Evaluation of Adaptive Phased Array Antenna Far-Field Nulling Performance in theNear-Field Region

摘要

A theory for analyzing the behavior of adaptive phased array antennas illuminatedby a near-field interference test source is presented. Conventional phased array near-field focusing is used to produce an equivalent far-field antenna at a range distance of one to two aperture diameters from the adaptive antenna under test. The antenna is assumed to be a linear array of isotropic receive elements. The interferer is assumed to be a bandlimited noise source radiating from an isotropic antenna. The theory is developed for both partially and fully adaptive arrays. Results are presented for the fully adaptive array case with single and multiple interferers which indicate that near-field and far-field adaptive nulling can be equivalent. The adaptive nulling characteristics studied in detail are the array radiation patterns, adaptive cancellation, covariance matrix eigenvalues, and adaptive array weights. Keywords: Adaptive phased array antenna, Near-field interference test, Near-field focusing, Far-field antenna pattern. Reprints. (jes)