A longstanding limitation of radio-frequency (RF) systems has been the inability of collocated transmitters and receivers to operate concurrently because of strong self-interference. This limitation restricts the capabilities and performance of various systems including communication networks, radars, spectral sensing, and electronic warfare systems. This seminar will provide an overview of self-interference technologies developed at MIT Lincoln Laboratory, including a novel phased array architecture called aperture-level simultaneous transmit and receive (ALSTAR). ALSTAR uses adaptive digital beamforming to minimize the total coupling between transmit and receive apertures, and digital cancellation to eliminate residual signal and noise due to self-interference. Measured results of an eight-channel ALSTAR phased array will be presented, demonstrating 140dB isolation over 100MHz instantaneous bandwidth.