  Distributed transmit beamforming enables cooperative radios to act as one
virtual antenna array, extending their communications' range beyond the
capabilities of a single radio. Most existing distributed beamforming
approaches rely on the destination radio sending feedback to adjust the
transmitters' signals for coherent combining. However, relying on the
destination radio's feedback limits the communications range to that of a
single radio. Existing destination-feedback-free approaches rely on phase
synchronization and knowing the node locations with sub-wavelength accuracy,
which becomes impractical for radios mounted on high-mobility platforms like
UAVs. In this work, we propose and demonstrate a destination-feedback-free
distributed beamforming approach that leverages the radio's mobility and coarse
location information in a dominant line-of-sight channel. In the proposed
approach, one radio acts as a guide and moves to point the beam of the
remaining radios towards the destination. We specify the radios' position
requirements and verify their relation to the combined signal at the
destination using simulations. A proof of concept demo was implemented using
software defined radios, showing up to 9dB SNR improvement in the beamforming
direction just by relying on the coarse placement of four radios.
