Absorptivity Modulation with Salisbury-Inspired Structures for X-Band

Absorptivity control is a very desired feature in many RF applications as it allows enhancing electromagnetic performances such as antenna radiation patterns and reducing radar cross section. In this paper, two Salisbury-inspired structures with absorption level of 20% and 50% in X-band frequencies (8–12 GHz) are presented. Both structures are fabricated by electron beam evaporation technique with Nickel Chrome as material for the resistive coating on PEKK dielectric substrates, which are manufactured by thermal compressing. The RF characterization in non-anechoic environment confirms the results obtained by numerical computations. For both vertical and horizontal polarizations, quasi-perfect agreement over the frequency band of interest is found with a maximal variation of the absorptivity less than 5% between the center frequency at 10 GHz and the edges frequencies at 8 GHz and 12 GHz. The absorption behavior of the two structures was also evaluated under oblique incidence.