| 摘要 |
An antenna feed having a common circular waveguide with a longitudinally extending rectangular slot in a wall thereof and defining a receive port. An iris is rotatably connected adjacent the receive port permitting selective relative polarization of the transmit and receive signals. The relative polarization may be readily selected by a technician in the field without the need for changing antenna feeds when, for example, changing from co-polarization to cross-polarization. The iris includes a rectangular opening therein permitting the passage therethrough of the transmit signal while blocking the passage of a signal of the same frequency as the receive signal. The iris is positioned adjacent the receive port to enhance coupling of the receive signal into the receive port. The antenna feed provides high isolation between transmit and receive ports without the need for a filter on the transmit port. The antenna feed may be used in a microwave communications link, such as an earth station to satellite communications link.
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