Research on the curvature parameter in the S-shaped inlet's stealth design

The inlet is a strong scattering source in the aircraft head important attitude angle. One way to reduce RCS (Radar Cross Section) is to make the inlet S-shaped to increase the electromagnetic wave reflection time to reduce backward wave energy. A series of S-shaped inlets bended vertically and horizontally are tested in the microwave anechoic chamber to study relative curvature's influence. Experimental result shows that when the incident is vertically polarized, the head direction RCS average's variation along the relative curvature is of ″W″ shape and has 2 minimum values; when horizontally polarized, the head direction RCS average's variation is different in two bend fashions. The variation is of ″W″ shape when vertically bended and monotonously descends when horizontally bended. Generally speaking, a proper relative curvature can reduce the backward's RCS of the inlet.