Li To achieve the best possible estimation performance with an antenna array, signal processing algorithms must consider both sensor and wave properties, and exploit the advantages of these properties. The main objectives of this research are: 1. to exploit the advantages of different polarization sensitive arrays; 2. to develop the direction and polarization estimation techniques for both completely and partially polarized waves; and 3. to take into account the mutual coupling effects between antenna sensors for direction and polarization estimation and for modeling nearby scatters with antenna theory. The algorithms are being applied to both simulated and experimental data from industrial and government sources. The performance of the algorithms are being evaluated for both types of data.