The TTN-method - A phase shift calibration technique for vector network analyzers

Accurate measurements of complex scattering parameters are important concerning many applications. Especially free space measurements get more and more important with regard to material characterization. While calibration methods for embedded setups are well-known, the calibration of a free space setup is still a challenge. In particular the precise positioning of the calibration standards in the free space or the precise displacement of antennas lead to measurement errors. This contribution deals with a new calibration method based on the well-known TLN calibration. This so-called TTN-method enables accurate measurements without the necessity of moving antennas or placing calibration standards at specific positions. The TTN-method makes use of the assumption that free space measurement setups have a fairly flat frequency response. Additionally, this method requires a sufficient length of the setup. Thus, taking a second neighboring frequency point into account, offers the possibility to realize a certain phase shift, which yields additional information for the calibration procedure. This information can be used for calibrating the setup without inducing appreciable measurement errors.