Radar clutter as a communications-enabling ambient signal

Radar systems - especially when undertaking search functions - always generate reverberation from the surrounding environment, referred to as clutter in Radar parlance. This chapter shows that ground clutter - produced by stationary reflectors located in the patrolled region - enables data delivery from a sender, also referred to as a tag, to a receiver (referred to as a Reader). In particular, we show that the tag - which is only enabled to vary the amplitude and/or the phase of the incoming signal - may modulate the clutter returns adopting diverse modulation schemes, the only limitation being that the length of the transmitted frame be smaller than the ground clutter coherence time. Sample plots of the performance achievable through two simple modulation schemes are also offered to show the feasibility of the proposed architecture.