| 摘要 |
This invention relates to periodic electromagnetic structures ( 20 ) for use over a relatively large range of frequencies. In particular, this invention relates to microwave applications, such as antennas and low reflectivity structures. A periodic electromagnetic structure ( 20 ) is provided that comprises an array of conducting LC elements ( 22;22 a ,22 b ;42;52;68 ) in superposition with a frequency-dependent dielectric ( 30;44;54;70 ) whose permittivity and/or permeability varies according to the frequency of radiation incident thereon such that the resonant frequency of the LC elements ( 22;22 a ,22 b; 42;52;68 ) follows the frequency of the incident radiation. |
