Telecommunications device using electromagnetic waves
US5173705A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1991 |
| Grant date | Dec 22, 1992 |
| Priority date | — |
| Expiry date | Nov 15, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/0008
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The disclosure relates to the field of data exchange by microwaves between a fixed station, or reader, and a mobile station, or badge. To achieve economy in the energy consumption of the badge, which has a "chip card" format, its input circuit or modem connected to the antenna does not transmit the modulated signal towards the reader. It reflects, in varying degrees, the carrier transmitted by the reader. The modulation of the reflection coefficient of the antenna is obtained by variation of the gate-source junction capacitance, which it itself related to the variation of the gate-source bias voltage of the input transistor of the modem. Application to remote-control toll-gates, remote money transactions and security checks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.