Application of the Three Short Calibration Technique in a Low Frequency Focus Beam System

摘要

Electromagnetic material characterization is the process of determining the constitutive parameters of matter. In simple media, these parameters are permittivity and permeability. Characterization of these values is often accomplished through the use of waveguides, transmission lines, coaxial cables, and resonant cavities. Free space measurements systems are employed since they are non destructive (i.e., no sample machining is required) and broadband. Traditionally, time domain gating is utilized to mitigate systematic errors. However, an artifact of this calibration technique is band edge corruption due to data windowing. The goal of this research is to develop and apply a Three Short Calibration Technique to the General Electric Low Frequency (0.5-2GHz) Focus Beam System in order to preserve band edge data. It is shown that when working with low frequencies, such as the focus of this research, coupling effects due to multiple bounces within the collimating and focusing lenses as well as lens-sample interaction are not easily calibrated out. Although the coupling effects introduce extraneous clutter into the extracted constitutive parameter values, the results obtained agree with the known reference values of tested dielectric samples. It is concluded that with a more in depth study in sample/lens interaction at low frequencies, this calibration technique could prove useful in the accurate extraction of the desired low frequency constitutive parameter values.