In this paper we report on nonreciprocal wave propagation in a 2D radial sonic crystal with space–time varying properties. We show that a modulation traveling along the radial direction reflects in omni-directional and isotropic nonreciprocal wave propagation between inner and outer shells. The nonreciprocal behavior is verified both analytically and numerically, demonstrating that space–time radial crystals can be employed as one-way emitter or receiver of acoustic or elastic signals.
