超小形メアンダラインアンテナにおける放射効率向上の実験的確認(光・電波ワークショップ) Experimental Confirmation of Improvement of Radiation Efficiencies of a Very Small Meander Line Antenna

メアンダラインアンテナは小形化しても比較的大きな放射抵抗が得られる特徴を有し,2線式の構成とすることにより更に放射抵抗を増大できることが示されている.これまでの検討では,アンテナ長が0.1波長より大きな領域に限られていることと,入力抵抗値についての議論が主であり,アンテナ効率に影響する導体抵抗を考慮した検討は成されていなかった.本報告では,0.1波長の小形メアンダラインアンテナを試作し,入力抵抗を室温時と液体窒素冷却時に測定することにより,アンテナの導体抵抗の値を評価した.また,アンテナ放射効率の測定も室温時と液体窒素冷却時について実施し,導体抵抗による効率低下量を明らかにした.

Meander line antennas have features of having relatively high radiation resistances in small sizes. Moreover, radiation resistances were increased more than four times by folded meander line structures. These results were ensured through input resistance measurements for antenna length of more than 0.1 wavelength. However, antenna efficiencies and ohmic resistances were not discussed. In this report, 0.1 wavelength meander line antennas were manufactured. Input resistances were measured at room temperature and very low temperature cooled by liquid nitrogen. Through this measurement, ohmic resistances could be estimated. Moreover, radiation efficiencies were measured in these temperature conditions. Radiation efficiency decreases by ohmic resistances were clarified.