Whitepaper

Broadband Phase Resolving Spectrum Analyzer Measurement for EMI Scanning Applications

Published by Amber Precision Instruments

This conference paper presents the precursor work to the full Marathe et al. journal paper above. It introduces two hardware implementations for extracting phase from magnitude-only SA measurements between 5 and 12 GHz. Implementation I uses sum and difference measurements with two cable lengths and a 180° hybrid coupler; Implementation II replaces the expensive hybrid with three cable lengths for phase shifts. A variable attenuator with six 5 dB steps (30 dB range) ensures the reference and probe signals have comparable magnitudes for accurate phase retrieval. Phase is recovered via Nelder-Mead optimization within ±20° error, with each scan point requiring 18–24 SA sweeps. The method is practical for far-field prediction using Huygens' box methods, which are relatively insensitive to phase errors of this magnitude.