Carbon Foams with Special Electromagnetic Loss Characteristics and Broad Absorbing Band

Abstract

AbstractCarbon foams with a reticulated macrostructure were prepared by a polymer sponge replication method. The electromagnetic parameters of carbon foams with variable electric conductivity were measured at a frequency of 2450MHz. Compared with the same composition pulverized powders, carbon foams have relatively lower dielectric constant but much larger dielectric loss, and more remarkably, carbon foams have magnetic loss. The microwave absorbing property measurement of carbon foams was also conducted. A relatively broad absorbing band performance has been got for carbon foams, and the absorbing values exceeds 7dB almost in the whole measured frequency range of 4-15GHz, while the frequencies range for absorbing values exceeding 8dB are about 7 GHz for the carbon foam with an electric conductivity of 0.46S/m. It is worthy that the broad absorbing band feature of the carbon foam is obtained without any impedance match design, which indicates carbon foams have a great possibility of being applied as RAMs. The special electromagnetic loss characteristics and prominent radar absorbing properties about carbon foams indicate macrostructure modification is possibly a new and effective way to modulate the electromagnetic properties of RAMs besides the traditional composition variation.