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Abstract

A radio frequency antenna is provided wherein an array of antenna elements is adapted to establish linearly polarized radio frequency energy. A polarizer means is disposed between the array of antenna elements and free space for converting the linearly polarized radio frequency energy associated with the antenna elements into circularly polarized radio frequency energy in free space, such polarizer means being disposed about a frontal portion and side portions of the array antenna elements. A polarization filter means for rejecting radio frequency energy having a selected linear polarization is disposed between the side portions of the array of antenna elements and the polarizer means. In a preferred embodiment of the invention, the polarization filter is disposed to reject radio frequency energy having a linear polarization, such linear polarization being disposed at an acute angle with respect to the linear polarization provided by the antenna elements. More specifically, the polarization filter is oriented 45 degrees with respect to the polarization of the radio frequency energy associated with the antenna elements. With such arrangement, the degree of circular polarization of the radio frequency energy in free space provided by the array antenna is improved for beams directed at relatively large scan angles.

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First Claim