Directional Modulation With Dynamic Distributed Time-Modulated Arrays

A novel dynamic distributed time-modulated array (DD-TMA) that uses 2-bit phase control for continuous beam scanning directional modulation (DM) is presented. The element positions of the DD-TMA change randomly and can be easily implemented by using single-pole double-throw (SPDT) switches and redundant elements. The position of each array element follows a Bernoulli distribution, resulting in a radiation far-field of the TMA being described by a Gaussian distribution. Theoretical analysis of the statistical model shows that the TMA signal is made up of two components: the first accurately carries baseband information related to the mean pattern, while the second introduces artificial noise whose power corresponds to the variance of the radiation far field. This noise could prevent eavesdroppers, situated in any direction besides the desired receiver, from effectively intercepting the transmitted data. An approach to prevent DM performance degradation due to phase quantization errors is introduced to support continuous beam scanning with 2-bit phase control. Numerical examples are used to validate the theory. The proposed DD-TMA has significant potential for physical layer secure communication.