ON THE INFLUENCE OF COUPLING AMC RESONANCES FOR RCS REDUCTION IN THE SHF BAND

A novel approach to Radar Cross-Section reduction using a thin Artificial Magnetic Conductor (AMC) structure is presented. The novel AMC structure combines two unit-cell metallization sizes and so it presents two resonant frequencies. RCS reduction is based on destructive interference of two partial reflections. Taking as starting point a previous work showing significant RCS reduction based on the combination of two AMC surfaces with overlapped AMC operation bandwidths (so that they have similar reflection coefficient amplitude) without a 180º-phaseshift, the key point of this contribution is to analyze the influence of the degree of the aforementioned overlapping on RCS reduction and to show that this achievement is based on coupling phenomena. A comparison of the achieved RCS reduction when combining two AMCs whose AMC operation bandwidth overlaps, two AMCs with non-overlapped AMC operation bandwidths, and PEC-AMC is presented. Prototypes of these three combinations have been manufactured (having them the same size) and their RCS has been measured in an anechoic chamber.