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Abstract

A Multi-Band Concentric Helical Antenna (20) operating in a novel conical mode, useful for general and satellite communications is disclosed. A higher frequency helix (24) is placed concentrically inside a lower frequency one (22). In one embodiment, each helix has four helical elements (22a-d, 24a-d). The outer helix is fed at a first frequency (f.sub.1) and the inner helix (24) is fed at a second frequency (f.sub.2). The second frequency (f.sub.2) may be greater than twice the first frequency (f.sub.1). Both helices (22, 24) have the same polarization. The pitch (P.sub.1, P.sub.2), diameter (D.sub.1, D.sub.2), and length (AL.sub.1, AL.sub.2) of the helices are chosen so that said antenna (20) radiates with approximately equal flux at all points in a far-field plane. Alternatively, two inner helices (24, 25) are placed concentrically within an outer helix (22). In a space application, the helices (22, 24) may be air wound springs (22a-d, 24a-d), compressed flat prior to a launch and deployed to fall length in flight. Another embodiment (50) features helically-wound tape (54, 56) wound on inflatable, non-conducting supports (52, 58) concentrically positioned and deployed in space to form the concentric helices (54, 56).

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First Claim