On Cancellation Capability of Full-Duplex RF Self-Interference Cancellation Schemes

Figure 1

Auxiliary antenna cancellation. TX2 is placed half carrier wavelength () further away from RX than TX1 to cause their signals to get a phase delay difference of π at the carrier frequency and thus add destructively when arriving at RX. Variable attenuators and are adjusted to make signals from TX1 and TX2 arrive at RX with the same gain.