OBJECTIVE: Develop a compact multi-input, multi-output Ka-band radar system to provide over-the-horizon maritime target detection and tracking utilizing evaporation duct propagation. DESCRIPTION: The long-range detection, tracking, and classification of maritime surface contacts including detection and discrimination of small targets such as periscope masts is an essential Naval capability. Long-range, over-the-horizon microwave propagation over the sea is a very desirable means to achieve this capability. Over the horizon propagation may occur in the presence of atmospheric and hydrological environments with super-refraction or atmospheric waveguide (low height and evaporation) conditions. These conditions are extremely common. In addition, as a result of changes in the troposphere complex weather phenomena, atmospheric inhomogeneity, turbulence and level of stratification, the recurrent emergence of strong convection can cause scattering layer so that a long-range performance can also be achieved through troposphere scattering. Multiple-input multiple-output (MIMO) radar technology may be particularly well suited for this very wide angle surveillance task. Some analyses indicate that MIMO radar may outperform its phased-array counterpart significantly in parameter identifiability, spatial spectral estimation resolution, clutter suppression capability and transmit beampattern design. Another potential advantage of coherent MIMO radars is that they enable the use of sparse arrays without the adverse effects of sidelobes. For maritime target moving indicator radars MIMO may provide improved angle estimation and minimum detectable velocity. In order to take full advantage of the complex propagation conditions, the adaptive tailoring of the transmitted waveform to the propagation medium and the target scattering characteristics may significant enhance overall detection and false-alarm performance. To date the analyses supporting MIMO performance have not been sufficiently validated through experimentation to the satisfaction of the radar community. In fact, the merits of MIMO radar and a matter of strong dispute in the community with many members polarized on opposite ends of the opinion spectrum. The goal of this work is to design and demonstrate of a proof-of-concept Ka-band MIMO radar system for over-the-horizon maritime target detection and tracking utilizing evaporation duct propagation. The demonstration shall be executed in a manner to allow full assessment of fundamental MIMO radar capabilities. The effort should include the design of signal processing algorithms including adaptive waveform design and receiver signal synthesis. PHASE I: Demonstrate the feasibility of a Ka-band MIMO radar system through modeling and simulation demonstrations. Candidate tasks are (1) comprehensive modeling of evaporation duct propagation as it relates to the radar usage; (2) adaptive waveform designs for improved detection performance; (3) performance evaluations of the design in terms of target detection and localization capabilities; (4) identification of performance limitations and hardware requirements to prepare for Phase II hardware implementation. Preliminary hardware design should be in place and ready for Phase II effort. PHASE II: Develop a prototype Ka-band MIMO radar system. The design initiated in Phase I should be implemented using commercial-of-the-self hardware components. Effort should fully investigate adaptive waveform design and the performance and capability of the demonstration system. PHASE III: Further refine algorithms and the design to improve performance robustness for practical operation scenarios. Effort may be focused on further developing the capability and transition to military programs. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial applications include homeland security maritime area monitoring. REFERENCES: 1. Anderson, K.D. Radar detection of low-altitude targets in a maritime environment. (1995)."Antennas and Propagation, IEEE Transactions on", 43(6), 609 - 613. 2. Li , J. & Stoica, P. (Eds.). (2009)."MIMO Radar Signal Processing."New York: Wiley. 3. Lin, Jiao & Zhang, Yong-gang. The effects of radar detection in heterogeneous evaporation duct conditions."Antennas, Propagation and EM Theory, 2008. ISAPE 2008. 8th International Symposium on", 1402 1405. 4. Yuanwei Jin, Moura, J.M.F., & O'Donoughue, N. Time Reversal Transmission in MIMO Radar."Signals, Systems and Computers, 2007. ACSSC 2007. Conference Record of the Forty-First Asilomar Conference on", 2204 2208.