| 摘要 |
1. A dual band, higher and lower frequency range transducer with a circular coaxial waveguide feed, a first junction for connection of a lower frequency range outer waveguide of the coaxial waveguide feed to at least two rectangular or ridge waveguides offset from the longitudinal axis of the transducer, a second junction for connection of the at least two rectangular or ridge waveguides to a further waveguide and a third junction for connecting an inner waveguide of the coaxial waveguide feed to a higher frequency range waveguide, characterised in that the transducer comprises at least first and second parts joined across a first plane substantially perpendicular to the longitudinal axis and including at least a portion of the higher frequency range waveguide extending within the first plane of the join. 2. The transducer according to claim 1, wherein the higher frequency range waveguide extends away from the inner waveguide of the coaxial feed in a direction at an angle to the longitudinal axis. 3. The transducer according to claim 1 or 2, wherein the higher frequency range waveguide extends away from the inner waveguide of the coaxial feed in a direction substantially perpendicular to the longitudinal axis. 4. The transducer according to any previous claim, further comprising a water seal provided between the first and second parts in the first plane of the join. 5. The transducer according to any previous claim, wherein all the junctions include impedance matching devices. 6. The transducer according to any previous claim, further comprising a feed horn attached to the coaxial feed. 7. The transducer according to claim 6, wherein the feed horn has internal corrugations. 8. The transducer according to any previous claim, wherein the first and second junctions comprise third and fourth parts which are joined to the first and second parts, respectively along planes parallel to the first plane. 9. The transducer according to any of claims 6 to 8, wherein the horn is sealingly joined to the first junction part along a plane parallel to the first plane. 10. The transducer according to any of claims 6 to 9, wherein a dielectric rod antenna is located in the inner waveguide at the end facing the horn. 11. The transducer according to claim 10, wherein a beamwidth of the rod antenna is smaller than a flare angle of the horn. 12. The transducer according to claim 10 or 11, wherein an end of the inner waveguide is provided with a device for preventing backscattering from the rod antenna. 13. The transducer according to claim 12, wherein the backscattering preventing device is a flare opening outwardly towards the horn. 14. The transducer according to any previous claim, wherein the lower frequency range is 10.7 to 12.7 GHz and the higher frequency range is 29.5 to 30 GHz. |
