Comment on ‘Enhancing the security of communication via directly modulated antenna arrays’

In a recent study by Hong Zhe Shi et al., a new approach to enhance the security of data transmission using a two-element array based on the directly modulated antenna array technique has been shown. Consequently, Hong Zhe Shi et al. have presented the phase shift values of the array to synthesise a directional modulation (DM) signal in the desired direction. In this current comment, the author demonstrates that the DM signal cannot be synthesised by a two-element phase array because the relative phase information maintain as the conventional baseband modulation signal. The DM signal synthesised using a phase array needs at least three elements.