| 摘要 |
<p>1500279 Aerials PLESSEY CO Ltd 5 May 1975 [1 Aug 1974] 33936/74 Heading H4A An asymmetric dipole whip antenna comprises a stub portion 6, a stepped line impedance transformer device 8 giving simultaneous impedance match between a feed point 24 and an output port 26 over two frequency bands which are separated from each other, and a choke 10. The choke 10, made by coiling a 75 ohm cable 28 on a ferrite core 30, isolates the lower part of the antenna from the ground plane 4 which may be the body of a vehicle. The centre frequencies of the bands may be in the ratio 2:1. Outer covering 21 may be of glass fibre and the inner antenna element 23 may be a Be-Cu alloy.</p> |
