Phased array antenna technologies have been used for communications and Intelligence, Surveillance and Reconnaissance (ISR) for many decades to create steerable beams that more efficiently focus energy in desired directions. Generally they have been based on the classical approach of fixed antenna elements evenly spaced at some fraction of a wavelength, all connected to a single transceiver. Distributed transmit beamforming is a more recent approach that does not conform to these design constraints. Individual radios are array elements that are dispersed far beyond a single wavelength from each other and which are allowed to move around the battlespace, with the distributed transmit beamforming protocol maintaining the necessary synchronisation between array nodes to ensure energy is concentrated on a distant receiver. In this paper we report on progress to develop an implementation of distributed transmit beamforming that is based on the receiver providing explicit feedback of channel information to the array nodes using a separate backchannel, allowing for high speed, accurate frequency and phase synchronisation of nodes to build an array as required.