Different type carbon-based fabrics, namely woven or nonwoven fabric, were employed to investigate the electromagnetic wave shielding effectiveness of the fabrics in the wide operating frequency range, namely 0.4GHz to 40GHz. The surface and cross sectional morphologies of the fabrics, their electrical conductivities, and their electromagnetic wave shielding effectiveness were investigated. In the case of woven fabric, the value of the electrical conductivity was much different according to the measuring direction in the woven fabric. For the nonwoven fabric, however, this value was independent on the measuring direction. The shielding effectiveness of the woven fabric was above 20dB in the range of 0.04GHz to 4GHz and then it decreased to below 20dB in the range of 4GHz to 40GHz. In contrast, the shielding effectiveness of nonwoven fabric was above 40dB in the whole operating frequency range in this work. Based on these results, the dependence of the shielding effectiveness of the woven or nonwoven fabrics according to the operating frequency and the optimal shielding effectiveness material in the wide operating frequency range was suggested and discussed.
Reconfigurable multi-band microwave photonic radar transmitter with a wide operating frequency range