[54] CLOSED SLOT ANTENNA HAVING OUTER AND INNER MAGNETIC LOOPS
[75] Inventor: Cornells Maria Johannes van Erven,
Enschede, Netherlands
[73] Assignee: Texas Instruments Incorporated,
Dallas, Tex.
[21] Appl. No.: 481,010
[22] Filed: Jun. 7,1995
Related U.S. Application Data
[62] Division of Ser. No. 76,036, Jun. 15, 1993, Pat. No. 5,432, 518.
[51] Int CI.6 H01Q 11/12
[52] U.S. CI 343/742; 343/788; 343/842;
343/867
[58] Field of Search 343/742, 743,
343/788, 842, 866, 867
[56] References Cited
U.S. PATENT DOCUMENTS
1,683,773 9/1928 Goldsmith 343/867
2,202,368 5/1940 Berndt 343/866
3,576,567 4/1971 Shively 343/704
Primary Examiner—Donald T. Hajec
Assistant Examiner—Tho Phan
Attorney, Agent, or Firm—-Mark A. Valetti; Wade James
Brady; Richard L. Donaldson
[57] ABSTRACT
An RF identification system having an interrogator operable to send RF interrogations to a transponder and to receive RF responses from the transponder. The interrogator is in electrical communication with a closed slot antenna. The closed slot antenna is formed by an an outer visual magnetic loop and an inner visual magnetic loop such that the antenna has a superior magnetic field when compared to a balanced double loop antenna with an equal area and a superior far-field noise suppression when compared to the single loop antenna. The antenna receives said RF responses from the transponder and provides said RF responses to said interrogator. Other devices, systems and methods are also disclosed.
8 Claims, 4 Drawing Sheets
