05461386 is referenced by 95 patents and cites 13 patents.

An improved inductor/antenna (100)improves the selectivity of a recognition system (10) by ensuring that only the transponder (14) closest to the inductor/antenna (100) of an interrogator (12) receives therefrom, and reacts to, an interrogation signal (S1). The improved inductor/antenna (100) also receives the resulting recognition signal (S2) from the transponder (14)for analysis by the interrogator (12). The inductor/antenna (100) includes two or more coils (102,104; 124,126,128,130; 132,134) which may be wound on ferromagnetic cores (108), spaced around a metal mass (46,48) such as a lock cylinder (46) of an ignition switch (24). The shape, number, location and relative winding sense of the coils are selected to shape and locate the energy field (F; 118,122) radiated by the inductor/antenna (100) so that only the transponder (14) in a key (26) which is inserted into or operating the ignition switch (24) responds to the interrogation signal (S1) radiated by the inductor/antenna (100).

Title
Inductor/antenna for a recognition system
Application Number
8/193322
Publication Number
5461386
Application Date
February 8, 1994
Publication Date
October 24, 1995
Inventor
Michael Knebelkamp
Freising
DE
Agent
Richard L Donaldson
James C Kesterson
Bret J Petersen
Assignee
Texas Instruments Incorporated
TX, US
IPC
G01S 13/74
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