Adaptive RF front-ends for digital wireless communications

Phased array systems find many applications in both military and commercial communication systems. The retrodirective array has been of particular interest due to its cost effectiveness and compactness. A retrodirective array transmits a signal back to the interrogator's position without any a priori knowledge of the incoming angle, without relying on sophisticated digital signal processing algorithms. In recent years many microwave/millimeter wave researchers started paying more attention to this self-phasing array, realizing that the retrodirective array can be an attractive candidate for advanced digital mobile communication systems where high link gain and self-beam-tracking are desired. A retrodirective array can efficiently be used in a mobile communication system such as from a ground station to moving vehicles, aircrafts or satellites.; The dissertation reports recent progress in active and passive retrodirective arrays using phase conjugation techniques. The arrays presented here are designed for wireless communications in microwave bands have other features in addition to the self-phasing aspects such that they can be applied to practical communication systems.