Dielectric constant measurements of finite-size sheet at microwave frequencies by pseudo-Brewster´s angle method

Dielectric constant (ε_r) measurements for finite-size dielectric sheets (DS´s) at centimeter wavelengths are presented using the method-of-measuring pseudo-Brewster´s angle. This method is applied to measure ε_r of sheets of Plexiglas and window glass. In the experiment, two horn antennas are used to transmit and receive p-polarized waves. A dielectric sheet is located between the two antennas and rotated 180°, which produces two peaks in the transmittance curves. For a more accurate measurement of Brewster´s angle, an optical spectrometer with 1-min accuracy is also used. By this method, ε_r of Plexiglas and window glass are obtained to be 2.55±0.13 and 5.35±0.1, respectively. This method measures |ε_r|, but the measurement is easy and nondestructive for DS´s. Finally, an accurate method of error calculation is used to calculate the error in the measured values of ε_r