What are Calibration Standards?

A Vector Network Analyzer (VNA) must be calibrated to perform precision measurements. The process of calibration requires the measurement of known calibration standards. A mathematical algorithm takes in the known data of the standards and their measurements to create a correction formula. Systematic measurement errors of the VNA plus test cables and connectors are thereby reduced to very small values, which are called residual errors. Re-measurements of the standards used for calibration will then match the known characteristics, and measurements of unknown devices will be accurate. This is well known to those who study calibration theory.

There are several calibration methods. Among them Short-Open-Load-Thru (SOLT),Short-Open-Load-Reciprocal (SOLR), Thru-Reflect-Line (TRL), and Line-Reflect-Match(LRM).