Abstract. An original method is developed
for determining the loss tangent (tand) of thin dielectric plates
and films in the millimeter and submillimeter ranges. The method is based on
comparing the Q factors of an empty semisymmetric confocal open
resonator and a resonator in which a sample under test is placed near the plane
mirror. The change of losses in the resonator due to the insertion of a sample is
represented as a difference between the reflection losses from the plane mirror
and from the sample placed in front of the mirror. The additional phase shift
due to the insertion of a sample into the resonator is compensated for by a
decrease in the resonator length. The loss tangent tand of thin films was
measured in the cavity resonator at 69.4 GHz. To determine the refraction index
of the films, a method is proposed that is based on measuring the reflection
coefficient of a plane electromagnetic wave formed by the horn-lens system incident on a sample.
The refraction index is measured at frequency of 103.1 GHz. The method is
applied to measuring the parameters of Mylar films of various types and
thickness (from 20 to 250 mm). The data obtained allowed one to calculate the
characteristics of quasioptical beam splitters (the reflection coefficient into
a side channel and transmission through the working channel). An algorithm is
developed for calculating the characteristics of beam splitters, and the
characteristics of beam splitters are measured for films of various thicknesses
at frequency of 92 GHz. The reflection coefficients of the film and a metal
plate are compared for TE and TM waves incident at 45o. When
measuring the transmission coefficient, the amplitude of the transmitted wave is
measured for a film situated at 45o to the incident wave and without
Key words: dielectric films, dielectric
permittivity, open resonator, quasioptical methods of measurement, millimeter
1. Chigryai E.E., Ignatov
B.G., Khokhlov G.I., et al., Radiowave introscope in the millimeter range, Electromagnetic
Waves and Electronic Systems., 2010, vol. 15, no. 1, pp. 50-54.
2. Vlasov S.N., Parshin V.V.,
and Serov E.A., Methods for investigating thin films in the millimeter range,
Tech. Phys., 2010, vol. 55, no. 12, pp. 1781–1787.
3. Born M., Wolf E., Principles of Optics,
London: Pergamon Press, 1970, 4th ed.
4. Gerasimov V.G., Grudinskii P.G., and Zhukov P.A.,
Elektrotekhnicheskii spravochnik v 3-kh tomakh. T. 1.Obshchie voprosy.Elektrotekhnicheskie
materialy [Handbook of Electrical Engineering, vol. 1: General Problems. Electrical
Engineering Materials], Ed. by professors of Moscow Power Institute,
Moscow: Energiya Publ., 1982, p. 364.