JP3662446B2 - Dual frequency feed - Google Patents

Description

【００３４】
このとき、ステップ変換器４の特性インピーダンスＺ₀から導き出されるステップ変換器４内の波長λ₃から、ステップ変換器４の軸方向の長さＬが定められる。長さＬは、好ましくは、λ₃／４である。
【００３５】
第１導波管１と第２導波管２とステップ変換器４とは、それぞれの軸が同じ直線を通るように接続される。
【００３６】
次に、１次放射器１００での電波の受信について説明する。高い周波数帯の信号（波長λ₁）は、電磁ホーン部３に入ってきて、第２導波管２を通り、ステップ変換器４に進入する。ステップ変換器４は、第１導波管１と第２導波管２の特性インピーダンスを整合させるため、高い周波数帯の信号は、ステップ変換器４で反射することなく第１導波管１へ進入する。第１導波管１に進入した信号は、第１プローブ１１に給電される。
【００３７】
低い周波数帯の信号（波長λ₂）は、電磁ホーン部３に入ってきて第２導波管を通り、第２プローブ２１に給電される。このとき、ステップ変換器４の内径は、第２導波管２の内径より小さいので、低い周波数帯に対してはカットオフとなる。このため、低い周波数帯の信号はステップ変換器４を通過することなく反射する。
【００３８】
第１プローブ１１に給電された信号は高い周波数帯用のローノイズブロックコンバータに供給される。第２プローブ２１に給電された信号は、低い周波数帯用のローノイズブロックダウンコンバータに供給される。
【００３９】
以上説明したとおり、第１の実施の形態における１次放射器１００では、２つの異なる周波数帯の直線偏波を送信または受信することができる。
【００４０】
また、本実施の形態における１次放射器１００では、高い周波数帯用の第１導波管１と、低い周波数帯用の第２導管２との間に、第１導波管１の特性インピーダンスと第２導波管２の特性インピーダンスとを整合させるためのステップ変換器４を設けた。これにより、低い周波数帯の信号は、第２プローブ２１で良好に給電され、高い周波数帯の信号は第１プローブ１１に良好に給電される。
【００４１】
さらに、ステップ変換器４を円筒形状としたため、ステップ変換器４の軸方向の長さを導波管内波長の４分の１とすることができる。このため、１次放射器１００の軸方向の長さをできるだけ短くすることができる。
【００４２】
また、第１導波管１とステップ変換器４と第２導波管２とを、それぞれ円筒形状としたため、簡単な構成とすることができる。さらに、構成が簡単なので、２周波共用フィードを製造するための金型を容易に製造することができ、金型のコストを安くすることができる。さらに、２周波共用フィードの構成を簡単にしたので、容易に製造することができ、製造コストを低減させることができる。
【００４３】
なお、第１の実施の形態における１次放射器は、第１プローブ１１と第２プローブ２１とを互いに直交する方向に配置したが、これは受信あるいは送信する偏波に合せて配置したためである。通常、低い周波数帯と高い周波数帯の信号のアイソレーションができるだけ高くとれるように、異なる偏波が使用される。したがって、プローブの方向は、受信あるいは送信する偏波に応じて定まる。このため、２つのプローブの方向は必ずしも垂直である必要はなく、平行であっても構わない。
【００４４】
［第２の実施の形態］
次に第２の実施の形態における１次放射器について説明する。図４は、第２の実施の形態における１次放射器１１０の斜視図である。図４を参照して、１次放射器１１０は、第１の実施の形態における１次放射器１００の第１導波管１内に第１円偏波変換器として第１誘電体板１３を設け、第２導波管２内に第２円偏波変換器として第２誘電体板２３を設けたものである。その他の構成については第１の実施の形態における１次放射器１００と同じなので、ここでの説明は繰返さない。
【００４５】
第１の実施の形態における１次放射器１００が直線偏波を受信あるいは送信するために用いられるのに対し、第２の実施の形態における１次放射器１１０は、円偏波を受信あるいは送信するために用いられる。
【００４６】
図５は、第２の実施の形態における１次放射器１１０の正面図である。図５を参照して、第１誘電体板１３は、第１導波管１内に設けられ、第１プローブ１１とステップ変換器４との間に第１プローブ１１に対して４５°の角度で配置される。第２誘電体板２３は、第２導波管２内に設けられ、第２プローブ２１と電磁ホーン部３との間に第２プローブ２１に対して４５°の角度で配置される。第１誘電体板１３と第２誘電体板２３とは、所定の形状を有し、誘電体板１３，２３と平行な方向の電界の位相を遅らせる働きをする。
【００４７】
図６は、第２の実施の形態における第２導波管２の正面図である。図６を参照して円偏波について説明する。円偏波は、直交する２つの直線偏波Ｅ１およびＥ２のベクトル合成された電界Ｅである。２つの直線偏波Ｅ１，Ｅ２の位相がお互いに９０°ずれている場合に円偏波となる。一方、直交する２つの直線偏波Ｅ１，Ｅ２の位相が同相の場合は直線偏波となる。このように、直交する２つの直線偏波Ｅ１，Ｅ２の位相を９０°ずれている状態から同相にすることによって円偏波を直線偏波に変換することができる。逆に同相の状態から９０°ずれた状態にすることによって、直線偏波を円偏波に変換することができる。
【００４８】
プローブ１１，２１で受信することができる電波は、直線偏波に限られる。したがって、１次放射器を受信用のアンテナに用いる場合は、円偏波を直線偏波に変換する必要がある。第１誘電体板１３と第２誘電体板２３とはこのために用いられる。
【００４９】
図５を参照して、第１誘電体板１３と第２誘電体板２３とは互いに直交する方向に配置されている。これは次の理由による。すなわち、低い周波数帯の円偏波信号は、電磁ホーン部３に入ってきて、第２導波管２の第２誘電体板２３を通過する。このとき、第２誘電体板２３と平行な方向の直線偏波の位相が９０°ずれることにより、低い周波数帯の円偏波信号が直線偏波信号に変換される。そして、変換された直線偏波が第２プローブ２１に給電される。一方、高い周波数帯の円偏波信号は、低い周波数帯の円偏波信号と同様に、電磁ホーン部３に入ってきて、第２導波管２の第２誘電体板２３を通過する。このとき、第２誘電体板２３と平行な方向の直線偏波の位相が遅れる。第２誘電体板２３は、低い周波数帯の円偏波信号に合せて設計されているため、高い周波数帯の円偏波信号に対しては、位相の遅れ量が９０°とはならず位相の遅れ量が９０°を超えてしまう。このため、高い周波数帯の円偏波信号が完全な直線偏波に変換されない。
【００５０】
たとえば、高い周波数帯を約２０ＧＨｚとして、低い周波数帯を約１２ＧＨｚとする場合、低い周波数帯の円偏波信号を直線偏波に変換するための誘電体板（円偏波変換器）に高い周波数帯の円偏波信号を通すと、位相の遅れ量が約１２０°となってしまう。図７は、低い周波数帯（約１２ＧＨｚ）用に設計された誘電体板に低い周波数帯の信号を通したときの位相の遅れを示す図である。図８は、低い周波数帯（約１２ＧＨｚ）用に設計された誘電体板に高い周波数帯（２０ＧＨｚ）の信号を通したときの位相の遅れ量を示す図である。図７および図８から明らかなように、低い周波数帯（約１２ＧＨｚ）の信号では、位相遅れ量は約９０°であるのに対し、高い周波数帯（約２０ＧＨｚ）の信号では、位相遅れ量が約１２０°となってしまっている。
【００５１】
このため、第１導波管１の第１誘電体板１３は、第２誘電体板２３と互いに直交する方向に配置している。すなわち、第２誘電体板２３と直交する方向の直線偏波の位相を第１誘電体板１３で３０°遅らせることにより遅れすぎた位相を補正し、位相遅れ量を９０°に戻す（直交する２つの直線偏波を同相にする）。これにより、高い周波数帯（約２０ＧＨｚ）の円偏波信号が直線偏波に変換される。そして、変換された直線偏波が第１導波管１の第１プローブ１１に給電される。
【００５２】
以上説明したとおり、第２の実施の形態における１次放射器１１０は、第１の実施の形態における１次放射器１００の効果に加えて、円偏波で送られてくる信号を受信することができる。
【００５３】
また、第１誘電体板１３を、第２誘電体板２３と直交する方向に配置したので、第２誘電体板２３により遅れすぎた位相を第１誘電体板１３で補正することができ、高い周波数帯の円偏波を直線偏波に変換することができる。これにより、高い周波数帯の円偏波信号を第１プローブ１１に給電させることができる。
【００５４】
なお、本実施の形態においては、第１誘電体板１３と第２誘電体板２３とを直交する方向に配置するようにしたが、平行となるように配置してもよい。この場合には、第２誘電体板２３で遅れすぎた位相を第１誘電体板１３でさらに遅らせることにより、直交する２つの直線偏波が同相となるようにすればよい。ただしこの場合には、第１誘電体板１３が大きくなってしまうので、１次変換器１１０が大型化してしまうというデメリットがある。
【００５５】
［第３の実施の形態］
第３の実施の形態における１次放射器１２０は、第１の実施の形態における１次放射器１００に円偏波変換器として複数の金属ビスを、第１導波管１と第２導波管２とにそれぞれ設けたものである。第１の実施の形態における１次放射器が直線偏波を受信するために用いられるのに対し、第３の実施の形態における１次放射器１２０は、円偏波を受信するために用いられる。
【００５６】
図９は、第３の実施の形態における１次放射器１２０の斜視図である。図９を参照して、第３の実施の形態における１次放射器１２０は、１次導波管１内に、第１プローブ１１とステップ変換器４との間に複数本の金属ビス１４が第１プローブ１１に対して４５°の角度をつけて配置されている。第２導波管２内には、第２プローブ２１と電磁ホーン部３との間に複数本の金属ビス２４が第２プローブ２１に対して４５°の角度をつけて配置されている。第１導波管１に設けられた複数本の金属ビス１４と第２導波管２に設けられた複数本の金属ビス２４とはすべて同じ方向に配置されている。
【００５７】
第１導波管１に設けれた複数本の金属ビス１４と第２導波管内に設けられた複数本の金属ビス２４は、円偏波変換器として働く。この円偏波変換器としての複数本の金属ビス１４，２４以外の構成については、第１の実施の形態における１次放射器と同じであるのでここでの説明は繰返さない。
【００５８】
第２の実施の形態における１次放射器１１０では、円偏波変換器として誘電体板１３，２３とを用いた。第３の実施の形態における１次放射器では、円偏波変換器として複数本の金属ビス１４，２４を用いている。この複数本の金属ビス１４，２４は、第２の実施の形態における誘電体板１３，２３と同様に、２つの直交する直線偏波のうち、複数本の金属ビスの列と平行な方向の直線偏波の位相を９０°遅らせる働きをする。
【００５９】
したがって、誘電体板１３，２３と同様に、円偏波を直線偏波に変換したり、直線偏波を円偏波に変換したりすることができる。しかし、第２導波管２内の複数本の金属ビス２４は、低い周波数帯の直線偏波の位相を９０°遅らせることができるが、この低い周波数帯用に設計された複数本の金属ビス２４を通る高い周波数帯の直線偏波は、位相の遅れ量が９０°より小さくなる。
【００６０】
たとえば、高い周波数帯を約２０ＧＨｚとし、低い周波数帯を約１２ＧＨｚとする。低い周波数帯の円偏波を直線偏波に変換するように設計された複数本の金属ビス２４に、高い周波数帯（約２０ＧＨｚ）の信号を通すと、高い周波数帯の位相の遅れ量が約５０°となる。
【００６１】
図１０は、低い周波数帯（約１２ＧＨｚ）用に設計された複数本の金属ビスの列に低い周波数帯の信号を通したときの位相の遅れ量を示す図である。図１１は、低い周波数帯（１２ＧＨｚ）用に設計された複数本の金属ビスの列に高い周波数帯の信号を通したときの位相の遅れ量を示す図である。図１０および図１１に示される測定データから明らかなように、低い周波数帯（約１２ＧＨｚ）の信号では位相遅れ量が約９０°であるのに対し、高い周波数帯（約２０ＧＨｚ）の信号では位相遅れ量が約５０°と小さくなる。
【００６２】
このため、第１導波管１の複数本の金属ビス１４を、第２導波管２の複数本の金属ビス２４と同じ方向に配置することにより、位相遅れ量をさらに増やして９０°にする。すなわち、位相遅れ量を９０°にすることにより、２つの直交する直線偏波を同相にする。これにより、高い周波数帯の円偏波信号は直線偏波信号に変換される。そして、変換された直線偏波信号が、第１導波管１の第１プローブ１１に給電される。
【００６３】
なお、複数本の金属ビス１４，２４で構成される円偏波変換器は、金属ビス１本ごとに対して導波管内への挿入量を調整する必要がある。最適な状態に調整された円偏波変換器では、偏波の変換の程度が良好で反射損失の非常に少ない円偏波変換器とすることができる。
【００６４】
以上説明したとおり、第３の実施の形態における１次放射器１２０では、円偏波変換器として、複数本の金属ビスを用いた。このため、第１の実施の形態における１次放射器１００の効果に加えて、円偏波の信号を受信することができる。また、円偏波を直線偏波に良好に変換することができ、反射損失を少なくすることでができる。
【００６５】
［第４の実施の形態］
図１２は、第４の実施の形態における１次放射器１３０の斜視図である。図１３は、１次放射器１３０の横断面図である。第４の実施の形態における１次放射器１３０は、反射板１６と第１導波管１とステップ変換部４と第２導波管２と電磁ホーン部３とが、第１の実施の形態における１次放射器１００と同様であるのでここでの説明は繰返さない。
【００６６】
ここで、第４の実施の形態における１次放射器で受信する高周波帯の信号の波長をλ₁とし、第２導波管２で受信する低周波帯の信号の波長をλ₂とする。
【００６７】
反射板１６には、第１導波管１の断面径方向に直方体の第２反射板１５が設けられている。第１プローブ１１は、第２反射板１５からλ₁／４の距離だけ離れた位置に設けられている。第３プローブ１２は、反射板１６からλ₁／４の距離だけ離れた位置に設けられている。第１プローブ１１と第２反射板１５とは平行である。
【００６８】
第２導波管２のステップ変換器４との接続部分には、直方体の第３反射板２５が設けられている。第３反射板２５は、第２導波管２の径方向に対向して２つ設けられており、２つの第３反射板２５の距離は、ステップ変換部４の内径と同じである。第２プローブ２１はステップ変換部４からλ₂／４の距離だけ離れた位置に設けられている。第４プローブ２２は、第３反射板２５からλ₂／４の距離だけ離れた位置に設けられている。
【００６９】
第４の実施の形態における１次放射器１３０は、第１導波管１に第１プローブ１１と第３プローブ１２とを互いに直交する方向に設け、第２導波管２に第２プローブ２１と第４プローブ２２とを互いに直交する方向に配置している。これにより、高い周波数帯の直交する２つの直線偏波を、第１プローブ１１と第３プローブ１２とで受信することができ、低い周波数帯の直交する２つの直線偏波を第２プローブ２１と第４プローブ２２とで受信することができる。
【００７０】
第１プローブ１１と第３プローブ１２、または、第２プローブ２１と第４プローブ２２とを、それぞ導波管の軸方向にずらして配置したのは次の理由による。第１プローブ１１と第３プローブ１２とを導波管１の軸方向に同じ位置に設置すると、第１プローブと第３プローブがお互いに干渉し、２つの直線偏波のアイソレーション、すなわち交差偏波特性が悪化するからである。第２導波管の第２プローブ２１と第４プローブ２２とにおいても、同様の理由で軸方向に位置がずれている。
【００７１】
一方、プローブは受信する周波数帯の信号の波長の４分の１の距離だけ反射部から離れた位置に設ける必要がある。そこで、第１導波管１には、反射部１６上に第２反射部１５を設けて、第１プローブ１１の反射部としている。これにより、第１プローブ１１と第２反射部１５との距離がλ₁／４となる。一方第３プローブ１２に対しては反射部１６との間の距離がλ₁／４に維持される。
【００７２】
第２導波管２においては、第３反射部２５が第４プローブ２２と平行な方向に対向して２つ設けられている。第４プローブ２２の反射部は第３反射板２５となり、第４プローブ２２と第３反射板２５との距離はλ₂／４とされる。一方第２プローブ２１の反射部は、ステップ変換部４となり、ステップ変換部４と第２プローブ２１との距離はλ₂／４に維持される。
【００７３】
以上説明したとおり第４の実施の形態における１次放射器１３０は、第１導波管１に互いに直交する第１プローブ１１と第３プローブ１２とを設け、第２導波管２に互いに直交する第２プローブ２１と第４プローブ２２とを設けたので、第１の実施の形態における１次放射器１００の効果に加えて、高周波の２つの直交する直線偏波と低周波の２つの直交する直線偏波とを受信することができる。
【００７４】
また、第１導波管１において、第２反射板１５を設けることにより第１プローブ１１と第２プローブ１２とを第１導波管１の軸方向に位置をずらしたので、第１プローブ１１と第３プローブ１２とがお互いに干渉することなく、高い周波数帯の２つの直線偏波の交差偏波特性を良好にすることができる。同様に、第２導波管２において、第３反射板２５を設けることにより、第２プローブ２１と第４プローブ２２とを第２導波管２の軸方向に位置をずらしたので、低い周波数帯２つの直線偏波の交差偏波特性を良好にすることができる。
【００７５】
［第５の実施の形態］
第５の実施の形態における１次放射器は、第４の実施の形態における１次放射器が直線偏波を受信するために用いられるのに対し、円偏波を受信するために用いられる１次放射器である。
【００７６】
図１４は、第５の実施の形態における１次放射器１４０の斜視図である。図１５は、１次放射器１４０の第２導波管２の正面図である。図１６は、１次放射器１４０の第１導波管１の正面図である。図１４、図１５および図１６とを参照して、１次放射器１４０は、第４の実施の形態における１次放射器２の第１導波管１に円偏波変換部として第１誘電体板１３を設け、第２導波管２に円偏波変換部として第２誘電体板２３を設けた構成である。誘電体板１３，２３を除く構成については、第４の実施の形態における１次放射器１３０と同じであるのでここでの説明は繰返さない。第２導波管２に設けられる第２誘電体板２３と第１導波管１に設けられる第１誘電体板１３とは互いに直交する方向に配置されている。第１誘電体板１３と第２誘電体板２３との働きについては、第２の実施の形態において説明した第１誘電体板１３と第２誘電体板２３との働きと同じであるのでここでの説明は繰返さない。
【００７７】
以上説明したとおり、第５の実施の形態における１次放射器１４０は、第１導波管１に第１誘電体板１３を設け、第２導波管２に第２誘電体板２３を設けたので、第４の実施の形態における１次放射器１３０の効果に加えて低い周波帯の円偏波を直線偏波に変換することができ、高い周波数帯の円偏波を直線偏波に変換することができる。
【００７８】
［第６の実施の形態］
図１７は、第６の実施の形態における１次放射器１５０の斜視図である。第６の実施の形態における１次放射器１５０は、第５の実施の形態における１次放射器１４０の第１誘電体板１３と第２誘電体板２３とを、それぞれ複数本の金属ビス１４と複数本の金属ビス２４とに置換えた構成である。その他の構成については第５の実施の形態における１次放射器１４０と同様であるのでここでの説明は繰返さない。第６の実施の形態における１次放射器１５０によれば、第１導波管１に複数本の金属ビス１４を設け、第２導波管２に複数本の金属ビス２４を設けたので、第４の実施の形態における１次放射器１３０の効果に加えて、高周波帯の円偏波を直線偏波に変換することができ、低周波帯の円偏波を直線偏波に変換することかできる。また、円偏波を直線偏波に変換する際に、金属ビス１４，２４を用いたので、円偏波を直線偏波に良好に変換することができ、反射損失の少ない１次放射器とすることができる。
【００７９】
［第７の実施の形態］
図１８は、第７の実施の形態における１次放射器１６０の側面図である。図１９は、１次放射器１６０の第２導波管２Ａの正面図である。図２０は、１次放射器１６０の第１導波管１Ａの正面図である。図１８、図１９および図２０を参照して、１次放射器１６０は、断面形状が正方形の第１導波管１Ａと、断面形状が正方形のステップ変換部４Ａと、断面形状が正方形の第２導波管２Ａと、第２導波管２Ａに接続された電磁ホーン部３Ａとを含む。
【００８０】
第２導波管２Ａの断面内壁により構成される正方形の一辺の長さａ₂は、第２導波管２Ａの遮断周波数により定められる。同様に、第１導波管１の断面で、内壁により構成される正方形の一辺の長さａ₁は、第１導波管１Ａの遮断周波数により定められる。ステップ変換部４Ａの断面内壁により構成される正方形の一辺の長さａ₃は、第１導波管１Ａの特性インピーダンスＺ₁と第２導波管２Ａの特性インピーダンスＺ₂とから求められるステップ変換部４Ａの特性インピーダンスＺ₀に基づき定められる。特性インピーダンスＺ₀は、特性インピーダンスＺ₁と特性インピーダンスＺ₂とが整合する値に定められる。また、ステップ変換器４Ａの軸方向の長さは、ステップ変換器４Ａ内の波長λ₃から定められ、好ましくはλ₃／４である。
【００８１】
このように、第１導波管１Ａとステップ変換部４Ａと第２導波管２Ａとの大きさを定めることにより、第１導波管１Ａの特性インピーダンスと第２導波管２Ａの特性インピーダンスとが整合される。その結果、高い周波数帯の信号は、ステップ変換部４Ａで反射することなく、第１導波管１Ａへ進入することができる。
【００８２】
第１導波管１Ａには、互いに直交する方向に設けられた第１プローブ１１Ａと第３プローブ１２Ａとが配置される。また、第１導波管１Ａのステップ変換部４Ａと反対側の端には、反射板１６Ａが設けられている。さらに、反射板１６Ａ上には、第１プローブ１１Ａと平行に直方体の第２反射板１５Ａが設けられている。
【００８３】
ここで、第１導波管１で受信するための高い周波数帯の信号の波長をλ₁とし、第２導波管２Ａで受信する低い周波数帯の信号の波長をλ₂とする。
【００８４】
第１プローブ１１Ａは、第２反射板１５Ａから第１導波管１Ａの軸方向にλ₁／４の距離だけ離れた位置に設けられている。第３プローブ１２Ａは、反射板１６Ａから第１導波管１Ａの軸方向にλ₁／４の距離だけ離れた位置に設けられている。したがって、第１プローブ１１Ａと第２プローブ１２Ａとは第１導波管１の軸方向にずれて配置される。これにより、第１プローブ１１Ａと第３プローブ１２Ａとがお互いに干渉することなく、２つの直線偏波の交差偏波特性が良好となる。
【００８５】
第１導波管１Ａには、第１プローブ１１Ａとステップ変換部４Ａとの間に第１誘電体板１３Ａが設けられている。第１誘電体板１３Ａは、図２０を参照して、第１プローブ１１Ａと第３プローブ１２Ａとそれぞれ４５°の角度をなして配置されている。
【００８６】
第２導波管２Ａは、互いに直交する第２プローブ２１Ａと第４プローブ２２Ａとを備える。第２導波管２Ａのステップ変換部４Ａ側には、第４プローブ２２Ａと平行な方向に対向して直方体の第３反射板２５Ａが２つ設けられている。２つの第３反射板２５Ａの距離は、ステップ変換部４Ａの内壁により構成される正方形の一辺の長さａ₃と同じである。第２プローブ２１Ａは、ステップ変換部４Ａから第２導波管２Ａの軸方向にλ₂／４だけ離れた位置に配置される。第４プローブ２２Ａは、第３反射板２５Ａから第２導波管２Ａの軸方向にλ₂／４の距離だけ離れた位置に配置される。したがって、第２プローブ２２Ａと第４プローブ２２Ａとは第２導波管２Ａの軸方向で異なる位置に配置される。これにより、第２プローブ２１Ａと第４プローブ２２Ａとがお互いに干渉することなく、２つの直線偏波の交差偏波特性が良好となる。
【００８７】
第２導波管２Ａはさらに、第４プローブ２２Ａと電磁ホーン部３との間に第２誘電体板２３Ａを備える。第２誘電体板２３Ａは、第２プローブ２１Ａと第４プローブ２２Ａとそれぞれ４５°傾いて配置される。また、第２誘電体板２３Ａは、第１誘電体板１３Ａと互いに直交する方向に配置される。これは、第２の実施の形態において説明した、第１誘電体板１３と第２誘電体板２３との関係と同じである。なお、第２の実施の形態で説明したように、第１誘電体板１３Ａと第２誘電体板２３Ａとを平行に配置するようにしてもよい。
【００８８】
以上説明したとおり第７の実施の形態における１次放射器１６０は、第１導波管１Ａとステップ変換部４Ａと第２導波管２Ａの断面内部形状を正方形としたので、簡単な形状とすることができる。また、形状が簡単であるので、１次放射器１６０を製造するための金型の作製も容易となり、１次放射器１６０自体も容易に製造することができ、製造コストを削減することができる。
【００８９】
また、第１導波管１Ａと第２導波管２Ａとの間にそれぞれの導波管の特性インピーダンスを整合させるためのステップ変換部４Ａを設けたので、高い周波数帯の信号をステップ変換器Ａ４で反射させることなく、第１導波管１Ａに進入させることができる。
【００９０】
また、ステップ変換器４Ａの軸方向の長さを、導波管内波長λの４分の１としたので、１次放射器を小型化することができる。
【００９１】
また、第１導波管１Ａと第２導波管２Ａとの断面形状を正方形としたので、２つの異なる直線偏波の波長を同じにすることができ、プローブに良好に給電することができる。
【００９２】
さらに、第１導波管１Ａにおいて、反射板１６Ａ上に第２反射板１５Ａを設けることにより、第１プローブ１１Ａと第３プローブ１２Ａとの第１導波管１Ａの軸方向の位置をずらすようにしたので、第１プローブ１１Ａと第３プローブ１２Ａとがお互いに干渉することなく、２つの直線偏波の交差偏波特性を良好にすることができる。
【００９３】
同様に、第２導波管２において、ステップ変換部４側の端に第３反射板２５Ａを第４プローブ２２Ａの方向に対向して２つ設けたので、第２プローブ２１Ａと第４プローブ２２Ａとの第２導波管２の軸方向の位置をずらすことができる。これにより、第２プローブ２１Ａと第４プローブ２２Ａとがお互いに干渉することなく、２つの直線偏波の交差偏波特性を良好にすることができる。
【００９４】
さらに、第２導波管２Ａに誘電体板２３Ａを設け、第１導波管１Ａに誘電体板１３Ａを設けたので、低い周波帯の円偏波を直線偏波に変換して第２プローブ２１Ａと第４プローブ２２Ａとで受信することができるとともに、高い周波数帯の円偏波を直線偏波に変換して第１プローブ１１Ａと第３プローブ１２Ａとに給電することができる。
【００９５】
なお、第１誘電体板１３Ａと第２誘電体板２３Ａとを複数本の金属ビスに置換えることができるのは言うまでもない。
【００９６】
また、第１〜第４の実施の形態で示した１次放射器を断面形状を円形ではなく正方形にした１次放射器とすることができるのも言うまでもない。
【００９７】
さらに、第１〜第７の実施の形態における１次放射器１００，１１０，１２０，１３０，１４０，１５０，１６０は、１つのステップ変換器４Ａを有するものとしたが、ステップ変換器を複数設けるようにしてもよい。この場合には、１次放射器が増加したステップ変換器の分だけ大きくなるが、反射を少なくすることができるメリットがある。
【００９８】
今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【図面の簡単な説明】
【図１】 第１の実施の形態における１次放射器１００が用いられるパラボラアンテナを示す概略図である。
【図２】 第１の実施の形態における１次放射器１００の斜視図である。
【図３】 第１の実施の形態における１次放射器１００の横断面図である。
【図４】 第２の実施の形態における１次放射器１１０の斜視図である。
【図５】 第２の実施の形態における１次放射器１１０の正面図である。
【図６】 第２の実施の形態における第２導波管２の正面図である。
【図７】 低い周波数帯（約１２ＧＨｚ）用に設計された誘電体板に低い周波数帯の信号を通したときの位相の遅れ量を示す図である。
【図８】 低い周波数帯（約１２ＧＨｚ）用に設計された誘電体板に高い周波数帯（約２０ＧＨｚ）の信号を通したときの位相の遅れ量を示す図である。
【図９】 第３の実施の形態における１次放射器１２０の斜視図である。
【図１０】 低い周波数帯（約１２ＧＨｚ）用に設計された複数本の金属ビスの列に低い周波数帯の信号を通したときの位相の遅れ量を示す図である。
【図１１】 低い周波数帯（約１２ＧＨｚ）用に設計された複数本の金属ビスの列に高い周波数帯（約２０ＧＨｚ）の信号を通したときの位相の遅れ量を示す図である。
【図１２】 第４の実施の形態における１次放射器１３０の斜視図である。
【図１３】 第４の実施の形態における１次放射器１３０の横断面図である。
【図１４】 第５の実施の形態における１次放射器１４０の斜視図である。
【図１５】 １次放射器１４０の第２導波管２の正面図である。
【図１６】 １次放射器１４０の第１導波管１の正面図である。
【図１７】 第６の実施の形態における１次放射器１５０の斜視図である。
【図１８】 第７の実施の形態における１次放射器１６０の側面図である。
【図１９】 第７の実施の形態における１次放射器１６０の第２導波管２Ａの正面図である。
【図２０】 第７の実施の形態における１次放射器１６０の第１導波管１Ａの正面図である。
【図２１】 従来のパラボラアンテナに用いられる１次放射器の横断面を含む斜視図である。
【符号の説明】
１ 第１導波管、２ 第２導波管、３ 電磁ホーン部、４ ステップ変換部、１１ 第１プローブ、１２ 第３プローブ、１３ 第１誘電体板、１４ 金属ビス、１５ 第２反射板、１６ 反射板、２１ 第２プローブ、２２ 第４プローブ、２３ 第２誘電体板、２４ 金属ビス、２５ 第３反射板。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dual-frequency shared feed, and more particularly to a dual-frequency shared feed used for a parabolic antenna that transmits or receives signals in two frequency bands.
[0002]
[Prior art]
As a frequency band used for satellite broadcasting and satellite communication, a C band (3.4 to 4.2 GHz), a Ku band (10.7 to 14.5 GHz), and the like are often used. In the future, with an increase in communication speed and multimedia, the Ka band (17.7 to 21.2 GHz) suitable for high-speed and wideband communication is gradually used.
[0003]
Usually, parabola antennas are often used as antennas used to transmit or receive signals in these frequency bands. Parabolic antennas vary in size and electrical specifications of the primary radiator depending on the frequency band transmitted or received. The difference between these specifications is determined mainly by the difference in the wavelength of the signal used.
[0004]
On the other hand, as one of the effective uses of radio waves, there is a method of simultaneously using two orthogonal polarized waves. The two polarizations are a horizontal polarization and a vertical polarization if they are linearly polarized waves, and a right-handed circularly polarized wave and a left-handed circularly polarized wave if they are circularly polarized waves. Horizontally polarized waves and vertically polarized waves, or right-handed circularly polarized waves and left-handed circularly polarized waves are less likely to interfere with each other because their electric field directions are orthogonal to each other, and can be handled as completely different signals. Therefore, radio waves can be effectively used for a limited frequency band. Currently, two polarized antennas and low-noise block down converters are often used. For example, most domestic CS broadcast reception antennas and overseas satellite broadcast reception antennas share these two polarizations. This method is adopted.
[0005]
An antenna using two polarized waves in each of two frequency bands is described in JP-A-58-172002. FIG. 21 is a perspective view including a cross section of a primary radiator used in a conventional parabolic antenna. Referring to FIG. 21, the conventional primary radiator includes an electromagnetic horn unit 203, a circular waveguide 202 for a low frequency band, and a circular waveguide 201 for a high frequency band. The low frequency band circular waveguide 202 includes a horizontally polarized wave rectangular waveguide 221 and a vertically polarized wave rectangular waveguide 222 for feeding. The circular waveguide 201 for high frequency band includes a rectangular waveguide 212 for horizontal polarization and a rectangular waveguide 211 for vertical polarization for feeding. Further, the circular waveguide 201 for a high frequency band further includes circular hole mode filters 231, 232, and 233.
[0006]
The circular waveguide 201 for the high frequency band and the circular waveguide 202 for the low frequency band are determined in diameter so that the feeding section operates in the best state in each frequency band, The diameter of the circular waveguide 201 is smaller than the diameter of the circular waveguide 202 for the low frequency band. The difference in diameter is that a low frequency band signal is fed only by the low frequency band circular waveguide 202, and the high frequency band signal passes through the circular waveguide 202 and the circular waveguide 201. This is to make it happen. However, since the circular waveguide 202 for the low frequency band and the circular waveguide 201 for the high frequency band have different diameters, a step is generated at the joint portion, and a signal in the high frequency band has a characteristic at the step portion. Causes impedance mismatch. In order to match the characteristic impedance of the signal in the high frequency band in the stepped portion, circular mode filters 231, 232, and 233 are provided.
[0007]
This circular mode filter functions as a characteristic impedance matching unit for two waveguides for high frequency band and low frequency band, and as a reflection (short circuit) of the circular waveguide 202 for low frequency band. work.
[0008]
Here, the primary radiator includes an electromagnetic horn portion and a waveguide, and a portion obtained by removing the electromagnetic horn portion from the primary radiator is called a feed.
[0009]
[Problems to be solved by the invention]
However, in the conventional primary radiator, since the mode filters 231, 232, and 233 have a shape having a circular hole at the center thereof, the structure of the waveguide is complicated. For this reason, the waveguide cannot be manufactured with one mold, and it has to be manufactured by assembling several parts. Therefore, it is inferior in mass productivity and manufacturing cost becomes high.
[0010]
Further, since the rectangular waveguides 211, 212, 221, 222 to be fed are configured at positions perpendicular to the circular waveguides 201, 202, the shape of the primary radiator product itself is increased. There was a problem. In addition, the mold structure is complicated, the cost of the mold is increased, and it is difficult to manufacture the primary radiator.
[0011]
The present invention has been made to solve the above-mentioned problems, and can provide a dual-frequency shared feed that can be easily manufactured using a mold having a simple structure, is inexpensive, and has a small shape. Objective.
[0012]
[Means for Solving the Problems]
According to one aspect of the present invention to achieve the above-mentioned object, the dual-frequency shared feed is a dual-frequency shared feed used for transmitting or receiving signals in two frequency bands. A first waveguide, a second waveguide having a second inner diameter larger than the first inner diameter, and a second waveguide having a second inner diameter greater than the first inner diameter, provided between the first waveguide and the second waveguide. A step converter having a third inner diameter smaller than the inner diameter of the first waveguide, a first reflector provided at an end of the first waveguide opposite to the step converter, and a high frequency band provided in the first waveguide. A first probe fed with the first signal, a second probe provided in the second waveguide and fed with a second signal in a low frequency band, provided in the first waveguide, A third in a high frequency band disposed at a position separated from the first probe by a first length in the axial direction of one waveguide; A third probe No. is powered, is provided on the first reflector, in the axial direction of the first waveguide has a first length, a second reflector which is arranged parallel to the third probe And a fourth signal in a low frequency band, which is provided in the second waveguide and is arranged at a position separated from the second probe by a second length in the axial direction of the second waveguide. 4 probes, provided at the end of the second waveguide on the step conversion portion side, having a second length in the axial direction of the second waveguide, and facing the direction parallel to the fourth probe And the distance between the two third reflectors is the same as the diameter of the portion of the step converter that contacts the second waveguide, The first waveguide, the second waveguide, and the step conversion unit are arranged on the same axis.
[0015]
According to another aspect of the present invention, the dual-frequency shared feed is a dual-frequency shared feed used to transmit or receive signals in two frequency bands, and includes a first waveguide having a square cross section and a cross section. A second waveguide having a square shape larger than the cross section of the first waveguide, and provided between the first waveguide and the second waveguide, the cross section being larger than the cross section of the first waveguide and the second waveguide. A square step converter smaller than the cross section of the tube, a first reflector provided on the opposite end of the first waveguide to the step converter, and a first waveguide having a high frequency band provided on the first waveguide. A first probe fed with one signal, a second probe fed to the second waveguide and fed with a second signal in a low frequency band, and a first probe fed to the first waveguide. A third signal in a high frequency band arranged at a position separated from the first probe by a first length in the axial direction of the wave tube A third probe which is powered, is provided on the first reflector, in the axial direction of the first waveguide has a first length, a second reflector which is arranged parallel to the third probe And a fourth signal in a low frequency band, which is provided in the second waveguide and is arranged at a position separated from the second probe by a second length in the axial direction of the second waveguide. 4 probes, provided at the end of the second waveguide on the step conversion portion side, having a second length in the axial direction of the second waveguide, and facing the direction parallel to the fourth probe The distance between the two third reflectors is the same as the length of one side of the square section in the portion of the step converter that contacts the second waveguide, The first waveguide, the second waveguide, and the step conversion unit are arranged on the same axis.
[0018]
More preferably, the dual frequency shared feed includes a first circular polarization conversion unit provided at a predetermined position of the first waveguide and a second circular polarization conversion provided at a predetermined position of the second waveguide. And a section.
[0019]
More preferably, the dual frequency shared feed is characterized in that the first and second circular polarization converters are dielectric plates and are arranged on orthogonal planes.
[0020]
More preferably, the dual-frequency shared feed is characterized in that the first and second circular polarization converters are a plurality of metal screws.
[0021]
According to these inventions, the dual frequency shared feed can be easily manufactured using a mold having a simple structure, and can provide a dual frequency shared feed that is inexpensive and has a small shape.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The primary radiator according to the embodiment of the present invention will be described below. In the drawings, the same reference numerals denote the same or corresponding members.
[0023]
[First Embodiment]
FIG. 1 is a schematic diagram showing a parabolic antenna in which a primary radiator according to the present embodiment is used. Referring to FIG. 1, the parabolic antenna includes a reflecting mirror 103 having one focal point and a primary radiator 100. The primary radiator 100 includes an electromagnetic horn unit 3 and a dual frequency shared feed 101. The electromagnetic horn unit 3 of the primary radiator 100 is installed at the focal point of the reflecting mirror 103. For this reason, radio waves for satellite broadcasting or the like are reflected by a reflecting mirror and have the same path length in all paths until they are input to the primary radiator, and are input in the same phase.
[0024]
A low noise block down converter 102 is connected to the primary radiator 100. The signal received by the primary radiator 100 is amplified and frequency-converted by the low noise block down converter 102. When a parabolic antenna is used as a transmission antenna, a transmitter may be connected to the primary radiator 101 instead of the low noise block down converter 102. In this case, the output signal from the transmitter is output from the primary radiator and transmitted by being reflected by the reflecting mirror 103.
[0025]
Since the configuration of the primary radiator is the same when the parabolic antenna is used as the transmission antenna and when it is used as the reception antenna, the primary radiator when the parabolic antenna is used as the reception antenna will be described below.
[0026]
FIG. 2 is a perspective view of primary radiator 100 in the first embodiment. FIG. 3 is a cross-sectional view of the primary radiator 100. Referring to FIGS. 2 and 3, primary radiator 100 includes a reflector 16, a first waveguide 1 for a high frequency band, a step converter 4, and a second waveguide for a low frequency band. A tube 2 and an electromagnetic horn unit 3 are included. A dual frequency shared feed is configured by removing the electromagnetic horn unit 3 from the primary radiator 100.
[0027]
The first waveguide 1 is a hollow cylinder, and its inner diameter is determined by the cutoff frequency of the first waveguide. A reflecting plate 16 is attached to one end of the first waveguide 1, and a step converter 4 is attached to the other end. The second waveguide 2 for a low frequency band is connected to the other end of the step converter 4. The second waveguide 2 is a hollow cylinder, and its inner diameter is determined by the cutoff frequency.
[0028]
Here, the wavelength in the first waveguide of the radio wave (high frequency band) received by the first waveguide 1 is λ. ₁ And the wavelength in the second waveguide of the radio wave (low frequency band) received by the second waveguide 2 is λ ₂ And
[0029]
Λ from the reflector 16 of the first waveguide 1 ₁ A first probe 11 for receiving radio waves in a high frequency band is provided at a position separated by / 4. Λ from the step converter 4 of the second waveguide ₂ A second probe 21 for receiving radio waves in a low frequency band is provided at a position separated by / 4. This is because, in general, in order to effectively supply power from the waveguide to the probe, it is necessary to provide reflection at a distance of ¼ of the wavelength λ in the waveguide from the probe.
[0030]
The first probe 11 and the second probe 21 are arranged in directions orthogonal to each other.
[0031]
The step converter 4 is a matching device for matching the characteristic impedance of the first waveguide 1 and the characteristic impedance of the second waveguide 2. Since the inner diameters of the first waveguide 1 and the second waveguide 2 are different, there is a difference in their characteristic impedance. If the characteristic impedances of the two waveguides are not matched, the radio wave in the high frequency band is reflected at the step portion where the inner diameter changes. In the present embodiment, by providing the step converter 4 between the first waveguide 1 and the second waveguide 2, the characteristic impedance of the first waveguide and the characteristic impedance of the second waveguide. Align. Thereby, a signal in a high frequency band can enter the first waveguide without being reflected by the step converter 4.
[0032]
Here, the characteristic impedance Z of the circular waveguide is expressed by the following equation (1). The characteristic impedance of the first waveguide 1 is Z ₁ And the characteristic impedance of the second waveguide 2 is Z ₂ The characteristic impedance Z of the step converter 4 ₀ Is represented by the following equation (2).
[0033]
[Expression 1]

[0034]
At this time, the characteristic impedance Z of the step converter 4 ₀ The wavelength λ in the step converter 4 derived from _Three From this, the axial length L of the step converter 4 is determined. The length L is preferably λ _Three / 4.
[0035]
The first waveguide 1, the second waveguide 2, and the step converter 4 are connected such that their axes pass through the same straight line.
[0036]
Next, reception of radio waves by primary radiator 100 will be described. High frequency band signal (wavelength λ ₁ ) Enters the electromagnetic horn unit 3, passes through the second waveguide 2, and enters the step converter 4. Since the step converter 4 matches the characteristic impedances of the first waveguide 1 and the second waveguide 2, a signal in a high frequency band is not reflected by the step converter 4 and is sent to the first waveguide 1. enter in. The signal that has entered the first waveguide 1 is fed to the first probe 11.
[0037]
Low frequency band signal (wavelength λ ₂ ) Enters the electromagnetic horn unit 3 and passes through the second waveguide to be fed to the second probe 21. At this time, since the inner diameter of the step converter 4 is smaller than the inner diameter of the second waveguide 2, it is cut off for a low frequency band. For this reason, the signal in the low frequency band is reflected without passing through the step converter 4.
[0038]
The signal fed to the first probe 11 is supplied to a low noise block converter for a high frequency band. The signal fed to the second probe 21 is supplied to a low noise block down converter for a low frequency band.
[0039]
As described above, the primary radiator 100 according to the first embodiment can transmit or receive linearly polarized waves of two different frequency bands.
[0040]
In the primary radiator 100 according to the present embodiment, the characteristic impedance of the first waveguide 1 is between the first waveguide 1 for the high frequency band and the second conduit 2 for the low frequency band. And a step converter 4 for matching the characteristic impedance of the second waveguide 2 with each other. As a result, a signal in a low frequency band is favorably fed by the second probe 21, and a signal in a high frequency band is favorably fed to the first probe 11.
[0041]
Furthermore, since the step converter 4 has a cylindrical shape, the length in the axial direction of the step converter 4 can be set to a quarter of the wavelength in the waveguide. For this reason, the axial length of the primary radiator 100 can be made as short as possible.
[0042]
In addition, since the first waveguide 1, the step converter 4 and the second waveguide 2 are each cylindrical, a simple configuration can be achieved. Furthermore, since the configuration is simple, a mold for manufacturing a dual frequency shared feed can be easily manufactured, and the cost of the mold can be reduced. Furthermore, since the configuration of the dual frequency shared feed is simplified, it can be easily manufactured and the manufacturing cost can be reduced.
[0043]
In the primary radiator in the first embodiment, the first probe 11 and the second probe 21 are arranged in directions orthogonal to each other because this is arranged in accordance with the polarized wave to be received or transmitted. . Usually, different polarizations are used so that the isolation between the low and high frequency band signals is as high as possible. Therefore, the direction of the probe is determined according to the polarization to be received or transmitted. For this reason, the direction of two probes does not necessarily need to be perpendicular, and may be parallel.
[0044]
[Second Embodiment]
Next, a primary radiator according to the second embodiment will be described. FIG. 4 is a perspective view of primary radiator 110 in the second embodiment. Referring to FIG. 4, primary radiator 110 includes first dielectric plate 13 as a first circular polarization converter in first waveguide 1 of primary radiator 100 according to the first embodiment. The second dielectric plate 23 is provided in the second waveguide 2 as a second circular polarization converter. Since other configurations are the same as those of primary radiator 100 in the first embodiment, description thereof will not be repeated here.
[0045]
The primary radiator 100 in the first embodiment is used to receive or transmit linearly polarized waves, whereas the primary radiator 110 in the second embodiment receives or transmits circularly polarized waves. Used to do.
[0046]
FIG. 5 is a front view of primary radiator 110 in the second embodiment. Referring to FIG. 5, the first dielectric plate 13 is provided in the first waveguide 1 and has an angle of 45 ° with respect to the first probe 11 between the first probe 11 and the step converter 4. It is arranged with. The second dielectric plate 23 is provided in the second waveguide 2 and is disposed at an angle of 45 ° with respect to the second probe 21 between the second probe 21 and the electromagnetic horn unit 3. The first dielectric plate 13 and the second dielectric plate 23 have a predetermined shape and function to delay the phase of the electric field in the direction parallel to the dielectric plates 13 and 23.
[0047]
FIG. 6 is a front view of the second waveguide 2 according to the second embodiment. The circularly polarized wave will be described with reference to FIG. The circularly polarized wave is an electric field E that is a vector composition of two linearly polarized waves E1 and E2 that are orthogonal to each other. A circularly polarized wave is obtained when the phases of the two linearly polarized waves E1 and E2 are shifted by 90 ° from each other. On the other hand, when the phases of two orthogonally polarized waves E1 and E2 that are orthogonal to each other are in phase, they are linearly polarized waves. As described above, the circularly polarized wave can be converted into the linearly polarized wave by changing the phase of the two orthogonally polarized waves E1 and E2 from being in the same phase from 90 °. On the other hand, by making the state shifted by 90 ° from the in-phase state, the linearly polarized wave can be converted into the circularly polarized wave.
[0048]
Radio waves that can be received by the probes 11 and 21 are limited to linearly polarized waves. Therefore, when the primary radiator is used as a receiving antenna, it is necessary to convert circularly polarized waves into linearly polarized waves. The first dielectric plate 13 and the second dielectric plate 23 are used for this purpose.
[0049]
Referring to FIG. 5, the first dielectric plate 13 and the second dielectric plate 23 are arranged in directions orthogonal to each other. This is due to the following reason. In other words, the circularly polarized signal in the low frequency band enters the electromagnetic horn unit 3 and passes through the second dielectric plate 23 of the second waveguide 2. At this time, when the phase of the linearly polarized wave in the direction parallel to the second dielectric plate 23 is shifted by 90 °, the circularly polarized signal in the low frequency band is converted into the linearly polarized signal. The converted linearly polarized wave is supplied to the second probe 21. On the other hand, the circularly polarized signal in the high frequency band enters the electromagnetic horn unit 3 and passes through the second dielectric plate 23 of the second waveguide 2 in the same manner as the circularly polarized signal in the low frequency band. At this time, the phase of the linearly polarized wave in the direction parallel to the second dielectric plate 23 is delayed. Since the second dielectric plate 23 is designed for a circularly polarized signal in a low frequency band, the phase delay amount is not 90 ° for a circularly polarized signal in a high frequency band. The amount of delay exceeds 90 °. For this reason, a circularly polarized signal in a high frequency band is not converted into a completely linearly polarized wave.
[0050]
For example, when the high frequency band is about 20 GHz and the low frequency band is about 12 GHz, the dielectric plate (circular polarization converter) for converting the circularly polarized signal in the low frequency band into a linearly polarized wave has a high frequency. When the circularly polarized signal of the band is passed, the amount of phase delay becomes about 120 °. FIG. 7 is a diagram showing a phase delay when a signal in a low frequency band is passed through a dielectric plate designed for a low frequency band (about 12 GHz). FIG. 8 is a diagram showing a phase delay amount when a signal in a high frequency band (20 GHz) is passed through a dielectric plate designed for a low frequency band (about 12 GHz). As is apparent from FIGS. 7 and 8, the phase delay amount is about 90 ° in the signal in the low frequency band (about 12 GHz), whereas the phase delay amount is in the signal in the high frequency band (about 20 GHz). It is about 120 °.
[0051]
Therefore, the first dielectric plate 13 of the first waveguide 1 is arranged in a direction orthogonal to the second dielectric plate 23. That is, the phase of the linearly polarized wave in the direction orthogonal to the second dielectric plate 23 is delayed by 30 ° with the first dielectric plate 13 to correct the phase that is too late, and the phase delay amount is returned to 90 ° (orthogonal). Two linear polarizations are in phase). As a result, a circularly polarized signal in a high frequency band (about 20 GHz) is converted into a linearly polarized wave. Then, the converted linearly polarized wave is fed to the first probe 11 of the first waveguide 1.
[0052]
As described above, primary radiator 110 in the second embodiment receives a signal transmitted in circular polarization in addition to the effect of primary radiator 100 in the first embodiment. Can do.
[0053]
Further, since the first dielectric plate 13 is arranged in a direction orthogonal to the second dielectric plate 23, the phase delayed too much by the second dielectric plate 23 can be corrected by the first dielectric plate 13, A circularly polarized wave in a high frequency band can be converted into a linearly polarized wave. As a result, a circularly polarized signal in a high frequency band can be fed to the first probe 11.
[0054]
In the present embodiment, the first dielectric plate 13 and the second dielectric plate 23 are arranged in the orthogonal direction, but may be arranged in parallel. In this case, the phase delayed too much by the second dielectric plate 23 may be further delayed by the first dielectric plate 13 so that two orthogonal linearly polarized waves are in phase. However, in this case, since the first dielectric plate 13 becomes large, there is a demerit that the primary converter 110 becomes large.
[0055]
[Third Embodiment]
The primary radiator 120 in the third embodiment includes a plurality of metal screws as a circular polarization converter in the primary radiator 100 in the first embodiment, and the first waveguide 1 and the second waveguide. The pipes 2 are provided respectively. The primary radiator in the first embodiment is used to receive linearly polarized waves, whereas the primary radiator 120 in the third embodiment is used to receive circularly polarized waves. .
[0056]
FIG. 9 is a perspective view of primary radiator 120 according to the third embodiment. Referring to FIG. 9, the primary radiator 120 in the third embodiment includes a plurality of metal screws 14 in the primary waveguide 1 between the first probe 11 and the step converter 4. The first probe 11 is arranged at an angle of 45 °. In the second waveguide 2, a plurality of metal screws 24 are arranged at an angle of 45 ° with respect to the second probe 21 between the second probe 21 and the electromagnetic horn portion 3. The plurality of metal screws 14 provided in the first waveguide 1 and the plurality of metal screws 24 provided in the second waveguide 2 are all arranged in the same direction.
[0057]
The plurality of metal screws 14 provided in the first waveguide 1 and the plurality of metal screws 24 provided in the second waveguide function as a circular polarization converter. Since the configuration other than the plurality of metal screws 14 and 24 as the circularly polarized wave converter is the same as the primary radiator in the first embodiment, the description thereof will not be repeated here.
[0058]
In primary radiator 110 in the second embodiment, dielectric plates 13 and 23 are used as circular polarization converters. In the primary radiator according to the third embodiment, a plurality of metal screws 14 and 24 are used as circular polarization converters. The plurality of metal screws 14 and 24 are arranged in a direction parallel to the plurality of metal screw rows of two orthogonal linearly polarized waves, like the dielectric plates 13 and 23 in the second embodiment. It works to delay the phase of linear polarization by 90 °.
[0059]
Therefore, similarly to the dielectric plates 13 and 23, the circularly polarized wave can be converted into a linearly polarized wave, or the linearly polarized wave can be converted into a circularly polarized wave. However, although the plurality of metal screws 24 in the second waveguide 2 can delay the phase of the linearly polarized wave in the low frequency band by 90 °, the plurality of metal screws 24 designed for this low frequency band. The linearly polarized wave in the high frequency band passing through 24 has a phase delay amount smaller than 90 °.
[0060]
For example, the high frequency band is about 20 GHz and the low frequency band is about 12 GHz. When a signal in a high frequency band (about 20 GHz) is passed through a plurality of metal screws 24 designed to convert a circularly polarized wave in a low frequency band into a linearly polarized wave, the amount of phase delay in the high frequency band is reduced to about 50 °.
[0061]
FIG. 10 is a diagram showing the amount of phase delay when a signal in a low frequency band is passed through a row of metal screws designed for a low frequency band (about 12 GHz). FIG. 11 is a diagram showing the amount of phase delay when a signal in a high frequency band is passed through a row of metal screws designed for a low frequency band (12 GHz). As is apparent from the measurement data shown in FIGS. 10 and 11, the phase delay amount is about 90 ° in the signal in the low frequency band (about 12 GHz), whereas the phase is in the signal in the high frequency band (about 20 GHz). The amount of delay is as small as about 50 °.
[0062]
For this reason, by arranging the plurality of metal screws 14 of the first waveguide 1 in the same direction as the plurality of metal screws 24 of the second waveguide 2, the phase delay amount is further increased to 90 °. To do. That is, by setting the phase delay amount to 90 °, two orthogonal linearly polarized waves are made in phase. As a result, a circularly polarized signal in a high frequency band is converted into a linearly polarized signal. Then, the converted linearly polarized signal is fed to the first probe 11 of the first waveguide 1.
[0063]
Note that a circularly polarized wave converter composed of a plurality of metal screws 14 and 24 needs to adjust the amount of insertion into the waveguide for each metal screw. A circularly polarized wave converter adjusted to an optimum state can be a circularly polarized wave converter having a good degree of polarization conversion and very low reflection loss.
[0064]
As described above, in the primary radiator 120 according to the third embodiment, a plurality of metal screws are used as the circular polarization converter. For this reason, in addition to the effect of the primary radiator 100 in the first embodiment, a circularly polarized signal can be received. In addition, it is possible to convert circularly polarized waves into linearly polarized waves and reduce reflection loss.
[0065]
[Fourth Embodiment]
FIG. 12 is a perspective view of primary radiator 130 in the fourth embodiment. FIG. 13 is a cross-sectional view of primary radiator 130. The primary radiator 130 according to the fourth embodiment includes the reflector 16, the first waveguide 1, the step conversion unit 4, the second waveguide 2, and the electromagnetic horn unit 3 according to the first embodiment. Since this is the same as primary radiator 100 in FIG. 4, description thereof will not be repeated.
[0066]
Here, the wavelength of the signal in the high frequency band received by the primary radiator in the fourth embodiment is λ. ₁ And the wavelength of the low frequency band signal received by the second waveguide 2 is λ ₂ And
[0067]
The reflecting plate 16 is provided with a rectangular parallelepiped second reflecting plate 15 in the cross-sectional radial direction of the first waveguide 1. The first probe 11 is separated from the second reflector 15 by λ ₁ It is provided at a position separated by a distance of / 4. The third probe 12 is separated from the reflector 16 by λ ₁ It is provided at a position separated by a distance of / 4. The first probe 11 and the second reflector 15 are parallel.
[0068]
A rectangular parallelepiped third reflector 25 is provided at the connection portion of the second waveguide 2 with the step converter 4. Two third reflectors 25 are provided opposite to each other in the radial direction of the second waveguide 2, and the distance between the two third reflectors 25 is the same as the inner diameter of the step converter 4. The second probe 21 receives λ from the step converter 4. ₂ It is provided at a position separated by a distance of / 4. The fourth probe 22 is separated from the third reflector 25 by λ ₂ It is provided at a position separated by a distance of / 4.
[0069]
The primary radiator 130 in the fourth embodiment is provided with the first probe 11 and the third probe 12 in the first waveguide 1 in directions orthogonal to each other, and the second probe 21 in the second waveguide 2. And the fourth probe 22 are arranged in directions orthogonal to each other. Accordingly, the two orthogonally polarized waves in the high frequency band which are orthogonal can be received by the first probe 11 and the third probe 12, and the two orthogonally polarized waves in the low frequency band which are orthogonal to the second probe 21. It can be received by the fourth probe 22.
[0070]
The reason why the first probe 11 and the third probe 12 or the second probe 21 and the fourth probe 22 are shifted from each other in the axial direction of the waveguide is as follows. When the first probe 11 and the third probe 12 are installed at the same position in the axial direction of the waveguide 1, the first probe and the third probe interfere with each other, thereby isolating two linearly polarized waves, that is, cross polarization. This is because the wave characteristics deteriorate. The second probe 21 and the fourth probe 22 of the second waveguide are also displaced in the axial direction for the same reason.
[0071]
On the other hand, it is necessary to provide the probe at a position away from the reflecting portion by a distance of a quarter of the wavelength of the signal in the frequency band to be received. Therefore, the first waveguide 1 is provided with the second reflecting portion 15 on the reflecting portion 16 to serve as the reflecting portion of the first probe 11. As a result, the distance between the first probe 11 and the second reflector 15 is λ. ₁ / 4. On the other hand, the distance between the third probe 12 and the reflecting portion 16 is λ. ₁ / 4 is maintained.
[0072]
In the second waveguide 2, two third reflecting portions 25 are provided so as to face each other in a direction parallel to the fourth probe 22. The reflecting portion of the fourth probe 22 is the third reflecting plate 25, and the distance between the fourth probe 22 and the third reflecting plate 25 is λ. ₂ / 4. On the other hand, the reflection part of the second probe 21 becomes the step conversion part 4, and the distance between the step conversion part 4 and the second probe 21 is λ. ₂ / 4 is maintained.
[0073]
As described above, the primary radiator 130 in the fourth embodiment is provided with the first probe 11 and the third probe 12 orthogonal to the first waveguide 1 and orthogonal to the second waveguide 2. Since the second probe 21 and the fourth probe 22 are provided, in addition to the effect of the primary radiator 100 in the first embodiment, two orthogonal linear polarizations of high frequency and two orthogonals of low frequency are provided. Can be received.
[0074]
Further, in the first waveguide 1, since the first probe 11 and the second probe 12 are displaced in the axial direction of the first waveguide 1 by providing the second reflector 15, the first probe 11. The cross polarization characteristics of two linearly polarized waves in a high frequency band can be improved without interfering with the third probe 12. Similarly, by providing the third reflector 25 in the second waveguide 2, the second probe 21 and the fourth probe 22 are displaced in the axial direction of the second waveguide 2, so that the low frequency The cross polarization characteristics of the two linearly polarized bands can be improved.
[0075]
[Fifth Embodiment]
The primary radiator in the fifth embodiment is used to receive circularly polarized waves, whereas the primary radiator in the fourth embodiment is used to receive linearly polarized waves. Next radiator.
[0076]
FIG. 14 is a perspective view of primary radiator 140 in the fifth embodiment. FIG. 15 is a front view of the second waveguide 2 of the primary radiator 140. FIG. 16 is a front view of the first waveguide 1 of the primary radiator 140. Referring to FIG. 14, FIG. 15 and FIG. 16, primary radiator 140 includes a first dielectric as a circularly polarized wave conversion section in first waveguide 1 of primary radiator 2 in the fourth embodiment. The body plate 13 is provided, and the second dielectric plate 23 is provided in the second waveguide 2 as a circular polarization conversion unit. Since the configuration excluding dielectric plates 13 and 23 is the same as that of primary radiator 130 in the fourth embodiment, description thereof will not be repeated here. The second dielectric plate 23 provided in the second waveguide 2 and the first dielectric plate 13 provided in the first waveguide 1 are arranged in directions orthogonal to each other. Since the functions of the first dielectric plate 13 and the second dielectric plate 23 are the same as the functions of the first dielectric plate 13 and the second dielectric plate 23 described in the second embodiment, here The explanation in is not repeated.
[0077]
As described above, the primary radiator 140 in the fifth embodiment is provided with the first dielectric plate 13 in the first waveguide 1 and the second dielectric plate 23 in the second waveguide 2. Therefore, in addition to the effect of the primary radiator 130 in the fourth embodiment, it is possible to convert the circularly polarized wave in the low frequency band into the linearly polarized wave, and convert the circularly polarized wave in the high frequency band into the linearly polarized wave. Can be converted.
[0078]
[Sixth Embodiment]
FIG. 17 is a perspective view of primary radiator 150 in the sixth embodiment. The primary radiator 150 according to the sixth embodiment includes a plurality of metal screws 14 each of the first dielectric plate 13 and the second dielectric plate 23 of the primary radiator 140 according to the fifth embodiment. And a plurality of metal screws 24. Since other configurations are similar to those of primary radiator 140 in the fifth embodiment, description thereof will not be repeated here. According to the primary radiator 150 in the sixth embodiment, since the plurality of metal screws 14 are provided in the first waveguide 1 and the plurality of metal screws 24 are provided in the second waveguide 2, In addition to the effect of the primary radiator 130 in the fourth embodiment, the circularly polarized wave in the high frequency band can be converted into the linearly polarized wave, and the circularly polarized wave in the low frequency band can be converted into the linearly polarized wave. I can do it. Further, since the metal screws 14 and 24 are used when converting the circularly polarized wave into the linearly polarized wave, the circularly polarized wave can be favorably converted into the linearly polarized wave. can do.
[0079]
[Seventh Embodiment]
FIG. 18 is a side view of primary radiator 160 in the seventh embodiment. FIG. 19 is a front view of the second waveguide 2 </ b> A of the primary radiator 160. FIG. 20 is a front view of the first waveguide 1 </ b> A of the primary radiator 160. 18, 19, and 20, primary radiator 160 includes first waveguide 1 </ b> A having a square cross-sectional shape, step converter 4 </ b> A having a square cross-sectional shape, and a first cross section having a square cross-sectional shape. 2A and 2A, and an electromagnetic horn portion 3A connected to the second waveguide 2A.
[0080]
The length a of the side of the square formed by the inner wall of the cross section of the second waveguide 2A ₂ Is determined by the cutoff frequency of the second waveguide 2A. Similarly, in the cross section of the first waveguide 1, the length a of one side of the square constituted by the inner wall ₁ Is determined by the cutoff frequency of the first waveguide 1A. The length of one side a of the square formed by the inner wall of the cross section of the step converter 4A _Three Is the characteristic impedance Z of the first waveguide 1A ₁ And the characteristic impedance Z of the second waveguide 2A ₂ The characteristic impedance Z of the step converter 4A obtained from ₀ It is determined based on. Characteristic impedance Z ₀ Is the characteristic impedance Z ₁ And characteristic impedance Z ₂ Is set to a value that matches. The length in the axial direction of the step converter 4A is the wavelength λ in the step converter 4A. _Three And preferably λ _Three / 4.
[0081]
Thus, by determining the sizes of the first waveguide 1A, the step converter 4A, and the second waveguide 2A, the characteristic impedance of the first waveguide 1A and the characteristic impedance of the second waveguide 2A are determined. And are consistent. As a result, a signal in a high frequency band can enter the first waveguide 1A without being reflected by the step converter 4A.
[0082]
A first probe 11A and a third probe 12A provided in directions orthogonal to each other are arranged in the first waveguide 1A. A reflecting plate 16A is provided at the end of the first waveguide 1A opposite to the step converter 4A. Furthermore, a rectangular parallelepiped second reflecting plate 15A is provided on the reflecting plate 16A in parallel with the first probe 11A.
[0083]
Here, the wavelength of the signal in the high frequency band to be received by the first waveguide 1 is λ ₁ And the wavelength of the low frequency band signal received by the second waveguide 2A is λ ₂ And
[0084]
The first probe 11A is λ in the axial direction of the first waveguide 1A from the second reflector 15A. ₁ It is provided at a position separated by a distance of / 4. The third probe 12A is λ in the axial direction of the first waveguide 1A from the reflector 16A. ₁ It is provided at a position separated by a distance of / 4. Therefore, the first probe 11 </ b> A and the second probe 12 </ b> A are arranged so as to be shifted in the axial direction of the first waveguide 1. As a result, the cross polarization characteristics of the two linearly polarized waves are improved without the first probe 11A and the third probe 12A interfering with each other.
[0085]
In the first waveguide 1A, a first dielectric plate 13A is provided between the first probe 11A and the step converter 4A. Referring to FIG. 20, first dielectric plate 13A is arranged at an angle of 45 ° with each of first probe 11A and third probe 12A.
[0086]
The second waveguide 2A includes a second probe 21A and a fourth probe 22A that are orthogonal to each other. Two rectangular parallelepiped third reflecting plates 25A are provided on the step converter 4A side of the second waveguide 2A so as to face each other in a direction parallel to the fourth probe 22A. The distance between the two third reflectors 25A is the length a of one side of the square formed by the inner wall of the step converter 4A. _Three Is the same. The second probe 21A extends from the step converter 4A to the second waveguide 2A in the axial direction λ ₂ / 4. The fourth probe 22A is λ in the axial direction of the second waveguide 2A from the third reflector 25A. ₂ It is arranged at a position separated by a distance of / 4. Therefore, the second probe 22A and the fourth probe 22A are arranged at different positions in the axial direction of the second waveguide 2A. As a result, the second probe 21A and the fourth probe 22A do not interfere with each other, and the cross polarization characteristics of the two linearly polarized waves are improved.
[0087]
The second waveguide 2A further includes a second dielectric plate 23A between the fourth probe 22A and the electromagnetic horn unit 3. The second dielectric plate 23A is disposed with an inclination of 45 ° with respect to the second probe 21A and the fourth probe 22A. The second dielectric plate 23A is disposed in a direction orthogonal to the first dielectric plate 13A. This is the same as the relationship between the first dielectric plate 13 and the second dielectric plate 23 described in the second embodiment. As described in the second embodiment, the first dielectric plate 13A and the second dielectric plate 23A may be arranged in parallel.
[0088]
As described above, the primary radiator 160 in the seventh embodiment has a simple shape because the first waveguide 1A, the step converter 4A, and the second waveguide 2A have square internal cross-sectional shapes. can do. Further, since the shape is simple, it is easy to manufacture a mold for manufacturing the primary radiator 160, and the primary radiator 160 itself can be easily manufactured, and the manufacturing cost can be reduced. .
[0089]
In addition, since the step converter 4A for matching the characteristic impedance of each waveguide is provided between the first waveguide 1A and the second waveguide 2A, a step converter converts a signal in a high frequency band. The light can enter the first waveguide 1A without being reflected by A4.
[0090]
Further, since the length in the axial direction of the step converter 4A is set to ¼ of the in-waveguide wavelength λ, the primary radiator can be reduced in size.
[0091]
In addition, since the cross-sectional shapes of the first waveguide 1A and the second waveguide 2A are square, the wavelengths of two different linearly polarized waves can be made the same, and the probe can be fed well. .
[0092]
Further, in the first waveguide 1A, by providing the second reflecting plate 15A on the reflecting plate 16A, the first probe 11A and the third probe 12A are shifted in the axial direction of the first waveguide 1A. Therefore, the cross polarization characteristics of the two linearly polarized waves can be improved without the first probe 11A and the third probe 12A interfering with each other.
[0093]
Similarly, in the second waveguide 2, two third reflectors 25A are provided at the end on the step conversion unit 4 side so as to oppose the direction of the fourth probe 22A. Therefore, the second probe 21A and the fourth probe 22A are provided. The position of the second waveguide 2 in the axial direction can be shifted. Thereby, the cross polarization characteristics of two linearly polarized waves can be improved without the second probe 21A and the fourth probe 22A interfering with each other.
[0094]
Further, since the dielectric plate 23A is provided in the second waveguide 2A and the dielectric plate 13A is provided in the first waveguide 1A, the second probe is converted into a circularly polarized wave in a low frequency band and converted into a linearly polarized wave. It can be received by 21A and the fourth probe 22A, and a circularly polarized wave in a high frequency band can be converted into a linearly polarized wave and fed to the first probe 11A and the third probe 12A.
[0095]
Needless to say, the first dielectric plate 13A and the second dielectric plate 23A can be replaced with a plurality of metal screws.
[0096]
Needless to say, the primary radiator shown in the first to fourth embodiments can be a primary radiator whose cross-sectional shape is not a circle but a square.
[0097]
Further, the primary radiators 100, 110, 120, 130, 140, 150, and 160 in the first to seventh embodiments have one step converter 4A, but a plurality of step converters are provided. You may do it. In this case, the primary radiator becomes larger by the increased step converter, but there is an advantage that reflection can be reduced.
[0098]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a parabolic antenna in which a primary radiator 100 according to a first embodiment is used.
FIG. 2 is a perspective view of primary radiator 100 in the first embodiment.
FIG. 3 is a cross-sectional view of primary radiator 100 according to the first embodiment.
FIG. 4 is a perspective view of primary radiator 110 in the second embodiment.
FIG. 5 is a front view of a primary radiator 110 in the second embodiment.
FIG. 6 is a front view of a second waveguide 2 in the second embodiment.
FIG. 7 is a diagram showing the amount of phase delay when a low frequency band signal is passed through a dielectric plate designed for a low frequency band (about 12 GHz).
FIG. 8 is a diagram showing a phase delay amount when a signal in a high frequency band (about 20 GHz) is passed through a dielectric plate designed for a low frequency band (about 12 GHz).
FIG. 9 is a perspective view of a primary radiator 120 in a third embodiment.
FIG. 10 is a diagram showing a phase delay amount when a signal in a low frequency band is passed through a row of metal screws designed for a low frequency band (about 12 GHz).
FIG. 11 is a diagram showing a phase delay amount when a signal in a high frequency band (about 20 GHz) is passed through a plurality of metal screw rows designed for a low frequency band (about 12 GHz).
FIG. 12 is a perspective view of a primary radiator 130 in the fourth embodiment.
FIG. 13 is a cross-sectional view of a primary radiator 130 in the fourth embodiment.
FIG. 14 is a perspective view of a primary radiator 140 according to a fifth embodiment.
15 is a front view of the second waveguide 2 of the primary radiator 140. FIG.
16 is a front view of the first waveguide 1 of the primary radiator 140. FIG.
FIG. 17 is a perspective view of a primary radiator 150 according to a sixth embodiment.
FIG. 18 is a side view of a primary radiator 160 in a seventh embodiment.
FIG. 19 is a front view of the second waveguide 2A of the primary radiator 160 in the seventh embodiment.
FIG. 20 is a front view of a first waveguide 1A of a primary radiator 160 according to a seventh embodiment.
FIG. 21 is a perspective view including a transverse section of a primary radiator used in a conventional parabolic antenna.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st waveguide, 2nd waveguide, 3 Electromagnetic horn part, 4 step conversion part, 11 1st probe, 12 3rd probe, 13 1st dielectric plate, 14 Metal screw, 15 2nd reflecting plate , 16 reflector, 21 second probe, 22 fourth probe, 23 second dielectric plate, 24 metal screw, 25 third reflector.

Claims (5)

A dual frequency shared feed used to transmit or receive signals in two frequency bands,
A first waveguide having a first inner diameter;
A second waveguide having a second inner diameter greater than the first inner diameter;
A step converter having a third inner diameter provided between the first waveguide and the second waveguide and having a third inner diameter larger than the first inner diameter and smaller than the second inner diameter;
A first reflector provided at an end of the first waveguide opposite to the step converter;
A first probe provided in the first waveguide and fed with a first signal in a high frequency band;
A second probe provided in the second waveguide and fed with a second signal in a low frequency band;
A third signal of a high frequency band provided in the first waveguide and disposed at a position separated from the first probe by a first length in the axial direction of the first waveguide is fed. A third probe;
A second reflector provided on the first reflector, having the first length in the axial direction of the first waveguide, and disposed in parallel with the third probe ;
A fourth signal in a low frequency band provided in the second waveguide and disposed at a position separated from the second probe by a second length in the axial direction of the second waveguide is fed. A fourth probe;
Provided at an end of the second waveguide on the step conversion unit side, has the second length in the axial direction of the second waveguide, and faces in a direction parallel to the fourth probe. Two arranged third reflectors,
The distance between the two third reflectors is the same as the diameter of the portion of the step converter that contacts the second waveguide;
The dual-frequency shared feed, wherein the first waveguide, the second waveguide, and the step converter are arranged coaxially. A dual frequency shared feed used to transmit or receive signals in two frequency bands,
A first waveguide having a square cross section;
A second waveguide having a square cross section larger than that of the first waveguide;
A step converter having a square shape provided between the first waveguide and the second waveguide and having a cross section larger than that of the first waveguide and smaller than that of the second waveguide;
A first reflector provided at an end of the first waveguide opposite to the step converter;
A first probe provided in the first waveguide and fed with a first signal in a high frequency band;
A second probe provided in the second waveguide and fed with a second signal in a low frequency band;
A third signal of a high frequency band provided in the first waveguide and disposed at a position separated from the first probe by a first length in the axial direction of the first waveguide is fed. A third probe;
A second reflector provided on the first reflector, having the first length in the axial direction of the first waveguide, and disposed in parallel with the third probe ;
A fourth signal of a low frequency band provided in the second waveguide and disposed at a position separated from the second probe by a second length in the axial direction of the second waveguide is fed. A fourth probe;
Provided at an end of the second waveguide on the step conversion unit side, has the second length in the axial direction of the second waveguide, and faces in a direction parallel to the fourth probe. Two arranged third reflectors,
The distance between the two third reflectors is the same as the length of one side of the square section in the portion of the step converter that contacts the second waveguide,
The dual-frequency shared feed, wherein the first waveguide, the second waveguide, and the step converter are arranged coaxially. A first circular polarization converter provided at a predetermined position of the first waveguide;
The dual-frequency shared feed according to claim 1 or 2 , further comprising a second circular polarization converter provided at a predetermined position of the second waveguide. 4. The dual frequency shared feed according to claim 3 , wherein the first and second circularly polarized wave conversion units are dielectric plates and are disposed on orthogonal planes. 5. The dual-frequency shared feed according to claim 3 , wherein the first and second circularly polarized wave conversion units are a plurality of metal screws.

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