Multiple targets direction‐of‐arrival estimation in frequency scanning array antennas

Abstract

In this study, the authors address the problem of resolving angular position of multiple targets in the same range and separated by less than an antenna beamwidth using frequency scanning array (FSA) antennas. First, the frequency scanning antenna signal model is derived and then the necessary compensation methods to overcome antenna pattern variations with frequency during the scan in FSAs are presented. Two direction-of-arrival (DOA) estimation algorithms, the minimum variance beamforming and the maximum-likelihood estimation are applied on the signal model. Simulation results show that both methods can separate targets with angular separations smaller than a beamwidth by selecting correct parameters. The performance of the two DOA estimation methods with respect to different system parameters are investigated based on the signal model through Monte Carlo simulations and compared with the Cramér–Rao lower bound. In addition, an FSA antenna is presented in this work and simulations of the DOA estimation algorithms are performed using the measured antenna pattern of this antenna. The performance and limitations of target DOA estimation methods for the measured antenna patterns are also discussed.