An array antenna based localization using Spatial Smoothing Processing (SSP) is proposed for wireless security and monitoring, referred to as array sensor. The proposed method is based on the array sensor that exploits an array antenna at the receiver to detect the propagation environment of interest. If an event occurs, e.g., human motion, the propagation environment is changed. Thus the eigenvector and eigenvalue spanning the signal subspace that is inherent to its environment changes as well. Using a machine learning technique based on the eigenvector and eigenvalue, the authors can detect the event accurately. The proposed method is improved from their previous work which uses only a limited number of signal subspace features.