Test Method of Electromagnetic Shielding Effectiveness of Transparent Conductive Films Based on Coaxial Resonant Cavity

With the wide application of transparent conductive films (TCFs) in the field of electromagnetic shielding, the demand for in-situ evaluation of their electromagnetic performance in the installed state has become increasingly urgent. The existing method of placing transmitting and receiving sensors on both sides of the TCF is only applicable to the uninstalled state and cannot meet the in-situ testing requirements of the installed TCF. To address this limitation, this paper proposes a single-sided in-situ testing sensor based on an open coaxial resonant cavity. It can measure the microwave surface resistivity (MSR) of the TCF and further derive the electromagnetic shielding effectiveness (SE) from the measured MSR. The sensor operates in S and C bands. Test results for ITO films indicate that the SE test range of the sensor covers 25-55 dB, and the test accuracy is better than ±2 dB. The proposed sensor and test method provide a feasible solution for the rapid detection and accurate evaluation of the SE of the TCFs under service conditions.