A broadband high-dynamic time-domain system for EMI measurements in K-Band up to 26 GHz

In this work, a low-noise, high-dynamic time-domain EMI measurement system that allows for measurements from 9 kHz - 26 GHz is presented. It combines ultra-fast analog-to-digital-conversion and real-time digital signal processing on a field-programmable-gate-array (FPGA) with ultra-broadband multi-stage down-conversion. The system IF dynamic range is shown to exceed the requirements of CISPR 16-1-1 by over 20 dB and allows for the measurement of high-dynamic range signals like radar pulses. The system sensitivity is increased by the use of low-loss components and integrated, broadband low-noise amplifiers (LNA). This yields an ultra-low noise floor power spectral density of typically below -150 dBm/Hz over the complete frequency range. The high system sensitivity allows for the characterization of broadband, low-level signals near the noise floor, like ultra-wideband (UWB) communication. Scan time is decreased by several orders of magnitude compared to heterodyne EMI receivers. A scan from 9 kHz to 26 GHz with a 9 kHz IF filter and a dwell-time of 100 ms is completed in under 200 s, while over 5-10⁶ frequency points are calculated.