FIBEROPTIC TRUE TIME STEERING OF AN ULTRAWIDE-BAND RECEIVE ARRAY

We report the development and demonstration of the first true time-del ay (TTD) fiber-optic beamformer for ultrawide-band antenna receive ope ration, The beamformer is based on a dispersive-fiber prism configurat ion that properly time delays the signals originating at each receivin g element for coherent combining in the microwave domain, The time-ste ered receive antenna consists of eight spiral elements arranged into a one-dimensional (1-D) sparsely populated array, The receive array sho ws an instantaneous bandwidth of 6-18 GHz, limited by the available ma tched microwave amplifiers, The array performance is measured in an an echoic chamber and exhibits unprecedented squint-free steering over an azimuth scan of 120 degrees over the full frequency range.