Multichannel transponder and a method of determining a most strongly coupled channel or more strongly coupled channels

A transponder comprising:

• a multichannel front-end circuit, each channel of the multichannel front-end circuit including:
• a resonant circuit associated with a respective antenna and configured and arranged to produce, in use, an input voltage;
• a conditioning circuit configured to provide a conditioned input voltage from the input voltage, the conditioned input voltage representing a voltage envelope for the input voltage, and
• a comparator configured to compare the conditioned input voltage with a reference voltage;
• wherein the front-end circuit further comprises:
• a variable load circuit connectable to the resonant circuit, and
• a controller circuit configured to, in use:
• vary a variable load value for the variable load circuit,
• detect an output from each of the comparators at different variable load values, and
• determine, based upon the detected outputs at the different variable load values, relative coupling strengths for the channels of the multichannel front-end circuit.