| 摘要 |
A multiple ring dipole array comprises a plurality of dipole elements arranged in concentric rings and in a common plane. Each ring has a plurality of circumferentially spaced dipole elements, preferably folded dipoles, having equal lengths and disposed in opposed parallel pairs with elements of each pair spaced by one-half wavelength at center frequency. The elements of adjacent arrays have different lengths selected to provide contiguous or slightly overlapping operating frequency bands, the elements of one ring extending in directions transversely of the elements in the adjacent ring to minimize mutual coupling. Each element is fed by a pair of phase-matched coaxial lines connected to suitable switching circuitry by a hybrid junction. The array has a common phase center over the entire band and so has particular utility as a feed for a parabolic reflector.
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