Simple and Accurate Received Signal Strength-Based Localization Using Compact Null-Steering Antennas

This letter proposes, theoretically studies, and experimentally demonstrates received signal strength-based localization using two null-steering antennas. The localization accuracy is evaluated using null scanning performance by introducing the null depth as an estimation threshold. The result shows that the antenna scanning a null greater than-40 dB reduces the estimation error to 10 cm in a 7.6 m × 5.0 m room. Furthermore, null-steering antennas and feeding circuits that enable deep null scanning over-30 dB are designed to realize the concept. Finally, a simple localization experiment is conducted in an indoor environment, where the direct wave is dominant in propagation. Experiment data verifies good agreement with simulation data in the null-steering performance, and estimation errors are less than 30 cm.