As part of the FRM4SAR project, DLR (Deutsches Zentrum für Luft- und Raumfahrt e.V.) and UZH (University of Zurich) have written two documents addressing the topic of the geometric calibration for SAR:

• The TN-100  (UZH-FRM4SAR-TN-100, Issue 1.03, 2017-08-22)
 aims at explaining how to deploy a proper site based on Corner Reflectors.
• The TN-200  (DLR-FRM4SAR-TN-200, Issue 1.4, 2018-04-26) aims at defining a protocol for performing the measurements and corrections for a proper survey

They are available for download at the following link