A time-domain system for the measurement of non-stationary EMI up to 40 GHz

In this paper, a time-domain measurement system for EMI measurements according to CISPR 16-1-1, MIL-461 and DO-160 in the frequency range from 10 Hz-40 GHz is presented. Signals with a frequency of up to 1.1 GHz are sampled by an ultra-fast floating-point analog-to-digital-converter (ADC), whereas signals from 1.1-40 GHz are first down-converted by an ultra-broadband multi-stage down-converter. With integrated preamplifiers, the system offers high sensitivity and maintains a low system noise floor of below 20 dBμV at 1 MHz IF-bandwidth up to 40 GHz. With a high system dynamic range of more than 70 dB, the system is well suited for the measurement of broadband, transient emissions. Non-stationary emissions can be measured via the real-time spectrogram or via the multi-channel amplitude probability distribution (APD) measuring method.