2-DIMENSIONAL FIBEROPTIC CONTROL OF A TRUE TIME-STEERED ARRAY TRANSMITTER

We report a first demonstration of a fiber-optic beamformer for indepe ndent two-dimensional (2-D) true time-delay steering of a transmitter array. The fiber-optic beamformer is based on a simple dispersive pris m optical delay approach, with separate azimuth and elevation control stages. The azimuth dispersive prism stage includes an amount of dispe rsion in each link proportional to the corresponding column position i n the array. The microwave signals, properly time delayed for azimuth steering, are amplified and serve as inputs to identical dispersive pr isms feeding the elements in each column. The elevation dispersive pri sm stages include an amount of dispersion in each link proportional to the corresponding row position in the array. Each time-delayed microw ave signal feeds a single flared-notch element in a 4 x 4 array, The 2 -D array pattern measurements in an anechoic chamber clearly demonstra te independent +/-30 degrees azimuth and +/-30 degrees elevation steer ing. There is no observed squint over the microwave-component determin ed bandwidth of 6-18 GHz.