A Novel Time-Based Beamforming Strategy for Enhanced Localization Capability

The letter describes an original time-based driving strategy of a compact antenna array suitable for future 5G Internet of Things (IoT) applications. Subsets of array elements are selectively activated in real-time for agile and precise localization of tagged objects, randomly distributed in harsh electromagnetic environments. A new layout, starting from a standard time-modulated array (TMA) solution, is implemented, which allows us to fruitfully exploit the sideband radiation capability, typical of this array family. One radiating element of the array is replaced by a multiantenna architecture, thus enabling the designer to have a total control of the maximum radiation direction of the array not only at the sideband harmonics, as for standard TMAs, but also at the fundamental. In this way, an extremely accurate localization capability is obtained by properly driving the nonlinear switches at each antenna port, without resorting to complex feeding networks or phase shifters. The antenna system design must be carried out through an accurate circuit/electromagnetic cosimulation approach, thus accounting for the electromagnetic couplings among the radiating elements and the nonlinear behavior of the switches. This is demonstrated with a compact-size planar patch array operating at 5.8 GHz compatible with portable device equipment for concurrent future wireless operations.