| 摘要 |
A lens system with a lens formed of a material having a negative index of refraction in an operational frequency range, a first surface of the material having a convex hyperbolic curvature, and a second surface of the material having a concave circular curvature. A lens system can include two of these lenses, arranged with the concave circular surfaces facing each other. Far field radiation arriving at the hyperbolic surface of the the first lens is refracted by the lens material toward the circular surface, out of the first lens in a direction parallel to the original radiation direction, and into the circular surface of the second lens, where it is refracted toward the hyperbolic surface of the second lens, and exits the second lens in a direction parallel to the original direction. The lens material can have a tunable or fixed negative refractive index and/or resonant frequency.
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