Photonic true time delay beamformer demonstrator for a radio astronomical array antenna

The design and characterisation results of a prototype beamformer for receive application are presented. The four channel system uses switched fibre delay lines and signals are combined optically before addition on a single detector. An SFDR of 101 dB/spl middot/Hz/sup 2/3/ has been measured, which is good, given the use of a low power directly modulated laser diode.