Method for fabricating a textured dielectric substrate for an RF circuit. The ferrule includes a shelf portion, a wall portion, and at least one supporting tab connected to the wall portion. The percentage of hydrocarbon gas needed in the intake is inversely proportional to the amount of moisture in the granular material. Also described is a method of making such optical transducers by producing an intermediate matrix of a plurality of such light sources, light detectors and optical shields and cutting the matrix into individual optical units.