伝送線路理論に基づき、周波数変換とチェビシェフ型フィルタの合成理論とを組み合わせることにより、超広帯域フィルタの合成新手法を構築し、提案した．本稿では、まず、周波数変換を具体的に定式化し、先端短絡直列スタブ、先端開放並列スタブ、単位素子などの基本回路素子の回路変換を示した．次に、新提案のフィルタの合成手法を具体的な設計例（比帯域幅が67％である広帯域フィルタ）により、詳細に説明した．更に、回路シミュレータ及びEMシミュレータを用い、設計したフィルタをマイクロストリップ線によって構成し、最適化後に、実際に作製し、測定した．シミュレーション結果とネットワークアナライザによる測定結果はよく一敦していることより、合成理論の妥当性及び有効性が確認された．%A novel methodology is proposed for the design of ultra-wideband filters by the combination of the transmission-line-theory-based frequency-mapping-technique to a recently-proposed Chebyshev-filter-based synthesis technique. Firstly, the frequency-mapping-technique is mathematically formulated and applied to the basic distributed transmission lines elements — short-circuited shunt stubs, open-circuited series stubs and unit elements. Then, the detailed procedure of the filter synthesis is described and demonstrated by designing an example filter with an FBW of 67%. For confirmation, a circuit simulator is used to model the synthesized filter in microstrip line. Then the filter is optimized by an EM simulator, practically fabricated and then characterized by network analyzer. The measurement results are compared with the simulation ones and the theoretical ones. Very good agreements are found and the correctness and effectiveness of the proposed technique are validated accordingly.
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