Abstract: An RFID transponder detector is provided having a coupled oscillator system. Coupled first and second LC pairs of the system produce a detection signal each time a combination of pulses is applied to the LC pairs. Application of the pulses is repeated periodically to produce a sequence fo detection signals having two different first and second detection frequencies. Transmitting the sequence of detection signals results in corresponding first and second response signals having the first and second detection frequencies at the LC pairs. Values of a preselected detection parameter for the detection signals are compared to the values of the detection parameter for the response signals to determine if a transponder having a transponder resonant frequency corresponding to the first or second detection frequency is present in a proximal space of the transponder detector.