A PHOTONIC VARIABLE RF DELAY-LINE FOR PHASED-ARRAY ANTENNAS

It is shown that by applying spatial frequency dependent phase compensation in an optical heterodyne process, a variable RF delay line can be synthesized over a prescribed frequency band. Experimental results which demonstrate the performance of the delay line with regard to both maximum delay and resolution over a broad bandwidth are presented. Additionally, a spatially integrated optical system is proposed for control of phased array antennas. The integrated system provides mechanical stability, essentially eliminates the drift problems associated with free-space optical systems, and can provide high-packing density. The approach uses a class of spatial light modulator known as deformable mirror device and leads to a steerable arbitrary antenna radiation pattern of the true time delay type.