Moment Method Analysis of Near-Field Adaptive Nulling
Abstract
A near-field technique which can be used to evaluate the far-field nulling characteristics of an adaptive phased array is investigated. The method of moments is used to analyze the performance of a side-lobe canceller adaptive phased-array antenna operating in the presence of near-field interference. Bandwidth, polarization, mutual coupling, and finite array edge effects are taken into account. Phased-array near-field focusing is used to produce an equivalent far-field antenna pattern at a range distance of one to two aperture diameters from the adaptive antenna under test. It is shown that the near-field adaptive nulling performance, with sources located on a test plane at one- to two-aperture-diameters range, is equivalent to conventional far-field adaptive nulling. The antenna analyzed is a planar array of monopole elements having multiple auxiliary channels. The interferer is assumed to be a band-limited noise source radiating from a dipole antenna. The adaptive nulling characteristics studied in detail are the array radiation patterns, adaptive cancellation, covariance matrix eigenvalues (degrees of freedom), and adaptive array weights.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 07, 1989
- Accession Number
- ADA208228
Entities
People
- Alan J. Fenn
Organizations
- Massachusetts Institute of Technology