效应物置入对环境电磁辐射场强测试的影响

为降低效应物置入对环境电场强度测量的影响，提高电磁辐射敏感度测试准确度，采用电磁场数值计算与实验验证相结合的方法，以正立方良导体作为效应物的模型，分别研究了效应物置入均匀电场环境或电磁混响室中导致的电场分布变化规律，以效应物置入前的环境电场强度作基准，确定了在典型方位测量环境电场强度时由于电场畸变导致的相对误差，给出了测量误差随距效应物相对距离的变化曲线.研究结果表明:在效应物前端面对角线方向测量环境电场误差较小，当相对距离l/λ>1时，均可将环境电场强度的相对误差控制在±10%以内，低频测量时，测试距离处于（0.15~0.25）λ之间时，环境电场强度测试误差可控制在15%以内，满足测量误差要求；混响室中置入效应物，电场畸变主要影响其表面附近的平均场强分布，只要偏离效应物表面大于0.4λ，效应物置入引起的电场畸变对环境电场强度测量造成的误差就能控制在2 dB以内；距离效应物表面（0.5~0.9）λ时，电场相对误差更小，建议在该范围内进行环境电场强度测试. 

The Effect of EUT on Environment Electromagnetic Radiation E-Field Test

To reduce the effect of EUT on the measurement of environment E-field intensity and to improve the measurement accuracy of electromagnetic radiation susceptibility test, a method was proposed by combining electromagnetic field numerical calculation with experimental verification. A cube electrical conductor was taken as EUT model to study the change laws of E-field distribution effected by EUT in uniform electrical field environment or electromagnetic reverberation chamber. Taking the environment E-field intensity before the EUT placed as reference, the relative error caused by electric field distortion in typical direction was determined, and the curve of the measurement error varying with the distance to the EUT was presented. It is concluded that the relative measurement error of environment E-field intensity is less on the diagonal line of EUT front surface,the error can be decreased to ±10% or less when the distance is greater than the wavelength λ. As for the low frequency measurement, while the distance is in the interval of(0.15~0.25)λ, the measurement error can be decreased to 15%, which can meet the test error requirements. When the EUT is put into the reverberation chamber, the E-field distortion mainly affects the mean E-field intensity distribution near its surface, as long as the distance to the surface of EUT is greater than 0.4λ, the measurement error caused by E-field distortion can be decreased to 2 dB, when the distance to the surface of EUT is in the interval of(0.5~0.9)λ, the relative error of E-field is smaller, it is best to measure the environment E-field intensity in this interval.