Photonic technology offers an alternative implementation for the control of phased array antennas providing large time bandwidth products and low weight, flexible feeding networks. Measurements of an optical beamforming network for phased array antennas with fast beam steering operation for space scenarios are presented. Experimental results demonstrate fast beam steering between 4 and 8？GHz without beam squint. 1. Introduction The evolution of satellite communication and Earth observation missions has shown a clear trend towards systems with higher performance resulting in higher complexity. More in particular, a key requirement for modern space missions is the operation at wide bandwidths. As far as communication satellites are concerned, wide bandwidths are of great interest in order to accommodate broadband data connections, multiuser operation rates, and wider communications coverage. On the other side, Earth observation platforms also benefit from broadband microwave instruments which can provide a larger number of channels from which more complete and diverse remote sensing information can be extracted. Additionally, advanced satellite missions are expected to provide high versatility through capabilities such as scanning and multibeam operation which combined to on-board information processing that allow the assignment of resources dynamically. Wide bandwidth operation requires antenna array systems capable of providing true-time delay (TTD) to avoid beam squint (i.e., changes in the beam steering angle with frequency). However microwave implementations of TTD beamforming networks are rather bulky and heavy with poor harness characteristics, sensitivity to electromagnetic interference and a relatively large crosstalk level which degrade the performance of remote sensing instruments. On the other hand, photonics allows the implementation of TTD beamforming networks without the problems associated with microwave implementations. Optical beamforming has been studied since the early 90s [1] because it provides many advantages over microwave and digital beamforming, such as light-weight, small size, wideband operation, flexibility, remoting capability, and immunity to electromagnetic interference. Different optical beamforming networks have been presented using a variety of components and arrangements [1–9]. Additionally, some optical beamforming architectures [10–13] offer the capability to control a set of independent beams simultaneously, that is, multibeam operation, although at the cost of increasing the complexity. This paper reports on the
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