Effects of Adaptive Antenna Arrays on Broadband Signals.
Abstract
This paper develops a complex baseband model for an adaptive array with N isotropic elements and T tapped delay lines behind each element. Three aspects of arrays are represented: spatial and temporal propagation delays and the weighting coefficients. The model is used to determine the steady state effect of arrays on wideband signals. Optimum weights are calculated based on the noise covariance matrix produced by single and multiple narrowband jammers and single broadband jammers. It is shown that discrete spectral lines can be used to model a broadband jammer. For a jammer with 4% f0 bandwidth, this approximation yields a correlation function which is accurate to within 0.53%. For a linear, equally spaced adaptive array the output consists of the input signal and its first time derivative. This first derivative distortion is reduced by the addition of tapped delay lines only when the noise environment contains broadband jammers. This performance improvement is quantified by increased null depth. The improvement, for a 4% f0 bandwidth jammer, was 6.2 db with a jammer located at 10 degrees and 2.5 db for a jammer at 50 degrees. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1980
- Accession Number
- ADA085708
Entities
People
- William Artman Riski
Organizations
- Air Force Institute of Technology