| 摘要 |
A wireless communication receiver 10 comprises a detector 20 for detecting a signal, a filter 16, having a filter surface, a first optical collecting device 12 which converges incident radiation R towards the filter and an optical diverging device 14 disposed between the collecting device and the filter which diverges radiation from the first collecting device and narrow the angle of the radiation incident on the filter relative to the normal to the filter surface. Lens 12 may be be a converging Fresnel lens.
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