RPVs. Tiny, microwave powered, remotely piloted vehicles

As the name implies, a remotely piloted vehicle (RPV) has its motion controlled by an outside source. A commonly encountered example is a radio controlled model airplane. In this case, the pilot always has the aircraft and ground in view. It is a simple process (in principle) to fly and land. For vehicles that move out of the pilot's view, an onboard sensor is needed to determine motion and location relative to the terrain. Usually the sensor is a video camera, but radar and infrared systems also can be used. The design for such a small vehicle presents some unique engineering challenges. Several basic trade-offs must be performed in the areas of aerodynamics, propulsion, energy sources, control and onboard sensors. Obviously as the vehicle's size is reduced, the weight and power consumption of the systems on board must also be reduced. One way to reduce weight is to "beam" microwave energy to the vehicle. This energy is then converted to a DC signal which drives a motor. The author outlines this approach which is called wireless power transmission.