Leo One Ip, L.l.c.

David P Grybos

James Milton Marshall

Charles C Hung

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).

Multi-band concentric helical antenna

Methods and apparatus are disclosed which allow many satellites (A1-M, B1-N) in a plurality of Systems (A, B) to use the same radio frequencies (f1-n) so long as there is no interference between radio signals. The methods compute times (t) when satellite radio signals (32, 36) have overlapping reception areas or 'footprints' (30, 35) on the Earth's surface (E) whereby a user's reception or transmission of a message would be interfered unless different frequencies (f1-n) are used for the 'competing' signals. The methods use a timing algorithm that does not allow two satellites (Ai, Bi) which are 'visible' at the same point on the Earth (E) to transmit on the same frequency (fi). In one preferred embodiment, a timing algorithm (48) produces a radio frequency use schedule (49) computed on the Earth from orbital data maintained in an ephemeris (46) of satellite communications systems (A, B) which communicate on frequencies (f1-n) giving rise to interfering radio signals. The radio frequency use schedule (49) is updated frequently, and is transmitted to and stored on board each satellite in System A (A1-M). System A satellites (A1-M) are then operated in accordance with the radio frequency use schedule (49).

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San Jose, CA, United States of America

David P Grybos