Multi-port frequency-reconfigurable antenna optimization

This work deals with the automated optimization of highly functional antennas as required for advanced mobile terminals. The focus is on multi-port antennas since these devices afford appealing capabilities such as as diversity gain and/or simplified duplexing (isolation of different operation bands) at the cost of a significantly stronger challenge with respect to the single port case. The starting point is a template structure that provides potential for good performance: it is a compact antenna of the stacked patch type; the patches are connected to a small ground plane via switches and provide for reconfigurable performance to allow the coverage of a broad operation band that clearly exceeds the theoretical performance limit for a “static” radiator having the same dimensions. A general methodology based on global and local optimization and exhaustive search algorithms is used in optimizing the initial template: candidate solutions are generated by removing metal sectors and connectors to ground (including the respective switches) from the initial structure with the purpose of optimizing a performance measure that reflects the specifications sought after. The performance measure is computed by a highly efficient full-wave solver that makes practical a considerable exploration of the search space of candidate structures. The approach is tested in the optimization of a 2-port antenna to fulfill specifications of practical relevance: i) broad band independent tuning of ports and ii) broadband tuning of both ports at the same frequency with low mutual coupling. Simulation results support the potential of the initial template and the applicability of the optimization technique.