An improved stability broadband/mm-wave VNA structure

In the past, the stability and quality of broadband mm-wave network analysis measurements have sometimes been challenges because of required high frequency multiplexing schemes, physically large and inhomogeneous measurement structures and complex receiver chains. A newer structure for this class of VNA measurements will be presented where a broadband, miniature front-end receiver is used for more of the acquisition with a single receiver chain. Using this system structure, improved stabilities have been demonstrated including thru line S21 deviations below 0.02 dB and 0.5 degree over 24 hours from 70 kHz to 120 GHz and temperature sensitivities on the order of 0.01 dB/C and 0.1 deg/C over the same range. This could allow for longer intervals between calibration and improved measurement results.