Trenching apparatus comprises a cutting device, preferably an endless chain cutter, mounted on a prime mover for positioning the cutting device in a trench with the prime mover movable on the ground surface above the level of the trench. The solid, non-crystalline radiation-transmissible materials comprise glasses and other suitable materials that transmit at least about 40% of radiation having a wavelength from about 180 to about 600 nanometers. The silicon oxide is precipitated in fluffy form. A pair of magnets are oriented to force the member to move from its remote position, against the action of a spring, to its intersecting position, to prevent the latch from disengaging the fixed part of the truck. The patch antenna may be optimized to receive multiple RF bands. More specifically, in one embodiment, there is provided a method, comprising assigning each of a plurality of micromirrors on a digital micromirror device a unique identifier, projecting light toward at least one of the plurality of micromirrors, and actuating the at least one micromirror in a pattern corresponding to its identifier.