JP2687415B2 - Reflector antenna - Google Patents
Reflector antennaInfo
- Publication number
- JP2687415B2 JP2687415B2 JP63096112A JP9611288A JP2687415B2 JP 2687415 B2 JP2687415 B2 JP 2687415B2 JP 63096112 A JP63096112 A JP 63096112A JP 9611288 A JP9611288 A JP 9611288A JP 2687415 B2 JP2687415 B2 JP 2687415B2
- Authority
- JP
- Japan
- Prior art keywords
- reflecting mirror
- sub
- antenna
- reflector
- primary radiator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Aerials With Secondary Devices (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ この発明は、地上マイクロ波通信や衛星通信の地球局
に用いられる小型のアンテナに関するものである。TECHNICAL FIELD The present invention relates to a small antenna used in an earth station for terrestrial microwave communication or satellite communication.
［従来の技術］ 第２図（ａ）及び（ｂ）は、例えば「三菱電機技報」
Vol.48,No.7,1974,P808に開示された従来の軸対称形反
射鏡アンテナの概略構成を示す側面及び正面図である。
図において、１は主反射鏡、２は副反射鏡、３は一次放
射器、４は副反射鏡２を主反射鏡１と接続して保持する
支持柱である。[Prior Art] FIGS. 2A and 2B show, for example, "Mitsubishi Electric Technical Report".
FIG. 3 is a side view and a front view showing a schematic configuration of a conventional axisymmetric reflector antenna disclosed in Vol.48, No.7,1974, P808.
In the figure, 1 is a main reflecting mirror, 2 is a sub-reflecting mirror, 3 is a primary radiator, and 4 is a support column for connecting and holding the sub-reflecting mirror 2 with the main reflecting mirror 1.
第３図（ａ）及び（ｂ）は、例えば「三菱電機技報」
Vol.54,No.12,1980,P58に開示された従来のオフセット
形反射鏡アンテナの概略構成を示す側面図及び正面図で
ある。図において、１は主反射鏡、２は副反射鏡、３は
一次放射器、４は副反射鏡２を主反射鏡１と接続して保
持する支持柱である。3 (a) and 3 (b) show, for example, "Mitsubishi Electric Technical Report".
FIG. 14 is a side view and a front view showing a schematic configuration of a conventional offset reflector antenna disclosed in Vol. 54, No. 12, 1980, P58. In the figure, 1 is a main reflecting mirror, 2 is a sub-reflecting mirror, 3 is a primary radiator, and 4 is a support column for connecting and holding the sub-reflecting mirror 2 with the main reflecting mirror 1.
次に、上記従来の軸対称形反射鏡アンテナ及びオフセ
ット形反射鏡アンテナの動作について説明する。一次放
射器３により放射された電波は副反射鏡２によって反射
された後、主反射鏡１により反射され空間に放射され
る。Next, the operations of the conventional axially symmetric reflector antenna and offset reflector antenna will be described. The radio wave radiated by the primary radiator 3 is reflected by the sub-reflecting mirror 2 and then reflected by the main reflecting mirror 1 and radiated into the space.
［発明が解決しようとする課題］ 上記した従来の反射鏡アンテナは以上のように構成さ
れているので、まず、第２図（ａ）及び（ｂ）に示す軸
対称形反射鏡アンテナの場合には、主反射鏡１により反
射された電波のうち、電界強度の大きい開口の中央部付
近の電波が副反射鏡２及び支持柱４により遮へいされる
ため、利得の低下やサイドローブレベルの上昇といった
放射特性の劣化が問題点となっていた。さらに、一次放
射器３により放射された電波のうちで、一次放射器３の
中心軸付近の電界強度の大きい電波が副反射鏡２により
反射され、再び一次放射器３に入り込むため一次放射器
３のVSWR（定在波比）特性が劣化する問題点があった。[Problems to be Solved by the Invention] Since the conventional reflector antenna described above is configured as described above, first, in the case of the axisymmetric reflector antenna shown in FIGS. 2 (a) and 2 (b), Among the radio waves reflected by the main reflecting mirror 1, the radio waves near the center of the opening having a large electric field strength are shielded by the sub reflecting mirror 2 and the supporting column 4, so that the gain is decreased and the side lobe level is increased. The deterioration of radiation characteristics has been a problem. Further, among the radio waves radiated by the primary radiator 3, the radio waves having a high electric field strength near the central axis of the primary radiator 3 are reflected by the sub-reflecting mirror 2 and enter the primary radiator 3 again, so that the primary radiator 3 There was a problem that VSWR (standing wave ratio) characteristics were degraded.
また、第３図（ａ）及び（ｂ）に示すオフセット形反
射鏡アンテナの場合には、上記軸対称形反射鏡アンテナ
における副反射鏡２及び支持柱４の電波の遮へいによる
放射特性の劣化や、副反射鏡２の反射によるVSWR特性の
劣化の問題はないが、両者のアンテナの開口径を一致さ
せた場合、アンテナの機械的寸法はオフセット形反射鏡
アンテナの方が大きくなる問題点があった。さらに、一
般に一次放射器３の中心軸が主反射鏡１の鏡軸と一致し
ないため、アンテナの方向調整が煩雑になる問題点があ
った。Further, in the case of the offset type reflector antenna shown in FIGS. 3 (a) and 3 (b), the radiation characteristic is deteriorated due to the radio wave shielding of the sub-reflector 2 and the supporting column 4 in the above-mentioned axisymmetric reflector antenna. However, there is no problem of deterioration of VSWR characteristics due to reflection of the sub-reflecting mirror 2, but when the aperture diameters of both antennas are made to coincide, the mechanical size of the antenna is larger in the offset reflecting mirror antenna. It was Further, since the central axis of the primary radiator 3 generally does not coincide with the mirror axis of the main reflecting mirror 1, there is a problem that the direction adjustment of the antenna becomes complicated.
この発明は上記のような問題点を解消するためになさ
れたもので、アンテナの機械的寸法を小さくできると共
に、副反射鏡の遮へいによる放射特性の劣化や、副反射
鏡の反射によるVSWR特性の劣化を低減でき、さらにアン
テナの方向調整が容易な反射鏡アンテナを得ることを目
的とする。This invention has been made to solve the above problems, and can reduce the mechanical size of the antenna, deterioration of the radiation characteristics due to the shielding of the sub-reflecting mirror, and VSWR characteristics due to the reflection of the sub-reflecting mirror. It is an object of the present invention to obtain a reflector antenna which can reduce deterioration and can easily adjust the direction of the antenna.
［課題を解決するための手段］ この発明に係る反射鏡アンテナは、一次放射器及び副
反射鏡を、主反射鏡の開口面を含む平面上に投影した全
写像が開口面内にあり、かつこの開口面の中心からオフ
セットするように一次放射器及び副反射鏡を配置し、一
次放射器の中心軸を主反射鏡の鏡軸方向と一致させ、さ
らに一次放射器の開口面上の法線方向を、アンテナの構
造上の対称面内において主反射鏡の鏡軸方向から傾けた
ものである。[Means for Solving the Problem] In the reflector antenna according to the present invention, a total image obtained by projecting the primary radiator and the sub-reflector onto a plane including the aperture surface of the main reflector is within the aperture surface, and The primary radiator and the sub-reflector are arranged so as to be offset from the center of this opening surface, the central axis of the primary radiator is aligned with the mirror axis direction of the main reflecting mirror, and the normal line on the opening surface of the primary radiator is arranged. The direction is tilted from the mirror axis direction of the main reflecting mirror in the plane of symmetry of the antenna structure.
［作用］ この発明における反射鏡アンテナは、一次放射器によ
り放射された電波が副反射鏡により反射された後主反射
鏡により反射され、電界強度の小さい開口の周辺部付近
で副反射鏡及び支持柱により遮へいされる部分を除いて
空間に放射される。[Operation] In the reflector antenna according to the present invention, the radio wave radiated by the primary radiator is reflected by the sub-reflector and then reflected by the main reflector, and the sub-reflector and the support are provided in the vicinity of the opening having a small electric field strength. It is radiated to the space except the part shielded by the pillars.
［実施例］ 第１図（ａ）及び（ｂ）はこの発明の一実施例である
反射鏡アンテナの概略構成を示す側面図及び正面図であ
り、カセグレンアンテナ形式の場合を示している。図に
おいて、１は点F1を焦点とする主反射鏡、２は点F1及び
点F2を焦点とする副反射鏡、３は点F2にその位相中心を
配置した一次放射器である。[Embodiment] FIGS. 1A and 1B are a side view and a front view showing a schematic configuration of a reflector antenna according to an embodiment of the present invention, showing a case of a Cassegrain antenna type. In the figure, 1 is a main reflecting mirror having a point F 1 as a focal point, 2 is a sub-reflecting mirror having a point F 1 and a point F 2 as focal points, and 3 is a primary radiator having its phase center placed at a point F 2. .
次に、上記第１図（ａ）及び（ｂ）に示すこの発明の
一実施例である反射鏡アンテナの動作について、送信の
場合を例にとり説明する。一次放射器３より放射される
点F2を曲率中心とする球面波は、副反射鏡２により反射
された後は点F1を曲率中心とする球面波に変換され、最
後に主反射鏡１により反射された後に平面波に変換さ
れ、主反射鏡１の鏡軸に放射される。この主反射鏡１に
より平面波に変換された電波は、副反射鏡２により一部
が遮へいされる。一次放射器３の中心軸方向は主反射鏡
１の鏡軸方向と一致しているので、一次放射器３の機械
軸とアンテナの電気軸が一致し、アンテナの放射ビーム
方向の調整が容易になる。ここで、アンテナの構造上の
対称面内における副反射鏡２の外周上の点をS1及びS2と
し、一次放射器３の中心軸が副反射鏡２と交わる点をS0
とする。また、∠S1F2S0,∠S2F2S0をそれぞれθ１及び
θ、２とすると、一般にθ１とθ２は等しくない。一次
放射器３の開口面上の法線方向をその中心軸方向に一致
させた場合、副反射鏡２に照射される電波の電界強度は
点S1と点S2とで異なる。例えば、θ１＞θ２の場合、電
界強度は点S1の方が点S2よりも小さくなる。このため、
主反射鏡１に対し電波を有効に照射することができず利
得が低下する。Next, the operation of the reflector antenna which is one embodiment of the present invention shown in FIGS. 1 (a) and 1 (b) will be described by taking the case of transmission as an example. The spherical wave having a curvature center at the point F 2 emitted from the primary radiator 3 is converted into a spherical wave having a curvature center at the point F 1 after being reflected by the sub-reflecting mirror 2, and finally, the main reflecting mirror 1 After being reflected by, the light is converted into a plane wave and emitted to the mirror axis of the main reflecting mirror 1. A part of the radio wave converted into the plane wave by the main reflecting mirror 1 is shielded by the sub reflecting mirror 2. Since the central axis direction of the primary radiator 3 coincides with the mirror axis direction of the main reflecting mirror 1, the mechanical axis of the primary radiator 3 coincides with the electric axis of the antenna, which facilitates adjustment of the radiation beam direction of the antenna. Become. Here, points on the outer circumference of the sub-reflecting mirror 2 in the plane of symmetry of the antenna are defined as S 1 and S 2 , and the point where the central axis of the primary radiator 3 intersects with the sub-reflecting mirror 2 is S 0.
And Further, if ∠S 1 F 2 S 0 and ∠S 2 F 2 S 0 are θ 1 and θ, 2 , respectively, θ 1 and θ 2 are generally not equal. When the normal direction on the opening surface of the primary radiator 3 is made to coincide with the central axis direction, the electric field strength of the radio wave with which the sub-reflecting mirror 2 is irradiated differs between the points S 1 and S 2 . For example, when θ 1 > θ 2 , the electric field strength at the point S 1 is smaller than that at the point S 2 . For this reason,
Radio waves cannot be effectively emitted to the main reflecting mirror 1, and the gain is reduced.
そこで、一次放射器３の開口面上の法線方向がアンテ
ナの構造上の対称面内において、θ１とθ２の大きい方
に傾くように一次放射器３の開口をカットすることによ
り、一次放射器３の放射ビーム方向が変化し、点S1と点
S2における電界強度を等しくすることができる。その結
果、副反射鏡２により反射された電波は主反射鏡１を有
効に照射し、利得の低下が改善される。次に主反射鏡１
により変換された平面波は機構の中心部で電界強度が強
く、上記開口の周辺部で弱いテーパ状の電界強度分布を
持つ。副反射鏡２は上記開口の周辺部に配置されている
ので、遮へいされる電波の電界強度は上記した従来の軸
対称形反射鏡アンテナの場合に比べて弱くなり、利得の
低下やサイドローブレベルの上昇といった放射特性の劣
化が改善される。さらに、一次放射器３及び副反射鏡２
を主反射鏡１の開口面を含む平面上に投影した全写像が
上記開口面内にあるため、アンテナの機械的寸法は主反
射鏡１の開口径と一致する。これと、上記した従来のオ
フセット形反射鏡アンテナに対し主反射鏡１の開口径を
等しくした場合と比較すると、アンテナ全体の機械的寸
法は前者の方が小さくなる。また、一次放射器３の中心
軸に沿って放射された光線は副反射鏡２上の点S0で反射
された後に主反射鏡１上の点M0に向かうので、上記した
従来の軸対称形反射鏡アンテナの場合に比べて、副反射
鏡２で反射された電波が一次放射器３に入り込む電力は
小さくなりVSWR特性が改善される。Therefore, by cutting the opening of the primary radiator 3 so that the normal direction on the opening surface of the primary radiator 3 inclines toward the larger θ 1 and θ 2 in the plane of symmetry of the antenna structure, the primary The radiation beam direction of the radiator 3 changes, and the points S 1 and
The electric field strengths in S 2 can be made equal. As a result, the radio wave reflected by the sub-reflecting mirror 2 effectively irradiates the main reflecting mirror 1 and the decrease in gain is improved. Next, the main reflector 1
The plane wave converted by has a strong electric field strength in the central part of the mechanism and has a weak tapered electric field strength distribution in the peripheral part of the opening. Since the sub-reflecting mirror 2 is arranged in the peripheral portion of the opening, the electric field strength of the shielded radio wave is weaker than that of the conventional axisymmetric reflecting mirror antenna described above, and the gain is reduced and the side lobe level is reduced. The deterioration of the radiation characteristic such as the rise of the temperature is improved. Further, the primary radiator 3 and the sub-reflecting mirror 2
Since the entire image obtained by projecting on the plane including the aperture surface of the main reflecting mirror 1 is within the aperture surface, the mechanical size of the antenna matches the aperture diameter of the main reflecting mirror 1. Comparing this with the case where the aperture diameter of the main reflecting mirror 1 is made equal to that of the conventional offset type reflecting mirror antenna described above, the mechanical size of the entire antenna is smaller in the former. Further, since the light beam emitted along the central axis of the primary radiator 3 is reflected at the point S 0 on the sub-reflecting mirror 2 and then goes to the point M 0 on the main reflecting mirror 1, the above-mentioned conventional axial symmetry As compared with the case of the shape reflector antenna, the electric power reflected by the sub-reflector 2 and entering the primary radiator 3 becomes smaller, and the VSWR characteristic is improved.
なお、上記実施例では、主反射鏡１をパラボラ、副反
射鏡２を双曲面から構成されるカセグレンアンテナ形式
の場合を示したが、主反射鏡１をパラボラ、副反射鏡２
を楕円面から構成されるグレゴリアンアンテナ形式の場
合でも良い。また、主反射鏡１及び副反射鏡２を非２次
曲面から構成される鏡面修整アンテナ形式の場合であっ
ても良い。In the above embodiment, the case where the main reflecting mirror 1 is a parabola and the sub-reflecting mirror 2 is a hyperboloid is used in the Cassegrain antenna type, but the main reflecting mirror 1 is a parabola and the sub-reflecting mirror 2.
May be a Gregorian antenna type composed of an ellipsoid. Further, the main reflecting mirror 1 and the sub-reflecting mirror 2 may be a mirror-modified antenna type in which the non-quadric surface is used.
［発明の効果］ 以上のように、この発明の反射鏡アンテナによれば、
一次放射器及び副反射鏡を、主反射鏡の開口面を含む平
面上に投影した全写像が開口面内にあり、かつこの開口
面の中心からオフセットされるように一次放射器及び副
反射鏡を配置し、一次放射器の中心軸を主反射鏡の鏡軸
方向と一致させ、さらに一次放射器の開口面上の法線方
向を、アンテナの構造上の対称面内において主反射鏡の
鏡軸方向から傾けた構成としたので、アンテナの機械的
寸法を小さくでき、副反射鏡による電波の遮へいを原因
とする放射特性の劣化や主反射鏡への電波の照射分布の
不平衡による放射特性の劣化、及び副反射鏡の反射波に
よるVSWR特性の劣化等を改善でき、さらにアンテナの放
射ビーム方向の調整が容易にできるなどの優れた効果を
奏するものである。[Effects of the Invention] As described above, according to the reflector antenna of the present invention,
The primary radiator and the sub-reflecting mirror are so arranged that the entire image obtained by projecting the primary radiator and the sub-reflecting mirror on a plane including the aperture surface of the main reflecting mirror is within the aperture surface and is offset from the center of the aperture surface. , The center axis of the primary radiator is aligned with the mirror axis direction of the main reflector, and the normal direction of the aperture of the primary radiator is aligned with the mirror of the main reflector in the plane of symmetry of the antenna structure. Since the structure is tilted from the axial direction, the mechanical size of the antenna can be reduced, and the radiation characteristics deteriorate due to the shielding of the radio waves by the sub-reflector and the radiation characteristics due to the imbalance of the irradiation distribution of the radio waves to the main reflector. And the deterioration of VSWR characteristics due to the reflected wave of the sub-reflecting mirror and the adjustment of the radiation beam direction of the antenna can be easily performed.
第１図（ａ）及び（ｂ）はこの発明の一実施例である反
射鏡アンテナの概略構成を示す側面図及び正面図、第２
図（ａ）及び（ｂ）は従来の軸対称形反射鏡アンテナの
概略構成を示す側面図及び正面図、第３図（ａ）及び
（ｂ）は従来のオフセット形反射鏡アンテナの概略構成
を示す側面図及び正面図である。 図において、１……主反射鏡、２……副反射鏡、３……
一次放射器、４……支持柱である。 なお、図中、同一符号は同一、又は相当部分を示す。1 (a) and 1 (b) are a side view and a front view showing a schematic configuration of a reflector antenna which is an embodiment of the present invention, and a second view.
FIGS. 3A and 3B are side and front views showing a schematic configuration of a conventional axially symmetric reflector antenna, and FIGS. 3A and 3B are schematic diagrams of a conventional offset reflector antenna. It is the side view and front view which show. In the figure, 1 ... main reflecting mirror, 2 ... sub-reflecting mirror, 3 ...
Primary radiator, 4 ... Support pillar. In the drawings, the same reference numerals indicate the same or corresponding parts.
Claims (1)
成される反射鏡アンテナにおいて、上記一次放射器及び
副反射鏡を、上記主反射鏡の開口面を含む平面上に投影
した全写像が上記開口面内にあって、この開口面の中心
からオフセットするように上記一次放射器及び副反射鏡
を配置しており、上記一次放射器の中心軸を上記主反射
鏡の鏡軸方向と一致させており、かつ上記一次放射器の
開口面上の法線方向を、アンテナの構造上の対称面内に
おいて上記主反射鏡の鏡軸方向から傾けたことを特徴と
する反射鏡アンテナ。1. A reflector antenna comprising a main reflector, a sub-reflector and a primary radiator, wherein the primary radiator and the sub-reflector are all projected onto a plane including an opening surface of the main reflector. The map is in the aperture plane, and the primary radiator and the sub-reflecting mirror are arranged so as to be offset from the center of the aperture plane, and the central axis of the primary radiator is the mirror axis direction of the main reflecting mirror. And a normal line direction on the opening surface of the primary radiator is tilted from the mirror axis direction of the main reflecting mirror in a plane of structural symmetry of the antenna.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63096112A JP2687415B2 (en) | 1988-04-19 | 1988-04-19 | Reflector antenna |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63096112A JP2687415B2 (en) | 1988-04-19 | 1988-04-19 | Reflector antenna |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01268207A JPH01268207A (en) | 1989-10-25 |
| JP2687415B2 true JP2687415B2 (en) | 1997-12-08 |
Family
ID=14156307
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63096112A Expired - Lifetime JP2687415B2 (en) | 1988-04-19 | 1988-04-19 | Reflector antenna |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2687415B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5967009U (en) * | 1982-10-27 | 1984-05-07 | 三菱電機株式会社 | antenna device |
-
1988
- 1988-04-19 JP JP63096112A patent/JP2687415B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01268207A (en) | 1989-10-25 |
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