Direction Finding of Linear Frequency Modulation Signal in Time Modulated Array With Pulse Compression

A novel direction-finding method with time-modulated array (TMA) is proposed for modulating the echo linear frequency modulation (LFM) signal and analyzing its harmonic characteristics. Unlike conventional analysis method where each coefficient of harmonic components is analyzed by discrete Fourier transform, in the proposed method, the harmonic coefficients of modulated signals are calculated by using the pulse compression technology. After the modulated LFM signal is compressed by the matched filter, a closed-form expression of the corresponding output signal is derived and the harmonic coefficients of the input modulated signals can also be obtained. Meanwhile, in order to avoid being affected by other harmonic components in the process of analyzing each harmonic coefficient, the constraints to acquire independent harmonic coefficients are highlighted. Numerical simulations are provided to verify the performance of the proposed method, and a simple S-band eight-element TMA is constructed to experimentally verify its feasibility.