Interferometric array design: Distributions of Fourier samples for imaging

Abstract

Abstract. This paper is complementary to (Boone 2001) in which an optimization method was introduced. An analysis is developed in order to define the distributions of uv-plane samples that should be used as targets in the optimization of an array. The aim is to determine how should be distributed the uv-plane samples of a given interferometer array in order to allow imaging with the maximum of sensitivity at a given resolution and with a given level of side-lobes. A general analysis is developed taking into account the levels of interpolation and extrapolation that can be achieved in the uv-plane and the loss of sensitivity implied by an imperfect distribution. For a given number of antennas and a given antenna diameter two characteristic instrument sizes are introduced. They correspond to the largest size allowing single configuration observations and to the largest size allowing imaging with the full sensitivity of the instrument. The shape of the distribution of uv-plane samples minimizing the loss of sensitivity is derived for intermediate sizes and when a Gaussian beam is wanted. In conclusion it is shown that the shape of the distribution of samples and therefore of the array itself is entirely determined by a set of five parameters specifying the work (interpolation and extrapolation) that can be demanded to the imaging process, the level of side-lobes and the resolution at a given wavelength. It is also shown that new generation interferometers such as ALMA and ATA will be able to make clean images without deconvolution algorithms and with the full sensitivity of the instrument provided that the short spacings problem is solved.

Optimal arrays for compressed sensing in snapshot-mode radio interferometry

“…Though this contradicts the general agreement on centrally condensed arrays in the well-sampled case, it is linked to previous results that arrays with small numbers of antennas should aim for a more uniform baseline distribution (Boone 2002;Holdaway 1997;Woody 2001a) so that the near-in side-lobes do not overpower the far side-lobes. The URA also showed promise in allowing for super-resolution in CS recovery, whereas the performance of all other tested arrays decayed rapidly in the under-resolved case.…”

“…In the wellsampled case, the general consensus is that a centrally condensed or bell-shaped distribution of baselines produces more favorable near-in and far side-lobe patterns, and thus superior images, than a uniform distribution of baselines (Boone 2002;Holdaway 1996Holdaway , 1997Kogan 1997;Woody 2001a,b). Such distributions pursue an ideal clean beam that is both highly localized and free of lobes, e.g., a Gaussian.…”

Measuring the Earth's Synchrotron Emission From Radiation Belts With a Lunar Near Side Radio Array

“…There exist several algorithms for the optimization of array configuration for a given number of antenna and location. Iterative algorithms for specific topographies (Boone, 2001) and imaging targets (Boone, 2002) may be used to find a high performing configuration better than simple arrangements such as logarithmically spaced circles. These techniques may be extended in different ways to take obstacles such as craters into (Lower right) Three-kilometer radius array, elevation = 2.8 m. These elevation maps show different 1,024-element array configurations of logarithmically spaced concentric circles.…”

Optimization of Positioning of Interferometric Array Antennas Using Division Algorithm for Radio Astronomy Applications

“…There are several notable works doneonoptimization of antenna arrays, among them: Kogan 2000; Boone 2001Boone , 2002Cohanim et al 2004;Su et al 2004;Karastergiou et al 2006;Jin & Rahmat-Samii 2008;Oliveri et al 2010;Beardsley et al 2012;Kiehbadroudinezhad et al 2014. In particular, Karastergiou et al (2006) obtained the most appropriate u-v plane sampling for lowdensity interferometers, based on the work of Keto (1997) and Boone (2001Boone ( , 2002, but they did not consider SLL suppression, which is important in astronomy applications to capture a clear image of a radio point source.…”

“…In particular, Karastergiou et al (2006) obtained the most appropriate u-v plane sampling for lowdensity interferometers, based on the work of Keto (1997) and Boone (2001Boone ( , 2002, but they did not consider SLL suppression, which is important in astronomy applications to capture a clear image of a radio point source. Oliveri et al (2010) applied the Almost Difference Sets method based on binary sequences to improve the correlation properties in interferometric arrays.…”