Technique to assess group delay variation using scalar measurements

A new method of assessing the group delay response of microwave circuits has been developed. The Hilbert Transform Derived Relative Group Delay (HGD) method avoids the complications of calibration with different input and output frequencies requiring the use of a reference mixer by using only amplitude data which can be derived from a scalar network analyzer using broadband detectors. The principal compromise is in accepting a relative measurement of group delay rather than the absolute measurement which is possible with a VNA, but comparative data is likely to be sufficient for many measurements and the savings in cost and complexity can be significant.