Initial calibration and beamforming results from the thousand element phased-array

The next generation of radio telescopes for astronomy are planned to have a receiving area of a square kilometer, known as a Square Kilometer Array (SKA). The technology can be based on phased arrays. ASTRON is currently building a THousand Element Array (THEA) to develop this technology. THEA consists of sixteen one square meter tiles each consisting of an eight by eight half wavelength spaced regular grid of antenna elements. The beamforming for THEA is done at two levels; radio frequency (RF) beamforming on every tile (64 elements) and digital beamforming with the sixteen tiles. The two level beamforming hierarchy is a cost effective method of producing large antenna arrays. This paper presents some initial results from a single THEA tile. Calibration of the tile is broken into two separate parts; the individual phase shifters (vector modulators) and the gain and phase offsets introduced by each receiving antenna and circuitry. Calibration results are presented, as well as, the resulting beam patterns produced by the tile.