Optimal radar transmitter and receiver architectures are proposed for increasing the degrees of freedom for beamforming optimisation by transmitting linearly independent waveforms from each element of a phased array radar. This effectively encodes clutter returns with a spatial signature which enhances clutter-rejection performance in the spatial processing. The theory which enables the exploitation of these additional degrees of freedom is developed for a general set of linearly independent waveforms and considered in the context of both conventional beamforming applications as well as novel applications.