Texas Instruments Corporation

Matthew L Pecak

Dean A Hofer

Daniel J Carlson

A folded broadband antenna provides a symmetrical radiation pattern comparable to corresponding planar antennas (such as a planar spiral). The folded antenna can be integrated into a leading edge radome, eliminating the forward antenna cavity, and thereby, eliminating the internal wall reflections that cause radiation pattern distortion. A broadband antenna (61/62), such as an archimedean spiral, is folded at an apex area (64) that includes a fold-slot (66). The fold-slot enhances flexure, and allows a center-feed balun shielding tube (84) to extend into close proximity to the antenna aperture (61) for increased balun shielding.

Folded broadband antenna with a symmetrical pattern

A broadband two arm planar/conical/helix antenna is disclosed. The antenna radiation element includes a two arm planar spiral antenna section, a two arm conical spiral section connected to the planar spiral section and a four arm helix section connected to the conical spiral section for termination. The antenna element is formed on a fiberglas substrate which contains a molded internal load absorber. A tapered magnetic external load absorber covers the antenna radiation element. The supporting fiberglas substrate is fixed to a balun housing. The balun housing has a centrally disposed, upwardly extending tubular means for passing a feed line to the planar spiral section. The internal load absorber comprises a molded body including a first part of silicone resin having graded layers of carbon and micro balloons for absorbing without reflection back lobe radiation of the planar spiral and to absorb the internal electric fields present owing to the conical spiral and a second part of silicone resin filled with iron powder for improving low level frequency response. The external load absorber is a silicone body filled with iron powder; it has a cylindrical portion of uniform thickness around the helix spiral and a smooth tapered portion around the conical spiral. The external load absorber so shaped coacts with the radiation elements and internal load absorber in reducing the effective diameter of the antenna while maintaining uniform broadband antenna performance.

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Allen, TX, United States of America

Matthew L Pecak