EOARD FA8655-04-1-3076 2 Six Monthly Report Electronically Reconfigurable Microwave Lens Antennas

The purpose of this report is to present the results of further investigations into the operation and design of two-dimensional Luneburg Lenses at 24 GHz, with the possibility for electronic control of their behavior. Various lens design techniques are illustrated; these include a holey dielectric lens (drilled dielectric) and, a holey plate lens (etched holes on the upper metal plate). Ray tracing theory is presented which shows the general properties of the gradient index lens. These results indicate that it may be possible to synthesize a tuneable lens whose focal length and /or radiation pattern can be adjusted by electronic modification of the lens dielectric properties. In addition a uniform outer layer lens and a two-shell lens are also demonstrated. Some preliminary investigations are presented with regard to the general properties of Liquid Crystal materials for tuneable lens use. Also we present preliminary design work on a MMIC reflection amplifier for ultimate deployment in active planar lens reflector for RCS enhancement.