Cascading prism dispersion [phased array antenna]

There have been numerous efforts to use fiber-optic techniques in array antennas. Fiber-optics is attractive for the same reasons it is the technology of choice for telecommunications applications. Advantages include: a natural resistance to electromagnetic interference (EMI), low weight, small size, low intrinsic losses and the ability to easily remote components. Additionally, its unique processing capabilities permit simplifying the arrays and adding system functionality, e.g., dynamic beam shaping (adaptive beamforming) and time-steering. A wide variety of optical implementations have been proposed for time-steered array antennas. The Naval Research Laboratory (NRL) has developed a practical, fiber optic technique for implementing time-steered arrays. The approach is based upon a dispersive, fiber-optic delay line combined with a simplified beamforming architecture. This method solves many of the problems associated with optical true time delay (TTD) beamformers. It has been dubbed the fiber-optic dispersive prism. The basis for the approach is shown.