Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
2000-12-05
2001-12-25
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S850000, C343S876000
Reexamination Certificate
active
06333723
ABSTRACT:
FIELD OF THE INVENTION
The present relates to transceivers, and more particularly to a transceiver having an antenna switchable between a receive mode and a transmit mode.
BACKGROUND OF THE INVENTION
Transceivers comprise a radio transmitter and a radio receiver combined in a single unit with a switch to permit both transmission and reception of signals. In designing a transceiver, it is highly desirable to utilize a single antenna for sending and receiving. However, using the same antenna for transmitting and receiving presents a number of problems.
The principle problem for a single antenna design is the trade-off between sufficient sensitivity for receiving signals and maintaining manageable voltage levels and losses for transmitting. In order to provide sufficient sensitivity for receiving signals, it is desirable to increase the number of turns (wire) in the antenna. While increasing the number of turns improves the sensitivity for reception, higher voltage levels are required to drive the additional turns when the antenna is used for the transmission of signals. There are also the associated electrical losses in the turns of the coil for the antenna. Since most transceivers are battery powered, power needs and losses are an important design consideration.
Accordingly, there remains a need for antenna configuration suitable for a transceiver which overcomes these problems.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an antenna for a transceiver which is switchable between a receive and a transmit mode. In receive mode, the antenna is configured to provide increased sensitivity for improved inductive pickup of signals that are transmitted via either magnetic fields or electromagnetic waves, such as radio signals. In transmit mode, the antenna is configured to provide efficient power output without undue losses.
According to one aspect of the invention, the antenna is arranged using Litz-type wire. Litz wire comprises a plurality of bunched strands of fine wire. In transmit mode, all of the bunched strands are switched into a parallel configuration. In receive mode, all of the bunched strands are switched into a series configuration. In transmit mode, the parallel configuration has the effect of reducing proximity effect and power losses, thereby increasing battery life for the transceiver. In receive mode, the series configuration of the bunched wire strands effectively increases the number of turns which in turn improves the sensitivity of the transceiver by allowing more inductive pickup of signal.
In a first aspect, the present invention provides an antenna coil for a transceiver having a receiver module for receiving signals and a transmitter module for transmitting signals, the antenna coil comprises: (a) a plurality of conductors, each of the conductors having a first end and a second end; (b) a switch mechanism for coupling the conductors in parallel for operation in transmit mode, and the switch including an input port for connecting the first ends of the conductors to a first output terminal on the transmit module and second input port for connecting the second ends of the conductors to a second output terminal on the transmit module, the first and second output terminals forming an output port for the transmit module; (c) a switch mechanism for coupling the conductors in series for operation in receive mode, and the switch including a first port for connecting the first end of one of the conductors to a first input terminal on the receive module and a second port for connecting the second end of another of the conductors to a second input terminal on the receive module, the first and second input terminals forming an input port for the receive module; (d) a control mechanism for switching the switch mechanism between the receive mode and transmit mode of operation.
In a second aspect, the present invention provides an antenna coil for a transceiver, the transceiver being operable in a receive mode and a transmit mode, and the transceiver includes a receiver module for receiving signals in the receive mode and a transmitter module for transmitting signals in the transmit mode, the antenna coil comprises. (a) at least two conductors, each of the conductors having a first end and a second end; (b) a switching module having at least two first switch inputs, at least two second switch inputs, each of the first switch inputs being coupled to one of the first ends of each of the conductors, and each of the second switch inputs being coupled to one of the second ends of each of the conductors; (c) the switching module including at least two receive switch output ports and at least two receive switch input ports, and the switching module including at least two transmit switch input ports and at least two transmit switch output ports; (d) in the receive mode of operation, the first receive switch output is coupled to a first input terminal in the receiver module and the second receive switch output is coupled to a second input terminal in the receiver module, the second receive switch output port is coupled to the first receive switch input port, so that the conductors are coupled in series; (e) in the transmit mode of operation, the first and the second transmit switch input ports are coupled to a first output terminal in the transmit module, and the first and the second transmit switch output ports are coupled to a second output terminal in the transmit module, so that the conductors are coupled in parallel to the first and the second output terminals in the transmit module.
In yet another aspect, the present invention provides, a transceiver operable in a receive mode for receiving signals and operable in a transmit mode for transmitting signals, the transceiver comprises: (a) a receive module; (b) a transmit module; (c) a controller for selectively enabling the receive module to receive incoming radio signals to the transceiver, and for selectively enabling the transmit module to transmit outgoing signals from the transceiver; (d) an antenna coil, the antenna coil includes, (i) a plurality of conductors, each of the conductors having a first end and a second end; (ii) a switch mechanism for coupling the conductors in parallel for operation in the transmit mode, and the switch including an input port for connecting the first ends of the conductors to a first output terminal on the transmit module and second input port for connecting the second ends of the conductors to a second output terminal on the transmit module, the first and second output terminals forming an output port for the transmit module; (iii) a switch mechanism for coupling the conductors in series for operation in receive mode, and the switch including a first port for connecting the first end of one of the conductors to a first input terminal on the receive module and a second port for connecting the second end of another of the conductors to a second input terminal on the receive module, the first and second input terminals forming an input port for the receive module; (iv) a control mechanism for switching the switch mechanism between the receive mode and transmit mode of operation.
REFERENCES:
patent: 5250944 (1993-10-01), Urbas et al.
patent: 5428363 (1995-06-01), D'Hont
patent: 5515285 (1996-05-01), Garrett, Sr. et al.
patent: 5608417 (1997-03-01), de Vall
patent: 5650778 (1997-07-01), Urbas et al.
patent: 5686927 (1997-11-01), Simmons
patent: 5786763 (1998-07-01), Canipe
patent: 6059718 (2000-05-01), Taniguchi et al.
Dinesh Agarwal, P.C.
Le Hoang-anh
Magneto-Inductive Systems Limited
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