In a helical antenna having an antenna pattern of a helical shape, the antenna pattern extends along a cylindrical body formed by an insulating film member which is rolled into a cylindrical shape. The process extracts endmembers from a spectral dataset using a knowledge-based approach. Said tunnels are embodied as a single link providing access to the remote network. The fixed rollers minimize the gap between the ends of the belts and the transitions while permitting the belts, particularly with cleats, to pass by the fixed rollers.