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AssigneeFord Aerospace & Communications Corporation
InventorsChing C. Han, Herman W. Bilenko, Yeongming Hwang
Estimating the term…
The antenna system employs a parabolic reflector fed by an offset feed array of circular wave guides located substantially at the focus of the parabolic reflector, but offset from the axis thereof. A plurality of aperture tuning mechanisms disposed at the mouths of the circular waveguides of the waveguide feed array, and having physical lengths much shorter than one wavelength at the frequencies involved, are provided to reduce cross-polarization and mutual coupling between adjacent feeds. The short resonant length of these tuning mechanisms, and their shape which is chosen to generate the TM.sub.11 mode E-field contour line ensures that they are effective over a broad bandwidth of as much as 20% or more. Within this bandwidth, they act as inductive suppressors to control both cross-polarization and mutual coupling between adjacent feeds.
A microwave antenna system for producing when energized by a source of microwave signals, first and second simultaneously propagating beams of microwave radiation, said first beam being of left-hand circularly polarized radiation, said second beam being of right-hand circularly polarized radiation, comprising in combination:
A microwave feed array for propagating microwave energy toward, and receiving microwave energy from, a microwave reflective surface, comprising a plurality of circular waveguide feed elements disposed mutually adjacent to one another and axially in alignment with one another along the axis of microwave energy propagation of said array, each of said circular waveguides terminating in a circular aperture, said circular apertures lying generally in a plane orthogonal to said axis of microwave energy propagation, and a plurality of generally U-shaped inductive tuning stubs disposed within and projecting from each of said apertures, each of said inductive stubs having an outer leg in contact with an inner wall of said waveguides, an inner leg generally parallel to said outer leg, and a root portion joining said inner and outer legs within said aperture, said inner and outer legs each being tapered from a width b.sub.1 at said root portion to a width b.sub.2 at the tip of each of said legs, where b.sub.1 >b.sub.2, said outer legs each having a length h.sub.1, said inner legs each having a length h.sub.2, where h.sub.1 >h.sub.2.
Dependencies are inferred from the claim text.