Patent ID: 8396516

Claim:
A vehicle transponder comprising: an antenna, and a power directing means, the power directing means having a first port, a second port and a third port, where the power directing means is arranged to direct power from the first port to the second port and/or the third port, where the transponder further comprises an active radio unit and a wake-up unit, and where furthermore the antenna is connected to the first port of the power directing means and the second port of the power directing means is connected to the radio unit, wherein the third port of the power directing means is connected both to a power detection port at the radio unit and to the wake-up unit, such that during a first mode of operation, a part of a signal that is transmitted from the radio unit to the antenna is coupled from the second port of the power directing means to the third port of the power directing means and further fed to the power detection port, enabling control of transmitted output power from the radio unit, where the degree of signal that is coupled from the second port to the third port is dependent on the connection properties between said second port and third port.