Patent ID: 7796965
Filing Date: 2010-09-14
Classification: B60R,G01R,H04B

Abstract:
1. A method for determining a field strength of a carrier signal at an antenna element of an antenna circuit of an electronic key, wherein the antenna circuit includes at least one circuit element and generates an output value, which is a function of the field strength and a function of characteristic parameters of the antenna circuit, the method comprising: generating a reference input value within said electronic key; supplying the antenna circuit with the reference input value; measuring the characteristic parameters, while the antenna circuit is supplied with the reference input value, wherein said characteristic parameters are directly related to values of said antenna element and said at least one circuit element forming said antenna circuit; storing the characteristic parameters; measuring a first output value of the antenna circuit; and determining the field strength as a function of the first output value and the characteristic parameters, wherein an effect of the characteristic parameters on the field strength is compensated.