Microwave absorbing properties of activated carbon fibre polymer composites

Abstract

Microwave absorption of composites containing activated carbon fibres (ACFs) was investigated. The results show that the absorptivity greatly depends on increasing ACF content in the absorbing layer, first increasing and then decreasing. When the content is 0·76 wt.%, the bandwidth below −10dB is 12·2 GHz. Comparing the absorption characteristics of the ACF composite with one containing unactivated fibres, it is found that carbon fibre activation increases the absorption of the composite.

Carbon black/ polyurethane nanocomposite-coated fabric for microwave attenuation in X & Ku-band (8–18 GHz) frequency range

“…Initially, with increase of carbon content up to 7 g, the absorption increases from CNC_1 (31.848-40.196%) to CNC_3 (45.938-46.006%) due to increase of permittivity, on further increase of carbon content up to 10 g, absorption decreases from sample CNC_4 (37.816-32.491%) to CNC_6 (33.683-29.122%) due to increased reflecting behaviour of coated fabric (Figure 6e). Similar observations are also reported by Lopes et al [19] and Zou et al [27].…”

“…Conductivity (s) is reduced to = 1/r = 1/ t.R, t is the thickness of sample. The attenuation constant for each sample have been worked out at frequencies 12.4 GHz and 18 GHz using equation (12) and is demonstrated in Figure 7. Attenuation constant increases exponentially from CNC_1 to CNC_6.…”

Ultra-lightweight hybrid woven fabric containing stainless steel/polyester composite yarn for total EMI shielding in frequency range 8–18 GHz

“…Bonaldi et al [14] offered a relation to express EMI shielding effectiveness in percentage from dB unit; SEð%Þ ¼ 1 À Here, EMI shielding has been studied for samples 1, 3, 5 and 7 (containing SS yarn in weft) and samples 2, 4 and 6 (containing BY2 yarn in weft) in both perpendicular and parallel polarization of wave in [8][9][10][11][12][13][14][15][16][17][18] GHz. EMI shielding is demonstrated graphically in Figure 11((a) and (b)).…”

“…[10] ACF/epoxy composite (0.76 wt% ACF, 32 mm length and 13-16 μm diameter) offered absorption bandwidth of 12.2 GHz below −10 dB in 4 mm thickness. [11] Due to inherent high conductivity, carbon nanotube has also gained its importance as a radar absorbing material. Lee et al developed multilayered RAS structure using multiwalled carbon nanotube (MWCNT) in glass/Epoxy fabric in the concentration of 0.0, 0.4, 0.7, 1.0, 1.3, 1.6, 3.0 and 5.0% and thickness of 3.0, 5.0 and 15.0 mm, reflectance loss of up to 20 dB in the frequency band 9.1-10.1 GHz was reported.…”

Preparation and microwave absorbing property of carbon fiber/polyurethane radar absorbing coating

“…Otherwise continuous conductive network is likely to form and reect most of electromagnetic wave, and therefore the absorbing property of carbon ber is refrained. In the majority of current studies, the absorbing property of carbon ber is enhanced by activating treatment of carbon ber, 7,8 or modifying treatment of carbon ber with nanometer iron powder, 9 nickalloy, 10 carbonyl iron powder 11 and other materials while there are fewer studies on multi-layer matching radar absorbing coating which is prepared with carbon ber radar absorbing coating as matrix.…”