Constrained lens arrays for communication systems with polarization and angle diversity.

摘要

Constrained lens arrays are a special group of multibeam antenna arrays. They can be designed with up to four degrees of freedom. A two-degree-of-freedom lens array with planar front and back faces allows for a simple, lightweight, and cost effective construction.; The emphasis of this research is to design and analyze constrained lens arrays with polarization and angle diversity and for wide scan range. Several arrays are fully characterized in terms of their radiation characteristics and polarization isolation. Simulated results are confirmed with measurements. Loss mechanisms in spatial combining networks are investigated and analyzed. Results are used in the final design leading to a significant reduction in the total loss. When the lens array and the feeds are designed as a system, losses and radiation characteristics can be optimized for a wide scan range.; Application of the constrained lens arrays in several communication systems is discussed. The lens array is used in a controlled multipath environment resulting in a significant reduction in fading at the point of reception. A full duplex Ka-band lens is used for fixed-formation satellites with amplitude controlled small-angle scanning. A system that performs optical processing of RF signals with a lens array at the RF front end is presented. To put the work in this thesis in perspective, lens arrays are compared with other multibeam systems: dielectric lenses and phased arrays.; This thesis demonstrates on several practical examples that constrained lens arrays can be efficiently used as RF front ends in various communication systems.