On the Feasibility of a Generic Phased Array Feed for the European VLBI Network

The feasibility of using a generic Phased Array Feed (PAF) for the radio telescopes within the European VLBI Network (EVN) is explored. Taking into consideration the variations in size (14 m−100 m) and primary focal distance to diameter ratios f/D(0.3−0.5) of the EVN reflectors, the achievable aperture efficiency of a generic array feed is investigated. For the scan range of 0∘−5∘, a parametric study based on encircled power is performed to find the optimum location, shape and size of the array. It is concluded that for a generic PAF design, the smallest f/D ratio decides the required array size for a certain aperture efficiency and scan angle. A spherical array with specific radius of curvature and displacement from the focus is found to achieve 80% aperture efficiency with smaller size, both in terms of radius projected onto the focal plane and surface area, than a planar array placed in the focal plane.