Radio Frequency Interference Mitigation via Null Steering for the Multipath Limiting Antenna in Local Area Augmentation Systems

Radio frequency interference (RFI) is one of the major sources of error that can degrade the performance of the local area augmentation system (LAAS). The multipath limiting antenna (MLA) takes care of the ground multipath error that occur in airport environments by having a severely reduced gain below the horizon. This work presents a potential RFI mitigation technique for L1 band (1575.42 MHz) that reduces its effect on the accuracy, availability, and integrity of the LAAS architecture. A planar antenna array of microstrip patches is designed and simulated, and the resulting steered beam in the RFI direction is subtracted from the MLA one to reduce its effect on the received signals. The effect of such technique on the desired-to-undesired gain ratio, phase center variation, and group delay is presented