Reciprocal and non-reciprocal devices
Non-reciprocal microwave systems

In a reciprocal device, electromagnetic energy flows in the same way in both directions of propagation when the source and receiver of the device are swapped. There is no difference when the direction of wave propagation is reversed. This is the case for most passive microwave devices (lines, guides, etc.), with the exception of ferrite devices, which use effects derived from the Faraday effect (§ 3.3.1 ), and other more recent devices. These are referred to as non-reciprocal devices (§