A method and apparatus comprises providing a vector network analyzer having at least two measurement ports and presenting a high reflect calibration standard, a line calibration standard, a source terminated thru calibration standard, and a locally terminated through calibration standard at each measurement...http://www.google.de/patents/US20050030047?utm_source=gb-gplus-sharePatent US20050030047 - Method and apparatus for measuring a device under test using an improved through-reflect-line measurement calibration
