Scan performance of small spherical retro-reflectors

A number of historical small spherical lens retroreflectors were simulated in a commercially available antenna simulator. This 1dBm² class retro-reflectors had radii of 2 free space wavelengths, allowing the use of a minimal number of layers to approximate the theoretical Luneburg profile. It was found that further simplification to a 2-layer lens or a single custom material lens were practical. In both cases, RCS of 1.5dBm² were achieved with 3dB scan ranges of 110° in simulation.