Assessment of the Multi-Beam Performance of Wideband Arrays Using the Observable Field

Multi-beam systems are a key technology for the high-speed links of the next-generation communication standards. Due to the stringent space constraints for allocating antennas on a platform, it is of paramount importance to assess - with respect to the physical size - the multi-beam performance of the antenna in terms of the maximum number of simultaneous orthogonal beams. This is done by resorting to the concept of the observable field, which is here extended to planar domains. Then, this concept is used to assess the multi-beam performance of a wideband phased array prototype developed for mobile communications. The Signal-to-Interference Ratio (SIR), computed from the measured radiation patterns of the prototype, is analyzed versus the frequency and the number of beams and compared to the benchmark case of an ideal antenna radiating the observable field.