Method of detecting a redirection or relaying of a contactless data transmission using at least two sequentially driven transmitting antennas

A method of detecting a relaying of a contactless electromagnetic data transmission, comprising the steps:

• a) transmitting a first electromagnetic field from a first transmitting antenna of a first unit having at least a transmitting capability;
• b) sequentially after said step a), transmitting a second electromagnetic field from a second transmitting antenna of said first unit, wherein said first and second transmitting antennas are spatially separated from each other;
• c) sequentially receiving said first electromagnetic field and said second electromagnetic field with a second unit having at least a receiving capability;
• d) determining a first actual field strength value of a field strength of said first electromagnetic field and a second actual field strength value of a field strength of said second electromagnetic field as respectively received by said second unit;
• e) comparing said first and second actual field strength values respectively with prescribed first and second nominal field strength values of a nominal value field;
• and
• f) detecting that a relaying of at least one of said first and second electromagnetic fields has occurred if said comparing determines that said first and second actual field strength values unacceptably deviate from said prescribed first and second nominal field strength values of said nominal value field.