The DRAO Phased Array Feed Demonstrator: Recent results

Future radio telescopes will be used by astronomers to make high-sensitivity wide-band and wide-field surveys of the radio sky. A candidate technology to provide these expanded capabilities is to place high-sensitivity phased-arrays at the focal plane of reflector antennas. Since this technology has not been proven yet, we have constructed the PHased-Array feed Demonstrator (PHAD) with the goal of exploring engineering aspects of this new technology. PHAD comprises 180 densely-packed Vivaldi elements operating from 1 to 2 GHz. Each element feeds a low-noise amplifier and a receiver (both commercial integrated circuits), with the outputs digitized and stored. Beamforming is performed off-line using a matrix language, providing great flexibility in diagnostics and algorithm development. PHAD testing began in a near-field range and has progressed to tests on a dedicated 10-m reflector antenna. Early results (with emphasis on calibration) are reported here.