Performance Analysis of Beam Position Design for a Spaceborne Radar MMTI System

As an important part of the spaceborne radar system design, the beam position design has a great impact on subsequent ship detection performance in a spaceborne marine moving target indication radar system. Although the forward-looking mode can achieve the large-scale target searching in the front area, traditional single-beam-based position design methods may not lead to the optimal ship detectability due to the special clutter variation characteristic. Based on this, a new combined beam position design method is proposed for a spaceborne forward-looking radar system. First, the distortion characteristic of the ground footprint projected by the transmitted radar beam is analyzed theoretically, providing an important foundation for subsequent ground beam position arrangement. After that, the limited scanning time is calculated, and the variation characteristic of clutter-plus-noise ratio related to the azimuth scanning angle is analyzed. Based on the variation characteristic, the broadened beam and the narrow beam are selectively transmitted with certain dwell time allocated from the limited scanning time. In order to optimize the azimuth scanning angle boundary of beam switching and the scanning time allocation ratio, a 2-D cost function is established and maximized by the 2-D grid searching. Finally, an optimal beam design scheme can be obtained, and the overall ship detection performance can be improved. Simulations are implemented to verify the effectiveness of the proposed method.