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Schiller has a nice US patent which covers certain types of feed systems such as those used by Force-12 on the C-series of tribanders. You can obtain the entire text of this patent by going to the USPTO web site and searching there - www.uspto.gov I've copied the abstract in below for interested parties to save y'all some effort. As for infringement issues I think it's best to let Force-12 comment if they choose to. This is their reflector after all :) United States Patent 5,995,061 Schiller November 30, 1999 ------------------------------------------------------------------------------ -- No loss, multi-band, adaptable antenna Abstract A no-loss, multi-band, adaptable Yagi style antenna employs a multi-element driven cell having a center element and one or more adjacent elements on each side of the center element. The adjacent elements of the driven cell are electrically shorter than the center element, thereby permitting the driven cell to be tuned to two or more frequency bands. The antenna is fed by a feedline connected to a common feed point at the center of the center element in the driven cell. Parasitic director elements are positioned in front of the driven cell and are tuned to the highest band of the driven cell. Parasitic reflector elements for one or more frequency bands are positioned behind the driven cell, with these elements tuned to actual operating frequencies of the antenna. The invention also provides a multi-band dipole antenna array covering three or more frequency bands comprising a set of dipole elements having a center element and one or more adjacent elements and one or more adjacent elements on each side of the center element. The adjacent elements are electrically shorter than the center element and are of unequal lengths. The antenna is fed by a feedline connected to a common feedpoint at the center of the center element of the set of dipole elements. Parasitic director elements are positioned in front of the set of dipole elements and parasitic reflector elements are positioned behind the set of dipole elements. -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 Submissions: send to Force12Talk@qth.com To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk For problems with the list, contact force12@qth.com |
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