Time Frequency Direction Modulation Based on Nonlinear Frequency Diverse Array

The conventional frequency diversity array (FDA) can generate arcsine form of continuous direction modulation (DM) waveforms which automatically scan the entire space range. However, single waveform and time varying phase FDA cannot meet requirements practical security communication application scenarios. Thus, a new transmit technique, called (TFDM), is proposed to improve azimuth security. In this paper, unique time-frequency information at given was formed by designing beam steering term each element on basis characteristics FDA. duration, DM be divided into linear (LDM) nonlinear (NDM) according shape. For LDM, for specific observation direction, reaches set value when energy maximum scans but uniqueness no longer exists in other directions. NDM, pass through multiple times pairs information, provides idea realizing multi-directional solving rate problems. Finally, uni-directional based three different safe methods: time-direction (TDM), frequency-direction (FDM), time-frequency-direction (TFDM) are realized validity method corresponding theory verified extensive numerical results.