1GHz超の妨害波測定サイトの特性評価と測定不確かさとの関係

摘要

CISPR（国際無線障害特別委員会）では，1－18GHzの妨害波測定法，1－6GHzの情報通信機器の許容値を標準化した．また，1GHz以上の放射妨害波測定不確かさ評価法に関しても検討中である．測定不確かさの主要因として，測定サイトの不完全性があり，これはCISPR規格では，SVSWRというパラメータで評価している．本論文では，SVSWR評価方法の妥当性を示し，さまざまな特性のサイトにおいてSVSWRの値と妨害波測定結果のばらつきの関係を調べるとともに，SVSWRの値に基づく放射妨害波測定の不確かさ導出法を提案する．%The International Special Committee on Radio Interference (CISPR) has standardized the method for measuring electromagnetic disturbance in the frequency range of 1-18 GHz. CISPR also standardized the limit of interference due to radiation from information technology equipment in the 1-6 GHz range. Measurement uncertainty above 1 GHz is, however, under discussion. Measurement uncertainty is affected by site imperfection evaluated by the site voltage standing wave ratio (SVSWR). In this paper, we first evaluated the relation between the SVSWR values and the measurement parameters such as frequency step and positions. Thereafter, we measured the SVSWR and the field strength radiated from the equipment under test by changing the area covered by the RF absorber on the metal ground plane. Finally, we proposed a determination method of the measurement uncertainty based on the SVSWR values.