Location estimation of multiple near-field broadband sources by combined use of DOA-Matrix method and SAGE algorithm in array antenna processing

It is important to understand the radio wave propagation structures in wireless communications. One of useful techniques for the purpose is high-resolution DOA (Direction Of Arrival) estimation using array antenna[1]. However, for the near field sources, different signal models are required since the incident wave fronts are spherical. In this paper, we deal with the near-field DOA-Matrix method for source localization[2]. This is an ESPRIT-like method and features not needing peak search of spectrum, thus leading to high computational efficiency. Also, the near-field DOA-Matrix method can be incorporated into the SAGE algorithm, and hence the combined algorithm can perform successful estimation of multiple waves incident on the array[3]. However, the near-field DOA-Matrix method requires that source signals are narrowband[2][4]. Therefore, we improve herein the method so that it can be applied to broadband signals.