Situational awareness in military surveillance and emergency responder scenarios requires detection of long range targets and secure communication of this information across a multi-sensor network. A potential approach towards this requirement is to harness the coexisting advantages of radar sensing and wireless communications. A multi-functional communications-embedded radar design that implicitly develops into a cross-layered multi-radar secure wireless ad hoc network is proposed to address this need. First, we demonstrate radar and communications coexistence through analysis of our novel composite orthogonal frequency division multiplexing (OFDM)-embedded ultra wideband (UWB) noise waveform's bit error rate and ambiguity function formulations. Second, to solve the medium access problem of allocating the multiple OFDM frequencies between different ad hoc radars nodes, we propose a simple yet fully distributed, channel-diversity-aided algorithm. It constructs a contention-free network, scaling logarithmically with the number of radar nodes, and analytically guarantees a provable fraction of the maximum throughput achieved by any optimal centralized allocation algorithm. Furthermore, our solution dynamically adapts with channel variations and topology changes. Working in-sync with the UWB noise-based single radio multi-channel wireless platform, this distributed resource allocation builds a synergistic cross-layered ad hoc network of radars.