| 摘要 |
<p>The invention relates to a device for transmitting data by means of electromagnetic wave radiation in a contactless transmission/reception system to a contactless object. The data bits transmitted correspond to the alternation of a first time interval during which the electromagnetic waves are transmitted at a pre-determined carrier frequency and a second cut-off time interval during which the transmission of electromagnetic waves at the pre-determined carrier frequency is cut-off. According to the invention, during said second cut-off time interval, generation means (40, 42, 44, 46, 48) are used to generate electromagnetic waves having a frequency that is double the pre-determined carrier frequency, thereby causing an attenuation of the field radiated by the antenna, said attenuation being greater than a pre-determined value such as 30 dB.</p> |
