センチ波・ミリ波帯プリント線路帯域フィルタの構成法に関する考察

摘要

プリント伝送線路は安価・量産性を特徴とするが、導体の表皮効果の影響で、使用周波数がセンチ波帯からミリ波帯と高周波化するほど、その伝送損失は増加し、このような特性劣化は、帯域通過フィルタ等の共振器を利用した回路素子で顕著になる。そこで本論では特性の劣イヒ度合いを調べるため、高域フィルタと低域フィルタの縦続接続で構成されたマイクロストリップ線路帯域フィルタと、分布結合形マイクロストリップ伝送線路帯域フィルタを設計し、それらの散乱行列を計算することにより、両帯域フィルタの性能比較を行った。その結果、3GHzのセンチ波帯であっても、後者の帯域フィルタの挿入損失は大きく、前者の帯域フィルタにおける優位性が確認できた。%Although printed transmission lines have good advantages such as cost-effective and mass-productive natures, they usually suffer from considerable dissipation losses due to the skin effect in metal foils at centimeter and millimeter wave regions. In particular, the transmission performance drastically degrades using resonator circuits such as bandpass filters. To investigate the degradation of the transmission performance, two types of bandpass filters which were made by a low-pass filter connected with a high-pass filter and were made by coupled transmission lines were designed based on the microstrip line. In the calculated results, it was obvious that the latter filter had high insertion loss compared with the former filter even though such filters were designed at 3 GHz, and thus the advantage of the construction manner of the former filter was confirmed.