低频强磁场屏蔽效能的测试方法与测试设备研制

Measurement Method and Measurement Equipment Development for Low-frequency Magnetic Field

为了合理评估屏蔽体对低频强磁场的屏蔽效果,为工程中屏蔽室质量验收提供必要的检测手段,根据小环天线法测量电磁屏蔽室屏蔽效能的原理,提出了低频强磁场屏蔽效能测试系统的整体结构和设计方案,研制了以PIC16F73单片机为核心的低频大电流源,设计和制作了磁场发射、接收环天线,构建了低频强磁场屏蔽效能测试设备;采用研制的测试设备对屏蔽室进行了屏蔽效能实测。测试结果与理论值符合较好,表明测试设备能够满足实际测量的需要,同时验证了计算结果的可信性。

In order to provide guidance for the design of low-frequency magnetic shielding and to evaluate the shielding effectiveness（SE） of shielding enclosures,a portable measurement device is developed.A novel SE measurement system for low-frequency magnetic field is designed based on small-loop antenna theory.The measurement device consists of low-frequency large current source,transmitting antenna,receiving antenna and computer aided measurement and signal processing unit.The dynamic range of the current source is（20～300）A,and it can produce magnetic field from 100 A/m to 1600 A/m at the distance of 30 cm,with bandwidth of（30～1000） Hz.PIC16F73 single chip is employed to control the current source.The measurement software including data acquisition and signal processing is also designed.SE for low-frequency magnetic field of an enclosure is measured by this device.Test results fit well with the analysis results,indicating that the measurement device is highly effective and reliable.At the same time,test results also demonstrate that the calculated result is reliable.