Hard metallic lens and radome at out-of-band frequencies

The electrical characteristics of a hardenable metallic lens or radome having a near-unity index of refraction are described. The near-unity index of refraction constrains lens designs by either restricting the maximum lens diameter or greatly increasing the focal length. An alternative is to use a metallic grating as a radome, which would retain the hardness properties of the metallic lens. This radome design was experimentally measured at 10 GHz using a parallel-plate grating with spacings between 1 and 4 in. Measured pattern and gain characteristics are reported.