Optical true time-delay feeder for X-band phased array antennas composed of 2×2 optical MEMS switches and fiber delay lines

We proposed an optical true time-delay (TTD) feeder for X-band linear phased array antennas (PAAs), which possesses high-speed beam scan capability by selecting different lengths of fiber delay lines with fast 2×2 optical microelectromechanical system switches. For proof of concept, a 3-bit optical TTD has been built for a 10-GHz linear PAA composed of two antenna elements. Experimental results show that the maximum time-delay error is less than 0.2 ps, corresponding to a radiation angle error of less than 0.84°, which is within the equipment resolution. We have also designed a 10-GHz linear PAA composed of eight microstrip patch antenna elements driven by the proposed TTD. The radiation patterns of this PAA have been obtained by simulation.