Abstract: A multiple-frequency feed assembly for an antenna system having two coaxial cavities, with a smaller, high-frequency cavity mounted coaxially within a larger, low-frequency cavity. A separate rotatable probe is mounted within each cavity. The smaller cavity is mounted within the larger cavity by any of several structures, such as a ring-shaped spider, a ring-shaped spacer in the form of a planar washer, or a harp extending rearwardly in the larger cavity. In all of the embodiments, a continuous, uninterrupted signal path is provided within the low-frequency cavity, around the high-frequency cavity, for conveying incident electromagnetic signals to the low-frequency probe mounted at the rear of the low-frequency cavity. In other embodiments, the feed assembly is adapted to detect incident electromagnetic signals in a third band of frequencies, lower than the low-frequency band, using a third probe located within the low-frequency cavity, immediately adjacent to the high-frequency cavity.

Abstract: A dual frequency feed assembly for antenna systems employing a pair of rotatably mounted probes each in respective coaxial cavities. The smaller cavity is supported by the rotating means for the larger probe and the smaller probe rotates with the larger probe driven by a common motor. The higher frequency signal is taken from the side wall of the lower frequency cavity. In an alternate embodiment, the smaller cavity is supported by a spider which rotates the smaller probe by means of external gearing and a separate motor. Other embodiments show coaxial lines which enter from the front face of the assembly and allow rotation of the smaller probe.