Publications

Since the introduction of return-oriented programming, increasingly compiles defenses and subtle attacks that bypass them have been proposed. Unfortunately the lack of a unifying threat model among code reuse security papers makes it difficult to evaluate the effectiveness of defenses, and answer critical questions about the interoperability, composability, and efficacy...

It has long been thought that macroscopic phase coherence breaks down in effectively lower-dimensional superconducting systems even at zero temperature due to enhanced topological quantum phase fluctuations. In quasi-one-dimensional wires, these fluctuations are described in terms of 'quantum phase-slip' (QPS): tunneling of the superconducting order parameter for the wire between...

This paper describes a semiautonomous approach to calibrate a phased array system, with particular use on an S-band aperture that is being developed at MIT Lincoln Laboratory. Each element of the array is controlled by an independent digital phase shifter, whose control signal may be uniquely defined. As active electronically...

This paper describes a method to answer the following questions: can several of the elements of a phased array be employed as auxiliary (AUX) elements and how can the phase of each be adjusted so that the (1) cross-polarization (cross-pol) isolation is minimized to 40 dB, (2) the sidelobe levels...

We demonstrate a 149 W Yb:LiYF4 laser with diffraction-limitation beam quality at 995 nm. The laser, Q-switched at 10 kHz pulse repetition frequency, produces linearly polarized 52 ns pulses with a slope efficiency of 73%. The combination of cryogenic cooling and a low (3.5%) quantum defect results in minimal thermo-optic...

This paper summarizes the challenges in achieving (and even specifying) the antenna polarization accuracy requirements for the Multifunction Phased Array Radar (MPAR) and the progress that has been made towards meeting these requirements through demonstrations and theoretical investigations.

Hands-on instruction in engineering education is beneficial to the development of a workforce that understands the complexity of building radar systems. Unfortunately, building phased array systems tends to be too costly to allow student access to the hardware necessary for developing these skills. This paper presents a low cost phased...

Transmit and receive Ku-band phased array designs are described for testing an airborne sense and avoid radar. The arrays are small with a size of 24 cm x 9 cm and operate from 13 to 17 GHz with electronic scanning from plus of minus 45 degrees in azimuth and plus...

MIT Lincoln Laboratory is working towards the development of a tileable radar panel to satisfy multimission needs. A combination of custom and commercial off-the-shelf (COTS) Monolithic Microwave Integrated Circuits (MMICs) have been developed and/or employed to achieve the required system functionality. The integrated circuits (ICs) are integrated into a low...

An ultrawideband fixed time-delay steered UHF dipole array antenna has been developed for coverage in the 300 to 450 MHz frequency range for communications or radar applications. The antenna utilizes a parasitically-tuned dipole array for linear polarization and is mounted over a ground plane. Numerical electromagnetic simulations were used to...