| 摘要 |
A structure having controllable scattering when excited by an incident electromagnetic field (I) comprises a pair of conductive elements (22, 24) extending substantially parallel and mounted in a support structure. One of the elements (22) has a largely inductive impedance and the excitation current induced in the element (22) has a phase lag (y DEG ) compared to the phase of the incident wave (I). The second element (24) has a largely capacitive impedance and the excitation current induced has a phase load (Z DEG ) compared with the incident field (I). By control of the impedance characteristics of the two conductive elements (22, 24) the energy radiated by the excited conductive elements can be minimised in a pre-selected direction to reduce the disturbance caused to the incident wave and prevent detection of the structure due to changes in the uniformity of the incident wave. The inductive element (22), being a continuous conductor, may be used to provide an antenna element or feed structure having controlled scattering. <IMAGE> |
