A mobile wireless communications device may include a housing, a main dielectric substrate carried by the housing, circuitry carried by the main dielectric substrate, and a ground plane conductor on the main dielectric substrate. The engine includes a rotary piston engine body mounted on the vehicle in an orientation where an output shaft of the rotary piston engine body extends substantially horizontally, an intake passage connected with an intake port formed in the rotary piston engine body, and an exhaust passage connected with an exhaust port formed in the rotary piston engine body. By requiring a restoration path to be node and span disjoint from the normal communication path, error detection circuitry need only be placed at the end nodes of the normal communication path. The attenuation portion may be provided by spraying particles of radiation attenuating material on the head cover. The inlet opening of one passage includes an element for aligning the passage in a matching position to the dispensing device and the inlet openings of the two passages are of different cross-sectional shape to each other.