Instantaneous directivity optimisation in time-modulated array receivers

As of the periodic on-off modulation of the static excitations, the number and the positions of the active elements in time-modulated arrays can vary significantly within the modulation period and the radiated pattern can drastically differ instant-by-instant. Since the fluctuations of the antenna gain could severely affect the behaviour of the received signal and its correct retrieval, the switching sequence is here properly optimised to keep constant the instantaneous directivity of the main beam, while generating a desired average radiation pattern at the frequency of the impinging signal. This allows one to avoid the spreading of the desired signal power into the harmonics generated by the on-off commutations of the switches. A set of representative results concerned with a benchmark linear case is reported and discussed to show the effectiveness of the proposed approach also in comparison with state-of-the-art solutions.