Sadao Kurazono

Analysis of cylindrical microstrip lines utilizing the finite difference time-domain method

This paper presents full-wave analysis of the cylindrical striplines and the cylindrical microstrip lines utilizing the finite difference time-domain method in a circular-cylindrical coordinate system. Numerical results on the normalized characteristic impedance are in good agreement with the available results. Furthermore, the junctions of the coaxial transmission line and the cylindrical microstrip line are analyzed to show the usefulness of this method. >

Transmission characteristics of optical asymmetric Y junction with a gap region

A novel type of asymmetric Y junction structure is proposed. This Y junction has a gap region so that the required power splitting ratio can be obtained simply even when the branching angle is kept fixed. The transmission characteristics of the proposed Y junction are simulated by means of a beam propagation method (BPM). It is shown that this Y junction has a marked advantage of flexibility in practical use over the conventional asymmetric Y junction. It is estimated that, when the configuration is applied to the 3-dB power divider, a drastic reduction in radiation losses compared with usual symmetric Y junction results. >

Design method of Yagi-Uda two-stacked circular loop array antennas

A design method which works as a single balanced feed antenna is presented for the Yagi-Uda two-stacked circular-loop array antenna. The antenna is analyzed with a theoretical model consisting of loop elements and feeder sections. The results are compared with experiments. By using the computed and measured antenna currents, the gain enhancement of the antenna is confirmed to be due to both the stacked-loop-array and endfire-array effects. A method of compensation for the reflection loss and a design procedure are discussed in detail. A graphical method is given to estimate the optimum size of the antenna without detailed numerical calculations, and the performance of the designed antenna is demonstrated by experiments. Experimental results are presented for several antennas arranged with different numbers of loops in the endfire and broadside directions. >

Design and Expeiments of the Short Back-fire Antenna Composed of Two-stacked Circular-loop Yagi-Uda Array and a Reflector Plate in UHF TV Band

都市部における電波環境の悪化に対応するために, 円形双ループアンテナの高利得, 広帯域性, 特に垂直面の放射ビームの鋭さに注目して, これを八木-宇田配列し, 高利得化と反射波や散乱および都市雑音等の除去を配慮してバックファイア型とした, UHFテレビ共聴用2素子ショートバックファイア型双ループアンテナを提案する.アンテナは, イメージを含んだループ群と平行2線部とに分けた解析モデルを設定して数値解析し, 各パラメータに対する詳細な設計資料を与えアンテナを設計している.また, アンテナからの反射損失はスリーブ法によって補償できることを示した.次に, 設計例をあげ実験によって条件の妥当性を確かめたところ, 半値幅E面55度, H面35度の鋭いビームを持ち, 動作利得最大約10dB, 3dB帯域幅35MHzと高利得, 広帯域を示し, 市販の8素子アレーに比較して3.5dB以上の動作利得の向上が認められることを示す.また, この高利得, 広帯域の理由を電流分布から考察し, 反射板の寸法についても板上の電流分布と指向性から検討を加えている.