Adaptive Beamforming Based on Time Modulated Array with Harmonic Characteristic Analysis

Adaptive beamforming based on the time modulated array (TMA) is proposed and verified, which exploits the characteristic of fundamental and harmonic components after the time modulation. By establishing the relationship between time modulation sequences added to RF switches of the TMA and generated harmonic components of received signals, the complex weights needed in adaptive beamforming can be calculated. Then the weights are mapped to time modulation sequences added to RF switches to generate the beam pointing to the received signal at the frequency of the positive first harmonic component. Compared to the adaptive beamforming based on the digital array, the proposed method exploits only a single RF channel, while its main calculation locates the Discrete Fourier Transform (DFT) of several harmonic components. Therefore, the proposed method has a simple structure and a concise signal processing. Numeric simulations are provided to show its effectiveness.