JP2004349886A - Antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an antenna system that can make a transmission/reception level nearly constant by compensating a decrease in gain during beam scanning. <P>SOLUTION: This antenna system is equipped with a parabolic reflector 1 having a plurality of primary radiators (2a, 2b, 2c) arranged nearby a focus and a feeding circuit 3 which distributes electric power to the primary radiators (2a, 2b, 2c), and also equipped with an electric power compensator 5 which compensates a decrease in transmission/reception level during beam scanning, for example, when the beam scanning is carried out at an electric power distribution ratio calculated by the feeding circuit 3 from beam directivity 6a by the primary radiator 1a to beam directivity 6b by the primary radiator 1b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１６】
【数２】

【００１７】
【数３】

【００１８】
【数４】

【００１９】
そして、θ_１方向のビームとθ_２方向のビームを合成した合成ビームにおけるパラボラ反射鏡１の開口分布ｆ（γ，θ_１，θ_２，ｘ）は次式（９）で与えられる。
【００２０】
【数５】

【００２１】
また、γ＝０のとき、パラボラ反射鏡１の開口分布ｆ（０，θ_１，θ_２，ｘ）は、次式（１０）で与えられ、ビーム指向性はθ_１方向となる。
【００２２】
【数６】

【００２３】
また、γ＝π／２のとき、パラボラ反射鏡１の開口分布ｆ（π／２，θ_１，θ_２，ｘ）は、次式（１１）で与えられ、ビーム指向性はθ_２方向となる。
【００２４】
【数７】

【００２５】
また、γ＝π／４のとき、パラボラ反射鏡１の開口分布ｆ（π／４，θ_１，θ_２，ｘ）は次式（１２）で与えられ、ビーム指向性はθ_１とθ_２の中間の方向となる。
【００２６】
【数８】

【００２７】
図３は、ビーム走査時の利得の軌跡を示す図であり、８は従来のビーム走査時の利得の軌跡を表し、９は電力補償後のビーム走査時の利得の軌跡を表す。上記式からわかるように、ビーム走査中にはパラボラ反射鏡１の開口分布に振幅テーパがつくため、利得低下が生じる。そこで、本実施の形態では、上記振幅テーパによる利得低下分を電力補償器５で補償することにより、アレー給電反射鏡アンテナにおける送受信レベルをほぼ一定とする。
【００２８】
以上のように、本実施の形態においては、給電回路３により計算される電力分配比により、一次放射器２ａによるビーム指向性６ａから一次放射器２ｂによるビーム指向性６ｂへアレー給電反射鏡アンテナのビーム走査を行う場合、電力補償器５にてビーム走査中の利得低下を補償する。これにより、アレー給電反射鏡アンテナにおける送受信レベルをほぼ一定とすることができる。
【００２９】
【発明の効果】
以上、説明したとおり、本発明によれば、給電回路により計算される電力分配比により、特定の一次放射器によるビーム指向性から他の一次放射器によるビーム指向性へビーム走査を行う場合、電力補償手段にてビーム走査中の利得低下を補償することとした。これにより、アンテナ装置（アレー給電反射鏡アンテナ）における送受信レベルをほぼ一定とすることができる、という効果を奏する。
【図面の簡単な説明】
【図１】本発明にかかるアンテナ装置の構成を示す図である。
【図２】パラボラ反射鏡１の座標系を示す図である。
【図３】ビーム走査時の利得の軌跡を示す図である。
【図４】従来のアンテナ装置の構成を示す図である。
【符号の説明】
１ パラボラ反射鏡、２ａ，２ｂ，２ｃ 一次放射器、３ 給電回路、４ 送受信機、５ 電力補償器。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antenna device that emits a multi-beam by using a complex type of a reflector type and an array type as an antenna type, and particularly to an antenna device that scans a beam directivity by a power distribution ratio of a feed circuit. It is.
[0002]
[Prior art]
Hereinafter, a conventional antenna device will be described. FIG. 4 is a diagram showing a configuration of an array-fed reflector antenna, which is a conventional antenna device, and includes a parabolic reflector 101, primary radiators 102a, 102b, 102c, a feed circuit 103, and a transceiver 104. You. Note that 106a, 106b, and 106c represent beam directivities radiated by the primary radiators 102a, 102b, and 102c.
[0003]
Here, the operation of the array-fed reflector antenna will be briefly described. The primary radiators 102a, 102b, and 102c include a focal point of the parabolic reflector 101, and are arranged in a plane perpendicular to a straight line from the focal point to the center of the parabolic reflector 101, and each of the beams is transmitted through the parabolic reflector 101. Beams are emitted to the directivities 106a, 106b, and 106c to form beams. The parabolic reflector 101 is of an offset type so that the primary radiators 102a, 102b, 102c do not block the beam directivities 106a, 106b, 106c.
[0004]
[Non-patent document 1]
Antenna Engineering Handbook (edited by the Institute of Electronics, Information and Communication Engineers, Ohmsha, 1st edition, 1st printing, p. 178-180)
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional antenna device, for example, when beam scanning is performed from the beam directivity 106a to the beam directivity 106b due to the power distribution ratio in the power supply circuit 103, the gain is reduced during beam scanning, and communication and communication are interrupted. There was a problem that it was easy.
[0006]
The present invention has been made in view of the above, and an object of the present invention is to provide an antenna device capable of compensating for a reduction in gain during beam scanning and making transmission and reception levels substantially constant.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, in an antenna device according to the present invention, a parabolic reflector in which a plurality of primary radiators are arranged near a focal point, and power is distributed to the primary radiators An antenna device having a feed circuit that performs beam scanning from a beam directivity by a specific primary radiator to a beam directivity by an adjacent primary radiator by a power distribution ratio calculated by the feed circuit. Power compensating means (corresponding to a power compensator 5 in an embodiment described later) for compensating for a decrease in the transmission / reception level during the beam scanning.
[0008]
According to the present invention, when predetermined beam scanning is performed based on the power distribution ratio calculated by the power supply circuit, for example, the transmission / reception level of the antenna device can be reduced by compensating for a decrease in gain during beam scanning by the power compensating means. Almost constant.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an antenna device according to the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited by the embodiment.
[0010]
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of an array-fed reflector antenna that is an antenna device according to the present invention. This array-fed reflector antenna includes a parabolic reflector 1, primary radiators 2a, 2b, 2c, a feed circuit 3, a transceiver 4, and a power compensator 5. 6a, 6b and 6c represent the beam directivities radiated by the primary radiators 2a, 2b and 2c.
[0011]
Here, the operation of the array-fed reflector antenna according to the present invention will be described in detail with reference to the drawings. The primary radiators 2a, 2b, and 2c are arranged in a plane including the focal point of the parabolic reflector 1 and perpendicular to a straight line from the focal point toward the center of the parabolic reflector 1, as in the prior art. 1, the beams are emitted to the beam directivities 6a, 6b, and 6c, respectively, to form beams.
[0012]
In the present embodiment, when beam scanning is performed from the beam directivity 6a by the primary radiator 2a to the beam directivity 6b by the primary radiator 2b by the power distribution ratio calculated by the power supply circuit 3, the power compensator 5 By compensating the gain reduction during beam scanning as described below, the transmission / reception level of the array-fed reflector antenna during beam scanning is made substantially constant. Here, a case where three beams are radiated will be described as an example, but the present invention is not limited to this case, and the same applies to a case where two or four or more beams are radiated.
[0013]
FIG. 2 is a diagram illustrating a coordinate system of the parabolic reflecting mirror 1. The z direction is the boresight direction. For example, it is assumed that beam scanning is performed from the beam directivity 6a of the primary radiator 2a to the beam directivity 6b of the primary radiator 2b using the coordinate system of FIG. Assuming that the direction of the beam directivity 6a is θ ₁ and the direction of the beam directivity 6b is θ ₂ , the following equations (1) to (4) are defined. Note that k represents a wave number.
k ₁ = k × sin θ ₁ (1)
k ₂ = k × sin θ ₂ (2)
k ₊ = (k ₁ + k ₂ ) / 2 (3)
k ₋ = (k ₁ −k ₂ ) / 2 (4)
[0014]
The aperture distribution f (θ ₁ , x) of the parabolic reflector 1 in the beam in the θ ₁ direction and the aperture distribution f (θ ₂ , x) of the parabolic reflector 1 in the beam in the θ ₂ direction are on the aperture surface. If the amplitude distribution is a (x), it is given by the following equations (5), (6), (7), and (8). Note that a (x) is constant for each beam direction.
[0015]
(Equation 1)

[0016]
(Equation 2)

[0017]
[Equation 3]

[0018]
(Equation 4)

[0019]
The aperture distribution f (γ, θ ₁ , θ ₂ , x) of the parabolic reflector 1 in the combined beam obtained by combining the beam in the θ ₁ direction and the beam in the θ ₂ direction is given by the following equation (9).
[0020]
(Equation 5)

[0021]
When γ = 0, the aperture distribution f (0, θ ₁ , θ ₂ , x) of the parabolic reflector 1 is given by the following equation (10), and the beam directivity is in the θ ₁ direction.
[0022]
(Equation 6)

[0023]
Further, when γ = π / 2, opening the distribution f of the parabolic reflector _{1 (π / 2, θ 1} , θ 2, x) is given by the following equation (11), the beam directivity and theta ₂ direction Become.
[0024]
(Equation 7)

[0025]
When γ = π / 4, the aperture distribution f (π / 4, θ ₁ , θ ₂ , x) of the parabolic reflecting mirror 1 is given by the following equation (12), and the beam directivity is θ ₁ and θ _2. In the middle direction.
[0026]
(Equation 8)

[0027]
FIG. 3 is a diagram showing a locus of a gain at the time of beam scanning, where 8 shows a locus of a gain at the time of conventional beam scanning, and 9 shows a locus of a gain at the time of beam scanning after power compensation. As can be seen from the above equation, during beam scanning, the aperture distribution of the parabolic reflector 1 has an amplitude taper, so that the gain is reduced. Therefore, in the present embodiment, the transmission / reception level in the array-fed reflector antenna is made substantially constant by compensating the gain reduction due to the amplitude taper with the power compensator 5.
[0028]
As described above, in the present embodiment, the power distribution ratio calculated by the feed circuit 3 changes the beam directivity 6a of the primary radiator 2a from the beam directivity 6b of the primary radiator 2b to the array-fed reflector antenna. When performing beam scanning, the power compensator 5 compensates for a decrease in gain during beam scanning. As a result, the transmission / reception level of the array-fed reflector antenna can be made substantially constant.
[0029]
【The invention's effect】
As described above, according to the present invention, when the beam scanning is performed from the beam directivity by a specific primary radiator to the beam directivity by another primary radiator by the power distribution ratio calculated by the feeding circuit, Compensation means compensates for the gain reduction during beam scanning. As a result, the transmission and reception levels of the antenna device (array-fed reflector antenna) can be made substantially constant.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an antenna device according to the present invention.
FIG. 2 is a diagram showing a coordinate system of the parabolic reflecting mirror 1;
FIG. 3 is a diagram illustrating a locus of gain during beam scanning.
FIG. 4 is a diagram showing a configuration of a conventional antenna device.
[Explanation of symbols]
1 parabolic reflector, 2a, 2b, 2c primary radiator, 3 feeding circuit, 4 transceiver, 5 power compensator.

Claims (1)

In a parabolic reflector in which a plurality of primary radiators are arranged near a focal point, and an antenna device including a feed circuit that distributes power to the primary radiators,
The power distribution ratio calculated by the power supply circuit compensates for a decrease in the transmission / reception level during beam scanning when performing beam scanning from the beam directivity of a specific primary radiator to the beam directivity of an adjacent primary radiator. Power compensation means,
An antenna device comprising:

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