昨日（9月18日）jr9mfkさんが報告されていたNATOの技術報告には，PLCモデムが接続された電力線からの漏洩電界強度に関する重要な指摘が含まれています。

7.1.2 CMRR/LCL Measurements
CMRR/LCL values are generally measured as the ratio between the DM and CM voltages at the injection point. This may not be a representative measurement with respect to radiation, since impedance mismatches and standing waves can cause large variations in the CM current along the line.　＜中略＞　Measurements presented in [69] show large variations in the CM current at different positions in a house (and also at different frequencies). For an injected power level of about 0 dBm the CM current varies between 10 dBμA and –30 dB dBμA at the same frequency.

Simulation results presented in [65] indicate that, for the case of a single straight power line with no branches, a LCL of 24 dB (asymmetrical loading) will cause the radiated power to increase by 50 – 70 dB compared to symmetrical loading. For more complicated network geometries, the increase in radiation due to asymmetrical loading is similar for low HF frequencies and higher for high HF frequencies. According to [70], the CM currents along the line can not be deduced from the CM signal at the feed point due to this kind of variations, and therefore the LCL can not directly be used to estimate the radiated fields in case of PLC. Similar arguments are given in [71].

注：[ ]内の番号は，同報告が引用している参考文献番号
CM = Common Mode，DM = Differential Mode，
CMRR = CM Rejection Ratio
LCL = Longitudinal Conversion Loss

要するに，PLCの場合，LCLによって漏洩電界強度を記述することはできない，ということです。