Characteristics of double layers of aluminium-epoxy composite in the X-band

Results of measurements performed on spaced layers of aluminium-epoxy composite at microwave frequencies in the X-band (8–12 GHz) are reported. These measurements were performed on pure epoxy, and on 55 and 90 wt.% composites using pairs of specimens with different spacings. These measurements include the insertion and return losses as functions of frequency. An evaluation of the shielding effectiveness (SE) of these composites in different geometrical arrangements is also included. It is observed that the SE is enhanced substantially in specimens with high concentrations of aluminium flakes, and it reaches more than 55 dB for double specimens with zero spacing. Furthermore, the SE value reaches around 80 dB when the spacing between the two specimens exceeds 50 mm. This observed level of SE may be applied successfully in the use of the composites for shielding purposes.