Near-Field Communication With Random Frequency Diverse Array

In this letter, we explore the benefits of applying a random frequency diversity array (RFDA) in near-field communications. To this end, we first derive the small-scale channel power gains (SSCPGs) for near-field systems both with and without RFDA. Our analysis reveals that RFDA achieves a significantly reduction in SSCPG at non-targeted locations, demonstrating that a superior level of beamfocusing performance can be achieved by RFDA in near-filed communications. Furthermore, we also investigate the SSCPG of a far-field system incorporating RFDA, which highlights that RFDA offers a lower SSCPG at non-targeted locations in near-field systems than in far-field systems.