Harmonic Equalizer for Decoupling Communication Bandwidth From Modulation Frequency in Time-Modulated Arrays

In this letter, a harmonic equalizer to mitigate aliasing-induced inter-harmonic interference in time-modulated arrays (TMAs) is proposed, which conventionally restricts the usable communication bandwidth. By prepending a pilot signal spanning integer modulation period to the communication signal at the transmitter, the harmonic characteristics of the TMA channel can be estimated at the receiver. Leveraging the consistency between the pilot and communication signal, a harmonic equalizer is designed to redistribute the signal energy across harmonics, suppress undesirable harmonic components, and concentrate the information in the fundamental band. This effectively suppresses inter-harmonic interference, thus decoupling the communication bandwidth from the modulation frequency, which enables higher data rates within modulation-frequency-limited TMAs.