Researchers at the University of California, Davis have developed nonreciprocal and reconfigurable reflectarray antennas based on time-modulation with demonstrated advantages over the state of the art.
Reflectarray antennas are tailored surfaces able to reflect electromagnetic waves coming from a feeder to conform high-gain radiation patterns. Thanks to their advantages compared to parabolic reflectors and phased-array antennas in terms of low-profile and much simpler feeding, reflectarrays have gained significant attention in radar as well as in wireless and satellite communication systems. Even though reconfigurable reflectarrays based on various technologies such as varactors, MEMS or liquid crystals have been explored, they are usually lossy and unable to provide full control of the radiated beam in space. Furthermore, to date, reflectarrays are bounded by reciprocity and thus offer identical response in transmission and reception, which limits their capabilities to deal with strong jamming or unwanted signals.
Researchers at the University of California, Davis have developed nonreciprocal and reconfigurable reflectarray antennas based on time-modulation. To this purpose, each unit-cell that compose the structure is modulated with a very low frequency signal. By adequately controlling the applied modulation, the resulting reflectarrays provide fully reconfigurable responses, polarization control, and nonreciprocal transmission/reception patterns. This low-loss technology offers extended flexibility in primary radar and communication systems as well as unprecedented capabilities to handle interferences and jamming signals without requiring magnetic components.