Millimeter-Wave Free-Space Dielectric Characterization

Millimeter wave technologies have widespread applications, for which dielectric permittivity is a fundamental parameter. The non-resonant free-space measurement techniques for dielectric permittivity using vector network analysis in the millimeter wave range are reviewed. An introductory look at the applications, significance, and properties of dielectric permittivity in the millimeter wave range is addressed first. The principal aspects of free-space millimeter wave measurement methods are then discussed, by assessing a variety of systems, theoretical models, extraction algorithms and calibration methods. In addition to conventional solid dielectric materials, the measurement of artificial metamaterials, liquid, and gaseous-phased samples are separately investigated. The pros of free-space material extraction methods are then compared with resonance and transmission line methods, and their future perspective is presented in the concluding part