Direction Finding Method in Harmonic Amplitude with One-Bit Time Modulated Array

The direction-finding method based on harmonic amplitude is established via a two-element time-modulated array (TMA) system, where the one-bit modulation scheme is utilized to reshape the distribution of the harmonic energy. By using such a scheme, the frequency interval between adjacent harmonics is expanded to the twice of the modulation frequency. The principle of the direction-finding system relies on establishing a mathematical relationship between the ratio of harmonic amplitudes and incident angles. By introducing the time delay in the modulation scheme, the amplitude ratio of harmonics will correspond to two values of incident angle, resulting in the limited scope of angular observation. To address the problem, two sets of relationships between amplitude ratios and angle are introduced to distinguish the ambiguous angle, where the value of the time delay is of importance. Numeric simulation results demonstrate that with a suitable choice of time delay under a one-bit modulated scheme, the direction-finding system can obtain correct estimation results across the full scope of the angle.