Research-based The Digital Oscilloscope Environmental Electromagnetic Testing Methods

In the defense industry, high power microwave weapons (HPW) can emit high-energy pulse, which has the characteristic of high power, narrow pulse and low duty cycle, by the antennas. Its high peaks will harm human and damage equipment seriously. At present, the measurements of electromagnetic field strength are mainly concentrated in frequency domain range, without time domain standards. The frequency domain method of standard cannot measure this kind of pulse signal. It is a blind spot to measure and evaluate ultra-low duty cycle transient pulse in our country.This paper is for the environment electromagnetic measurement and evaluation demands of the narrow and ultra-low duty cycle pulses and the limitation of this kind of signal measurement and evaluation through present standards is discussed. A set requirement of time domain environment electromagnetic test system is designed based on digital oscilloscope to the need of test narrow width and low duty cycle pulse. This system is mainly used for test different distance environment electric intensity of pulse signal and use the prevailing standards to judge whether it will harm to human. The continuous wave is excitation signal in the system theoretical analysis and experimental verification, by the current standards of the frequency selective type broadband radiation test instruments (PMM8053B electromagnetic radiation analyzer) and frequency selective radiometric (ESI40 EMI Test Receiver), proofing the measurement system based on digital oscilloscopes measurement results and other two systems'good uniformity. The impact analysis is completed from window function to FFT. Peak plus method is developed to suit for calculating modulation pulse signal by numerical simulation of the calculation method of comprehensive intensity of field.When analyes the relationship between total power and each frequency power, the line relationship between broadband signals and each frequency of voltage is discovered, and the duty cycle has no influence on the digital oscilloscopes measurement system,which are consisted with simulation results.so the digital oscilloscope measurement system is more suitable to modulate pulse signal comprehensive intensity of field measurements than other two systems.Furthermore, this paper introduces the expanded uncertainty of the system in measuring electromagnetic intensity of field is 2.8 dB.When use the related standards about environmental electromagnetic wave measurement and radiation protection, there are some fuzzy key contents and incoherency between those standards. Comprehensive intensity of field calculation, pulse intensity of field and near and far field are also discussed in detail. Some suggestions were put forward to expecting to provide help in future standards recession.