RFID readers configured to transmit a radio frequency signal include a sub-orthogonal self-jammer cancellation circuit that generates two or more distinct phase variants of the transmit signal, selects two of the phase variants with a vector projection of one of the selected phase variants on another of the selected phase variants being substantially greater than zero such that a canceling signal comprising a combination of the at least two phase variants is substantially opposite in phase to a self-jamming signal, and selects amplitudes for the at least two selected phase variants such that the canceling signal is substantially equal in amplitude to the self-jamming signal. The canceling signal is then combined with the self-jamming signal to reduce the amplitude of an RF signal received by a receive circuit.