The deployment of the Square Kilometre Array (SKA)  starts with a ~10% instrument, phase 1, commencing with construction in 2018. This includes the SKA1-Low, a sparse Aperture Array (AA) covering 50 to at least 350MHz. SKA1-Low will consist of 512 stations, each with 256 antennas creating a total of more than 130.000 antennas. The configuration will be closed packed with a large fraction of the antennas within a 1.7km radius central area and the remaining collecting area situated on three spiral arms, extending to a radius of ~45km.
The Square Kilometre Array (SKA) organisation is building a low frequency (50-350 MHz) aperture array to be located in remote Western Australia. The array consists of 512-stations, each consisting of 256-dual polarisation log-periodic antennas. The stations are distributed over a distance of 80km, with the greatest density of stations located in the central core. The input bandwidth is processed in a two stage polyphase filterbank, with the first stage channeliser producing 384 x 781 kHz narrow-band channels. Each station beamforms the antennas together to form a single dual polarisation beam with a bandwidth of 300 MHz (additional beams can also be traded for bandwidth). The second stage polyphase filterbank is located in a system called the Correlator and BeamFormer (CBF) which is the topic of this paper. In the CBF the station signals are first aligned in time. Thereafter the signals are simultaneously correlated and beamformed.
The surveying speed of large reflectors can be increased by one or two orders of magnitude when the focal fields are sampled with a dense phased array. In a dense array consisting of a large number of antenna elements (100 up to 1000), multiple beams can be synthesised and steered electronically. This collecting and manipulating of the entire electric field in the focal plane creates the possibility of a simultaneously improvement in the efficiency of existing telescopes and open up wide fields-of-view.
This paper will describe the first results of the EU project FARADAY. The approach chosen in FARADAY is to use a Vivaldi array of 72 antenna elements configured in 8x9 grid. The analogue beamformer, integrated with the antenna array, syntheses beams by using for example 3x3 elements combined in three rings, where each ring is given a specific weight factor. The number of beams has been limited to two in this demonstrator project.
Further more we will explore the possibilities and limitations of the large-scale use of Focal Plane Array's, in particular for the fourteen 25-meter reflectors of the Westerbork Syntheses Radio Telescope (WSRT).