Direction Finding of Linear Frequency Modulation Signal With Time-Modulated Array

This communication proposes a novel method for finding the direction of the linear frequency modulation (LFM) signal, which has a bandwidth that is much larger than that of the modulated frequency, based on the time-modulated array (TMA). The relationship between the LFM signal and the modulated frequency is discussed and the constraint to avoid aliasing is also derived. To verify the proposed constraint, simulation signals are separately analyzed in the time domain, time-frequency domain, and frequency domain. Meanwhile, simulation results are provided to examine the validation of the proposed method with different factors such as incident angles and signal noise ratios. An S-band two-element TMA is constructed and implemented to experimentally verify the feasibility of the method.