An electromagnetic wave circuit disruptor apparatus suitable for disrupting the action of electromagnetic signals (s1, S2), the apparatus comprising: (a) a biasable non-reciprocating device having terminals (t1, t2, t3) for receiving and transmitting the electromagnetic signals (s1, s2), wherein the electromagnetic signals propagate around the non-reciprocating device terminals in a first direction when the non-reciprocating device is biased to operate in a first mode and the electromagnetic signals propagate around the non-reciprocating device terminals in a second direction when the non-reciprocating device is biased in a second mode, the non-reciprocating device comprises four terminals, t1, t2, t3 and t4, and terminal t2 is adapted to connect with a propagation medium for receiving a received signal and transmitting a transmit signal, terminal t1 is adapted to receive the transmit signal as an input, terminal t3 is adapted to output the received signal, terminal t4 is adapted to have a load with an impedance matched to the non-reciprocating device so as to dissipate the transmit signal; (b) a controllable biaser coupled to the non-reciprocating device so as to bias the non-reciprocating device to operate in one of the first mode and second mode; (c) a signal detector connected to terminal t3 of the non-reciprocating device to detect the electromagnetic signals at terminal t3; and (d) a controller connected to the signal detector and the controllable biaser to selectively reverse the polarity of the controllable biaser in response to the detection of a condition in the electromagnetic signals at terminal t3. (a) a biasable non-reciprocating device having terminals (t1, t2, t3) for receiving and transmitting the electromagnetic signals (s1, s2), wherein the electromagnetic signals propagate around the non-reciprocating device terminals in a first direction when the non-reciprocating device is biased to operate in a first mode and the electromagnetic signals propagate around the non-reciprocating device terminals in a second direction when the non-reciprocating device is biased in a second mode, the non-reciprocating device comprises four terminals, t1, t2, t3 and t4, and terminal t2 is adapted to connect with a propagation medium for receiving a received signal and transmitting a transmit signal, terminal t1 is adapted to receive the transmit signal as an input, terminal t3 is adapted to output the received signal, terminal t4 is adapted to have a load with an impedance matched to the non-reciprocating device so as to dissipate the transmit signal; the electromagnetic signals propagate around the non-reciprocating device terminals in a first direction when the non-reciprocating device is biased to operate in a first mode and the electromagnetic signals propagate around the non-reciprocating device terminals in a second direction when the non-reciprocating device is biased in a second mode, the non-reciprocating device comprises four terminals, t1, t2, t3 and t4, and terminal t2 is adapted to connect with a propagation medium for receiving a received signal and transmitting a transmit signal, terminal t1 is adapted to receive the transmit signal as an input, terminal t3 is adapted to output the received signal, terminal t4 is adapted to have a load with an impedance matched to the non-reciprocating device so as to dissipate the transmit signal; (b) a controllable biaser coupled to the non-reciprocating device so as to bias the non-reciprocating device to operate in one of the first mode and second mode; (c) a signal detector connected to terminal t3 of the non-reciprocating device to detect the electromagnetic signals at terminal t3; and (d) a controller connected to the signal detector and the controllable biaser to selectively reverse the polarity of the controllable biaser in response to the detection of a condition in the electromagnetic signals at terminal t3.