Design and Construction of an Array of Vertically Oriented Bow-Tie Antennas for a New Generation of Radio Telescopes

In this paper an array of vertically oriented bow-tie antennas is described. This array is part of the One Square Meter Array (OSMA): A demonstrator phased array system (receive only) with mixed RF and digital beamforming. OSMA consists of 64 active vertical bow-tie elements surrounded by 80 dummy (passive) elements. The scan performance of the array was measured and simulated. Using the mutual coupling coefficients the active reflection coefficient and scan loss were determined. For a grid of scan angles from ¿50 to 50 degrees (in two dimensions) 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.