Robust Low-Sidelobe Transmit Beamforming under Peak-to-Average-Power Ratio Constraint.

Area of Science:

• Radar Systems Engineering
• Signal Processing
• Electromagnetics

Background:

• Transmit beamforming (TBF) is crucial for radar systems, especially low-altitude and slow-speed small (LSS) radar, to manage clutter and interference.
• Practical TBF applications face challenges due to target direction inaccuracies and array gain-phase errors, necessitating robust methods.
• Existing TBF methods may lack robustness and efficient sidelobe control in complex near-ground environments.

Purpose of the Study:

• To develop a robust transmit beamforming (TBF) method for LSS radar applications.
• To enhance TBF efficiency through peak-to-average-power ratio (PAPR) constraints on transmit weights.
• To achieve precise sidelobe control in predefined regions and improve robustness against steering vector mismatches.

Main Methods:

• A robust TBF method is proposed incorporating a norm upper bound for transmit weight fluctuation control.
• Steering vector mismatch is addressed using a spherical uncertainty set around the nominal steering vector.
• The nonconvex TBF problem is transformed into a tractable second-order cone programming (SOCP) problem using convex relaxation techniques, triangle inequality, and Cauchy-Schwartz inequality.

Main Results:

• The proposed robust TBF method demonstrates improved transmit efficiency due to the PAPR constraint.
• Sidelobe control in preset regions is effectively achieved, enhancing the method's applicability.
• Numerical results confirm superior robustness and efficiency compared to traditional TBF methods in challenging scenarios.

Conclusions:

• The developed robust TBF method offers significant improvements in efficiency and robustness for LSS radar.
• The approach effectively manages sidelobe levels and mitigates performance degradation caused by system imperfections.
• This work provides a practical and efficient solution for enhancing radar performance in cluttered near-ground environments.