| 摘要 |
A reflector antenna comprising a reflector system, and a feed system, eg a log-periodic feed system (1) the phase-centre of which moves with frequency, for illuminating the reflector system to produce a substantially focussed antenna beam. To compensate for frequency variations in the position of the phase-centre of the feed system, the reflector system includes a frequency dependent reflector (2) the effective surface of reflection of which (6a-6e) varies with frequency to cause the focus of the reflector system to move with the phase-centre of the feed system. A number of different forms of suitable frequency dependent reflectors are described, employing composite arrangements of frequency selective mesh or grid reflector elements, or arrays of reflecting horns or wedges. <IMAGE>
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