The calibration of Vector Network Analyzer (VNA) is carried out to compute the error coefficients and to correct the raw data. Several Calibration algorithms are used to calibrate 2-port VNA. Some of the well known calibration procedures are Thru-Short-Delay (TSD) and Thru-Reflect-Line (TRL), Short-Open-Load-Reciprocal (SOLR) and Line-Reflect-Match (LRM). In this book, all the state-of-art calibration techniques have been thoroughly studied. Some of the well known calibration procedures are mathematically analyzed and implemented. Several on wafer devices are measured and their data is corrected by different calibration algorithms mentioned above. Then all the experimental results of different calibration techniques are compared and commented. The advantages and disadvantages of different calibration algorithms are also discussed.