In this paper an array of vertical oriented bow-tie antennas is described. This array is part of the One Square Meter Array (OSMA): A demonstrator which consists of 64 active vertical bow-tie elements surrounded by 80 dummy (passive) elements. OSMA is a receive-only phased array with mixed RF and digital beamforming. The S-parameters of the array were measured and simulated. Using these S-parameters the active reflection coefficient and scan loss were determined. The relation between a blind scan angle in the measured element pattern and a high reflection coefficient will be discussed in detail. For a grid of scan angles from 0 to 50 degrees (with respect to broadside) the average scan loss as a function of frequency was determined. It became clear that the array has a 3:1 bandwidth with an average scan loss less than 1 dB. The radiation patterns of the elements were also measured. They were used to predict the array pattern. This was done for a uniform and a Taylor taper. The correspondence between predicted and ideal patterns is very good.
Perspectives on Radio Astronomy: Technologies for Large Antenna Arrays
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