| 摘要 |
The invention relates to a circuit board such as an SIM card for use in an apparatus such as a mobile telephone. The circuit board comprises an adaptive electromagnetic coupler, and is arranged to find the different resonance modes for the surrounding metallic structure of the apparatus, which may be of arbitrary geometry and character. The different resonance modes and resonance frequencies are influenced, and the resonance mode that gives the most efficient radiation of electromagnetic energy is selected on the desired frequency. The circuit board can be adapted to combined transmitters and receivers by the ability to put it into transmission or receiving mode with a selector switch. By connecting electromagnetic energy to the surrounding metallic structure, the electromagnetic coupler can be made small, viewed in connection with the frequency employed. This permits it to be designed as a small SIM card. New functionality can be supplied to the existing apparatus by an ordinary SIM card being replaced by an SIM card according to the invention. Additional communication is thereby achieved on other frequencies and protocols than those regularly handled by the apparatus. |
