Hierarchical configurations for cross-correlation interferometers with many elements

Array configurations built on a hierarchy of simple elements have excellent properties for cross-correlation imaging interferometers including a smooth distribution of measured Fourier components, high angular resolution, low side lobes, and compact array size. Compared to arrays with a Gaussian distribution of antenna separations, hierarchical arrays (H-arrays) produce beams with higher angular resolution and a tighter concentration of the total power (encircled energy) within a smaller area around the main beam. An attractive feature of H-arrays is their simplicity. The relationships between the Fourier coverage and the array configuration are easy enough to understand that they can be adjusted to achieve different design goals without the need for numerical optimization. H-arrays will be useful for future multi-element interferometers.