Effects of failed elements on sidelobes of array beampatterns

Area of Science:

• Antenna theory
• Signal processing
• Electromagnetics

Background:

• Antenna arrays can degrade due to element failures, leading to increased sidelobe levels.
• Understanding the impact of element failures on array performance is critical for reliable system operation.

Purpose of the Study:

• To analyze the sensitivity of sidelobe levels to element failures in arbitrarily shaded arrays.
• To develop mathematical expressions for predicting the performance degradation of antenna arrays.

Main Methods:

• Analysis of beampattern differences to isolate the contribution of failed elements.
• Application of weighted random phase analysis to derive statistical expressions for sidelobes.
• Investigation of the combined effects of element failures and random errors.

Main Results:

• The beampattern of failed elements dictates the degraded response in the deep sidelobe region.
• Expressions for the upper bound, mean, and standard deviation of power sidelobes were derived based on failed element characteristics.
• The upper bound on sidelobes is independent of array size but dependent on the failure percentage.
• Average sidelobe levels are influenced by the failed-to-good element ratio and the number of functional elements, indicating larger arrays are more robust.

Conclusions:

• The standard deviation of sidelobe levels is approximately equal to the mean.
• The ratio of failed to good elements is analogous to amplitude and phase variance.
• The study provides a framework for understanding and mitigating the effects of element failures in antenna arrays.