A measurement of complex permittivity of lossy dielectrics by using flanged rectangular waveguide

If it is possible to derive the complex permittivity of a dielectric materi al by measurement of the coefficient of reflection from the aperture of a f langed rectangular waveguide attached to a conductor-backed lossy dielectri c sheet, an effective nondestructive measurement method can be established. in this paper, by solving simultaneous equations derived by an application of the spectral. domain method, contour maps for derivation of the complex permittivity of a lossy dielectric from the reflection coefficient are for med and their characteristics are studied. The effectiveness of these conto ur maps is confirmed by experiments. In the region within the contour chart where the permittivity can be determined with good accuracy, it can be det ermined with an error of about 5% by means of a general-purpose network ana lyzer. Further, the attenuation of the electromagnetic wave within the loss y dielectric in the direction of propagation is studied in order to derive the dimensions of the sample and flange needed for actual measurement. (C) 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(4): 59-67, 2001.