Measurement of the characteristics of protective screens for microwave radiation made of thin conductive fibers

Abstract

In thin conductive fibers, which diameter is much smaller than the wavelength, under certain conditions, a very strong absorption of the microwave radiation can occur. The absorption efficiency factor can reach several thousand. It is suggested to use this effect for creation of protective screens. The absorption of radiation occurs in segments of graphite fibers with a diameter of tens micrometers (12…15 μm), which are randomly arranged on the paper or polyethylene film substrate. With such arrangement of fibers, characteristics of the screen do not depend on the radiation polarization. An advantage of the screens is also the uniformity of the frequency characteristics of transmission, absorption and reflection of radiation. The paper describes experiments on measurement of the transmission, reflection and absorption of radiation by screens in the centimeter wave range. The screens were placed in free space under different angles of the incident radiation. The measurement results were compared with the results obtained during measurements in waveguides. As it turned out, the results obtained by both methods are consistent. This makes it possible to recommend waveguide methods based on reflectometers. They are more convenient, fast and accurate than free space measurement methods.Formulas for estimating the transmission, absorption and reflection of screens are given.