The Murchison Widefield Array: Design Overview

The Murchison Widefield Array (MWA) is a dipole-based aperture arraysynthesis telescope designed to operate in the 80-300 MHz frequencyrange. It is capable of a wide range of science investigations, but isinitially focused on three key science projects. These are detection andcharacterization of 3-dimensional brightness temperature fluctuations inthe 21cm line of neutral hydrogen during the Epoch of Reionization (EoR)at redshifts from 6 to 10, solar imaging and remote sensing of the innerheliosphere via propagation effects on signals from distant backgroundsources,and high-sensitivity exploration of the variable radio sky. Thearray design features 8192 dual-polarization broad-band active dipoles,arranged into 512 tiles comprising 16 dipoles each. The tiles arequasi-randomly distributed over an aperture 1.5km in diameter, with asmall number of outliers extending to 3km. All tile-tile baselines arecorrelated in custom FPGA-based hardware, yielding a Nyquist-sampledinstantaneous monochromatic uv coverage and unprecedented point spreadfunction (PSF) quality. The correlated data are calibrated in real timeusing novel position-dependent self-calibration algorithms. The array islocated in the Murchison region of outback Western Australia. Thisregion is characterized by extremely low population density and asuperbly radio-quiet environment,allowing full exploitation of theinstrumental capabilities.