeding line. In other words, if the wavelength of the radio wave called the guide wavelength in the feed line is λ _g , then if the difference in the length of the feed line with respect to the adjacent antenna element is λ _g / 8 or λ _g / 16, The phase difference can be 45 degrees or 22.5 degrees, respectively. Further, the power is distributed by the distributor 11 so that the same power is supplied to each antenna element 1.

Next, the feed amplitude ratio between the circular arrays will be described. As shown in FIG. 1, at the connection point between the power feeding unit that feeds each antenna element in the first circular array 5 and the power feeding unit that feeds each antenna element in the second circular array 6 One variable power distributor 7 is provided. The variable power distributor 7 is connected to the instructing unit 20 that is instructed from outside to instruct the power distribution ratio, and distributes the power to each circular array antenna according to the ratio received by the instructing unit 20. When the power distribution ratio is changed as the feeding amplitudes A ₁ and A ₂ described above in action, as shown in the equation 4,
The size of the array factor is changed, and the elevation direction of the beam can be changed accordingly. At this time, the array radii r ₁ and r ₂ of each circular array are set so as to be proportional to the zero point of the Bessel function.

The beam can be swung by a method called an open loop method or a closed loop method. The open loop method is on the mobile side.
Equipped with a device that detects your position and the tilt of the moving body, calculates the azimuth and elevation angle of the communication satellite above the equator seen from the antenna mounted on the moving body from the output of the device, and from the calculation results the antenna mounted on the moving body The direction of the beam formed by is always directed toward the communication satellite above the equator. The closed-loop method is to detect the azimuth and elevation of the communication satellite above the equator as seen from the mobile body using only the radio waves of the communication satellite. Is shaken finely and the peak of the beam is directed to the direction where the received power is strong.

Further, instead of the variable power distributor 7, a variable attenuator is provided at the base of the power feeding section for feeding one of the circular array arrays so that the power ratio fed to the two power feeding circuits is changed. May be. This also makes it possible to achieve the same effect as the variable power distributor.

In the double circular array array, changes in the directivity characteristics of the double circular array array when the feed amplitude ratios for the inner circular array array and the outer circular array array are changed are shown in FIGS. It shows in FIG. Figure 2
In FIG. 0 and FIG. 21, 17 is the cross section of the directional characteristics of the antenna, 18 is the direction of the communication satellite above the equator, the direction of the beam formed by the double circular array, 19 is the antenna surface, and 20 is the antenna surface. A vertical zenith axis, 22 is a cross section of the directional characteristic made by the inner circular array, and 23 is a cross section of the directional characteristic made by the outer circular array. Figure 2
In FIG. 0 and FIG. 21, the directional characteristics obtained by synthesizing the cross section 22 of the directional characteristics made by the inner circular array array and the cross section 23 of the directional characteristics made by the outer circular array array may be represented by cross sections indicated by diagonal lines. it can. Further, in the directional characteristics shown in FIG. 21, the feeding amplitude for the inner circular array is made smaller and the feeding amplitude for the outer circular array is made larger than that of the circular array having the directional characteristics as shown in FIG. It shows the situation. As shown in these conceptual diagrams, when the feed amplitude ratios for the inner circular array and the outer circular array are changed, the direction 18 of their combined directional characteristics can also be changed.

Further, in FIG. 22, FIG. 23 and FIG.
The results of concrete calculation of the change in the combined directional characteristics when the feed amplitude ratio for the inner circular array and the outer circular array of the heavy circular array are changed are shown. 22, 23, and 24, the vertical axis represents the intensity of radio waves radiated from the antenna, and the horizontal axis represents the inclination from the axis perpendicular to the antenna and represents the zenith angle. Actually calculated 2
The heavy circular array array has 8 inner antenna elements and 16 outer antenna elements, and the radius of the inner circular array array is 0.61λ, which is a value standardized by the wavelength of radio waves.
The radius of the outer circular array is 1.12λ, which is the value standardized by the wavelength of the radio wave, and the feeding phase difference between the antenna elements in the inner and outer circular arrays is 1 for both.
It is set to 2π (Rad) in the lap. In this example, the feeding phase difference between adjacent antenna elements is 45 in the inner circular array.
And 22.5 degrees for the outer circular array.
Under these conditions, the feed amplitude ratio for the inner and outer circular array arrays is 1: 0.5 in FIG. 22, 1: 0.6 in FIG. 23, and 1: in FIG.
It is set to 0.75. As a result, as shown in FIG.
When the feed amplitude ratio is 1: 0.5, the beam direction is 36.7 degrees at the zenith angle. Further, as shown in FIG. 23, when the power supply amplitude ratio is 1: 0.6, the beam direction is 37.8 degrees at the zenith angle. As shown in FIG. 24, when the feed amplitude ratio is 1: 0.75, the beam direction is 39.2 degrees at the zenith angle. Thus, the beam direction can be changed by changing the respective feed amplitude ratios for the inner and outer circular array arrays.

Further, FIG. 6 shows an example of antenna element arrangement in the case of a triple circular array, and FIGS. 7 and 8 show configuration diagrams of the feeding circuit of the array antenna in FIG. 6 and 7
And in FIG. 8, 8 indicates a triple circular array array. In the case of the triple circular array as shown in FIG. 6, the variable power distributor 7 is provided for the second circular array as shown in FIG. The distributor 71 is provided, and by the two variable power distributors,
The relative feed amplitude ratio with respect to the circular array 5 serving as the innermost reference is changed. Further, for example, for the second circular array, the variable power distributor 7 changes the relative power supply amplitude ratio with respect to the reference circular array array 5, and it is variable for the third circular array. Without providing the power distributor 71,
A fixed variable power distributor may be provided.

As another embodiment, as shown in FIG. 8, one variable power divider is used for the entire feeding amplitude ratio of the second and third layers with respect to the circular array of the first layer. The relative feed amplitude ratio with respect to the innermost circular array may be changed. Further, the circular array array serving as a reference is not limited to the innermost one, and any circular array array may be used.

As described above, by changing the amplitude ratio of the power supplied to each of the circular array antennas, the beam is narrowed down to a specific elevation angle and the radio waves are radiated in all azimuth directions. The beam can be swung in the elevation direction. As a result, it is possible to communicate with the communication satellite above the equator in response to changes in the azimuth direction of the moving body without changing the directional characteristics of the antenna, and only when the tilt of the moving body changes. The peak direction of can be changed with respect to the elevation direction.

Up to now, the case of oscillating the cone beam in the elevation direction for a specific radius has been described, but the cone beam may be oscillated in the elevation direction with an arbitrary radius.

Next, a method of narrowing the beam in a specific azimuth direction and swinging this fan-shaped beam in the azimuth direction will be described. The fan beam is shown in FIG. In FIG. 18, 17 is a cross section of the directional characteristics of the antenna, 18 is the direction of the communication satellite above the equator, 19 is the antenna surface, 20 is an axis perpendicular to the antenna surface, and 21 is the direction in which the directional characteristics change. In this embodiment, in the multiple circular array antenna, the fan-shaped beam is changed in the azimuth direction by changing the phase of the electric power supplied to each circular array antenna.

FIG. 9 shows a feed circuit configuration for the double array circular array antenna shown in FIG. 3 in this case.
Shown in. In FIG. 9, 5 is a reference inner circular array array, 6 is a double circular array array, and 2 is a variable phase shifter capable of changing the phase of the supplied power. The power supplied from the transceiver 10 is distributed to each circular array antenna by the distributor 11, and at the branching portion of each circular array antenna for the antenna element,
Further, the distributor 11 distributes the power in consideration of the loss in the power supply line. In the present embodiment, in order to make the phases of the powers supplied to the reference circular array antenna 5 and the second circular array antenna 6 different,
The variable phase shifter 2 shifts the phase of the electric power to be fed, and the instruction unit 21 accepts the amount of the shifted phase from the outside and gives an instruction.

In the present embodiment, the circular array arrays 5 and 6 are supplied with electric power with different feeding phases.
2mπ in one round between each antenna element in and
(Rad.) This allows the beam to be narrowed down in a specific azimuth direction. In order to swing the beam narrowed down in a specific azimuth direction in the azimuth direction, as shown in FIG. 9, a variable phase shifter 2 is provided at the root of a power feeding circuit that feeds one circular array array, Part 21
A beam narrowed down in a specific direction can be swung in the azimuth direction of 360 degrees by instructing the phase amount of the feed phase by changing the relative feed phase between the two circular array arrays. . At this time, the array radii r ₁ and r ₂ of each circular array may be set to be proportional to the zero point of the Bessel function, or may be set at equal intervals.

Further, FIG. 10 and FIG. 11 show the feed circuit configuration for the triple circular array antenna shown in FIG.
Shown in. 10 and 11, 2 is a variable phase shifter, 5 is an innermost reference circular array array, 6 is a double circular array array, and 8 is an outermost third circular array array. Show. When using a triple circular array,
Compared with the double circular array array, when the beam is narrowed down in the azimuth direction, the design variables are increased, and the beam can be narrowed down to a desired shape. Further, in order to swing the beam in the azimuth direction, as in the power feeding circuit configuration shown in FIG. 10, the root of the power feeding circuit to the second circular array array 6 and the power feeding circuit to the outermost circular array array 8 are used. This is possible by providing the variable phase shifters 2 at the root of each of the above and instructing the phase amount of each variable phase shifter 2 from the instruction unit 21. Even if one variable phase shifter 2 is provided at the root of the power feeding circuit for the circular array array of the second and third layers as in the power feeding circuit configuration shown in FIG.
It is possible to swing the beam to 60 degrees. in this case,
Compared with the power supply circuit configuration shown in FIG. 10, it is possible to swing the beam in 360 degrees in the azimuth direction with a smaller number of variable phase shifters.

The structure of the variable phase shifter 2 is shown in FIG. FIG. 2 shows an example of a 3-bit digital phase shifter. In this example, a plurality of lines having different line lengths are prepared, and a line switching type shifter is used to switch which line is connected or not by a switch. It uses a phaser. 24-35 are
It is a switch and can be configured by a PIN diode or the like, and an upper or lower line is selected by turning on / off each PIN diode. In this case, the instruction unit 21 determines that each P
The phase amount is set by controlling the ON / OFF of the IN diode. In FIG. 2, it is 0 in 45 degree steps.
The phase can be changed from 0 to 360 degrees.

FIG. 29 is a block diagram of another variable phase shifter. FIG. 29 shows a configuration example of the analog phase shifter, and in this example, two varactor diodes 27 are used for the legs of the 90 ° hybrid circuit. Since the varactor diode 27 is an element whose capacitance can be changed, the phase of the output signal can be changed by changing the capacitance of the varactor diode 27 in response to an instruction from the outside by the instruction unit 22.

As described above, the fan-shaped beam can be swung in the azimuth direction by changing the feeding phase for feeding each of the circular array antennas.

Next, FIG. 12 shows the configuration of the power supply circuit when the beam is swung in both the azimuth direction and the elevation angle direction. The directional characteristics in this case are shown in FIG. In FIG. 19, 1
7 is a cross section of the directional characteristics of the antenna, 18 is the direction of the communication satellite above the equator, 19 is the antenna surface, 20 is an axis perpendicular to the antenna surface, and 21 is the direction in which the directional characteristics change.
The directional characteristics shown in FIG. 19 are the same as those shown in FIGS.
It also has the way of changing the directional characteristics shown in
A pencil beam having a peak only in the direction 18 of the communication satellite above the equator is formed. With respect to the tilt of the moving body, the pencil beam-shaped pointing is changed in the elevation angle direction, and with respect to the change of the direction of the moving body, the pencil-shaped pointing characteristic is centered on the zenith axis 20 of the antenna surface. Change in azimuth direction.

In this case, first, the feeding phase difference of each antenna element in each circular array array is made non-uniform and 2 m per round.
The feed phase difference of π (Rad.) is made possible, and the beam is narrowed down in the azimuth direction. The narrowed beam can be swung in the elevation angle direction by changing the feed amplitude ratio of the variable power distributor 7 feeding each circular array array, and the variable phase shifter 2 can change the circular shape. By making the feeding phase difference between the array arrays variable, it is possible to swing the beam in the azimuth direction.

Further, FIG. 13 shows an array arrangement when the circular loop antenna is a multiple array, FIG. 14 is an array arrangement when the elliptical loop antenna is a multiple array, and FIG. 15 is an array arrangement when the spiral antenna is a multiple array. The arrangement is shown respectively. These feeding circuits can be realized only by making the circular array arrays 5, 6 and 8 shown in FIGS. 1 and 7 to 12 into circular loop antennas, elliptical loop antennas and spiral antennas. In FIG. 13, 10a is
A reference feeding point is shown, and 10b is another feeding point, which is fed with a 90 ° phase shift in advance from the feeding phase fed to each circular loop at the feeding point 10a. Also,
Reference numerals 11a, 11b and 11c denote dielectric substrates having different permittivities, which are formed on the same plane. In FIG. 13, the inside of the circle indicated by the dotted line 101 is the dielectric substrate 11a having the same dielectric constant, and the dotted line 101
The portion between the circle indicated by and the circle indicated by the dotted line 102 is the dielectric substrate 11b, and the portion between the circle indicated by the dotted line 102 and the circle indicated by the dotted line 103 is the dielectric substrate 11c. is there. Conductive antenna elements are arranged in a circle on these dielectric substrates. In order to provide a feeding phase difference of 2π (Rad.) In each round of each circular loop, the phenomenon that the guide wavelength L of the radio wave differs depending on the dielectric constant is used in this embodiment. That is, each circular loop 1
Since the length of the circumference may be one wavelength, the length of the circumference is determined from the radius proportional to the zero point of the Bessel function. Therefore, the length of the circumference is determined by the guide wavelength L of the radio wave. age,
The dielectric constant that produces such a wavelength is determined. For example, as described above, when the radius of the innermost circular loop is obtained, it is normalized to the free space wavelength and becomes 0.61, and the radii of the second and third circular loops are 1.12 and 1.62, respectively. Desired. As a result, the dielectric substrate 11a having a dielectric constant such that the guide wavelength L of the radio wave is 0.61λ × 2 × 3.14 = 3.83λ is used. Dielectric substrate 11
Similarly, the dielectric constants of b and 11c are selected. The power feeding method is as shown in FIG.
The power is supplied to the power supply points 10a and 10b in. Here, φ = 90 degrees (φ is an angle formed with respect to the center O of the circular array), and the positions of the feeding points 10a and 10b form an angle of 90 degrees with respect to the center O of the circular array. Place in position. By doing so, the signals fed to the circular loop antennas have a phase difference of 2π (Rad.) In one round. Further, by changing the feeding amplitude and feeding phase for feeding to each loop antenna, the beam direction can be changed as in the above-described embodiment.

Next, applications of the variable directivity antenna in the above-described embodiments will be described. FIG. 16 shows an example in which the variable directivity antenna is mounted on a moving body. Figure 1
In FIG. 6, 12 is a communication satellite above the equator, 13 is a mobile satellite communication antenna mounted on the communication satellite, 14 is a land mobile, 15 is an air mobile, 16 is a sea mobile, 1
Reference numeral 7 denotes a beam which is mounted on each mobile unit and is radiated from a mobile satellite communication antenna, and 18 denotes a line which indicates the direction to each mobile unit and the communication satellite above the equator.

Since the communication satellite above the equator is a geostationary satellite,
The direction 18 looking at the communication satellite 12 from a range of mobiles on the earth does not change much. On the other hand, since the land mobile body 14, the air mobile body 15, and the sea mobile body 16 on the earth face various directions and show various inclinations, the communication satellite above the equator seen from the antenna mounted on the mobile body. Twelve directions 18 indicate different azimuths and different elevations. Therefore, in order for each mobile unit to perform high-quality communication with a communication satellite above the equator, a direction in which the directional characteristic 17 of the antenna is always directed toward the communication satellite 12 in accordance with the direction and inclination of the mobile unit. It must be a variable antenna. As described above, by mounting the variable directivity antenna on the moving body, the directional characteristics can be changed according to the direction and the inclination of the moving body.

According to this embodiment, in the directional variable array antenna, the number of variable phase shifters and variable power distributors can be dramatically reduced as compared with the conventional one. For example, in an S heavy circular array array, a maximum of S-1 variable phase shifters, that is, 2
The directivity can be changed in all azimuth angles with one variable phase shifter in the heavy circular arrangement. Alternatively, the S-heavy circular array array can change the directivity to all elevation angles with a maximum of S-1 variable power distributors, that is, one variable power distributor in the double circular array. Further, the directivity can be changed in all azimuth angles and all elevation angle directions by one variable phase shifter and one variable power distributor in the double circular arrangement.

[0055]

According to the present invention, the directivity is changed to all azimuth angles and / or all elevation angles by using a variable phase shifter and a variable power distributor which are smaller than those in the S-heavy circular array. be able to. This enables downsizing.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an array antenna feeding circuit when a feeding circuit configuration for changing directivity in an elevation direction is applied to a double circular array array.

FIG. 2 is a configuration diagram of a variable phase shifter.

FIG. 3 is a layout diagram of antenna elements when the present invention is applied to a double circular array array.

FIG. 4 is an explanatory diagram showing a power feeding method for an antenna element of a circular array array.

5 is a plan view of the power supply circuit configuration shown in FIG.

FIG. 6 is a layout diagram of antenna elements when the present invention is applied to a triple circular array.

FIG. 7 is a configuration diagram of an array antenna feeding circuit when a feeding circuit configuration for varying directivity in an elevation direction is applied to a triple circular array.

FIG. 8 is a configuration diagram of an array antenna feeding circuit when a feeding circuit configuration for changing directivity in an elevation direction is applied to a triple circular array array.

FIG. 9 is a configuration diagram of an array antenna feeding circuit when a feeding circuit configuration for varying directivity in an azimuth direction is applied to a double circular array array.

FIG. 10 is an array antenna feeding circuit configuration diagram when a feeding circuit configuration for varying directivity in the azimuth direction is applied to a triple circular array array.

FIG. 11 is a configuration diagram of an array antenna feeding circuit when a feeding circuit configuration for varying directivity in an azimuth direction is applied to a triple circular array array.

FIG. 12 is a configuration diagram of an array antenna feeding circuit when a feeding circuit configuration for changing directivity in an elevation direction and an azimuth direction is applied to a double circular array array.

FIG. 13 is a configuration diagram when a circular loop antenna is multiplexed.

FIG. 14 is a configuration diagram in the case where elliptical loop antennas are multiplexed.

FIG. 15 is an array layout diagram when multiple spiral antennas are provided.

FIG. 16 is an explanatory diagram showing applications of the variable directional antenna according to the present embodiment.

FIG. 17 is an explanatory diagram showing the directional characteristics of a cone beam.

FIG. 18 is an explanatory diagram showing directional characteristics of a fan-shaped beam.

FIG. 19 is an explanatory diagram showing directional characteristics of a pencil beam.

FIG. 20 is an explanatory diagram showing the directional characteristics of a cone beam.

FIG. 21 is an explanatory diagram showing the directional characteristics of a cone beam.

FIG. 22 is a directional characteristic diagram when the power supply amplitude ratio is 1: 0.5.

FIG. 23 is a directional characteristic diagram in the case where the power supply amplitude ratio is 1: 0.6.

FIG. 24 is a directional characteristic diagram in the case where the power supply amplitude ratio is 1: 0.75.

FIG. 25 is a configuration diagram of an array antenna feeding circuit for varying directivity by a conventional technique.

FIG. 26 is a layout diagram of antenna elements of an array antenna for changing directivity by a conventional technique.

FIG. 27 is a configuration diagram of a variable power distributor according to the present embodiment.

FIG. 28 is another configuration diagram of the variable power distributor in the present embodiment.

FIG. 29 is another configuration diagram of the variable phase shifter according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna element, 2 ... Variable phase shifter, 3 ... Fixed power distributor, 4 ... Feed line, 5 ... Circular array array used as a reference, 6 ...
Double circular array array, 7 ... Variable power divider, 8 ... 3
Heavy circular array array, 9 ... Circular loop antenna.

Claims (17)

[Claims] 1. A directional variable antenna in which circular array antennas having at least two antenna elements are concentrically arranged in S-weight (S is an integer of 2 or more), and the circular array array is arranged in S-weight. A circular array feeding part for feeding each of the antennas, and each of the antenna elements of the circular array array antenna, which is provided in each of the S-shaped circular array array antennas and supplies the power fed by the circular array feeding part. And an antenna power feeding unit that feeds power with equal power, wherein the circular array feeding unit outputs a power feeding circuit, a circular array distributing unit that distributes power to each of the circular array antennas, and the circular array. And a variable phase shift means capable of shifting the feeding phase of the power distributed to each of the array array antennas and changing the feeding phase. Variable directivity antenna according to claim. 2. The variable phase shift means according to claim 1,
As a line for feeding each of the circular array antennas arranged in the S-fold from the feeding circuit, a plurality of lines having different lengths are provided, and the line to be connected to the circular array antenna is a line of the plurality of lines. A directional variable antenna having a switching means for switching one of them according to an external instruction. 3. The switching means according to claim 2,
A directional variable antenna comprising a PIN diode controlled according to an instruction from the outside and connected to each of the plurality of lines. 4. The variable phase shift means according to claim 1,
An analog phase shifter including a varactor diode whose capacity changes in a line connected to each of the circular array antennas from the power feeding circuit, and an instruction means for changing the capacity of the varactor diode according to an external instruction. A variable directivity antenna, characterized by comprising: 5. The antenna feeding section according to claim 1, wherein the feeding phase difference is 2 mπ (Rad.) (Where m is an integer of 1 or more) in one round in the circular array antenna. A variable directivity antenna, comprising phase adjusting means for shifting a feeding phase for feeding each of the antenna elements based on a circular arrangement position of the circular array antenna of each of the antenna elements. 6. The phase adjusting means according to claim 5,
A variable directivity antenna, wherein the feeding phases are shifted by adjusting the line lengths connected to each of the antenna elements in advance. 7. A directional variable antenna in which circular array antennas having at least two antenna elements are arranged concentrically in an S-weight (S is an integer of 2 or more), and each circular array antenna is fed with power. And a circular array feeding section, and an antenna feeding section that feeds the power fed by the circular array feeding section to each of the antenna elements of the circular array array antenna with equal power, the circular array feeding section A power supply circuit for outputting power, and a circular array power variable distribution means capable of distributing the power to each of the circular array antennas and changing a power supply power ratio between the circular array antennas. Variable directivity antenna. 8. The variable power distributor according to claim 7, wherein the circular array variable power distribution means is provided corresponding to each of the circular array antennas, and varies the power ratio distributed to the circular array antennas. A variable directivity antenna, comprising: 9. The variable power distribution unit for circular array according to claim 7, wherein the variable power distribution unit for circular array is provided corresponding to each of the array antennas for circular array, and is variable for varying a power ratio to be distributed to the array antenna for circular array. A variable directivity antenna comprising an attenuator. 10. The antenna feeding unit according to claim 7, wherein the feeding angle difference of the circular array antenna in the circular array antenna is 2 mπ (Rad.) (Where m is an integer of 1 or more). A directional variable antenna comprising: a phase adjusting unit that shifts a feeding phase for feeding each of the antenna elements based on the circular arrangement position of each of the antenna elements. 11. The variable directivity antenna according to claim 10, wherein the phase adjusting means shifts the feeding phases by adjusting the line length connected to each of the antenna elements in advance. 12. The variable directivity antenna according to claim 7, further comprising phase shifting means for shifting a feeding phase of electric power distributed to each of the circular array antennas. 13. The phase shifting means according to claim 12,
A variable directivity antenna, wherein a feeding phase of electric power distributed to each of the circular array antennas can be changed. 14. The variable directivity antenna according to claim 1, wherein at least one of the circular array antennas is a loop antenna having an arbitrary shape. 15. The variable directivity antenna according to claim 1 or 7, wherein the variable directivity antenna is a spiral antenna. 16. The feed phase distributed to one circular array antenna according to claim 1, wherein the variable phase shift means distributes the feed phase of power distributed to each of the circular array antennas to each other. The variable directivity antenna is characterized in that the feeding phase distributed to each of the other circular array antennas is relatively shifted with respect to. 17. The phase shifting means according to claim 13,
In order to shift the feeding phase of the electric power distributed to each of the circular array antennas, the feeding phase distributed to one circular array array antenna and the feeding phase distributed to each of the other circular array antennas A variable directivity antenna characterized in that the antennas are relatively displaced.