| 摘要 |
1512681 Multi-band aerial system THOMSONCSF 8 Aug 1975 [9 Aug 1974] 33249/75 Heading H4A [Also in Division H1] A multi-band aerial system comprises an e-m wave filter grid of substantially uniformly spaced metal elements on a dielectric substrate, the grid being transmissive to a first frequency band and reflective to a second, higher frequency band. First and second primary feeds direct first and second beams, respectively in the two frequency bands, onto respective opposed faces of the grid such that on leaving the grid the two beams merge into a resultant beam, outside the path of which the second primary feed is located. Fig. 4 shows a Cassegrain system of mirrors 80, 81, scanning in azimuth and elevation, onto which the resultant beam is directed by mirror 82. Grid 86 reflects the higher frequency band, fed from source S2 via mirrors 88, 87, and passes the lower frequency band, fed from source S1 via mirrors 85, 84, 83. In the Fig. 7 embodiment the filter grid 31 in horn 30 combines the beams from a dual-band high frequency (11 and 14 GHz bands) multiplexer-demultiplexer 33 with the beams from a dual-band low frequency (4 and 6 GHz) multiplexer-demultiplexer 32. An embodiment using a plane filter grid and plane mirrors instead of the curved grid 86 and curved mirrors 83, 84, 87 is described (Fig. 5, not shown). In other embodiments the filter grid forms a curved wall of a horn (Fig. 2, not shown) or is used to direct the resultant beam upward to a mast-supported mirror which is angled to direct the resultant beam horizontally (Fig. 3, not shown). |
