Wideband Vector Corrected Measurements on a Modified Vector Network Analyzer (VNA) System

Abstract

Vector corrected wideband measurements on a modified vector network analyzer system are presented using wideband modulated signals as stimulus. The modified system allows intermediate frequency (IF) bandWidths exceeding 5 GHz based on external wideband IF access, signal conditioning and digitalization. A combined RF and IF calibration has been developed that allows full-band calibration using CW excitation, while measurements are made with wideband modulated signals. Impedance measurements verify excellent accuracy at -59dB deviation for an electrically switched impedance which is only a few dB less than for narrowband measurements. Repeatability of calculated error terms for consecutive calibrations also show comparable performance as for narrow-band measurements. Wideband one-port impedance measurements at 12.5 GHz using a Schroeder signal with 500 MHz instantaneous bandwidth show less than -50dB deviation with coherent averaging even without correcting for mixer distortion.