Advantages and disadvantages of the free-space arch method used for investigation of shielding materials at low gigahertz frequencies

In this paper, we present detailed description, advantages and disadvantages of the well-known free-space measurement technique which uses illumination of a material under test (MUT) under different angles of incidence. This technique is considered with applying to shielding materials investigation at 1-10 GHz. It has been shown how to extract own MUT´s electrical and magnetic parameters (complex relative permittivity and complex relative permeability) from a set of reflection coefficients measured at different angles of incidence, frequencies and electromagnetic (EM) wave polarizations using numerical methods. Shielding effectiveness (SE) than can be calculated easily using these parameters. Also experimental results obtained for special metalized materials measured at 2-2.5 GHz have been presented and analyzed with the use of elaborated model.