Beam Focusing by using Scattering From Drones

Beam focusing is commonly done by using phased arrays. However, the size of a phased array typically increases as the frequency is lowered, making beamforming at lower frequencies more difficult to achieve. For example, at 30 MHz, the wavelength is about 10 meters, making the needed element separation in the range of 5–10 meters. Such a large array would be difficult to easily make in a mobile or airborne form. One possible solution is to use drones as the radiating elements, since it is easy to position them almost arbitrarily in space. Such a drone-based array could be useful in certain applications. For example, communications between a transmitter and a remote receiver might be blocked, so that there is no direct line of sight between the transmitter and the receiver. This might happen, for example, if the transmitter is located inside of a forest or mountainous region. In this case the drone swarm could be used as a relay between the transmitter and receiver, flying at a sufficient altitude to overcome the blockage. (The transceiver that is located inside the forest or mountainous region is being thought of as the transmitter for convenience.)