JPH0468803A - Reformed beam antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is installed on a broadcasting satellite, etc., and connects a line to any specific area for each channel. The present invention relates to a reshaping beam antenna that changes the shape of a beam to increase antenna gain in areas with heavy rainfall, for example.

(Summary of the Invention) The present invention consists of a reshaping beam antenna that changes the shape of the beam cross section and the direction of the beam, and consists of a plurality of horns and a reflector. By interposing at least one auxiliary reflecting mirror between the mirror and changing the distribution ratio of power supplied to multiple horns, it is possible to more minutely change the beam directivity or reshape the beam. In doing so, the degree of molding is increased and low side lobes are made possible.

(Prior Art) Conventionally, as a method of reshaping the shape of a beam radiated from an antenna, for example, "ReCONflgur-ab" is used.
le Direct Radiating Arra
y Antenna, Y, 5uzukl etal,
The Transactions or the I
EICE, Vol.

E72. No, 3. March 1989. pp, 20
2-209”, a method for changing the excitation distribution of an array antenna, and “Technology
Advances In Reconfigur-a
ble Contoured Beas Ref'1
etor Antennas 1nEurope, G
, A, E, Crone etal, 1! tth AI
AA Inter-national Cotsunic
atlon! 1iatellite Systems
Con-terenae, AIAA-90-088
8-CP, March 1990. pp, 255-26
As shown in Figure 8, the antenna consists of a single reflecting mirror and a multi-horn, and a BFN (beam forming network) is used to control the amplitude and phase of the power that excites the multi-horn. There is a method in which the reflecting mirror of an antenna consisting of one feeding horn and one reflecting mirror is made into a flexible structure to change the shape of the mirror surface.

There is also a method of creating a multi-beam shaped beam by combining a cluster horn and a reflecting mirror.

In this case, some of the total horns are 1
Create two beams and combine them to create a shaped beam. At this time, the area of the cluster horn corresponding to each beam overlaps between each beam, and in some cases, one horn is commonly used for two beams. To reshape the overall beam, the BFN shall be used to control the amplitude and phase of the power supplied to each horn.

(Problem to be solved by the invention) However, with the conventional method of using an array antenna,
Compared to a multi-horn fed reflector antenna, it has the advantage of being able to reduce the beam separation angle, but on the other hand, it requires a larger antenna aperture when covering a relatively narrow coverage area with a high-gain shaped beam. Therefore, the number of elements in the array increases, and VPD (variable power divider) and VPS (
As the number of variable phase shifters (variable phase shifters) increases, the weight, volume, and loss of the BFN also increase.

In addition, in principle, the phase and amplitude distribution of an array antenna is controlled based on the area occupied by the constituent elements on the aperture surface, so the overall aperture distribution becomes discontinuous and discrete, resulting in a high degree of beam shaping. It was difficult to hope for improvement.

Furthermore, when setting the VPD and vPS of the BFN, the coupling between the constituent elements must be considered. Therefore, there is a problem in that complicated control is required for operation.

Although a multi-horn fed reflector antenna can easily obtain high gain within a coverage area, it has the same problems as the array antenna, such as the weight, volume, and loss of the BFN. Furthermore, the degree of beam shaping is limited by the horn spacing. In other words, the aperture diameter and focal length of the parabolic reflector.

When the distance is fixed, in order to narrow the distance between the elementary beams in the far field and improve the degree of shaping of the overall beam that is created by combining the elementary beams, the distance between the horns can be narrowed, but in this case, the aperture diameter of the horn becomes smaller, the width of the beam radiated from the horn becomes wider, and spillover leaking out of the reflector increases, leading to a decrease in antenna gain.

Furthermore, if the aperture diameter of the reflecting mirror is increased in order to reduce this spillover, the width of the elementary beam in the far field becomes narrower, and the degree of beam shaping does not improve. Note that the cluster horn fed reflector antenna has the disadvantage that the shape of the BFN becomes more complicated.

Furthermore, the method of changing the mirror surface shape of one feeding horn and the flexible structure reflector is an effective method when providing services with the same beam shape across all frequency bands (all channels). However, there are problems in that the mirror surface shape adjustment mechanism becomes large and that the beam cannot be directed in specific directions that differ from channel to channel.

In view of the above-mentioned points, the present invention effectively solves the problems of the prior art, has a simple configuration, and provides a vPS in the BFN.
The purpose of the present invention is to provide a reshaping beam antenna that reduces weight and loss, maintains high gain, and enables beam reshaping to direct beams in different directions for each channel. .

(Means for Solving the Problems) In order to achieve such an object, the present invention provides one main reflecting mirror and a plurality of power feeding horns, and the main reflecting mirror and the feeding horn are connected to each other for each feeding horn. At least one auxiliary reflecting mirror is provided between the feeding horn and the proportion of power supplied to each of the feeding horns is changed to change the shape of the beam radiated through the main reflecting mirror. .

(Function) With such technical means, the present invention provides one main reflecting mirror and a plurality of feeding horns, and for each feeding horn, at least one sheet is provided between the main reflecting mirror and the feeding horn. A variable phase shift in a beam forming network (BFN) is achieved by providing an auxiliary reflector and varying the proportion of power supplied to each of the feed horns to change the shape of the beam emitted from the main reflector. vessel (vps) is removed,
Weight and losses are reduced, high gain is maintained, beam reshaping is possible, and beam assignment to different directions for each channel is possible.

(Example) Next, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic configuration diagram of an embodiment of a reshaped beam antenna according to the present invention. In the figure, the reshaped beam antenna 10 includes one main reflector 1 and a plurality of mirrors, in this embodiment one
auxiliary reflectors 2, and one feeding horn 3 and 1
It consists of two power distributors 9. Auxiliary reflector 2
is arranged in each power supply horn 3, and the power divider 9 divides the supplied power and supplies it to each horn 3.

Note that this power divider 9 is used as a power combiner when used as a receiving antenna.

When the radio waves emitted from each horn 3 pass through the auxiliary reflector 2 and reach the main reflector 1, the auxiliary reflector 2 adjusts the path length of the radio wave, that is, the phase distribution of the current on the main reflector 1. This is what we do.

As a result, the beam (elementary beam) corresponding to each horn 3 can form a sharp beam with power concentrated in a specific direction different from the front direction of the antenna in the far field. However, good sidelobe characteristics cannot be obtained only by controlling the phase distribution, but the auxiliary reflector 2 also controls the amplitude of the current on the main reflector 1 in order to improve the low sidelobe characteristics. be.

FIG. 2 shows a schematic diagram of another embodiment of the reshaped beam antenna according to the present invention. In the figure, the reshaping beam antenna 11 has one auxiliary reflector 2.4 disposed in each feeding horn 3, and power distributed by a power divider is supplied to each horn 3. The radiated radio waves reach the main reflector 1 via the auxiliary reflector 2.4.

At this time, the auxiliary reflector 2.4 adjusts the path length of the radio wave, that is, the phase distribution of the current on the main reflector], and also controls the amplitude of the current on the main reflector 1 for the purpose of low side lobe characteristics. Make it easy.

In this way, the present invention decomposes a required shaped beam into a plurality of elementary beams, arranges a horn 3 corresponding to each beam, and places the horn 3 between each horn 3 and the main reflecting mirror 1. One auxiliary reflector 2 or two auxiliary reflectors 2.4 are arranged for each horn, and beam shaping in the far field is performed by changing only the distribution ratio of the power that excites each horn 3. be. Figure 3 shows a schematic configuration diagram of the power divider in Figures 1 and 2, and Figure (A) shows the case where the entire coverage area is covered with a common shaped beam over all frequency bands;
Figure (B) shows the case where each frequency band is assigned to an arbitrary shaped beam. In Figure (A), the power divider (channel combiner/divider) 9 is a variable power divider (V P D).
By adjusting the power distribution ratio supplied to each horn 3, the beams #l, #
This makes it possible to reshape the beams that are combined at 2°#■. In addition, in figure (B), each channel 1ch,
2ch, .nch is an arbitrary beam #1. #2 Assigned to #1, each channel lch, 2ch...
Switch the horn 3 corresponding to the required direction for each channel to the switch 5.
It is configured so that it can be selected. It is assumed that the channel combiner/distributor 9 is a combiner when this antenna is used for transmission, and a distributor when it is used for reception.

FIG. 4 is a map showing the position and power ratio of elementary beams corresponding to each horn in the far field. In the figure, the map of Japan 6 has a bundle diameter of 1. I is a diagram seen from a geostationary satellite at 0 degrees, and the 11 horns 3 are elementary beams #1, #2, . ...,
#11 is arranged corresponding to elementary beam #1. #2.
..., #11 is determined mainly by the phase distribution on the main reflecting mirror 1, and the positions of the elementary beams #1, #2, . ..., #1
The results of adjusting the phase distribution for 1 are shown. The center of the circle is elementary beam #1. #2. . . . represents the position of #11, and the radius of the circle and the numerical value represent the power ratio. This is an example of beam forming using a variable power divider (VPD) shown in FIG. 3(A), in which each elementary beam #
1. ...One shaped beam is obtained by in-phase combining #11 with the power ratio shown in Fig. 4, and as shown in Fig. 3 (A
) is readjusted to adjust the variable power divider (VPD) shown in FIG. ... By changing the power ratio of #11, shaped beams of different shapes can be obtained.

Furthermore, when the power divider 9 shown in FIG. 3(B) is used, the sizes of the circles in FIG. 4 are all the same, and by switching the switch 5 in FIG. Beam #1. ... It is possible to point #11 somewhere in the circle in Figure 4.

FIG. 5 is a schematic diagram of a shaped beam obtained by combining the elementary beams shown in FIG. 4. In the figure, although the goal is to cover all of Japan 6 with as uniform a gain as possible, it is possible to increase the gain in a specific area by changing the power ratio of the elementary beams. In this embodiment, the aperture diameter of the main reflecting mirror 1 is 112λ (λ: wavelength).

Next, the generation of the two auxiliary reflecting mirrors 2.4 will be explained using elementary beam #4 in FIG. 4 as an example, but the same applies to other elementary beams. As mentioned above, the angle between the center direction of elementary beam #4 in the far field and the mechanical axis of the antenna (the beam direction when the phase distribution is equal on the aperture surface of the main reflector 1) is mainly determined by the direction of the center of the elementary beam #4 in the far field. Determined by the phase distribution on the aperture plane.

FIG. 6 is a phase distribution diagram on the main reflecting mirror corresponding to beam #4 shown in FIG. 1114, and FIG. 7 is an amplitude distribution diagram on the main reflecting mirror. As shown in FIGS. 6 and 7, the phase/amplitude distribution is realized on the aperture surface of the main reflecting mirror 1, and the amplitude distribution is a concentric distribution. This amplitude distribution determines the beam width and sidelobe characteristics in the far field.

That is, if the amplitude distribution is a --like distribution, a minimum beam width will be obtained, and if it is a Taylor distribution, a low sidelobe characteristic will be obtained.

Next, a method of generating the auxiliary reflecting mirror 2 that realizes the phase/amplitude distribution shown in the sixth WJ and FIG. 7 will be explained.

Note that since the main reflecting mirror 1 is used in common for each elementary beam, it is assumed that it is provided in advance.

As shown in FIG. 8, the aperture surface 8 of the main reflecting mirror 1 is circular and is placed on the plane x, y, and the coordinates ρ, φ are measured from the center of the aperture surface 8. It is expressed by equation (1) or equation (2).

Z-f (x, y) ... (1) Z-
g (ρ, φ) ... (2) Also, the distance between the center of the aperture surface and the two axes is A, and the radius of the aperture surface 8 is ρ,
shall be. For example, in the case of a corrugated horn, the aperture diameter of the horn 3 is set to 0.76λ or more (λ: wavelength) so that the mode propagating through the horn 3 is not cut off.

Next, the position P (x h , y h
.

zh) is determined. The position of the horn 3 and the direction Zs of the horn axis are selected so as not to intersect with the adjacent auxiliary reflector 2 and horn 3. Also, the size of the auxiliary reflector 2 is the size of the horn 3.
The angle θ when looking into the auxiliary reflector 2 is determined dependently from the distance ``0'' between the horn 3 and the auxiliary reflector 2. It is vertical and inclined at an angle Ω in the y-axis direction from the Z-axis.

Note that the angle θ1 when viewing the auxiliary reflector 2 from the horn 3 is
In order to reduce spillover, the beam emitted from the horn 3 is electrically covered! (θ) (since a circular horn is used, it is axially symmetrical), the auxiliary reflector 2
For example, −
It is determined to be 14 dB.

Furthermore, the required phase distribution at the aperture surface 8 of the main reflecting mirror 1 is, for example, the distribution e(ρ, ψ) shown in FIG. 6, and the axially symmetrical power distribution is, for example, the distribution V(ρ) shown in FIG. do.

The shape γ (θ, φ) of the auxiliary reflecting mirror 2 is determined using the geometrical optics method with respect to the above-mentioned parameters. The conditions for such a formulation are: ■ Application of Fel 7's principle on the auxiliary reflector 2 ■ Horn 3
The optical path length from to the aperture surface 8 (phase condition) ■The law of conservation of energy.

For this purpose, as a starting point for generating the auxiliary reflecting mirror 2, the phase center p of the horn 3 is
Distance r from h to the intersection of the auxiliary reflector 2 and the ray. Determine.

The method is as follows. The optical path length of the ray in the horn axis direction to the center of the aperture surface 8 via the auxiliary reflecting mirror 2 and the main reflecting mirror 1 is expressed by the following equation (3) as shown in FIG.

D""r+8-1-2... (3) Select and place the reference elementary beam, for example beam #1 shown in FIG. 4, in advance from among all the elementary beams, and calculate the phase distribution corresponding to it. The phase at the center of the aperture surface 8 is e. The optical path length from the horn of the center ray of beam #1 to the center of the aperture surface. shall be. Further, if the phase at the center of the aperture plane of the phase distribution corresponding to beam #4 for which the auxiliary reflecting mirror 2 is to be generated is set to e, the following equation (4) holds true.

k(D-D) = −(e-f3o) +2nπ・
...(4) However, k-2π/λ, λ: wavelength.

n-Q, ±1. ... Therefore, the optical path length may be determined from equation (4), and the distance rO that satisfies equation (8) may be obtained.

Next, we will describe the introduction of equations for finding r(θ, φ) other than the distance ro. For S in equation (3), equations (5) and (6) hold true.

2 2 2 1/2 S-(△X +△y +△2) ... (5) △X
-p eO8ψ-xh-rsin ecos φ△y
= −A + p sinψ−yh−rsinθsin
φeO8Ω−r eO5θsinΩ △z−z−zh+rsln θsin φsin Ω−
r eO8θCOSΩ ...(6)th (
Equations (7) and (8) are obtained by applying Fell's principle to the auxiliary reflecting mirror 2 using equations (3) and (5).

r θ−(rRt / (SR))−fs/k (S
-R) le, ρθ ... (7) rφ-(r R
p / (S R) l (S /k (S-R
) l θψ (8) Here, the subscript means the partial differential with respect to the variable.

Rt-△x cos ecos φ-△y (-cos
θsin φ” cosΩ+sinθsinΩ)−△
z (cosθsin φ・SInΩ+sinθeO8
Ω) −<9)Rp−−△x sjn
θsin φ+△y sln θeO8φ' eO8Ω
−△z sin ecos φsinΩ −110>R
−△x sinθcosφ+△y (slnθsinφ
−eO8Ω+COSθsinΩ)−△z (sin
θaSln φsinΩ−cosθcosΩ)
-(11) In calculating equations (7) and (8), in the mapping from (θ, φ) to (ρ, φ), ψ−φ+π, ρ −0, ψφ−1 It is assumed that φ. This means that a group of circles with constant θ is mapped to a group of concentric circles with constant ρ.

Further, the energy conservation law is expressed by the following equation (12).

Vcv (ρ) ρ dρ dψ−■ (θ) sin θ
dθ dφ...(
12) Here, VC is given by the following equation (13).

VC-fl(θ)slnθ dθ/, j”V (ρ)
/) dρ (13) Using the above-mentioned concentric mapping conditions in equation (12), the following equation (14) is obtained.

ae=! (θ sin θ
/Vc V (ρ) p-(14) The auxiliary reflecting mirror 2 is generated using the equation obtained above.

First, give a sufficiently small θ, and for this θ, the (14th)
Calculate ρ by integrating the equation. Next, r is calculated by integrating equation (8) while changing φ from 0 to 2π.

Here, a small disc-shaped object constituting the auxiliary reflecting mirror 2 has been found.

Thereafter, each time θ is increased by a slight θ−, the (
By integrating equation (7) and equation (14), r(
θ, φ) can be calculated. In this way, the shape of the auxiliary reflection @2 is determined.

Next, the auxiliary reflecting mirror 4 will be explained. Figure 9 and 1
Figure 0 shows elementary beams #1 to #11 shown in Figure 4, respectively.
This is the phase and amplitude distribution on the aperture plane of the main reflecting mirror 2 when synthesized. The radiation pattern of this aperture distribution is shown in FIG. 5, and has low sidelobe characteristics. Consider using a shaped beam as shown in FIG. 5 as an elementary beam and creating a shaped beam by combining the shaped beams.

In this case, it is necessary to create the phase and amplitude as shown in FIGS. 9 and 10 on the aperture surface 8 of the main reflector 1 using one horn 3 and the auxiliary reflector 2, and as described above. When the amplitude distribution is a concentric distribution as shown in FIG. 7, this can be easily realized with one auxiliary reflecting mirror 2. However, in order to realize a complex amplitude distribution as shown in FIG. 10, an auxiliary reflecting mirror 4 is added to the auxiliary reflecting mirror 2 as shown in FIG. It is necessary.

A method for producing this auxiliary reflecting mirror 4 will be explained.

The horn 3 in FIG. 8 is replaced with a set consisting of a horn having radiation characteristics equivalent to the horn 3 and a quadratic curved reflector. That is, one of the two focal points of the quadratic curved surface is made to coincide with the horn position Ph shown in FIG. Next, another focal point P as shown in FIG.

Bring the phase center of the horn to . The mirror surface of the newly introduced auxiliary reflector 4 is modified, the ray from the horn to the main reflector 1 is tracked by applying the geometrical optics method, and the main reflector aperture 8 is
The amplitude distribution at is set to a desired distribution, for example, the distribution shown in FIG. By modifying the auxiliary reflector 4, the phase distribution on the aperture surface 8 of the main reflector 1 changes, so the auxiliary reflector 2 must be re-modified to obtain the desired phase distribution as shown in FIG. 9, for example. do. For this,
Also, since the amplitude distribution changes, the auxiliary reflecting mirror 4 is adjusted again. Thereafter, this operation is repeated until the desired aperture distribution is sufficiently approached.

(Effects of the Invention) As explained above, by providing at least one auxiliary reflector for each horn between one main reflector and a plurality of horns, the proportion of power supplied to each horn can be adjusted. By changing the conventional BFN, the problems of the conventional technology can be effectively solved.
The antenna performance and efficiency are improved by eliminating the need for vPS in the conventional technology, enabling reshaping of beams with low side lobes, and making it possible to use variable beams that direct beams in different directions for each channel, resulting in finer beams than conventional technology. Effects such as directional control being achieved with a simpler configuration are achieved.

[Brief explanation of the drawing]

Figure j11 is a schematic configuration diagram of one embodiment of the reshaped beam antenna according to the present invention, FIG. 2 is a schematic diagram of another embodiment of the reshaped beam antenna according to the present invention, and FIG. A schematic configuration diagram of the power divider in Figure 2 is shown. Figure (A) is for reshaping the 1-way beam, Figure (B) is for beam assignment to different directions for each channel, and Figure 4 is for each horn. A map showing the position and power ratio of elementary beams in the far field, Figure 5 is a radiation pattern diagram combining all elementary beams in Figure 4, and Figure 6 is the aperture phase distribution of the main reflecting mirror corresponding to the elementary beams. Figure 7 is the same amplitude distribution diagram, Figure 8 is a diagram explaining the generation of the auxiliary reflector, and Figure 9 is the aperture phase distribution of the main reflector corresponding to the radiation pattern obtained by combining all the elementary beams in Figure 4. Similarly, FIG. 10 is an amplitude distribution diagram, and FIG. 11 is an explanatory diagram of generation of an auxiliary reflecting mirror. 1... Main reflecting mirror 2... Auxiliary reflecting mirror 3...
・Power supply horn 4... Auxiliary reflector 5... Switch 6... Map of Japan 7... Raw beam
8... Main reflector aperture 10.11... Reshaping beam antenna agent Patent attorney Hidekazu Miyoshi lch 2ch nch Fig. 7 y Fig. 8

Claims (1)

[Claims] 1) One main reflecting mirror and a plurality of feeding horns are provided, and each feeding horn is provided with at least one auxiliary reflecting mirror between the main reflecting mirror and the feeding horn; A reshaping beam antenna characterized in that the shape of the beam radiated through the main reflecting mirror is changed by changing the proportion of the supplied power.