ALMA Memo #353
Investigation of suppression of sidelobes by simple displacement of clustered groups of regularly spaced antennas

Steven Heddle
March 2001

A means of suppressing beam sidelobes by simple displacements of subgroups of regularly spaced antennas is proposed and investigated. Previous experiments in the optical domain suggest that this should be possible, and the principle is developed first by analogy and then by a simple analysis to encompass the radio astronomical situation. Considering the specific example of a hexagonal array with the additional constraint of compactness, some improvement over a completely regularly placed configuration is demonstrated. An analysis suggests why the improvement is less than that hoped for. Alternative optimisation methods yield compact arrays with lower sidelobes, but the principle outlined here may prove useful in other configurations.

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