Hughes Aircraft Company

Hughes Electronics Corporation

Paramjit S Bains

Krishnan K Raghavan

Parthasarathy Ramanujam

Dean N Paul

Gary J Gawlas

In summary the present invention discloses a horn reflect array antenna system and a method for producing a signal using a horn reflect array antenna. The system comprises at least one reflective element illuminated by an incident radio frequency (RF) signal from a feed horn, the reflective element reflecting a portion of the incident RF signal as a portion of a reflected RF signal, and at least one phase shifting device, each phase shifting device coupled to a corresponding reflective element, wherein a beam pattern of the reflected RF signal is altered when the phase shifting element changes the phase of the portion of the reflected RF signal. A method in accordance with the present invention comprises illuminating a reflector with an RF signal emanating from a feed horn, wherein the reflector comprises at least one reflective element, reflecting at least a portion of the RF signal from the reflective element, wherein the reflective element comprises a phase shifting device, and changing a phase of the portion of the reflected RF signal with the phase shifting device, therein altering the radiation pattern of the reflected RF signal.

Horn reflect array

A feed network for an antenna system, e.g., a phased array antenna system, which is operatively associated with a signal source, e.g., satellite-based transponders, which generates first and second R.F. signals of circular polarization, and third and fourth R.F. signals of orthogonal linear polarizations. The feed network includes a 3dB hybrid coupler or the like for splitting each of the first and second R.F. signals into first and second signal components disposed in phase quadrature with each other. Facilities are provided for applying the first signal components of the first and second R.F. signals, and the third R.F. signal, to a first beam forming network (BFN); and, for separately applying the second signal components of the first and second R.F. signals, and the fourth R.F. signal, to a second BFN. Subsequent to their emergence from the BFN's, the first and second signal components of each of the first and second R.F. signals are applied to respective through and side ports of ortho-mode-tees (OMT's) which Function to re-combine the first and second signal components, in phase quadrature, in order to thereby produce output first and second R.F. signals of opposite-sense (i.e., dual) circular polarizations. The third and fourth R.F. signals pass unaffected through the OMT's as output third and fourth R.F. signals of orthogonal (i.e., dual) linear polarizations. The first, second, third, and fourth output R.F. signals are then fed through common transmission lines to excite the individual antenna elements of the antenna system.

Feed network for a dual circular and dual linear polarization antenna

A horn radiator assembly includes two horn radiators each of which is formed as a conical horn and a waveguide of constant cross section connected to the small end of the horn as a feed and providing a signal port. The first of the horn radiators is of relatively large cross section and serves to radiate electromagnetic waves at a relatively low frequency. The second of the horn radiators is of relatively small cross section and serves to radiate electromagnetic waves at a relatively high frequency. The second radiator is nested within the first radiator, and is positioned with its radiating aperture coplanar with the radiating aperture of the first radiator. In the second radiator, the waveguide feed is provided with a bend allowing the waveguide feed to pass through a wall of the first radiator. A strut may be affixed to the bend to provide a symmetrical transverse support within the first radiator for the second radiator. A doubly-tapered electrically conductive sheet extends from an apex within the throat of the first radiator horn to the transverse support, and from there tapers back to contact the horn of the second radiator. The tapered sheet guides low-frequency radiation past the strut and the bend to minimize standing wave ratio.

Nested horn radiator assembly

An antenna is constructed of an array of contiguous circular cylindrical radiators each of which extends forwardly of a radiator assembly producing two circularly polarized waves of opposite direction of rotation of their respective electric fields. The radiators measure one wavelength at the transmit frequency band, and approximately 1.5 wavelengths in diameter at the receive frequency band. A section of cylindrical waveguide in the back of each radiator assembly encloses a microwave structure for generating the circularly polarized waves, the microwave structure including an orthomode transducer at the back of the assembly and an electric field rotator disposed forward of the orthomode transducer. In each radiator assembly, there is disposed between the rotator and the radiator a transition between smaller diameter waveguide to larger diameter waveguide. The transition may have the form of a step or a flare for a more gradual transition. The transducer produces a higher order TM.sub.11 mode which is evanescent within the radiator 24. By attenuating the transverse magnetic mode, a match is made between electric field components thereof and those of curved electric fields of the dominant propagating modes to cancel curvature and reduce cross polarization between the two circularly polarized waves in each radiator.

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Los Angeles, CA, United States of America

Paramjit S Bains