Thomson Composants Microondes

Thomspon Composants Microondes

Marc Camiade

Dominique Geffroy

Veronique Serru

Pierre Quentin

Jean-Philippe Brandeau

Pierre Savary

Michel Gayral

A system including a first station (1) known as a beacon and at least one second station (2) known as a badge, each station having a transmission channel with an antenna and a reception channel with an antenna. To allow multiplex exchanges, using simultaneous transmission and reception, the two antennas (6, 11) (13, 15) in any given station are decoupled by cross-polarization but antennas which communicate with each other (6, 13) (11, 15) have compatible polarization. Applications to identification systems using microwave transmission.

Simultaneous data transmission and reception system using microwaves

In order to increase the sensitivity and range of a system for the exchange of data by microwaves between a fixed station, or reader, and a mobile station, or badge, the modem of the badge includes an oscillator. A single transistor works, under a first bias, as a detector of the wave transmitted by the reader and demodulates this wave, and then, under a second bias, it works as an oscillator and modulates the response transmitted by the badge. Applications to the exchange of data at a distance.

Device for the exchange of data by electromagnetic waves

A modem which is to be included in a badge or mobile station, in a system for the exchange of data by microwaves with a fixed station or beacon. The modem has at least one transistor that works as a detector in reception or as an amplifier for the transmission of a reflection signal, according to gate bias voltages (V.sub.gs0, V.sub.gs1) that are applied to it, and drain currents (I.sub.ds) that result therefrom. The transmission-reception switching is done by transistors that switch over loads, and hence currents, on an amplifier transistor, with amplitude or phase modulation. Such a modem may find particular application in short-distance telecommunication systems.

Modem for telecommunication system with a reflection amplifier function

This active antenna is incorporated in the terminal station of a system for data exchange with a central station, by the modulation of a microwave carrier. The terminal station is of the chip card type. The modem of the active antenna is constituted by a transistor, the bias current of which is switched over from a low value at demodulation to a high value at modulation. The switch-over is obtained by a circuit with three resistors (R.sub.d, R.sub.gd, R.sub.g), which themselves have their values switched over by two transistors parallel connected with the resistors, these transistors being controlled by two signals emitted by the control circuit of the terminal station. The active antenna can be applied to long-distance data exchange, for example in the remote management of toll-charge systems, remote cash dispensing, localization of moving bodies etc.

Active antenna for two-way transmission

In a system for the exchange of data by microwaves between a fixed station and a mobile station or portable badge, the information bit rate is limited, in the standby state, by the low power consumption of the badge and the high output impedance of the modem. To increase the information bit rate of the modem of a badge, the information processing circuit associated with the modem sends the modem an activation signal to reduce its output impedance. The means implemented are transistors that switch over the load of the detector transistor or of the amplifier transistor.

Circuit to increase the information bit rate in a system for the

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.

Telecommunications device using electromagnetic waves

The disclosure concerns a microwave amplifier. To improve the efficiency of an amplifier having a field-effect transistor, an input quadripole and an output quadripole, the voltage applied to the gate is limited to a deviation between the pinch-off voltage V.sub.P and the positive maximum gate voltage V.sub.GS, using a diode of a second order harmonic reverse feedback circuit. Application to microwave circuits.

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Antony, France

Marc Camiade