Single-Channel Direction Finding by Amplitude Correlation With Time-Modulated Array

A single-channel direction finding method is proposed with the time-modulated array (TMA), by comparing the amplitudes of generated harmonics. After periodic modulation by TMA, the magnitude spectra of generated harmonics vary with the incident direction of the signal. Therefore, the direction can be estimated from the received harmonics. The proposed method exploits the idea of correlation to achieve the following advantages. First, only amplitude measurements are needed rather than phase comparison, which can be implemented by a simple scalar frequency sweeper rather than complex signal acquisition. Second, like in the direction finding based on the phase correlation interferometer, the proposed method overcomes the influences of mismatch among elements and the environment. Besides, the interpolation method is investigated to improve the direction finding accuracy under limited sample points. Numeric simulations are provided to verify the proposed method, and related factors influencing direction finding accuracy are discussed. An <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i>-band eight-element TMA is fabricated and tested to examine its effectiveness.