Noise considerations for wideband true time delay photonic beamformers

With the advent of new forms of true time delay wideband beamformers -both photonic and digital-the effect of noise within the beamformer channels must be taken into account. As an example, in this paper, a multibeam photonic beamformer for a phased array working in receive mode using linear frequency modulated pulses is analyzed. A general expression is obtained showing the effect of the optical noise on the spatial antenna pattern and on the impulse response. The S/N (signal to noise ratio) of the beamformer is examined with regard to both uncorrelated and correlated noise between channels.