The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 1990
Filed:
Sep. 26, 1988
Hideo Sugawara, Ohtawara, JP;
Hideo Ashida, Ohtawara, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A radio-frequency identification (RF-ID) system including a master unit and a sub unit connected thereto by radio-communication, and used for identifying a moving article on which the sub unit is mounted. The master unit transmits a circularly polarized wave having two carrier components (CW1, CW2), and the sub unit, which does not include carrier generators and branching filters, is powered by a battery provided therein. The sub unit receives the circularly polarized wave, separates the two carrier components by a hybrid circuit, and transmits another circularly polarized wave base upon the received carrier component. The sub unit may be operated in response to a starting command from the main unit, and the main unit may have first and second detecting units separated by n.multidot..lambda.g/8, n: an odd integer, and .lambda.g: effective wave length, to eliminate the occurrence of null point phenomenon.