本稿では，L形プローブと導波管構造を組み合わせた広帯域円偏波アンテナの交差偏波低減を検討した.導波管内に発生する高次モードの影響を受けて，高次モードのカットオフ周波数以降の高周波帯で円偏波特性が劣化する.高域における円偏波特性を改善するため，導波管の短絡壁を曲面とし，高周波帯における交差偏波の低減効果について検討したので報告する.短絡壁を楕円形にすることで，高周波帯において交差偏波が5dBから10dB程度低減した.%Reduction of cross polarization at higher frequencies is performed for a circularly polarized broadband antenna using a waveguide and an L-shaped feed probe. Cross polarization was enhanced at higher frequencies beyond cutoff frequency of first higher order mode in previously proposed structures by the authors. To reduce the cross polarization, the surface of short wall of the waveguide is modified to be curved. As a result, cross polarization is reduced by 5 dB to 10dB by the short wall with an ellipse-shaped surface.
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