Occultation Judgment for the Hemispherical Coverage Multi-Planar Arrays Antenna

A flexible hemispherical coverage array antenna based on multi-planar arrays is proposed to meet the growing demands for multi-target TT&C. The advantages and disadvantages of multi-planar arrays and dome phased in engineering implement are compared. Meanwhile, the influence of different number of plane arrays on antenna pattern is analyzed. For the purpose of interference suppression a novel beamforming method by adding constraint conditions is analyzed to enhance the performance of antenna for TT&C system. Considering the influence of occultation effect on the antenna performance, an effective occultation algorithm is presented. Firstly, the faces in bright area are projected on the plane that is perpendicular with the direction of receiving wave. Secondly, adopting the principle of line segment intersection, the intersect relationship of projective planes is determined. Finally, the facets shadowing relationship is judged by the overlapping and depth-of-view of facets along the receiving wave direction. Theoretical analyses and simulation results show that the antenna has approximate uniform gain beampattern in different steered angle and the occultation algorithm is feasible and effective.

Overlay Algorithm for Simple Subdivision of Arbitrary Polygon in Plane

The overlay algorithm is an important branch in computational geometry field, it is an important process for computing exact Minkowski sum of two convex polyhedrons. By improving the existing plane sweep algorithm, the overlay algorithm for simple subdivision of arbitrary polygon in plane is given. The algorithm can be used to overlay arbitrary polygon after subdivision into simple polygon in the plane. It has lower time complexity than the existing overlay algorithm. The whole algorithm consists of three steps: line segment intersection, reconstructing topology and constructing the DCEL for overlay graph. The results show that the algorithm can compute the overlay of two planar subdivisions in linear time.