A Parasitic Element Technique for Deep Null Synthesis and the Application to Received Signal Strength (RSS)-Based Localization

This paper presents an antenna system that uses received signal strength (RSS) for localization. The proposed system has the benefits of small size, low cost, precise estimation, and low power consumption, which is suitable for the Internet of Things (IoT) applications. It estimates angle-of-arrival (AoA) using an antenna radiation null. A parasitic element technique is applied to steer a deep null without attenuators. The technical challenge to build the system is that amplitude errors in the feeding circuit degrade the null-steering performance. The impact of the errors on the AoA estimation is investigated, and the specific criteria are clarified. The simulation results reveal that a properly designed antenna and phase shifter can reduce the error by up to 15 degrees. Consequently, the system can localize a target with an error of less than four degrees in a range of 120 degrees.