Abstract:The design theory of absorbing structure with multilayer graded impedance is summarized and its application
in design of absorbing laminate and foam is introduced in this paper. Both calculation and experiment show
that design of multilayer graded impedance can extend absorbing bandwidth of the laminate and foam to low frequency
and enhance absorbing efficiency of the foam. Reflectivity of the 4 mm thick laminate with three layers of graded impedance
is less than -10 dB between 5 GHz and 18 GHz. Reflectivity of the 22 mm thick foam with six layers of graded
impedance is less than -10 dB between 2 GHz and 18 GHz, is less than -20dB between 6 GHz and 18 GHz, and
is less than -30 dB between 8 GHz and 12 GHz. Design of multilayer graded impedance is an effective method for enhancing
the absorbing properties of structural radar absorbing materials.
