THE DESIGN OF AN OPTICAL TIME STEERED ANTENNA BASED ON A NEW INTEGRATED TRUE TIME DELAY UNIT

In the framework of wide-band and ultra wide-band array antennas, an Optical Time Steered Antenna (OTSA) is presented, by considering the design strategies of a new True Time Delay (TTD) Control Unit in the Beam Forming Network (BFN). The unit has high reliability, low crosstalk, low switching time and potential low cost, being based on a low cost technology. Furthermore, due to its compactness and modularity, it can be easily grouped with other ones to make a control unit of large arrays. Different strategies and working configurations of the TTD control unit are presented as a trade-off among hardware complexity, insertion loss reduction and beam control capability. The design of an OTSA prototype is discussed by considering a realistic model simulating the behavior of a real world antenna and accounting for unavoidable non-realities, such as random, periodic and systematic errors introduced by each device exploited in the OTSA as well as mutual coupling between radiating elements. An optimal trimming strategy, able to compensate at best for BFN errors and based on the use of suitably located trimmers, is presented. Among other cases, to enlighten the potentialities of the OTSA, an all optical architecture providing a difference beam squint free pattern is also proposed.