Sparse Vector-Antenna Array Design for Dual-Functional Radar Communications

Dual functional radar communications (DFRC) has gained increased attention in both academia and industry due to its recognized prominence to alleviate the spectrum congestion. The key to the DFRC design is the separation between radar and communication signals, for example, in either time, frequency or spatial domain for most existing methods in the literature. In this work, we consider the design of DFRC systems using an array of vector-antennas, which consists of P = 2 orthogonal electric or magnetic dipole elements. To reduce the system cost caused by a complete front-end associated with each dipole, we further consider the sparse vector-antenna array design, which jointly optimizes the vector-antenna positions, the compositon of dipoles and the beamforming weights. The communication capacity can be doubled via modulating the complex beampattern in both H-and V-plane. Most importantly, the mutual interference between radar and communication can be mitigated when the polarizations of the beampattern towards the target and communication user are orthogonal to each other. Simulation results show that both the beampattern shape and polarization can be controlled using sparse vector-antenna arrays for DFRC applications.