Wideband Adaptive Antenna Nulling Using Tapped Delay Lines.
Abstract
For some applications, it is desirable to have an antenna which can adaptively form antenna pattern 'nulls' in the directions of a collection of interference sources. These nulls are generally required to be below some specified level of directive gain over the entire system bandwidth. Typically the nulls are formed by adaptively weighting each output of an N-port antenna, such as an N-element array. For large arrays operating over wide percentage bandwidths, some sort of frequency compensation is required at each output port to accomplish broadband nulling. One technique commonly used is to employ a 'tapped' delay line at each element output, with controllable weights (frequency independent) at the output of each tap. The objective of this report is to develop some insight into the way in which delay line compensation leads to improved performance, to develop some quantitative estimates of how performance varies with antenna and delay line parameters, and to develop some tools useful in the performance evaluation of frequency dependent weighting. Practical considerations dictate that only a minimum number of taps/element be utilized. A primary consideration is to minimize the number of taps required for a specific system performance. With this objective in mind, we develop an analytic solution characterizing the two element array, employing a two-tap delay line with each element. This provides valuable insight into the mechanism of delay line compensation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 26, 1979
- Accession Number
- ADA082854
Entities
People
- Alan J Simmons
- Joseph T. Mayhan
- William C. Cummings
Organizations
- Massachusetts Institute of Technology