| 摘要 |
A launching and/or receiving network is disclosed capable of coupling radio signals in a first frequency band, e.g., 2 GHz into and/or out of an existing antenna system without perturbing the signals being transmitted in other frequency bands, e.g., 4, 6 and/or 11 GHz. The first frequency band signal is launched through an evanescent mode waveguide filter which is both coupled to the flared sidewall of a feedhorn through an H-plane, T-junction, and provides a very broad stopband for the signals in the other frequency bands being launched in the feedhorn. To minimize mode conversion for the signals in the other frequency bands, a dummy evanescent mode waveguide filter is connected at one end thereof to the feedhorn facing the first frequency band launching network and at the other end thereof to a matched load through a waveguide section. A second launching and/or receiving network can be similarly coupled to the feedhorn in a plane normal to the first network to permit a different orthogonally polarized beam, at the first frequency band, to be simultaneously transmitted and/or received by each of the two networks.
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