Shielding Effectiveness of a Thin Film Window

The thin film investigated was designed to protect infra-red (IR) systems from electromagnetic interference (EMI), yet allow IR to pass through the thin film window. This experiment measured the properties of a thin film developed by Sienna Technologies, Inc., through a Phase II Small Business Innovative Research (SBIR) program. The objectives of this SBIR were to shield the system from EMI by at least 20 dB from 400 MHz to 18 GHz, and transmit at least 90% of the IR around 1 micrometer and between 8 - 12 micrometers. The measured shielding effectiveness of the thin film was 25 dB from 4 GHz to 12 GHz. The predicted shielding effectiveness was 29 dB based on theoretical calculations. The error analysis of the shielding effectiveness showed that this predicted value was within the measurement error of the experiment. The shielding effectiveness of the substrate was also measured, and it did not contribute to the shielding effectiveness of the thin film. Shielding effectiveness was measured in an electronically mode-stirred reverberation chamber to get a quick overview and in an anechoic chamber to measure the shielding effectiveness versus incident angle. The IR transmission of the thin film could not be determined because of the low IR transmission through the substrate.Air Force Research Lab Kirtland Afb Nmdirected Energy Directorate is the author of 'Shielding Effectiveness of a Thin Film Window', published 1998 under ISBN 9781423561026 and ISBN 1423561023.