Transponder

A method for generating a time base signal related from an interrogation signal, the method comprising:

• generating a first electrical signal derived from the interrogation signal received at a first antenna, the first antenna having a first axis;
• generating a second electrical signal derived from the interrogation signal received at a second antenna, the second antenna having a second axis aligned differently than the first axis;
• rectifying the first and second electrical signals;
• and
• summing the rectified first and second electrical signal, and generating a pulsating sum signal having a frequency that is different from the frequency of the interrogation signal by a factor.

A transponder comprising:

• a first antenna, coupled to receive the interrogation signal, the first antenna generates a first electrical signal from the interrogation signal;
• a second antenna, coupled to receive the interrogation signal, the second antenna generates a second electrical signal from the interrogation signal;
• a third antenna, coupled to receive the interrogation signal, the third antenna generates a third electrical signal from the interrogation signal, the axes of the first, second and third antennae are aligned differently;
• a first full-wave rectifier coupled to the first antenna, the first full-wave rectifier rectifying the first electrical signal;
• a second full-wave rectifier coupled to the second antenna, the second full-wave rectifier rectifying the second electrical signal;
• a third full-wave rectifier coupled to the third antenna, the third full-wave rectifier rectifying the third electrical signal;
• a summing element, coupled to receive at least a portion of the first, second and third rectified electrical signals, the summing element generates a pulsating sum signal having a frequency different from the frequency of the interrogation signal by a factor;
• a comparator coupled to the summing element, the comparator compares the pulsating sum signal with a reference signal in order to generate a first clock signal, a frequency of the first clock signal corresponding to the frequency of the pulsating sum signal.