A multi-array antenna system with optimal lattice for rectangular pyramidal scanning of space debris

The European Space Agency (ESA) is developing surveillance radars for detecting and cataloguing space debris objects. The surveillance radar, based on a phased-array antenna system, is typically required to scan a specific region of interest, called Field of Regard (FoR). The number of elementary radiators (array elements) in the phased arrays, expected to be very large to provide an adequate link margin to detect objects orbiting at low Earth orbits, has a strong impact on the cost of the final antenna. Therefore, strategies aimed at reducing the array element density, while maintaining uniform lattices and avoiding grating lobes (GLs), are largely welcomed. This work shows the preliminary design of a multi-array antenna system, given a FoR defined by a rectangular section. The array orientations in terms of polar coordinate angles will be provided in a local coordinate system, having z axis directed along the zenith. Then, the geometrical lattice of each array, analytically optimized for the minimization of the number of elements, will be explicitly derived in terms of array lattice parameters (horizontal and vertical distance, and skew angle).