Implementation of adjustable microwave transversal filters using fiber optic delay lines

The authors discuss the synthesis and design procedures for fiber optic delay line implementation of microwave transversal filters having adjustable transfer functions. They present a Fourier analysis technique for determining a filter configuration to realize a given transfer function. A design is numerically investigated in which the variable tap weights are implemented using integrated electrooptical couplers. A technique is discussed using several simple filters in parallel to reduce the complexity of optics. The effects of random variations in the length of delay lines and the tap weights on the performance of filter have also been studied